Companion: rules-based, context-aware writing advice

Replace the kitten's random generic tips with a deterministic, LLM-free
prose checker that reads the actual document and surfaces one gentle,
bilingual note at a time — quoting a slice of her own sentence so the
advice is clearly about *this* draft.

Rules (all conservative, tuned for a Mandarin-native ESL writer):
run-ons, comma splices, unclear antecedents, Oxford comma, a/an,
uncountable plurals, capitalize languages/days/months, subject-verb
agreement, plural-after-number, double determiner, "there is" + plural,
its/it's, than/then, comma-after-transition, doubled words, lowercase
"i", sentence capitals, and spacing around punctuation.

Each rule is paired with false-positive guards (e.g. "a university",
"After dinner, I went home and read", existing Oxford lists) and pinned
by a 45-case Vitest suite (npm test).

Also: bubbles now linger proportional to how much there is to read
(zh+en) and pause-on-hover, so denser advice no longer vanishes mid-read.

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

BUILD_PLAN.md

@@ -74,12 +74,40 @@ Multi-session build. **Source of truth for what's done and what's next.** Update
 - [x] `MisspellCard` popover + EditorCore wiring — soft **rose wavy underline** (`.petal-misspelling`, pastel take on the red squiggle, not classic red). Click a flagged word → `posAtCoords`→`wordAt` opens a bilingual card ("拼写 · Spelling") with up to 5 nspell corrections as pills (click to replace via `insertContentAt`) + "添加到词典 · Add to dictionary". Closes on outside-pointer-down, doc edit, or doc switch.
 - Verified: tsc clean, vite build OK (dict in `dist/dictionaries/en/`), go build/vet clean; live server serves both dict files (200, 3086B aff / 551762B dic); nspell smoke (`helllo→hello`, `recieve→receive`, `写作` untokenized, `NASA` ok, `add()` persists).
 
+### Phase 8 — Trust foundation (version history + export) ✅
+- [x] **Version history** — `document_versions` table (migration `0003`), full-body snapshots that cascade with the doc. Kinds: `auto` (throttled background, ≥3min apart, max 40/doc, pruned), `manual` (explicit restore point), `pre_restore` (safety copy taken before a restore, so restore is undoable). Snapshot taken post-save in `update` only when a real body came through and content changed (empties + bare renames never snapshot). Endpoints: `GET/POST /api/docs/:id/versions`, `GET /api/docs/:id/versions/:vid`, `POST /api/docs/:id/versions/:vid/restore`. All scoped to the owner via a join on `documents`. `versions_test.go` covers lifecycle/throttle/restore/pre_restore/404.
+- [x] **Export** — pure-Go Tiptap-JSON → Markdown / HTML / plain-text / **docx** (`export.go`), no cgo/pandoc, CJK-safe. docx is a hand-built OOXML zip (marks→run props, headings→built-in styles, lists→prefix). RFC 5987 `filename*=UTF-8''` so Chinese titles download cleanly. `GET /api/docs/:id/export?format=`. **PDF is client-side** via the browser print dialog + a `@media print` stylesheet (uses the reader's fonts → CJK for free, no embedded-font bloat). `export_test.go` asserts every format incl. valid-zip docx with CJK.
+- [x] **Frontend** — `ExportMenu` (download links + Print/PDF) and `HistoryPanel` (slide-over drawer: snapshot list w/ relative-time + kind badge, preview, restore; restore remounts the editor via an `editorEpoch` bump). Both bilingual zh-first, matching chrome. Wired into the title row; `.petal-no-print` strips all chrome for print.
+- [x] **Stop saving empty docs** — blank `Untitled` drafts now self-discard: `handleCreate` reuses an existing blank instead of stacking another; `openDoc` deletes the blank doc being left. Cleaned the 2 existing orphan empties from the live DB. (Backend also refuses to snapshot empties.)
+- Verified: go build/vet/test + tsc + vite all clean; live smoke on a throwaway binary — auto-snapshot on save, throttle holds at 1, manual snapshot, restore brings back exact text + leaves a `pre_restore`, empty doc → no snapshot, md/docx export with CJK+bold+heading+list, docx validates as "Microsoft Word 2007+".
+
+### Phase 9 — ESL superpowers ✅
+- [x] **Inline Chinese gloss (offline)** — embedded English→Chinese dictionary (`internal/lexicon/data/gloss.json.gz`, ~1.3MB, 57k common words built from ECDICT via `scripts/build_gloss.py`: frequency-gated to rank ≤50k, `[网络]`/slang/archaic sense-lines dropped, trimmed to ≤3 senses / 80 chars). `Lexicon` gains a `gloss` map + `Gloss(word)` (same `candidates()` de-inflection as defs/syns); `Result` gains a `Gloss` field. Two surfaces: the right-click **WordCard** now leads with the 中文 gloss, and a new lightweight `GET /api/gloss/{word}` (→ `{word, gloss}`, cached) backs the **hover tooltip**. Offline + instant, works with the LLM down (north-star reliability). Frontend: `GlossTip` (dark pointer-events-none bubble under the resting word; 350ms hover delay; reuses `wordAt` so CJK is never glossed — it's the source language), wired into `EditorCore`'s `onMouseMove`/`onMouseLeave` with a request-token guard, suppressed during selection/preview/other popovers.
+- [x] **"Say it more naturally" / tone-rewrite** — selecting text pops a `SelectionBubble` (✨更自然 + the tone vocabulary 学术/专业/轻松/幽默/创意/说服, mirrored from `ToneSelect`/`styleGuidance`). Picking a style calls `POST /api/docs/:id/rewrite` (`{text, style}` → `{rewrite}`), shown in a `RewritePreview` (original struck-through → rewrite, 用这个/取消, breathing-dot loading, gentle retry on failure). Accept applies it in-editor via `insertContentAt` over the captured PM range. Backend: `llm.RunRewrite` (one-shot Complete, `RewriteMaxRunes` 2000 cap, `cleanRewrite` strips stray wrapping quotes) + `rewriteSystemTemplate`/`styleGuidance` in `prompts.go`; handler in `internal/suggestions/rewrite.go` (owner-scoped 404, 400 on empty/too-long, 502 on LLM-down). **Stateless** — not persisted as a suggestion; the version history captures the resulting doc change.
+- Tests: `lexicon` gloss + Lookup-includes-gloss + inflection/miss; `suggestions` rewrite happy-path (style steering + de-quote asserted), empty→400, unknown-doc→404. go build/vet/test clean, tsc clean, vite build OK. Live smoke vs a fake vLLM (fresh port 8055, throwaway DB; pre-existing dev servers on :8077/:8099 untouched): gloss for `river`/inflected/CJK-empty/nonsense-empty, `word/happy` carries the gloss, rewrite returns text, empty→400, unknown→404, LLM-down→502; new CSS classes present in the built bundle.
+- **Known limitation**: `Gloss` tries the literal form first (matching defs/syns ordering), so an inflected word that is *itself* a separate ECDICT headword resolves to that entry rather than de-inflecting (e.g. `rivers` → the proper-noun "Rivers" sense, not `river`). The base form always glosses correctly; acceptable.
+
+### Phase 10 — Organization & polish ✅
+- [x] **Cross-document search (FTS5)** — migration `0004` adds a `documents_fts` virtual table over `title` + `content_text` using the **`trigram` tokenizer** (so search works for both English and space-free Chinese; the default unicode61 tokenizer treats a CJK run as one token). Kept in sync by `AFTER INSERT/UPDATE/DELETE` triggers on `documents`, back-filled from existing rows in the migration (verified: pre-existing docs are searchable immediately). `GET /api/search?q=` (`internal/docs/search.go`): queries of ≥3 runes use the FTS index (fast, `ORDER BY rank`); shorter queries fall back to a `LIKE` scan so **2-character Chinese words** (e.g. 公园) still resolve. Snippets are built in **Go** from the original text (clean word boundaries, rune-aware so CJK never splits mid-char), with the match wrapped in `\x01…\x02` sentinels; the client splits on these to highlight without `innerHTML`. Owner-scoped, capped at 50 hits. Frontend `SearchBox` in the sidebar: 220ms-debounced, results with highlighted two-line snippets, click to open.
+- [x] **Tags (organize)** — migration `0004` adds `tags` (user-scoped, `UNIQUE(user_id, name)`, `color` = palette key) + `document_tags` join (both sides cascade). `internal/docs/tags.go`: `GET/POST/PATCH/DELETE /api/tags` (create is **idempotent** on name; unknown colors coerced to rose) + `POST /api/docs/:id/tags` / `DELETE /api/docs/:id/tags/:tagId` (owner-validated, idempotent assign). The doc-list and search responses carry each doc's tags (loaded in one `tagsByDoc` query, no N+1). Frontend: `useTags` (roster + counts), `TagChip`, `TagPicker` (assign existing / create-and-attach with a color swatch), tag chips on each doc row, a **filter bar** (client-side filter by tag, shows in-use tags with counts). Colors map to the existing design tokens via `tagColorVar`.
+- [x] **Tablet / touch polish** — responsive sidebar: below 768px it becomes an overlay **drawer** toggled by a header hamburger, with a scrim (auto-closes on doc select). `@media (pointer: coarse)` enlarges tap targets (`.petal-tap` ≥44px, `.petal-tap-sm` ≥36px) and reveals the hover-only row actions (tag/delete). **Tap-to-open** for AI-suggestion cards (no hover on touch): a tap on a `.petal-suggestion` opens its card via the editor click handler, and a `pointerdown` outside the card/highlight dismisses it (mouse users keep the hover bridge).
+- [x] **Warm LLM-down failure states** — `useCheckpoint` now tracks an `llmDown` flag (set when a check/voice pass hits the server's 502/network path, cleared on the next success or doc switch). The `StatusBar` shows a gentle bilingual note — 🌙 **小助手在休息 · Petal's helper is resting · 文字已保存** — reassuring that the writing still saved locally (saving is independent of the LLM). Rewrite already had a gentle retry from Phase 9.
+- Tests: `tags_test.go` (full lifecycle — create/idempotent/color-coerce/rename-recolor/assign/unassign/doc-list inclusion/roster counts/delete-cascade/404s), `search_test.go` (EN FTS, CJK FTS, 2-char CJK LIKE fallback, title-only, case-insensitive, empty/no-match, **edit re-indexes via the update trigger**). go build/vet/test clean, tsc clean, vite build OK. Live smoke vs the binary on a throwaway DB (port 8061, LLM pointed at a dead host): search EN/CJK/2-char all highlighted, tag create+assign+roster-counts+doc-list-tags+delete-cascade, check→502 (warm path), new CSS classes (`petal-tag-chip`/`petal-scrim`/`petal-drawer-open`/`pointer:coarse`) and the 小助手在休息 string present in the served bundle. FTS backfill of pre-existing docs verified separately.
+- **Known limitations**: trigram FTS snippets/ranking treat the query as a contiguous phrase (multi-term relevance is substring, not BM25-per-term) — fine for a personal corpus. Search is title+body only (not tag names). Hover gloss and right-click word lookup remain pointer-oriented (long-press contextmenu on touch is browser-dependent); the spelling/suggestion cards and rewrite bubble are fully touch-reachable.
+
 ### Deferred (post-v1-local)
-- [ ] Authentik OIDC auth + session middleware
+- [ ] Authentik OIDC auth + session middleware  ← **on hold: user doing foundational work first**
 - [ ] Copyleaks Tier-2 + webhook HMAC
 - [ ] Dockerfile, docker-compose, Traefik, deploy to write.parodia.dev
 
+### Next-up (post-v1 product, agreed with user 2026-06-26)
+- [x] **Phase 9 — ESL superpowers**: inline Chinese gloss on hover/select; "say it more naturally" / tone-rewrite. ✅ (see Phase 9 above)
+- [x] **Phase 10 — organization & polish**: cross-doc search, tags, tablet/touch polish, warm LLM-down failure states. ✅ (see Phase 10 above; "tags only" chosen over folders, FTS5 over LIKE)
+
 ## Session log
+- 2026-06-26: **Phase 10 complete** (organization & polish). Scope confirmed with user: all four areas, **tags** (not folders), **FTS5** search. Backend: migration `0004_tags_and_search` (tags + document_tags + `documents_fts` trigram virtual table with sync triggers + back-fill); `db.Tag` model + color constants; `internal/docs/tags.go` (tag CRUD + idempotent assignment + `tagsByDoc` helper, doc list now carries tags); `internal/docs/search.go` (`GET /api/search`, FTS for ≥3 runes + LIKE fallback for 1-2, Go-built sentinel-highlighted rune-aware snippets, owner-scoped). Mounted `/api/tags` + `/api/search` in main.go. Frontend: `useTags`, `TagChip`/`TagPicker`/`SearchBox`, rewritten `DocList`/`DocListItem` (chips + filter bar + search), `api.search`/tag methods + `splitSnippet`/`tagColorVar`; responsive sidebar drawer (hamburger + scrim, <768px) + `pointer:coarse` tap-target/affordance CSS; tap-to-open + outside-pointerdown-close for suggestion cards (touch); `useCheckpoint` `llmDown` flag → warm bilingual "小助手在休息" StatusBar note. Tests: `tags_test.go`, `search_test.go` (incl. update-trigger re-index). All builds/tests/vet/tsc/vite clean; live smoke vs binary on :8061 (dead LLM host) verified search EN/CJK/2-char, full tag lifecycle, check→502 warm path, bundle contents; FTS backfill of pre-existing docs verified. **All v1 phases (0–7) + post-v1 product (8–10) done.** Remaining: deferred bucket (auth/Copyleaks/deploy), on hold per user.
+- 2026-06-26: **Phase 9 complete** (ESL superpowers: inline Chinese gloss + tone-rewrite). Decisions confirmed with user: gloss is an **offline EC dictionary** (instant, LLM-down-proof, fits the embedded-lexicon ethos), rewrite is a **selection bubble**. Data: `scripts/build_gloss.py` builds `internal/lexicon/data/gloss.json.gz` from ECDICT (66MB csv → 1.3MB gz, 57k freq-≤50k words, cleaned/trimmed). Backend: `lexicon` gloss map + `Gloss()`/`Result.Gloss` + `GET /api/gloss/{word}`; `llm.RunRewrite` + rewrite prompt/`styleGuidance`; `internal/suggestions/rewrite.go` (`POST /api/docs/:id/rewrite`, stateless, owner-scoped). Frontend: `GlossTip` hover tooltip (350ms delay, reuses `wordAt`, CJK-safe) + gloss line in `WordCard`; `SelectionBubble` + `RewritePreview` wired through `EditorCore` (onMouseMove/onSelectionUpdate, request-token guards, clears on edit/doc-switch); `api.glossWord`/`api.rewriteSelection`; CSS for the three new surfaces (+ print-hidden). Tests added in `lexicon` and `suggestions`. All builds/tests/vet/tsc/vite clean; live smoke vs fake vLLM on :8055 verified gloss + rewrite + 400/404/502 paths. Next: **Phase 10 (organization & polish).**
+- 2026-06-26: **Phase 8 complete** (Trust foundation: version history + export) + empty-doc fix. Backend: migration `0003_document_versions`; `internal/docs/versions.go` (throttled auto-snapshot wired into `update`, manual snapshot, restore-with-pre_restore, prune to 40 auto, owner-scoped via join) and `internal/docs/export.go` (pure-Go Tiptap-JSON → md/html/txt/docx, no deps, CJK-safe filenames via RFC 5987). `DocumentVersion` model + kind constants. Tests: `versions_test.go`, `export_test.go` (incl. valid-zip docx assertion). Frontend: `api.client` version/export methods; `ExportMenu` + `HistoryPanel` components wired into the title row; `@media print` stylesheet + `.petal-no-print` for the browser PDF path; `editorEpoch` remount on restore. Empty-doc fix in `App.tsx` (blank drafts reuse-on-create + discard-on-leave via refs to dodge stale closures); deleted 2 orphan empties from the live :8099 DB. Multi-session plan agreed: this session = Phase 8; **Phase 9 (ESL gloss + tone-rewrite)** next, then **Phase 10 (search/folders/polish)**; **auth/deploy (was Phase 11) shelved** until user's foundational work lands. All builds/tests/vet clean; live smoke verified the full version+export+restore flow end-to-end. Next: **Phase 9.**
 - 2026-06-25: Spec reviewed & amended (voice/grammar decoupled, ctx cap, routes, voice DB type, honey color, string-anchoring). Build plan created.
 - 2026-06-25: **Phase 0 complete.** Go module + chi server, config loader, React/Vite/Tailwind-v4 scaffold with full design tokens, frontend embedded & served by the binary, verified end-to-end. Toolchain: Go 1.24.4, Node 22, npm 10. Next: **Phase 1 (data layer)** — SQLite via modernc, models, seed `local` user.
 - 2026-06-25: **Phase 1 complete.** `internal/db` package: modernc.org/sqlite (pulled go toolchain → 1.25), `Open()` does mkdir + WAL/foreign-keys DSN + versioned migration runner + idempotent local-user seed. Models with type/status constants. Wired into `main.go`; tests pass (migrate/seed idempotency, CHECK reject, FK cascade). Verified server boots and writes `petal.db`. Next: **Phase 2 (document CRUD + auto-save)** — first "it works" milestone.

cmd/server/main.go

@@ -15,6 +15,7 @@ import (
 	"gitea.parodia.dev/drwily/petal/internal/config"
 	"gitea.parodia.dev/drwily/petal/internal/db"
 	"gitea.parodia.dev/drwily/petal/internal/docs"
+	"gitea.parodia.dev/drwily/petal/internal/lexicon"
 	"gitea.parodia.dev/drwily/petal/internal/llm"
 	"gitea.parodia.dev/drwily/petal/internal/suggestions"
 	"gitea.parodia.dev/drwily/petal/web"
@@ -61,12 +62,24 @@ func main() {
 
 		// Document CRUD plus the doc-scoped checkpoint/list suggestion routes,
 		// both under /api/docs.
-		docsRouter := docs.New(database).Routes()
+		docsHandler := docs.New(database)
+		docsRouter := docsHandler.Routes()
 		sug.RegisterDocRoutes(docsRouter)
 		api.Mount("/docs", docsRouter)
 
+		// Tag management (the roster) and cross-document full-text search.
+		api.Mount("/tags", docsHandler.TagRoutes())
+		api.Mount("/search", docsHandler.SearchRoutes())
+
 		// Per-suggestion actions (accept/dismiss) under /api/suggestions.
 		api.Mount("/suggestions", sug.Routes())
+
+		// Offline lexicon: full word lookups (gloss + definition + synonyms) for
+		// the right-click popover, and the lightweight Chinese-only gloss for the
+		// inline hover/select tooltip. One handler so the datasets load once.
+		lex := lexicon.NewHandler()
+		api.Mount("/word", lex.Routes())
+		api.Mount("/gloss", lex.GlossRoutes())
 	})
 
 	// Everything else: serve the embedded SPA (with index.html fallback for client routing).

internal/db/db.go

@@ -167,6 +167,99 @@ CREATE TABLE plagiarism_reports (
 
 CREATE INDEX idx_suggestions_doc_id ON suggestions(doc_id);
 CREATE INDEX idx_plagiarism_doc_id ON plagiarism_reports(doc_id);
+`,
+		},
+		{
+			// Per-document tone: guides the grammar-checkpoint LLM so advice fits
+			// the writer's target register (academic essay vs casual journal).
+			// 'general' means no specific tone steering.
+			name: "0002_document_tone",
+			stmt: `ALTER TABLE documents ADD COLUMN tone TEXT NOT NULL DEFAULT 'general';`,
+		},
+		{
+			// Version history: point-in-time snapshots of a document's body so a
+			// bad edit or LLM mishap is always recoverable. `kind` distinguishes
+			// throttled background snapshots ('auto'), explicit user restore
+			// points ('manual'), and the safety copy taken right before a restore
+			// ('pre_restore') so restoring is itself undoable. Snapshots cascade
+			// with the document. Stored fully (content + content_text) so a
+			// restore is a plain copy with no re-derivation.
+			name: "0003_document_versions",
+			stmt: `
+CREATE TABLE document_versions (
+    id           TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
+    doc_id       TEXT NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
+    title        TEXT NOT NULL,
+    content      TEXT NOT NULL,
+    content_text TEXT NOT NULL,
+    word_count   INTEGER NOT NULL DEFAULT 0,
+    kind         TEXT NOT NULL DEFAULT 'auto'
+                 CHECK(kind IN ('auto','manual','pre_restore')),
+    created_at   DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX idx_versions_doc_id ON document_versions(doc_id, created_at DESC);
+`,
+		},
+		{
+			// Organization & search (Phase 10). Two parts:
+			//
+			// 1. Tags. A small, user-scoped label set; `color` holds a palette key
+			//    (rose/mint/peach/lavender/sky/honey) the frontend maps to CSS.
+			//    document_tags is the many-to-many join; both sides cascade so
+			//    deleting a doc or a tag cleans up its assignments.
+			//
+			// 2. Full-text search. A standalone FTS5 virtual table over title +
+			//    content_text using the `trigram` tokenizer so search works for
+			//    both English and space-free Chinese (the default tokenizer treats a
+			//    CJK run as one token). It carries an UNINDEXED doc_id to map hits
+			//    back to documents, kept in sync by AFTER INSERT/UPDATE/DELETE
+			//    triggers, and is back-filled from the existing documents here.
+			//    (Trigram needs ≥3 chars to MATCH; the search handler falls back to
+			//    LIKE for shorter queries — common for 2-character Chinese words.)
+			name: "0004_tags_and_search",
+			stmt: `
+CREATE TABLE tags (
+    id         TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
+    user_id    TEXT NOT NULL REFERENCES users(id),
+    name       TEXT NOT NULL,
+    color      TEXT NOT NULL DEFAULT 'rose',
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(user_id, name)
+);
+
+CREATE TABLE document_tags (
+    doc_id  TEXT NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
+    tag_id  TEXT NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
+    PRIMARY KEY (doc_id, tag_id)
+);
+
+CREATE INDEX idx_document_tags_tag ON document_tags(tag_id);
+
+CREATE VIRTUAL TABLE documents_fts USING fts5(
+    doc_id UNINDEXED,
+    title,
+    content_text,
+    tokenize='trigram'
+);
+
+CREATE TRIGGER documents_ai AFTER INSERT ON documents BEGIN
+    INSERT INTO documents_fts (doc_id, title, content_text)
+    VALUES (new.id, new.title, new.content_text);
+END;
+
+CREATE TRIGGER documents_ad AFTER DELETE ON documents BEGIN
+    DELETE FROM documents_fts WHERE doc_id = old.id;
+END;
+
+CREATE TRIGGER documents_au AFTER UPDATE ON documents BEGIN
+    UPDATE documents_fts
+       SET title = new.title, content_text = new.content_text
+     WHERE doc_id = old.id;
+END;
+
+INSERT INTO documents_fts (doc_id, title, content_text)
+SELECT id, title, content_text FROM documents;
 `,
 		},
 	}

internal/db/models.go

@@ -21,11 +21,59 @@ type Document struct {
 	Title       string    `json:"title"`
 	Content     string    `json:"content"`      // Tiptap JSON
 	ContentText string    `json:"content_text"` // plain text for the LLM
+	Tone        string    `json:"tone"`         // target writing tone; steers LLM advice
 	WordCount   int       `json:"word_count"`
 	CreatedAt   time.Time `json:"created_at"`
 	UpdatedAt   time.Time `json:"updated_at"`
 }
 
+// DocumentVersion is a point-in-time snapshot of a document's body, captured so
+// a writer can recover from a bad edit or an unwanted change. `Content` mirrors
+// the document's Tiptap JSON at snapshot time; `Kind` records why it was taken
+// (see the kind constants). List responses omit the heavy Content/ContentText
+// fields (the `omitempty`-friendly zero strings) and load them only on preview
+// or restore.
+type DocumentVersion struct {
+	ID          string    `json:"id"`
+	DocID       string    `json:"doc_id"`
+	Title       string    `json:"title"`
+	Content     string    `json:"content,omitempty"`      // Tiptap JSON; omitted in list view
+	ContentText string    `json:"content_text,omitempty"` // plain text; omitted in list view
+	WordCount   int       `json:"word_count"`
+	Kind        string    `json:"kind"` // auto | manual | pre_restore
+	CreatedAt   time.Time `json:"created_at"`
+}
+
+// Document version kinds, mirrored from the schema CHECK constraint.
+const (
+	VersionKindAuto       = "auto"        // throttled background snapshot on save
+	VersionKindManual     = "manual"      // explicit "save a restore point"
+	VersionKindPreRestore = "pre_restore" // safety copy taken just before a restore
+)
+
+// Tag is a user-scoped label for organizing documents. `Color` is a palette key
+// (rose, mint, peach, lavender, sky, honey) the frontend maps to a CSS color;
+// storing the key (not a hex value) keeps tags in step with the design tokens.
+// `DocCount` is populated only by the tag-list endpoint (how many documents wear
+// the tag); it's omitted from per-document tag lists.
+type Tag struct {
+	ID       string `json:"id"`
+	Name     string `json:"name"`
+	Color    string `json:"color"`
+	DocCount int    `json:"doc_count,omitempty"`
+}
+
+// Tag color palette keys, mirrored on the frontend. Kept small and aligned with
+// the existing design tokens; unknown values fall back to rose client-side.
+const (
+	TagColorRose     = "rose"
+	TagColorMint     = "mint"
+	TagColorPeach    = "peach"
+	TagColorLavender = "lavender"
+	TagColorSky      = "sky"
+	TagColorHoney    = "honey"
+)
+
 // Suggestion is a single LLM-proposed edit anchored to a span of the document.
 //
 // FromPos/ToPos are plaintext offsets into ContentText for server-side use only;

internal/docs/export.go

@@ -0,0 +1,629 @@
+package docs
+
+import (
+	"archive/zip"
+	"bytes"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// exportRoutes registers the download endpoint: GET /api/docs/{id}/export?format=md|html|txt|docx
+func (h *Handler) exportRoutes(r chi.Router) {
+	r.Get("/{id}/export", h.export)
+}
+
+// exportFormat describes one downloadable format: how to render it and how to
+// label the resulting file.
+type exportFormat struct {
+	ext         string
+	contentType string
+	render      func(doc db.Document) ([]byte, error)
+}
+
+// exportFormats is the supported set. PDF is intentionally absent: a faithful,
+// CJK-safe PDF needs an embedded Unicode font (~10MB into the single binary) or
+// a headless browser (breaks the no-cgo, single-binary story). The frontend
+// offers "Print / Save as PDF" via the browser instead, which uses the reader's
+// own fonts and renders CJK correctly for free.
+var exportFormats = map[string]exportFormat{
+	"md":   {ext: "md", contentType: "text/markdown; charset=utf-8", render: renderMarkdown},
+	"html": {ext: "html", contentType: "text/html; charset=utf-8", render: renderHTMLFile},
+	"txt":  {ext: "txt", contentType: "text/plain; charset=utf-8", render: renderPlainText},
+	"docx": {
+		ext:         "docx",
+		contentType: "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+		render:      renderDocx,
+	},
+}
+
+// export streams the document in the requested format as a download.
+func (h *Handler) export(w http.ResponseWriter, r *http.Request) {
+	formatKey := r.URL.Query().Get("format")
+	if formatKey == "" {
+		formatKey = "md"
+	}
+	format, ok := exportFormats[formatKey]
+	if !ok {
+		badRequest(w, "unsupported export format")
+		return
+	}
+
+	doc, err := h.fetch(chi.URLParam(r, "id"))
+	if errors.Is(err, sql.ErrNoRows) {
+		notFound(w)
+		return
+	}
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+
+	body, err := format.render(doc)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+
+	filename := sanitizeFilename(doc.Title) + "." + format.ext
+	w.Header().Set("Content-Type", format.contentType)
+	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename*=UTF-8''%s", urlEscapeFilename(filename)))
+	w.Header().Set("Content-Length", fmt.Sprintf("%d", len(body)))
+	_, _ = w.Write(body)
+}
+
+// --- Tiptap document model --------------------------------------------------
+
+// pmNode is one ProseMirror/Tiptap node. The tree is what the editor stores in
+// Document.Content; we walk it to render every export format from one source.
+type pmNode struct {
+	Type    string         `json:"type"`
+	Attrs   map[string]any `json:"attrs"`
+	Marks   []pmMark       `json:"marks"`
+	Text    string         `json:"text"`
+	Content []pmNode       `json:"content"`
+}
+
+type pmMark struct {
+	Type string `json:"type"`
+}
+
+// parseDoc decodes Document.Content into a node tree. On empty or malformed JSON
+// it falls back to wrapping the plain-text mirror in paragraphs, so export never
+// fails just because the editor state is unusual.
+func parseDoc(doc db.Document) pmNode {
+	var root pmNode
+	if err := json.Unmarshal([]byte(doc.Content), &root); err != nil || root.Type == "" {
+		return fallbackDoc(doc.ContentText)
+	}
+	if len(root.Content) == 0 && strings.TrimSpace(doc.ContentText) != "" {
+		return fallbackDoc(doc.ContentText)
+	}
+	return root
+}
+
+// fallbackDoc builds a minimal doc node from plain text, one paragraph per line.
+func fallbackDoc(text string) pmNode {
+	root := pmNode{Type: "doc"}
+	for _, line := range strings.Split(text, "\n") {
+		p := pmNode{Type: "paragraph"}
+		if line != "" {
+			p.Content = []pmNode{{Type: "text", Text: line}}
+		}
+		root.Content = append(root.Content, p)
+	}
+	return root
+}
+
+func (n pmNode) hasMark(t string) bool {
+	for _, m := range n.Marks {
+		if m.Type == t {
+			return true
+		}
+	}
+	return false
+}
+
+func (n pmNode) level() int {
+	if n.Attrs == nil {
+		return 1
+	}
+	if l, ok := n.Attrs["level"].(float64); ok && l >= 1 {
+		return int(l)
+	}
+	return 1
+}
+
+// --- Markdown ---------------------------------------------------------------
+
+func renderMarkdown(doc db.Document) ([]byte, error) {
+	root := parseDoc(doc)
+	var blocks []string
+	for _, child := range root.Content {
+		if s := mdBlock(child, 0); s != "" {
+			blocks = append(blocks, s)
+		}
+	}
+	out := "# " + doc.Title + "\n\n" + strings.Join(blocks, "\n\n") + "\n"
+	return []byte(out), nil
+}
+
+func mdBlock(n pmNode, depth int) string {
+	switch n.Type {
+	case "heading":
+		return strings.Repeat("#", n.level()) + " " + mdInline(n.Content)
+	case "paragraph":
+		return mdInline(n.Content)
+	case "blockquote":
+		var lines []string
+		for _, c := range n.Content {
+			for _, l := range strings.Split(mdBlock(c, depth), "\n") {
+				lines = append(lines, "> "+l)
+			}
+		}
+		return strings.Join(lines, "\n")
+	case "codeBlock":
+		return "```\n" + textContent(n) + "\n```"
+	case "horizontalRule":
+		return "---"
+	case "bulletList", "orderedList":
+		var items []string
+		for i, item := range n.Content {
+			marker := "- "
+			if n.Type == "orderedList" {
+				marker = fmt.Sprintf("%d. ", i+1)
+			}
+			indent := strings.Repeat("  ", depth)
+			// A listItem holds block children (usually one paragraph).
+			var parts []string
+			for _, c := range item.Content {
+				parts = append(parts, mdBlock(c, depth+1))
+			}
+			items = append(items, indent+marker+strings.TrimSpace(strings.Join(parts, "\n")))
+		}
+		return strings.Join(items, "\n")
+	default:
+		// Unknown block: render any inline text it carries.
+		if len(n.Content) > 0 {
+			return mdInline(n.Content)
+		}
+		return ""
+	}
+}
+
+func mdInline(nodes []pmNode) string {
+	var b strings.Builder
+	for _, n := range nodes {
+		switch n.Type {
+		case "text":
+			b.WriteString(applyMdMarks(n))
+		case "hardBreak":
+			b.WriteString("  \n")
+		default:
+			b.WriteString(mdInline(n.Content))
+		}
+	}
+	return b.String()
+}
+
+func applyMdMarks(n pmNode) string {
+	t := n.Text
+	if n.hasMark("code") {
+		return "`" + t + "`" // code spans don't combine with other emphasis
+	}
+	if n.hasMark("bold") {
+		t = "**" + t + "**"
+	}
+	if n.hasMark("italic") {
+		t = "*" + t + "*"
+	}
+	if n.hasMark("strike") {
+		t = "~~" + t + "~~"
+	}
+	if n.hasMark("underline") {
+		t = "<u>" + t + "</u>"
+	}
+	return t
+}
+
+// --- Plain text -------------------------------------------------------------
+
+func renderPlainText(doc db.Document) ([]byte, error) {
+	root := parseDoc(doc)
+	var blocks []string
+	for _, child := range root.Content {
+		if s := txtBlock(child); s != "" {
+			blocks = append(blocks, s)
+		}
+	}
+	out := doc.Title + "\n\n" + strings.Join(blocks, "\n\n") + "\n"
+	return []byte(out), nil
+}
+
+func txtBlock(n pmNode) string {
+	switch n.Type {
+	case "bulletList", "orderedList":
+		var items []string
+		for i, item := range n.Content {
+			marker := "• "
+			if n.Type == "orderedList" {
+				marker = fmt.Sprintf("%d. ", i+1)
+			}
+			items = append(items, marker+strings.TrimSpace(textContent(item)))
+		}
+		return strings.Join(items, "\n")
+	case "horizontalRule":
+		return "----------"
+	default:
+		return textContent(n)
+	}
+}
+
+// textContent flattens all descendant text, joining hardBreaks as newlines.
+func textContent(n pmNode) string {
+	if n.Type == "text" {
+		return n.Text
+	}
+	if n.Type == "hardBreak" {
+		return "\n"
+	}
+	var b strings.Builder
+	for _, c := range n.Content {
+		b.WriteString(textContent(c))
+	}
+	return b.String()
+}
+
+// --- HTML -------------------------------------------------------------------
+
+func renderHTMLFile(doc db.Document) ([]byte, error) {
+	root := parseDoc(doc)
+	var body strings.Builder
+	for _, child := range root.Content {
+		body.WriteString(htmlBlock(child))
+	}
+	page := fmt.Sprintf(htmlTemplate, htmlEscape(doc.Title), htmlEscape(doc.Title), body.String())
+	return []byte(page), nil
+}
+
+// htmlTemplate is a standalone, self-contained page with a warm, readable
+// stylesheet and a CJK-first font stack so exported writing looks like Petal,
+// not a raw dump. No external assets — opens offline anywhere.
+const htmlTemplate = `<!doctype html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>%s</title>
+<style>
+  :root { color-scheme: light; }
+  body {
+    font-family: "Georgia", "Songti SC", "Noto Serif CJK SC", "Source Han Serif SC", serif;
+    line-height: 1.75; color: #463a3f; background: #fffafb;
+    max-width: 42rem; margin: 3rem auto; padding: 0 1.5rem;
+  }
+  h1, h2, h3 { font-family: "Georgia", "Songti SC", serif; color: #b04a6a; line-height: 1.3; }
+  h1 { font-size: 1.9rem; border-bottom: 2px solid #f6d6e0; padding-bottom: .4rem; }
+  blockquote { border-left: 3px solid #f3b6c8; margin: 1rem 0; padding: .2rem 1rem; color: #6b5860; background: #fff2f6; }
+  code { background: #fdeef3; padding: .1rem .35rem; border-radius: .3rem; font-size: .9em; }
+  pre { background: #fdeef3; padding: 1rem; border-radius: .6rem; overflow-x: auto; }
+  pre code { background: none; padding: 0; }
+  hr { border: none; border-top: 1px solid #f3cdd9; margin: 2rem 0; }
+  a { color: #b04a6a; }
+  ul, ol { padding-left: 1.4rem; }
+</style>
+</head>
+<body>
+<h1>%s</h1>
+%s</body>
+</html>
+`
+
+func htmlBlock(n pmNode) string {
+	switch n.Type {
+	case "heading":
+		tag := fmt.Sprintf("h%d", clampHeading(n.level()))
+		return fmt.Sprintf("<%s>%s</%s>\n", tag, htmlInline(n.Content), tag)
+	case "paragraph":
+		inner := htmlInline(n.Content)
+		if inner == "" {
+			return "<p><br></p>\n"
+		}
+		return "<p>" + inner + "</p>\n"
+	case "blockquote":
+		var b strings.Builder
+		for _, c := range n.Content {
+			b.WriteString(htmlBlock(c))
+		}
+		return "<blockquote>" + b.String() + "</blockquote>\n"
+	case "codeBlock":
+		return "<pre><code>" + htmlEscape(textContent(n)) + "</code></pre>\n"
+	case "horizontalRule":
+		return "<hr>\n"
+	case "bulletList", "orderedList":
+		tag := "ul"
+		if n.Type == "orderedList" {
+			tag = "ol"
+		}
+		var b strings.Builder
+		b.WriteString("<" + tag + ">\n")
+		for _, item := range n.Content {
+			var inner strings.Builder
+			for _, c := range item.Content {
+				// Unwrap a lone paragraph so list items aren't double-spaced.
+				if c.Type == "paragraph" {
+					inner.WriteString(htmlInline(c.Content))
+				} else {
+					inner.WriteString(htmlBlock(c))
+				}
+			}
+			b.WriteString("<li>" + inner.String() + "</li>\n")
+		}
+		b.WriteString("</" + tag + ">\n")
+		return b.String()
+	default:
+		if len(n.Content) > 0 {
+			return "<p>" + htmlInline(n.Content) + "</p>\n"
+		}
+		return ""
+	}
+}
+
+func htmlInline(nodes []pmNode) string {
+	var b strings.Builder
+	for _, n := range nodes {
+		switch n.Type {
+		case "text":
+			b.WriteString(applyHTMLMarks(n))
+		case "hardBreak":
+			b.WriteString("<br>")
+		default:
+			b.WriteString(htmlInline(n.Content))
+		}
+	}
+	return b.String()
+}
+
+func applyHTMLMarks(n pmNode) string {
+	t := htmlEscape(n.Text)
+	if n.hasMark("code") {
+		return "<code>" + t + "</code>"
+	}
+	if n.hasMark("bold") {
+		t = "<strong>" + t + "</strong>"
+	}
+	if n.hasMark("italic") {
+		t = "<em>" + t + "</em>"
+	}
+	if n.hasMark("underline") {
+		t = "<u>" + t + "</u>"
+	}
+	if n.hasMark("strike") {
+		t = "<s>" + t + "</s>"
+	}
+	return t
+}
+
+func clampHeading(level int) int {
+	if level < 1 {
+		return 1
+	}
+	if level > 6 {
+		return 6
+	}
+	return level
+}
+
+// --- DOCX -------------------------------------------------------------------
+
+// renderDocx builds a minimal but valid .docx (Office Open XML) in pure Go: a
+// zip of the few XML parts Word needs. Bold/italic/underline/strike map to run
+// properties; headings use Word's built-in styles; lists are rendered with a
+// bullet/number prefix (no numbering.xml dependency). CJK renders with the
+// reader's own fonts, so no font embedding is required.
+func renderDocx(doc db.Document) ([]byte, error) {
+	root := parseDoc(doc)
+
+	var body strings.Builder
+	body.WriteString(docxHeading(doc.Title, 1))
+	for _, child := range root.Content {
+		body.WriteString(docxBlock(child))
+	}
+
+	document := xmlHeader + `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">` +
+		`<w:body>` + body.String() +
+		`<w:sectPr><w:pgSz w:w="11906" w:h="16838"/><w:pgMar w:top="1440" w:bottom="1440" w:left="1440" w:right="1440"/></w:sectPr>` +
+		`</w:body></w:document>`
+
+	var buf bytes.Buffer
+	zw := zip.NewWriter(&buf)
+	parts := []struct{ name, content string }{
+		{"[Content_Types].xml", docxContentTypes},
+		{"_rels/.rels", docxRootRels},
+		{"word/_rels/document.xml.rels", docxDocRels},
+		{"word/document.xml", document},
+	}
+	for _, p := range parts {
+		fw, err := zw.Create(p.name)
+		if err != nil {
+			return nil, err
+		}
+		if _, err := fw.Write([]byte(p.content)); err != nil {
+			return nil, err
+		}
+	}
+	if err := zw.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+const (
+	xmlHeader        = `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>` + "\n"
+	docxContentTypes = xmlHeader + `<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">` +
+		`<Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>` +
+		`<Default Extension="xml" ContentType="application/xml"/>` +
+		`<Override PartName="/word/document.xml" ContentType="application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"/>` +
+		`</Types>`
+	docxRootRels = xmlHeader + `<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">` +
+		`<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/>` +
+		`</Relationships>`
+	docxDocRels = xmlHeader + `<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"></Relationships>`
+)
+
+func docxBlock(n pmNode) string {
+	switch n.Type {
+	case "heading":
+		return docxHeading(textContent(n), n.level())
+	case "paragraph":
+		return docxPara(n, "")
+	case "blockquote":
+		var b strings.Builder
+		for _, c := range n.Content {
+			b.WriteString(docxPara(c, "Quote"))
+		}
+		return b.String()
+	case "codeBlock":
+		// One paragraph per line preserves layout without a code style.
+		var b strings.Builder
+		for _, line := range strings.Split(textContent(n), "\n") {
+			b.WriteString(`<w:p><w:r><w:rPr><w:rFonts w:ascii="Consolas" w:hAnsi="Consolas"/></w:rPr>` +
+				`<w:t xml:space="preserve">` + xmlEscape(line) + `</w:t></w:r></w:p>`)
+		}
+		return b.String()
+	case "horizontalRule":
+		return `<w:p><w:pPr><w:pBdr><w:bottom w:val="single" w:sz="6" w:space="1" w:color="auto"/></w:pBdr></w:pPr></w:p>`
+	case "bulletList", "orderedList":
+		var b strings.Builder
+		for i, item := range n.Content {
+			prefix := "•  "
+			if n.Type == "orderedList" {
+				prefix = fmt.Sprintf("%d.  ", i+1)
+			}
+			for _, c := range item.Content {
+				b.WriteString(docxPara(c, "", prefix))
+			}
+		}
+		return b.String()
+	default:
+		if len(n.Content) > 0 {
+			return docxPara(n, "")
+		}
+		return ""
+	}
+}
+
+// docxPara renders a block's inline children as a Word paragraph. An optional
+// style name (e.g. "Quote") and an optional literal text prefix (for list
+// markers) may be supplied.
+func docxPara(n pmNode, style string, prefix ...string) string {
+	var b strings.Builder
+	b.WriteString("<w:p>")
+	if style != "" {
+		b.WriteString(`<w:pPr><w:pStyle w:val="` + style + `"/></w:pPr>`)
+	}
+	if len(prefix) > 0 && prefix[0] != "" {
+		b.WriteString(docxRun(pmNode{Type: "text", Text: prefix[0]}))
+	}
+	b.WriteString(docxInline(n.Content))
+	b.WriteString("</w:p>")
+	return b.String()
+}
+
+func docxHeading(text string, level int) string {
+	return `<w:p><w:pPr><w:pStyle w:val="Heading` + fmt.Sprintf("%d", clampHeading(level)) + `"/></w:pPr>` +
+		docxRun(pmNode{Type: "text", Text: text}) + `</w:p>`
+}
+
+func docxInline(nodes []pmNode) string {
+	var b strings.Builder
+	for _, n := range nodes {
+		switch n.Type {
+		case "text":
+			b.WriteString(docxRun(n))
+		case "hardBreak":
+			b.WriteString(`<w:r><w:br/></w:r>`)
+		default:
+			b.WriteString(docxInline(n.Content))
+		}
+	}
+	return b.String()
+}
+
+func docxRun(n pmNode) string {
+	var props strings.Builder
+	if n.hasMark("bold") {
+		props.WriteString("<w:b/>")
+	}
+	if n.hasMark("italic") {
+		props.WriteString("<w:i/>")
+	}
+	if n.hasMark("underline") {
+		props.WriteString(`<w:u w:val="single"/>`)
+	}
+	if n.hasMark("strike") {
+		props.WriteString("<w:strike/>")
+	}
+	rpr := ""
+	if props.Len() > 0 {
+		rpr = "<w:rPr>" + props.String() + "</w:rPr>"
+	}
+	return `<w:r>` + rpr + `<w:t xml:space="preserve">` + xmlEscape(n.Text) + `</w:t></w:r>`
+}
+
+// --- small helpers ----------------------------------------------------------
+
+func htmlEscape(s string) string {
+	r := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;", `"`, "&quot;", "'", "&#39;")
+	return r.Replace(s)
+}
+
+func xmlEscape(s string) string {
+	r := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;", `"`, "&quot;")
+	return r.Replace(s)
+}
+
+// sanitizeFilename makes a title safe as a download filename, preserving CJK and
+// most letters while dropping path separators and control characters.
+func sanitizeFilename(title string) string {
+	title = strings.TrimSpace(title)
+	if title == "" {
+		return "untitled"
+	}
+	var b strings.Builder
+	for _, r := range title {
+		switch {
+		case r < 0x20, r == '/', r == '\\', r == ':', r == '*', r == '?', r == '"', r == '<', r == '>', r == '|':
+			b.WriteRune('-')
+		default:
+			b.WriteRune(r)
+		}
+	}
+	out := strings.TrimSpace(b.String())
+	if out == "" {
+		return "untitled"
+	}
+	return out
+}
+
+// urlEscapeFilename percent-encodes a filename for the RFC 5987 filename*=
+// Content-Disposition form, which carries UTF-8 (CJK titles) safely.
+func urlEscapeFilename(s string) string {
+	var b strings.Builder
+	for _, c := range []byte(s) {
+		if (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
+			c == '-' || c == '_' || c == '.' || c == '~' {
+			b.WriteByte(c)
+		} else {
+			fmt.Fprintf(&b, "%%%02X", c)
+		}
+	}
+	return b.String()
+}

internal/docs/export_test.go

@@ -0,0 +1,135 @@
+package docs
+
+import (
+	"archive/zip"
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+// richDocJSON is a Tiptap document exercising headings, marks, and a list —
+// including CJK text, which every format must carry through intact.
+const richDocJSON = `{"type":"doc","content":[` +
+	`{"type":"heading","attrs":{"level":2},"content":[{"type":"text","text":"My Section"}]},` +
+	`{"type":"paragraph","content":[{"type":"text","text":"Hello "},{"type":"text","marks":[{"type":"bold"}],"text":"world"},{"type":"text","text":" 你好"}]},` +
+	`{"type":"bulletList","content":[` +
+	`{"type":"listItem","content":[{"type":"paragraph","content":[{"type":"text","text":"first"}]}]},` +
+	`{"type":"listItem","content":[{"type":"paragraph","content":[{"type":"text","text":"second"}]}]}` +
+	`]}` +
+	`]}`
+
+func seedRichDoc(t *testing.T, srv http.Handler) string {
+	t.Helper()
+	id := newDoc(t, srv)
+	body := `{"title":"日记 Diary","content":` + jsonString(richDocJSON) + `,"content_text":"My Section\nHello world 你好\nfirst\nsecond","word_count":6}`
+	if rec := do(t, srv, http.MethodPut, "/"+id, body); rec.Code != http.StatusOK {
+		t.Fatalf("seed rich doc: code=%d body=%s", rec.Code, rec.Body)
+	}
+	return id
+}
+
+// jsonString quotes a string as a JSON string literal (so the Tiptap JSON can be
+// embedded as the "content" field value).
+func jsonString(s string) string {
+	b, _ := json.Marshal(s)
+	return string(b)
+}
+
+func TestExportMarkdown(t *testing.T) {
+	srv := newTestServer(t)
+	id := seedRichDoc(t, srv)
+
+	rec := do(t, srv, http.MethodGet, "/"+id+"/export?format=md", "")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("export md: code=%d body=%s", rec.Code, rec.Body)
+	}
+	if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/markdown") {
+		t.Fatalf("unexpected content-type: %q", ct)
+	}
+	out := rec.Body.String()
+	for _, want := range []string{"## My Section", "**world**", "你好", "- first", "- second"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("markdown missing %q in:\n%s", want, out)
+		}
+	}
+	// CJK filename must survive in the RFC 5987 form.
+	if cd := rec.Header().Get("Content-Disposition"); !strings.Contains(cd, "filename*=UTF-8''") {
+		t.Fatalf("expected RFC 5987 filename, got %q", cd)
+	}
+}
+
+func TestExportHTML(t *testing.T) {
+	srv := newTestServer(t)
+	id := seedRichDoc(t, srv)
+
+	rec := do(t, srv, http.MethodGet, "/"+id+"/export?format=html", "")
+	out := rec.Body.String()
+	for _, want := range []string{"<!doctype html>", "<h2>My Section</h2>", "<strong>world</strong>", "你好", "<li>first</li>"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("html missing %q", want)
+		}
+	}
+}
+
+func TestExportPlainText(t *testing.T) {
+	srv := newTestServer(t)
+	id := seedRichDoc(t, srv)
+
+	rec := do(t, srv, http.MethodGet, "/"+id+"/export?format=txt", "")
+	out := rec.Body.String()
+	for _, want := range []string{"My Section", "Hello world 你好", "• first"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("txt missing %q in:\n%s", want, out)
+		}
+	}
+}
+
+func TestExportDocx(t *testing.T) {
+	srv := newTestServer(t)
+	id := seedRichDoc(t, srv)
+
+	rec := do(t, srv, http.MethodGet, "/"+id+"/export?format=docx", "")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("export docx: code=%d", rec.Code)
+	}
+	raw := rec.Body.Bytes()
+	zr, err := zip.NewReader(bytes.NewReader(raw), int64(len(raw)))
+	if err != nil {
+		t.Fatalf("docx is not a valid zip: %v", err)
+	}
+
+	want := map[string]bool{"[Content_Types].xml": false, "word/document.xml": false}
+	var docXML string
+	for _, f := range zr.File {
+		if _, ok := want[f.Name]; ok {
+			want[f.Name] = true
+		}
+		if f.Name == "word/document.xml" {
+			rc, _ := f.Open()
+			b, _ := io.ReadAll(rc)
+			rc.Close()
+			docXML = string(b)
+		}
+	}
+	for name, found := range want {
+		if !found {
+			t.Fatalf("docx missing part %q", name)
+		}
+	}
+	for _, w := range []string{"My Section", "你好", "<w:b/>", "Heading2"} {
+		if !strings.Contains(docXML, w) {
+			t.Fatalf("document.xml missing %q", w)
+		}
+	}
+}
+
+func TestExportUnsupportedFormat(t *testing.T) {
+	srv := newTestServer(t)
+	id := newDoc(t, srv)
+	if rec := do(t, srv, http.MethodGet, "/"+id+"/export?format=pdf", ""); rec.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400 for unsupported format, got %d", rec.Code)
+	}
+}

internal/docs/handlers.go

@@ -7,6 +7,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"errors"
+	"log"
 	"net/http"
 
 	"github.com/go-chi/chi/v5"
@@ -33,19 +34,25 @@ func (h *Handler) Routes() chi.Router {
 	r.Get("/{id}", h.get)
 	r.Put("/{id}", h.update)
 	r.Delete("/{id}", h.delete)
+	h.versionRoutes(r)
+	h.exportRoutes(r)
+	h.registerTagRoutes(r)
 	return r
 }
 
 // docSummary is the lightweight shape returned by the list endpoint — enough to
-// render the DocList sidebar without shipping every document's full body.
+// render the DocList sidebar without shipping every document's full body. Tags
+// ride along so the sidebar can show chips and filter without a second request.
 type docSummary struct {
 	ID        string   `json:"id"`
 	Title     string   `json:"title"`
 	WordCount int      `json:"word_count"`
 	UpdatedAt string   `json:"updated_at"`
+	Tags      []db.Tag `json:"tags"`
 }
 
-// list returns the local user's documents, most-recently-updated first.
+// list returns the local user's documents, most-recently-updated first, each
+// decorated with its tags.
 func (h *Handler) list(w http.ResponseWriter, r *http.Request) {
 	rows, err := h.DB.Query(
 		`SELECT id, title, word_count, updated_at
@@ -61,6 +68,7 @@ func (h *Handler) list(w http.ResponseWriter, r *http.Request) {
 	defer rows.Close()
 
 	out := []docSummary{} // non-nil so an empty list serializes as [] not null
+	ids := []string{}
 	for rows.Next() {
 		var d docSummary
 		if err := rows.Scan(&d.ID, &d.Title, &d.WordCount, &d.UpdatedAt); err != nil {
@@ -68,11 +76,24 @@ func (h *Handler) list(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 		out = append(out, d)
+		ids = append(ids, d.ID)
 	}
 	if err := rows.Err(); err != nil {
 		serverError(w, err)
 		return
 	}
+
+	byDoc, err := h.tagsByDoc(ids)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	for i := range out {
+		out[i].Tags = byDoc[out[i].ID] // nil → JSON null is fine; client treats as none
+		if out[i].Tags == nil {
+			out[i].Tags = []db.Tag{}
+		}
+	}
 	writeJSON(w, http.StatusOK, out)
 }
 
@@ -81,11 +102,11 @@ func (h *Handler) create(w http.ResponseWriter, r *http.Request) {
 	var doc db.Document
 	err := h.DB.QueryRow(
 		`INSERT INTO documents (user_id) VALUES (?)
-		 RETURNING id, user_id, title, content, content_text, word_count, created_at, updated_at`,
+		 RETURNING id, user_id, title, content, content_text, tone, word_count, created_at, updated_at`,
 		db.LocalUserID,
 	).Scan(
 		&doc.ID, &doc.UserID, &doc.Title, &doc.Content, &doc.ContentText,
-		&doc.WordCount, &doc.CreatedAt, &doc.UpdatedAt,
+		&doc.Tone, &doc.WordCount, &doc.CreatedAt, &doc.UpdatedAt,
 	)
 	if err != nil {
 		serverError(w, err)
@@ -115,6 +136,7 @@ type updateRequest struct {
 	Title       *string `json:"title"`
 	Content     *string `json:"content"`
 	ContentText *string `json:"content_text"`
+	Tone        *string `json:"tone"`
 	WordCount   *int    `json:"word_count"`
 }
 
@@ -134,10 +156,11 @@ func (h *Handler) update(w http.ResponseWriter, r *http.Request) {
 		    SET title        = COALESCE(?, title),
 		        content      = COALESCE(?, content),
 		        content_text = COALESCE(?, content_text),
+		        tone         = COALESCE(?, tone),
 		        word_count   = COALESCE(?, word_count),
 		        updated_at   = CURRENT_TIMESTAMP
 		  WHERE id = ? AND user_id = ?`,
-		req.Title, req.Content, req.ContentText, req.WordCount, id, db.LocalUserID,
+		req.Title, req.Content, req.ContentText, req.Tone, req.WordCount, id, db.LocalUserID,
 	)
 	if err != nil {
 		serverError(w, err)
@@ -153,6 +176,16 @@ func (h *Handler) update(w http.ResponseWriter, r *http.Request) {
 		serverError(w, err)
 		return
 	}
+
+	// Capture a throttled history snapshot when a real body save came through
+	// (not a bare rename) and the document has content. Best-effort: a failed
+	// snapshot must never fail the save itself.
+	if req.Content != nil && doc.ContentText != "" {
+		if err := h.maybeAutoSnapshot(doc); err != nil {
+			log.Printf("docs: auto-snapshot for %s failed: %v", id, err)
+		}
+	}
+
 	writeJSON(w, http.StatusOK, doc)
 }
 
@@ -177,13 +210,13 @@ func (h *Handler) delete(w http.ResponseWriter, r *http.Request) {
 func (h *Handler) fetch(id string) (db.Document, error) {
 	var doc db.Document
 	err := h.DB.QueryRow(
-		`SELECT id, user_id, title, content, content_text, word_count, created_at, updated_at
+		`SELECT id, user_id, title, content, content_text, tone, word_count, created_at, updated_at
 		   FROM documents
 		  WHERE id = ? AND user_id = ?`,
 		id, db.LocalUserID,
 	).Scan(
 		&doc.ID, &doc.UserID, &doc.Title, &doc.Content, &doc.ContentText,
-		&doc.WordCount, &doc.CreatedAt, &doc.UpdatedAt,
+		&doc.Tone, &doc.WordCount, &doc.CreatedAt, &doc.UpdatedAt,
 	)
 	return doc, err
 }
@@ -206,3 +239,4 @@ func serverError(w http.ResponseWriter, err error) {
 
 func badRequest(w http.ResponseWriter, msg string) { errorJSON(w, http.StatusBadRequest, msg) }
 func notFound(w http.ResponseWriter)               { errorJSON(w, http.StatusNotFound, "document not found") }
+func notFoundMsg(w http.ResponseWriter, msg string) { errorJSON(w, http.StatusNotFound, msg) }

internal/docs/search.go

@@ -0,0 +1,261 @@
+package docs
+
+import (
+	"net/http"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// Search snippet shaping.
+const (
+	// ftsMinRunes is the shortest query the trigram FTS index can match. Shorter
+	// queries (common for 2-character Chinese words) fall back to a LIKE scan.
+	ftsMinRunes = 3
+
+	// snippetContext is how many runes of context to show on each side of the
+	// matched term in a result snippet.
+	snippetContext = 28
+
+	// maxSearchResults caps how many hits we return — plenty for a personal
+	// corpus, and keeps the response small.
+	maxSearchResults = 50
+
+	// hlStart/hlEnd wrap the matched span in a snippet. They're control-character
+	// sentinels that never occur in real text, so the client can split on them to
+	// highlight the match without escaping user content.
+	hlStart = "\x01"
+	hlEnd   = "\x02"
+)
+
+// searchResult is one hit: a document summary plus a highlighted snippet showing
+// where the query matched.
+type searchResult struct {
+	ID        string   `json:"id"`
+	Title     string   `json:"title"`
+	WordCount int      `json:"word_count"`
+	UpdatedAt string   `json:"updated_at"`
+	Snippet   string   `json:"snippet"`
+	Tags      []db.Tag `json:"tags"`
+}
+
+// SearchRoutes returns the router mounted at /api/search.
+func (h *Handler) SearchRoutes() chi.Router {
+	r := chi.NewRouter()
+	r.Get("/", h.search)
+	return r
+}
+
+// search runs a cross-document full-text search for the local user. Queries of
+// three or more runes use the trigram FTS index (fast, ranked); shorter queries
+// fall back to a LIKE scan so 2-character Chinese words still resolve. Either way
+// the snippet is built in Go from the original text, for clean word boundaries
+// and a uniform highlight format.
+func (h *Handler) search(w http.ResponseWriter, r *http.Request) {
+	q := strings.TrimSpace(r.URL.Query().Get("q"))
+	if q == "" {
+		writeJSON(w, http.StatusOK, []searchResult{})
+		return
+	}
+
+	type row struct {
+		id, title, contentText, updatedAt string
+		wordCount                         int
+	}
+	var rows []row
+
+	if utf8.RuneCountInString(q) >= ftsMinRunes {
+		// Wrap the whole query as one FTS phrase (doubling embedded quotes), so
+		// special characters are treated literally and trigram does a contiguous
+		// substring match.
+		phrase := `"` + strings.ReplaceAll(q, `"`, `""`) + `"`
+		sqlRows, err := h.DB.Query(
+			`SELECT d.id, d.title, d.content_text, d.word_count, d.updated_at
+			   FROM documents_fts f
+			   JOIN documents d ON d.id = f.doc_id
+			  WHERE documents_fts MATCH ? AND d.user_id = ?
+			  ORDER BY rank
+			  LIMIT ?`,
+			phrase, db.LocalUserID, maxSearchResults,
+		)
+		if err != nil {
+			serverError(w, err)
+			return
+		}
+		defer sqlRows.Close()
+		for sqlRows.Next() {
+			var rw row
+			if err := sqlRows.Scan(&rw.id, &rw.title, &rw.contentText, &rw.wordCount, &rw.updatedAt); err != nil {
+				serverError(w, err)
+				return
+			}
+			rows = append(rows, rw)
+		}
+		if err := sqlRows.Err(); err != nil {
+			serverError(w, err)
+			return
+		}
+	} else {
+		// Short query: LIKE scan over title + body. Escape LIKE wildcards so a
+		// literal % or _ in the query matches itself.
+		like := "%" + escapeLike(q) + "%"
+		sqlRows, err := h.DB.Query(
+			`SELECT id, title, content_text, word_count, updated_at
+			   FROM documents
+			  WHERE user_id = ?
+			    AND (title LIKE ? ESCAPE '\' OR content_text LIKE ? ESCAPE '\')
+			  ORDER BY updated_at DESC
+			  LIMIT ?`,
+			db.LocalUserID, like, like, maxSearchResults,
+		)
+		if err != nil {
+			serverError(w, err)
+			return
+		}
+		defer sqlRows.Close()
+		for sqlRows.Next() {
+			var rw row
+			if err := sqlRows.Scan(&rw.id, &rw.title, &rw.contentText, &rw.wordCount, &rw.updatedAt); err != nil {
+				serverError(w, err)
+				return
+			}
+			rows = append(rows, rw)
+		}
+		if err := sqlRows.Err(); err != nil {
+			serverError(w, err)
+			return
+		}
+	}
+
+	out := make([]searchResult, 0, len(rows))
+	ids := make([]string, 0, len(rows))
+	for _, rw := range rows {
+		out = append(out, searchResult{
+			ID:        rw.id,
+			Title:     rw.title,
+			WordCount: rw.wordCount,
+			UpdatedAt: rw.updatedAt,
+			Snippet:   buildSnippet(rw.title, rw.contentText, q),
+		})
+		ids = append(ids, rw.id)
+	}
+
+	byDoc, err := h.tagsByDoc(ids)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	for i := range out {
+		out[i].Tags = byDoc[out[i].ID]
+		if out[i].Tags == nil {
+			out[i].Tags = []db.Tag{}
+		}
+	}
+	writeJSON(w, http.StatusOK, out)
+}
+
+// escapeLike escapes the LIKE metacharacters (% and _) and the escape character
+// itself so the query is matched literally. Pairs with `ESCAPE '\'`.
+func escapeLike(s string) string {
+	r := strings.NewReplacer(`\`, `\\`, `%`, `\%`, `_`, `\_`)
+	return r.Replace(s)
+}
+
+// buildSnippet returns a short excerpt around the first case-insensitive match of
+// query, with the matched span wrapped in the hl sentinels. It prefers a body
+// match (with surrounding context); if the query only appears in the title it
+// highlights the title instead; otherwise it shows the body's opening so a result
+// always shows something. Windowing is rune-aware so CJK is never split
+// mid-character.
+func buildSnippet(title, body, query string) string {
+	runes := []rune(body)
+	qLen := utf8.RuneCountInString(query)
+	if idx := runeIndexFold(runes, query); idx >= 0 {
+		start := idx - snippetContext
+		if start < 0 {
+			start = 0
+		}
+		end := idx + qLen + snippetContext
+		if end > len(runes) {
+			end = len(runes)
+		}
+		var b strings.Builder
+		if start > 0 {
+			b.WriteString("…")
+		}
+		b.WriteString(string(runes[start:idx]))
+		b.WriteString(hlStart)
+		b.WriteString(string(runes[idx : idx+qLen]))
+		b.WriteString(hlEnd)
+		b.WriteString(string(runes[idx+qLen : end]))
+		if end < len(runes) {
+			b.WriteString("…")
+		}
+		return b.String()
+	}
+
+	// Body had no literal match (title-only hit, or an FTS span the literal scan
+	// can't reproduce). Highlight the title if the query is there.
+	tRunes := []rune(title)
+	if idx := runeIndexFold(tRunes, query); idx >= 0 {
+		return string(tRunes[:idx]) + hlStart + string(tRunes[idx:idx+qLen]) + hlEnd + string(tRunes[idx+qLen:])
+	}
+
+	// Last resort: the body's opening as plain context.
+	return clip(runes, 0, 2*snippetContext+qLen)
+}
+
+// clip returns runes[start:start+n] (bounded), with a trailing ellipsis when the
+// body continues. Used for the no-direct-match fallback.
+func clip(runes []rune, start, n int) string {
+	if start >= len(runes) {
+		return ""
+	}
+	end := start + n
+	trailing := ""
+	if end < len(runes) {
+		trailing = "…"
+	} else {
+		end = len(runes)
+	}
+	return string(runes[start:end]) + trailing
+}
+
+// runeIndexFold finds the first index (in runes) where query occurs in runes,
+// case-insensitively. Returns -1 if absent. Simple O(n*m) scan — fine for
+// single-document snippet building.
+func runeIndexFold(runes []rune, query string) int {
+	q := []rune(strings.ToLower(query))
+	if len(q) == 0 {
+		return -1
+	}
+	lower := make([]rune, len(runes))
+	for i, r := range runes {
+		lower[i] = toLowerRune(r)
+	}
+	for i := 0; i+len(q) <= len(lower); i++ {
+		match := true
+		for j := 0; j < len(q); j++ {
+			if lower[i+j] != q[j] {
+				match = false
+				break
+			}
+		}
+		if match {
+			return i
+		}
+	}
+	return -1
+}
+
+// toLowerRune lowercases ASCII letters (the only case-bearing script here); CJK
+// and other runes pass through unchanged.
+func toLowerRune(r rune) rune {
+	if r >= 'A' && r <= 'Z' {
+		return r + ('a' - 'A')
+	}
+	return r
+}

internal/docs/search_test.go

@@ -0,0 +1,111 @@
+package docs
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+func TestSearch(t *testing.T) {
+	srv := newFullServer(t)
+
+	createDoc(t, srv, "My Essay", "The quick brown fox jumps over the lazy dog")
+	createDoc(t, srv, "我的日记", "今天天气很好，我去公园散步，心情非常愉快")
+	createDoc(t, srv, "Notes", "groceries and errands for the weekend")
+
+	search := func(q string) []searchResult {
+		t.Helper()
+		rec := do(t, srv, http.MethodGet, "/search?q="+urlQuery(q), "")
+		if rec.Code != http.StatusOK {
+			t.Fatalf("search %q: %d %s", q, rec.Code, rec.Body)
+		}
+		var out []searchResult
+		if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+			t.Fatalf("decode search %q: %v", q, err)
+		}
+		return out
+	}
+
+	// English, ≥3 chars → FTS path. Snippet wraps the match in sentinels.
+	res := search("quick")
+	if len(res) != 1 || res[0].Title != "My Essay" {
+		t.Fatalf("english search: %+v", res)
+	}
+	if !strings.Contains(res[0].Snippet, hlStart+"quick"+hlEnd) {
+		t.Fatalf("snippet not highlighted: %q", res[0].Snippet)
+	}
+
+	// Chinese, ≥3 chars → FTS path (trigram handles CJK).
+	res = search("天气很好")
+	if len(res) != 1 || res[0].Title != "我的日记" {
+		t.Fatalf("chinese fts search: %+v", res)
+	}
+	if !strings.Contains(res[0].Snippet, hlStart+"天气很好"+hlEnd) {
+		t.Fatalf("cjk snippet not highlighted: %q", res[0].Snippet)
+	}
+
+	// 2-character Chinese word → LIKE fallback (below the trigram minimum).
+	res = search("公园")
+	if len(res) != 1 || res[0].Title != "我的日记" {
+		t.Fatalf("cjk short (LIKE) search: %+v", res)
+	}
+	if !strings.Contains(res[0].Snippet, hlStart+"公园"+hlEnd) {
+		t.Fatalf("short cjk snippet not highlighted: %q", res[0].Snippet)
+	}
+
+	// Title-only match still returns the doc, highlighting the title.
+	res = search("Notes")
+	if len(res) != 1 || res[0].Title != "Notes" {
+		t.Fatalf("title search: %+v", res)
+	}
+
+	// Case-insensitive.
+	if got := search("QUICK"); len(got) != 1 {
+		t.Fatalf("case-insensitive search: %+v", got)
+	}
+
+	// No match → empty (non-nil) array.
+	if got := search("zzzznotthere"); len(got) != 0 {
+		t.Fatalf("expected no results, got %+v", got)
+	}
+
+	// Empty query → empty array, no error.
+	rec := do(t, srv, http.MethodGet, "/search?q=", "")
+	if rec.Code != http.StatusOK || strings.TrimSpace(rec.Body.String()) != "[]" {
+		t.Fatalf("empty query: %d %s", rec.Code, rec.Body)
+	}
+
+	// An edit re-indexes via the update trigger: the old term stops matching, the
+	// new term starts.
+	res = search("quick")
+	docID := res[0].ID
+	body := `{"content":"{}","content_text":"the slow purple turtle ambles along","word_count":6}`
+	do(t, srv, http.MethodPut, "/docs/"+docID, body)
+	if got := search("quick"); len(got) != 0 {
+		t.Fatalf("stale term still matches after edit: %+v", got)
+	}
+	if got := search("purple turtle"); len(got) != 1 || got[0].ID != docID {
+		t.Fatalf("new term not indexed after edit: %+v", got)
+	}
+}
+
+// urlQuery percent-encodes a search term for the query string.
+func urlQuery(s string) string {
+	var b strings.Builder
+	for _, r := range []byte(s) {
+		if r == ' ' {
+			b.WriteByte('+')
+		} else if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') {
+			b.WriteByte(r)
+		} else {
+			b.WriteString(percentByte(r))
+		}
+	}
+	return b.String()
+}
+
+func percentByte(b byte) string {
+	const hex = "0123456789ABCDEF"
+	return string([]byte{'%', hex[b>>4], hex[b&0xf]})
+}

internal/docs/tags.go

@@ -0,0 +1,303 @@
+package docs
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// validTagColors is the palette a tag may use, mirrored from the design tokens.
+// An unknown color on input is coerced to rose so the UI always has a token.
+var validTagColors = map[string]bool{
+	db.TagColorRose: true, db.TagColorMint: true, db.TagColorPeach: true,
+	db.TagColorLavender: true, db.TagColorSky: true, db.TagColorHoney: true,
+}
+
+func normalizeColor(c string) string {
+	if validTagColors[c] {
+		return c
+	}
+	return db.TagColorRose
+}
+
+// TagRoutes returns the router mounted at /api/tags for tag management (the
+// roster the writer creates and recolors), separate from the per-document
+// assignment routes registered on the docs router.
+func (h *Handler) TagRoutes() chi.Router {
+	r := chi.NewRouter()
+	r.Get("/", h.listTags)
+	r.Post("/", h.createTag)
+	r.Patch("/{id}", h.updateTag)
+	r.Delete("/{id}", h.deleteTag)
+	return r
+}
+
+// registerTagRoutes adds the per-document tag assignment routes onto the docs
+// sub-router so they resolve under /api/docs/{id}/tags.
+func (h *Handler) registerTagRoutes(r chi.Router) {
+	r.Post("/{id}/tags", h.assignTag)
+	r.Delete("/{id}/tags/{tagId}", h.unassignTag)
+}
+
+// listTags returns the user's tags alphabetically, each with the number of
+// documents that wear it (so the sidebar can show counts and hide empties later
+// if desired).
+func (h *Handler) listTags(w http.ResponseWriter, r *http.Request) {
+	rows, err := h.DB.Query(
+		`SELECT t.id, t.name, t.color, COUNT(dt.doc_id)
+		   FROM tags t
+		   LEFT JOIN document_tags dt ON dt.tag_id = t.id
+		  WHERE t.user_id = ?
+		  GROUP BY t.id
+		  ORDER BY t.name COLLATE NOCASE`,
+		db.LocalUserID,
+	)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	defer rows.Close()
+
+	out := []db.Tag{} // non-nil so an empty roster serializes as []
+	for rows.Next() {
+		var t db.Tag
+		if err := rows.Scan(&t.ID, &t.Name, &t.Color, &t.DocCount); err != nil {
+			serverError(w, err)
+			return
+		}
+		out = append(out, t)
+	}
+	if err := rows.Err(); err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, out)
+}
+
+type tagRequest struct {
+	Name  string `json:"name"`
+	Color string `json:"color"`
+}
+
+// createTag adds a tag. It's idempotent on (user, name): re-creating an existing
+// tag returns it unchanged rather than erroring, so the client can "create or
+// reuse" in one call. Recoloring is done via updateTag.
+func (h *Handler) createTag(w http.ResponseWriter, r *http.Request) {
+	var req tagRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		badRequest(w, "invalid JSON body")
+		return
+	}
+	name := strings.TrimSpace(req.Name)
+	if name == "" {
+		badRequest(w, "tag name is required")
+		return
+	}
+
+	var t db.Tag
+	err := h.DB.QueryRow(
+		`INSERT INTO tags (user_id, name, color) VALUES (?, ?, ?)
+		 ON CONFLICT(user_id, name) DO UPDATE SET name = excluded.name
+		 RETURNING id, name, color`,
+		db.LocalUserID, name, normalizeColor(req.Color),
+	).Scan(&t.ID, &t.Name, &t.Color)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusCreated, t)
+}
+
+// updateTag renames and/or recolors a tag. Both fields optional via pointers so
+// a recolor needn't resend the name.
+func (h *Handler) updateTag(w http.ResponseWriter, r *http.Request) {
+	id := chi.URLParam(r, "id")
+
+	var req struct {
+		Name  *string `json:"name"`
+		Color *string `json:"color"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		badRequest(w, "invalid JSON body")
+		return
+	}
+
+	var namePtr, colorPtr any
+	if req.Name != nil {
+		n := strings.TrimSpace(*req.Name)
+		if n == "" {
+			badRequest(w, "tag name cannot be empty")
+			return
+		}
+		namePtr = n
+	}
+	if req.Color != nil {
+		colorPtr = normalizeColor(*req.Color)
+	}
+
+	res, err := h.DB.Exec(
+		`UPDATE tags
+		    SET name  = COALESCE(?, name),
+		        color = COALESCE(?, color)
+		  WHERE id = ? AND user_id = ?`,
+		namePtr, colorPtr, id, db.LocalUserID,
+	)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	if n, _ := res.RowsAffected(); n == 0 {
+		notFoundMsg(w, "tag not found")
+		return
+	}
+
+	var t db.Tag
+	if err := h.DB.QueryRow(
+		`SELECT id, name, color FROM tags WHERE id = ? AND user_id = ?`,
+		id, db.LocalUserID,
+	).Scan(&t.ID, &t.Name, &t.Color); err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, t)
+}
+
+// deleteTag removes a tag; its document assignments cascade away via the FK.
+func (h *Handler) deleteTag(w http.ResponseWriter, r *http.Request) {
+	res, err := h.DB.Exec(
+		`DELETE FROM tags WHERE id = ? AND user_id = ?`,
+		chi.URLParam(r, "id"), db.LocalUserID,
+	)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	if n, _ := res.RowsAffected(); n == 0 {
+		notFoundMsg(w, "tag not found")
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// assignTag attaches a tag to a document. Both must belong to the local user;
+// the assignment is idempotent (re-assigning is a no-op, not an error).
+func (h *Handler) assignTag(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+
+	var req struct {
+		TagID string `json:"tag_id"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		badRequest(w, "invalid JSON body")
+		return
+	}
+	if req.TagID == "" {
+		badRequest(w, "tag_id is required")
+		return
+	}
+
+	// Verify both the doc and the tag belong to the user before linking, so a
+	// stray id can't cross-link another account's rows.
+	if !h.ownsDoc(docID) {
+		notFound(w)
+		return
+	}
+	if !h.ownsTag(req.TagID) {
+		notFoundMsg(w, "tag not found")
+		return
+	}
+
+	if _, err := h.DB.Exec(
+		`INSERT INTO document_tags (doc_id, tag_id) VALUES (?, ?)
+		 ON CONFLICT(doc_id, tag_id) DO NOTHING`,
+		docID, req.TagID,
+	); err != nil {
+		serverError(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// unassignTag detaches a tag from a document.
+func (h *Handler) unassignTag(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+	tagID := chi.URLParam(r, "tagId")
+
+	if !h.ownsDoc(docID) {
+		notFound(w)
+		return
+	}
+	if _, err := h.DB.Exec(
+		`DELETE FROM document_tags WHERE doc_id = ? AND tag_id = ?`,
+		docID, tagID,
+	); err != nil {
+		serverError(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// ownsDoc reports whether a document belongs to the local user.
+func (h *Handler) ownsDoc(docID string) bool {
+	var exists bool
+	_ = h.DB.QueryRow(
+		`SELECT EXISTS(SELECT 1 FROM documents WHERE id = ? AND user_id = ?)`,
+		docID, db.LocalUserID,
+	).Scan(&exists)
+	return exists
+}
+
+// ownsTag reports whether a tag belongs to the local user.
+func (h *Handler) ownsTag(tagID string) bool {
+	var exists bool
+	_ = h.DB.QueryRow(
+		`SELECT EXISTS(SELECT 1 FROM tags WHERE id = ? AND user_id = ?)`,
+		tagID, db.LocalUserID,
+	).Scan(&exists)
+	return exists
+}
+
+// tagsByDoc loads the tags for a set of documents in one query and groups them
+// by doc id. Used to decorate the document list and search results without an
+// N+1 of per-doc queries. Returns an empty (non-nil) map when ids is empty.
+func (h *Handler) tagsByDoc(ids []string) (map[string][]db.Tag, error) {
+	out := map[string][]db.Tag{}
+	if len(ids) == 0 {
+		return out, nil
+	}
+
+	// Build the IN (?, ?, …) placeholder list.
+	ph := strings.TrimSuffix(strings.Repeat("?,", len(ids)), ",")
+	args := make([]any, 0, len(ids)+1)
+	for _, id := range ids {
+		args = append(args, id)
+	}
+	args = append(args, db.LocalUserID)
+
+	rows, err := h.DB.Query(
+		`SELECT dt.doc_id, t.id, t.name, t.color
+		   FROM document_tags dt
+		   JOIN tags t ON t.id = dt.tag_id
+		  WHERE dt.doc_id IN (`+ph+`) AND t.user_id = ?
+		  ORDER BY t.name COLLATE NOCASE`,
+		args...,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var docID string
+		var t db.Tag
+		if err := rows.Scan(&docID, &t.ID, &t.Name, &t.Color); err != nil {
+			return nil, err
+		}
+		out[docID] = append(out[docID], t)
+	}
+	return out, rows.Err()
+}

internal/docs/tags_test.go

@@ -0,0 +1,167 @@
+package docs
+
+import (
+	"encoding/json"
+	"net/http"
+	"path/filepath"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// newFullServer mounts the document, tag, and search routers under the same base
+// paths as the real server (/docs, /tags, /search) so tests can exercise the
+// cross-router flows (create a doc, tag it, list, search).
+func newFullServer(t *testing.T) http.Handler {
+	t.Helper()
+	database, err := db.Open(filepath.Join(t.TempDir(), "test.db"))
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+	t.Cleanup(func() { database.Close() })
+
+	h := New(database)
+	r := chi.NewRouter()
+	r.Mount("/docs", h.Routes())
+	r.Mount("/tags", h.TagRoutes())
+	r.Mount("/search", h.SearchRoutes())
+	return r
+}
+
+// createDoc makes a document with the given title/body and returns its id.
+func createDoc(t *testing.T, srv http.Handler, title, text string) string {
+	t.Helper()
+	rec := do(t, srv, http.MethodPost, "/docs", "")
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("create doc: %d %s", rec.Code, rec.Body)
+	}
+	var d db.Document
+	_ = json.Unmarshal(rec.Body.Bytes(), &d)
+
+	body, _ := json.Marshal(map[string]any{
+		"title": title, "content": "{}", "content_text": text, "word_count": 1,
+	})
+	rec = do(t, srv, http.MethodPut, "/docs/"+d.ID, string(body))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("save doc: %d %s", rec.Code, rec.Body)
+	}
+	return d.ID
+}
+
+func TestTagLifecycle(t *testing.T) {
+	srv := newFullServer(t)
+
+	// Empty roster serializes as [].
+	rec := do(t, srv, http.MethodGet, "/tags", "")
+	if rec.Code != http.StatusOK || rec.Body.String() == "null\n" {
+		t.Fatalf("empty tags: %d %s", rec.Code, rec.Body)
+	}
+
+	// Create a tag.
+	rec = do(t, srv, http.MethodPost, "/tags", `{"name":"日记","color":"lavender"}`)
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("create tag: %d %s", rec.Code, rec.Body)
+	}
+	var tag db.Tag
+	_ = json.Unmarshal(rec.Body.Bytes(), &tag)
+	if tag.ID == "" || tag.Name != "日记" || tag.Color != "lavender" {
+		t.Fatalf("bad created tag: %+v", tag)
+	}
+
+	// Re-creating the same name is idempotent (returns the same id, keeps color).
+	rec = do(t, srv, http.MethodPost, "/tags", `{"name":"日记","color":"sky"}`)
+	var again db.Tag
+	_ = json.Unmarshal(rec.Body.Bytes(), &again)
+	if again.ID != tag.ID || again.Color != "lavender" {
+		t.Fatalf("create not idempotent: %+v vs %+v", again, tag)
+	}
+
+	// Unknown color is coerced to rose.
+	rec = do(t, srv, http.MethodPost, "/tags", `{"name":"work","color":"chartreuse"}`)
+	var work db.Tag
+	_ = json.Unmarshal(rec.Body.Bytes(), &work)
+	if work.Color != "rose" {
+		t.Fatalf("unknown color not coerced: %+v", work)
+	}
+
+	// Empty name is rejected.
+	if rec = do(t, srv, http.MethodPost, "/tags", `{"name":"  "}`); rec.Code != http.StatusBadRequest {
+		t.Fatalf("empty name should be 400: %d", rec.Code)
+	}
+
+	// Recolor + rename via PATCH.
+	rec = do(t, srv, http.MethodPatch, "/tags/"+tag.ID, `{"color":"honey"}`)
+	var recolored db.Tag
+	_ = json.Unmarshal(rec.Body.Bytes(), &recolored)
+	if recolored.Color != "honey" || recolored.Name != "日记" {
+		t.Fatalf("patch clobbered/failed: %+v", recolored)
+	}
+
+	// Assign both tags to a document.
+	docID := createDoc(t, srv, "My Journal", "today was a good day")
+	if rec = do(t, srv, http.MethodPost, "/docs/"+docID+"/tags", `{"tag_id":"`+tag.ID+`"}`); rec.Code != http.StatusNoContent {
+		t.Fatalf("assign tag: %d %s", rec.Code, rec.Body)
+	}
+	// Re-assigning is idempotent.
+	if rec = do(t, srv, http.MethodPost, "/docs/"+docID+"/tags", `{"tag_id":"`+tag.ID+`"}`); rec.Code != http.StatusNoContent {
+		t.Fatalf("re-assign tag: %d", rec.Code)
+	}
+	if rec = do(t, srv, http.MethodPost, "/docs/"+docID+"/tags", `{"tag_id":"`+work.ID+`"}`); rec.Code != http.StatusNoContent {
+		t.Fatalf("assign 2nd tag: %d", rec.Code)
+	}
+
+	// The doc list now carries both tags, ordered by name.
+	rec = do(t, srv, http.MethodGet, "/docs", "")
+	var docs []docSummary
+	_ = json.Unmarshal(rec.Body.Bytes(), &docs)
+	if len(docs) != 1 || len(docs[0].Tags) != 2 {
+		t.Fatalf("doc list tags: %+v", docs)
+	}
+
+	// Tag list reports doc counts.
+	rec = do(t, srv, http.MethodGet, "/tags", "")
+	var roster []db.Tag
+	_ = json.Unmarshal(rec.Body.Bytes(), &roster)
+	var found bool
+	for _, rt := range roster {
+		if rt.ID == tag.ID {
+			found = true
+			if rt.DocCount != 1 {
+				t.Fatalf("expected doc_count 1, got %d", rt.DocCount)
+			}
+		}
+	}
+	if !found {
+		t.Fatalf("tag missing from roster: %+v", roster)
+	}
+
+	// Unassign one tag.
+	if rec = do(t, srv, http.MethodDelete, "/docs/"+docID+"/tags/"+work.ID, ""); rec.Code != http.StatusNoContent {
+		t.Fatalf("unassign: %d", rec.Code)
+	}
+	rec = do(t, srv, http.MethodGet, "/docs", "")
+	_ = json.Unmarshal(rec.Body.Bytes(), &docs)
+	if len(docs[0].Tags) != 1 || docs[0].Tags[0].ID != tag.ID {
+		t.Fatalf("after unassign: %+v", docs[0].Tags)
+	}
+
+	// Deleting a tag cascades its assignments away.
+	if rec = do(t, srv, http.MethodDelete, "/tags/"+tag.ID, ""); rec.Code != http.StatusNoContent {
+		t.Fatalf("delete tag: %d", rec.Code)
+	}
+	rec = do(t, srv, http.MethodGet, "/docs", "")
+	_ = json.Unmarshal(rec.Body.Bytes(), &docs)
+	if len(docs[0].Tags) != 0 {
+		t.Fatalf("tag delete did not cascade: %+v", docs[0].Tags)
+	}
+
+	// Assigning a non-existent tag 404s; tagging a non-existent doc 404s.
+	if rec = do(t, srv, http.MethodPost, "/docs/"+docID+"/tags", `{"tag_id":"nope"}`); rec.Code != http.StatusNotFound {
+		t.Fatalf("assign unknown tag: %d", rec.Code)
+	}
+	if rec = do(t, srv, http.MethodPost, "/docs/nope/tags", `{"tag_id":"`+work.ID+`"}`); rec.Code != http.StatusNotFound {
+		t.Fatalf("assign to unknown doc: %d", rec.Code)
+	}
+}

internal/docs/versions.go

@@ -0,0 +1,245 @@
+package docs
+
+import (
+	"database/sql"
+	"errors"
+	"net/http"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// Version-history tuning.
+const (
+	// autoSnapshotInterval is the minimum gap between background ('auto')
+	// snapshots. Auto-save fires every ~1.5s; without a floor we'd store a
+	// version per keystroke-burst. A few minutes keeps history useful for
+	// recovery without unbounded growth.
+	autoSnapshotInterval = 3 * time.Minute
+
+	// maxAutoVersions caps how many 'auto' snapshots we retain per document.
+	// 'manual' and 'pre_restore' versions are never pruned — they're explicit
+	// restore points the writer (or a restore) deliberately created.
+	maxAutoVersions = 40
+)
+
+// versionRoutes registers the history endpoints on the docs sub-router. Paths
+// resolve to /api/docs/{id}/versions...
+func (h *Handler) versionRoutes(r chi.Router) {
+	r.Get("/{id}/versions", h.listVersions)
+	r.Post("/{id}/versions", h.createVersion)            // explicit "save a restore point"
+	r.Get("/{id}/versions/{vid}", h.getVersion)          // full body for preview
+	r.Post("/{id}/versions/{vid}/restore", h.restoreVersion)
+}
+
+// listVersions returns the document's snapshots, newest first, without the heavy
+// content fields (those load on preview/restore).
+func (h *Handler) listVersions(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+
+	// Scope through the documents table so a snapshot is only visible to the
+	// owner of its parent document.
+	rows, err := h.DB.Query(
+		`SELECT v.id, v.doc_id, v.title, v.word_count, v.kind, v.created_at
+		   FROM document_versions v
+		   JOIN documents d ON d.id = v.doc_id
+		  WHERE v.doc_id = ? AND d.user_id = ?
+		  ORDER BY v.created_at DESC`,
+		docID, db.LocalUserID,
+	)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	defer rows.Close()
+
+	out := []db.DocumentVersion{} // non-nil so an empty history serializes as []
+	for rows.Next() {
+		var v db.DocumentVersion
+		if err := rows.Scan(&v.ID, &v.DocID, &v.Title, &v.WordCount, &v.Kind, &v.CreatedAt); err != nil {
+			serverError(w, err)
+			return
+		}
+		out = append(out, v)
+	}
+	if err := rows.Err(); err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, out)
+}
+
+// getVersion returns one snapshot in full (including content) for preview.
+func (h *Handler) getVersion(w http.ResponseWriter, r *http.Request) {
+	v, err := h.fetchVersion(chi.URLParam(r, "id"), chi.URLParam(r, "vid"))
+	if errors.Is(err, sql.ErrNoRows) {
+		notFoundMsg(w, "version not found")
+		return
+	}
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, v)
+}
+
+// createVersion takes an explicit, user-requested ('manual') restore point from
+// the document's current saved state.
+func (h *Handler) createVersion(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+
+	doc, err := h.fetch(docID)
+	if errors.Is(err, sql.ErrNoRows) {
+		notFound(w)
+		return
+	}
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+
+	v, err := h.insertVersion(doc, db.VersionKindManual)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusCreated, v)
+}
+
+// restoreVersion copies a snapshot back onto the live document. Before
+// overwriting, it captures the current state as a 'pre_restore' version so the
+// restore is itself undoable. Returns the restored document.
+func (h *Handler) restoreVersion(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+	vid := chi.URLParam(r, "vid")
+
+	v, err := h.fetchVersion(docID, vid)
+	if errors.Is(err, sql.ErrNoRows) {
+		notFoundMsg(w, "version not found")
+		return
+	}
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+
+	current, err := h.fetch(docID)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	if _, err := h.insertVersion(current, db.VersionKindPreRestore); err != nil {
+		serverError(w, err)
+		return
+	}
+
+	res, err := h.DB.Exec(
+		`UPDATE documents
+		    SET title = ?, content = ?, content_text = ?, word_count = ?,
+		        updated_at = CURRENT_TIMESTAMP
+		  WHERE id = ? AND user_id = ?`,
+		v.Title, v.Content, v.ContentText, v.WordCount, docID, db.LocalUserID,
+	)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	if n, _ := res.RowsAffected(); n == 0 {
+		notFound(w)
+		return
+	}
+
+	doc, err := h.fetch(docID)
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, doc)
+}
+
+// maybeAutoSnapshot records a throttled background snapshot of the just-saved
+// document. It no-ops when the newest snapshot is younger than
+// autoSnapshotInterval, or when the body is unchanged since the last snapshot,
+// so an idle or rename-only save costs nothing. Best-effort: callers log but do
+// not fail the save if this errors. Prunes old 'auto' versions on success.
+func (h *Handler) maybeAutoSnapshot(doc db.Document) error {
+	var (
+		lastAt   time.Time
+		lastText string
+		hasPrev  bool
+	)
+	err := h.DB.QueryRow(
+		`SELECT created_at, content_text FROM document_versions
+		  WHERE doc_id = ? ORDER BY created_at DESC LIMIT 1`,
+		doc.ID,
+	).Scan(&lastAt, &lastText)
+	switch {
+	case errors.Is(err, sql.ErrNoRows):
+		hasPrev = false
+	case err != nil:
+		return err
+	default:
+		hasPrev = true
+	}
+
+	if hasPrev {
+		if lastText == doc.ContentText {
+			return nil // nothing meaningful changed
+		}
+		if time.Since(lastAt) < autoSnapshotInterval {
+			return nil // too soon; let edits accumulate
+		}
+	}
+
+	if _, err := h.insertVersion(doc, db.VersionKindAuto); err != nil {
+		return err
+	}
+	return h.pruneAutoVersions(doc.ID)
+}
+
+// insertVersion writes a snapshot row of the given kind and returns it (without
+// the heavy content fields, matching the list shape).
+func (h *Handler) insertVersion(doc db.Document, kind string) (db.DocumentVersion, error) {
+	var v db.DocumentVersion
+	err := h.DB.QueryRow(
+		`INSERT INTO document_versions (doc_id, title, content, content_text, word_count, kind)
+		 VALUES (?, ?, ?, ?, ?, ?)
+		 RETURNING id, doc_id, title, word_count, kind, created_at`,
+		doc.ID, doc.Title, doc.Content, doc.ContentText, doc.WordCount, kind,
+	).Scan(&v.ID, &v.DocID, &v.Title, &v.WordCount, &v.Kind, &v.CreatedAt)
+	return v, err
+}
+
+// pruneAutoVersions trims a document's 'auto' snapshots to the newest
+// maxAutoVersions, leaving 'manual' and 'pre_restore' restore points intact.
+func (h *Handler) pruneAutoVersions(docID string) error {
+	_, err := h.DB.Exec(
+		`DELETE FROM document_versions
+		  WHERE doc_id = ? AND kind = 'auto'
+		    AND id NOT IN (
+		        SELECT id FROM document_versions
+		         WHERE doc_id = ? AND kind = 'auto'
+		         ORDER BY created_at DESC LIMIT ?
+		    )`,
+		docID, docID, maxAutoVersions,
+	)
+	return err
+}
+
+// fetchVersion loads one full snapshot, scoped to its owner via the parent doc.
+func (h *Handler) fetchVersion(docID, vid string) (db.DocumentVersion, error) {
+	var v db.DocumentVersion
+	err := h.DB.QueryRow(
+		`SELECT v.id, v.doc_id, v.title, v.content, v.content_text, v.word_count, v.kind, v.created_at
+		   FROM document_versions v
+		   JOIN documents d ON d.id = v.doc_id
+		  WHERE v.id = ? AND v.doc_id = ? AND d.user_id = ?`,
+		vid, docID, db.LocalUserID,
+	).Scan(
+		&v.ID, &v.DocID, &v.Title, &v.Content, &v.ContentText,
+		&v.WordCount, &v.Kind, &v.CreatedAt,
+	)
+	return v, err
+}

internal/docs/versions_test.go

@@ -0,0 +1,107 @@
+package docs
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+)
+
+// newDoc creates a document and returns its id.
+func newDoc(t *testing.T, srv http.Handler) string {
+	t.Helper()
+	rec := do(t, srv, http.MethodPost, "/", "")
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("create doc: code=%d body=%s", rec.Code, rec.Body)
+	}
+	var d db.Document
+	if err := json.Unmarshal(rec.Body.Bytes(), &d); err != nil {
+		t.Fatalf("decode doc: %v", err)
+	}
+	return d.ID
+}
+
+func listVersions(t *testing.T, srv http.Handler, id string) []db.DocumentVersion {
+	t.Helper()
+	rec := do(t, srv, http.MethodGet, "/"+id+"/versions", "")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("list versions: code=%d body=%s", rec.Code, rec.Body)
+	}
+	var vs []db.DocumentVersion
+	if err := json.Unmarshal(rec.Body.Bytes(), &vs); err != nil {
+		t.Fatalf("decode versions: %v", err)
+	}
+	return vs
+}
+
+func TestVersionLifecycle(t *testing.T) {
+	srv := newTestServer(t)
+	id := newDoc(t, srv)
+
+	// A bare rename (no content) must not snapshot.
+	do(t, srv, http.MethodPut, "/"+id, `{"title":"Just A Name"}`)
+	if vs := listVersions(t, srv, id); len(vs) != 0 {
+		t.Fatalf("rename should not snapshot, got %d", len(vs))
+	}
+
+	// First real body save takes one auto snapshot (no prior version to throttle).
+	body := `{"content":"{\"type\":\"doc\"}","content_text":"first draft","word_count":2}`
+	do(t, srv, http.MethodPut, "/"+id, body)
+	vs := listVersions(t, srv, id)
+	if len(vs) != 1 || vs[0].Kind != db.VersionKindAuto {
+		t.Fatalf("expected 1 auto version, got %+v", vs)
+	}
+	// List view omits heavy content fields.
+	if vs[0].Content != "" {
+		t.Fatalf("list should omit content, got %q", vs[0].Content)
+	}
+
+	// A near-immediate second save is throttled (no new auto version).
+	do(t, srv, http.MethodPut, "/"+id, `{"content":"{\"type\":\"doc\"}","content_text":"first draft v2","word_count":3}`)
+	if vs := listVersions(t, srv, id); len(vs) != 1 {
+		t.Fatalf("second save within interval should be throttled, got %d", len(vs))
+	}
+
+	// Manual snapshot always records, capturing current saved state.
+	rec := do(t, srv, http.MethodPost, "/"+id+"/versions", "")
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("manual snapshot: code=%d body=%s", rec.Code, rec.Body)
+	}
+	var manual db.DocumentVersion
+	_ = json.Unmarshal(rec.Body.Bytes(), &manual)
+	if manual.Kind != db.VersionKindManual {
+		t.Fatalf("expected manual kind, got %q", manual.Kind)
+	}
+
+	// Mutate the live doc, then restore the manual snapshot.
+	do(t, srv, http.MethodPut, "/"+id, `{"content":"{\"type\":\"doc\"}","content_text":"ruined everything","word_count":2}`)
+	rec = do(t, srv, http.MethodPost, "/"+id+"/versions/"+manual.ID+"/restore", "")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("restore: code=%d body=%s", rec.Code, rec.Body)
+	}
+	var restored db.Document
+	_ = json.Unmarshal(rec.Body.Bytes(), &restored)
+	if restored.ContentText != "first draft v2" {
+		t.Fatalf("restore did not bring back snapshot text: %q", restored.ContentText)
+	}
+
+	// Restore left a pre_restore safety copy, so the bad state is itself recoverable.
+	var foundPreRestore bool
+	for _, v := range listVersions(t, srv, id) {
+		if v.Kind == db.VersionKindPreRestore {
+			foundPreRestore = true
+		}
+	}
+	if !foundPreRestore {
+		t.Fatal("restore should record a pre_restore safety snapshot")
+	}
+}
+
+func TestVersionNotFound(t *testing.T) {
+	srv := newTestServer(t)
+	id := newDoc(t, srv)
+	if rec := do(t, srv, http.MethodGet, "/"+id+"/versions/nope", ""); rec.Code != http.StatusNotFound {
+		t.Fatalf("expected 404 for unknown version, got %d", rec.Code)
+	}
+}

internal/lexicon/data.go

@@ -0,0 +1,29 @@
+// Package lexicon serves offline word lookups — a Chinese gloss, a definition,
+// and a list of synonyms for a single word — from public datasets compiled into
+// the binary. Definitions come from the Wordset dictionary (modern, concise
+// glosses with a part of speech and example, which read kindly for an ESL
+// writer); synonyms come from the Moby Thesaurus; the Chinese gloss comes from
+// ECDICT. All are gzipped JSON, decompressed lazily on first use so a writer who
+// never looks up a word pays nothing.
+package lexicon
+
+import _ "embed"
+
+// definitionsGz is the gzipped Wordset definitions map: word → [[pos, def,
+// example], …], lowercase keys. Built by the data-prep step (see commit notes).
+//
+//go:embed data/definitions.json.gz
+var definitionsGz []byte
+
+// synonymsGz is the gzipped Moby thesaurus map: headword → [synonym, …],
+// lowercase keys, capped per word to keep the popover (and the binary) small.
+//
+//go:embed data/synonyms.json.gz
+var synonymsGz []byte
+
+// glossGz is the gzipped English→Chinese gloss map: word → 中文 gloss, lowercase
+// keys. Built from ECDICT (scripts/build_gloss.py), filtered to common words so
+// an ESL writer who speaks Mandarin gets an instant translation on hover/lookup.
+//
+//go:embed data/gloss.json.gz
+var glossGz []byte

internal/lexicon/handlers.go

@@ -0,0 +1,81 @@
+package lexicon
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/url"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// Handler serves the word-lookup endpoint backed by a single shared Lexicon.
+type Handler struct {
+	Lex *Lexicon
+}
+
+// New constructs a Handler with a fresh (lazily-loaded) Lexicon.
+func NewHandler() *Handler { return &Handler{Lex: New()} }
+
+// Routes returns the router mounted at /api/word. The word is a path segment so
+// "/api/word/happy" reads naturally; it's URL-decoded to tolerate the rare
+// punctuated token.
+func (h *Handler) Routes() chi.Router {
+	r := chi.NewRouter()
+	r.Get("/{word}", h.lookup)
+	return r
+}
+
+// GlossRoutes returns the router mounted at /api/gloss — the lightweight
+// Chinese-only lookup behind the inline hover/select gloss. It shares the
+// Handler's Lexicon, so the datasets still load just once.
+func (h *Handler) GlossRoutes() chi.Router {
+	r := chi.NewRouter()
+	r.Get("/{word}", h.gloss)
+	return r
+}
+
+// lookup returns the definition + synonyms for one word. A word found in neither
+// dataset still returns 200 with empty lists, so the popover can show a friendly
+// "nothing found" rather than an error state.
+func (h *Handler) lookup(w http.ResponseWriter, r *http.Request) {
+	word := chi.URLParam(r, "word")
+	if decoded, err := url.PathUnescape(word); err == nil {
+		word = decoded
+	}
+
+	res, err := h.Lex.Lookup(word)
+	if err != nil {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusInternalServerError)
+		_ = json.NewEncoder(w).Encode(map[string]string{"error": err.Error()})
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	// Word lookups are static for the life of the build; let the browser cache
+	// them so repeated right-clicks on the same word are instant.
+	w.Header().Set("Cache-Control", "public, max-age=86400")
+	_ = json.NewEncoder(w).Encode(res)
+}
+
+// gloss returns just the Chinese translation for one word. Like lookup, a miss
+// is a 200 with an empty gloss so the hover tooltip can quietly skip rather than
+// error.
+func (h *Handler) gloss(w http.ResponseWriter, r *http.Request) {
+	word := chi.URLParam(r, "word")
+	if decoded, err := url.PathUnescape(word); err == nil {
+		word = decoded
+	}
+
+	res, err := h.Lex.Gloss(word)
+	if err != nil {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusInternalServerError)
+		_ = json.NewEncoder(w).Encode(map[string]string{"error": err.Error()})
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "public, max-age=86400")
+	_ = json.NewEncoder(w).Encode(res)
+}

internal/lexicon/lexicon.go

@@ -0,0 +1,249 @@
+package lexicon
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+	"sync"
+)
+
+// Meaning is one sense of a word: its part of speech, the gloss, and an optional
+// usage example. The frontend renders a few of these in the word popover.
+type Meaning struct {
+	PartOfSpeech string `json:"part_of_speech"`
+	Definition   string `json:"definition"`
+	Example      string `json:"example,omitempty"`
+}
+
+// Result is the full lookup for one word. Either list may be empty (the word
+// isn't a headword in that dataset); the frontend handles a partial or empty
+// result gracefully. Gloss is the Chinese translation (empty when the word isn't
+// in the gloss dataset) — shown first in the popover for the Mandarin-speaking
+// writer.
+type Result struct {
+	Word        string    `json:"word"`
+	Gloss       string    `json:"gloss"`
+	Definitions []Meaning `json:"definitions"`
+	Synonyms    []string  `json:"synonyms"`
+}
+
+// GlossResult is the lightweight payload for the inline hover/select gloss: just
+// the word and its Chinese translation, no definitions or synonyms. Kept small
+// so the hover tooltip is instant and trivially cacheable.
+type GlossResult struct {
+	Word  string `json:"word"`
+	Gloss string `json:"gloss"`
+}
+
+// maxSynonyms caps how many synonyms we hand the popover, even though the dataset
+// stores up to ~50 per word — a long flat wall of words overwhelms more than it
+// helps, especially for an ESL reader scanning for the right fit.
+const maxSynonyms = 16
+
+// maxDefinitions caps the senses shown so the popover stays a glance, not an
+// essay.
+const maxDefinitions = 4
+
+// Lexicon holds the lazily-loaded datasets. The maps are populated once, on the
+// first Lookup, behind a sync.Once so startup stays instant and a load error is
+// remembered rather than retried on every request.
+type Lexicon struct {
+	once     sync.Once
+	loadErr  error
+	defs     map[string][][]string // word → [[pos, def, example], …]
+	synonyms map[string][]string   // word → [synonym, …]
+	gloss    map[string]string     // word → Chinese gloss
+}
+
+// New returns a Lexicon. The datasets aren't read until the first Lookup.
+func New() *Lexicon { return &Lexicon{} }
+
+func (l *Lexicon) load() {
+	l.once.Do(func() {
+		if err := gunzipJSON(definitionsGz, &l.defs); err != nil {
+			l.loadErr = fmt.Errorf("load definitions: %w", err)
+			return
+		}
+		if err := gunzipJSON(synonymsGz, &l.synonyms); err != nil {
+			l.loadErr = fmt.Errorf("load synonyms: %w", err)
+			return
+		}
+		if err := gunzipJSON(glossGz, &l.gloss); err != nil {
+			l.loadErr = fmt.Errorf("load gloss: %w", err)
+			return
+		}
+	})
+}
+
+// Lookup returns the definition senses and synonyms for word. It first tries the
+// word as written (lowercased), then a few simple morphological reductions
+// (plurals, -ed/-ing/-ly) so "running" or "happily" still resolve. A word found
+// in neither dataset yields a Result with empty lists (not an error).
+func (l *Lexicon) Lookup(word string) (Result, error) {
+	l.load()
+	if l.loadErr != nil {
+		return Result{}, l.loadErr
+	}
+
+	norm := strings.ToLower(strings.TrimSpace(word))
+	res := Result{Word: word, Definitions: []Meaning{}, Synonyms: []string{}}
+	if norm == "" {
+		return res, nil
+	}
+
+	res.Gloss = lookupGloss(l.gloss, norm)
+
+	if raw := lookupDefs(l.defs, norm); raw != nil {
+		for _, m := range raw {
+			res.Definitions = append(res.Definitions, toMeaning(m))
+			if len(res.Definitions) >= maxDefinitions {
+				break
+			}
+		}
+	}
+
+	if syns := lookupSyns(l.synonyms, norm); syns != nil {
+		if len(syns) > maxSynonyms {
+			syns = syns[:maxSynonyms]
+		}
+		res.Synonyms = append(res.Synonyms, syns...)
+	}
+
+	return res, nil
+}
+
+// Gloss returns just the Chinese translation for word (empty when absent). This
+// is the fast path behind the inline hover/select gloss — it skips the
+// definition and synonym datasets entirely.
+func (l *Lexicon) Gloss(word string) (GlossResult, error) {
+	l.load()
+	if l.loadErr != nil {
+		return GlossResult{}, l.loadErr
+	}
+	norm := strings.ToLower(strings.TrimSpace(word))
+	return GlossResult{Word: word, Gloss: lookupGloss(l.gloss, norm)}, nil
+}
+
+// lookupGloss walks the candidate forms of a word and returns the first gloss
+// hit (so "running"/"studies" resolve via the same de-inflection as defs/syns).
+func lookupGloss(m map[string]string, word string) string {
+	if word == "" {
+		return ""
+	}
+	for _, c := range candidates(word) {
+		if v, ok := m[c]; ok {
+			return v
+		}
+	}
+	return ""
+}
+
+// lookupDefs / lookupSyns walk the candidate forms of a word and return the
+// first dataset hit. They're separate (rather than a generic helper) only
+// because the two maps have different value types.
+func lookupDefs(m map[string][][]string, word string) [][]string {
+	for _, c := range candidates(word) {
+		if v, ok := m[c]; ok {
+			return v
+		}
+	}
+	return nil
+}
+
+func lookupSyns(m map[string][]string, word string) []string {
+	for _, c := range candidates(word) {
+		if v, ok := m[c]; ok {
+			return v
+		}
+	}
+	return nil
+}
+
+// candidates returns the lemma forms to try, in priority order: the word itself,
+// then conservative de-inflections. This is deliberately lightweight — a full
+// stemmer would over-reduce ("business" → "busy") and surface wrong entries; a
+// handful of common English suffix rules covers the everyday cases without a
+// dependency. Duplicates are fine (map lookup is cheap); order is what matters.
+func candidates(word string) []string {
+	out := []string{word}
+	add := func(s string) {
+		if len(s) >= 2 && s != word {
+			out = append(out, s)
+		}
+	}
+
+	switch {
+	case strings.HasSuffix(word, "ies"): // studies → study
+		add(word[:len(word)-3] + "y")
+	case strings.HasSuffix(word, "es"): // boxes → box, wishes → wish
+		add(word[:len(word)-2])
+		add(word[:len(word)-1])
+	case strings.HasSuffix(word, "s"): // cats → cat
+		add(word[:len(word)-1])
+	}
+
+	if strings.HasSuffix(word, "ing") { // running → run, making → make
+		stem := word[:len(word)-3]
+		add(stem)
+		add(stem + "e")
+		add(undouble(stem))
+	}
+	if strings.HasSuffix(word, "ed") { // hoped → hope, stopped → stop
+		stem := word[:len(word)-2]
+		add(stem)
+		add(word[:len(word)-1])
+		add(undouble(stem))
+	}
+	if strings.HasSuffix(word, "ly") { // happily handled above via ies path? no — quickly → quick
+		add(word[:len(word)-2])
+	}
+	if strings.HasSuffix(word, "ily") { // happily → happy
+		add(word[:len(word)-3] + "y")
+	}
+
+	return out
+}
+
+// undouble collapses a doubled final consonant (stopp → stop, runn → run) so the
+// -ed/-ing stems of doubled-consonant verbs resolve to their base form.
+func undouble(stem string) string {
+	n := len(stem)
+	if n >= 2 && stem[n-1] == stem[n-2] {
+		return stem[:n-1]
+	}
+	return stem
+}
+
+// toMeaning maps a compact [pos, def, example] triple from the dataset onto the
+// JSON-friendly Meaning. The dataset always stores three elements, but we guard
+// the length so a malformed row can't panic.
+func toMeaning(m []string) Meaning {
+	var out Meaning
+	if len(m) > 0 {
+		out.PartOfSpeech = m[0]
+	}
+	if len(m) > 1 {
+		out.Definition = m[1]
+	}
+	if len(m) > 2 {
+		out.Example = m[2]
+	}
+	return out
+}
+
+// gunzipJSON decompresses gz and decodes the JSON into v.
+func gunzipJSON(gz []byte, v any) error {
+	r, err := gzip.NewReader(bytes.NewReader(gz))
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(data, v)
+}

internal/lexicon/lexicon_test.go

@@ -0,0 +1,118 @@
+package lexicon
+
+import "testing"
+
+func TestLookupKnownWord(t *testing.T) {
+	l := New()
+	res, err := l.Lookup("happy")
+	if err != nil {
+		t.Fatalf("Lookup: %v", err)
+	}
+	if len(res.Definitions) == 0 {
+		t.Errorf("expected definitions for %q, got none", "happy")
+	}
+	if len(res.Synonyms) == 0 {
+		t.Errorf("expected synonyms for %q, got none", "happy")
+	}
+	if len(res.Synonyms) > maxSynonyms {
+		t.Errorf("synonyms not capped: got %d, want <= %d", len(res.Synonyms), maxSynonyms)
+	}
+	if len(res.Definitions) > maxDefinitions {
+		t.Errorf("definitions not capped: got %d, want <= %d", len(res.Definitions), maxDefinitions)
+	}
+}
+
+func TestLookupMorphology(t *testing.T) {
+	l := New()
+	// Inflected forms should resolve to their base entry via candidates().
+	for _, w := range []string{"running", "studies", "boxes", "quickly", "stopped"} {
+		res, err := l.Lookup(w)
+		if err != nil {
+			t.Fatalf("Lookup(%q): %v", w, err)
+		}
+		if len(res.Definitions) == 0 && len(res.Synonyms) == 0 {
+			t.Errorf("expected some result for inflected %q, got nothing", w)
+		}
+	}
+}
+
+func TestLookupUnknownWord(t *testing.T) {
+	l := New()
+	res, err := l.Lookup("zzzxqqq")
+	if err != nil {
+		t.Fatalf("Lookup: %v", err)
+	}
+	if len(res.Definitions) != 0 || len(res.Synonyms) != 0 {
+		t.Errorf("expected empty result for nonsense word, got %+v", res)
+	}
+	// Empty result must still serialize as [] not null for the frontend.
+	if res.Definitions == nil || res.Synonyms == nil {
+		t.Errorf("empty slices must be non-nil for JSON []: %+v", res)
+	}
+}
+
+func TestGloss(t *testing.T) {
+	l := New()
+	// A common word carries a Chinese gloss...
+	res, err := l.Gloss("river")
+	if err != nil {
+		t.Fatalf("Gloss: %v", err)
+	}
+	if res.Word != "river" {
+		t.Errorf("Word = %q, want %q", res.Word, "river")
+	}
+	if res.Gloss == "" {
+		t.Errorf("expected a Chinese gloss for %q, got none", "river")
+	}
+	// ...and the inflected form resolves via the same de-inflection.
+	inflected, err := l.Gloss("rivers")
+	if err != nil {
+		t.Fatalf("Gloss(rivers): %v", err)
+	}
+	if inflected.Gloss == "" {
+		t.Errorf("expected a gloss for inflected %q, got none", "rivers")
+	}
+	// A nonsense word is a clean empty (not an error).
+	miss, err := l.Gloss("zzzxqqq")
+	if err != nil {
+		t.Fatalf("Gloss(miss): %v", err)
+	}
+	if miss.Gloss != "" {
+		t.Errorf("expected empty gloss for nonsense word, got %q", miss.Gloss)
+	}
+}
+
+func TestLookupIncludesGloss(t *testing.T) {
+	l := New()
+	res, err := l.Lookup("happy")
+	if err != nil {
+		t.Fatalf("Lookup: %v", err)
+	}
+	if res.Gloss == "" {
+		t.Errorf("expected Lookup to include a Chinese gloss for %q", "happy")
+	}
+}
+
+func TestCandidates(t *testing.T) {
+	cases := map[string]string{
+		"cats":    "cat",
+		"studies": "study",
+		"running": "run",
+		"hoped":   "hope",
+		"quickly": "quick",
+		"happily": "happy",
+	}
+	for word, want := range cases {
+		got := candidates(word)
+		found := false
+		for _, c := range got {
+			if c == want {
+				found = true
+				break
+			}
+		}
+		if !found {
+			t.Errorf("candidates(%q) = %v, missing expected base %q", word, got, want)
+		}
+	}
+}

internal/llm/checkpoint.go

@@ -31,9 +31,9 @@ type checkpointResponse struct {
 // RunCheckpoint sends the grammar checkpoint and parses the JSON result. It
 // applies the latency-guard truncation and the checkpoint sampling parameters
 // from the spec.
-func RunCheckpoint(ctx context.Context, client LLMClient, contentText string) ([]RawSuggestion, error) {
+func RunCheckpoint(ctx context.Context, client LLMClient, contentText, tone string) ([]RawSuggestion, error) {
 	raw, err := client.Complete(ctx, CompletionRequest{
-		Messages:          CheckpointMessages(TruncateDoc(contentText)),
+		Messages:          CheckpointMessages(TruncateDoc(contentText), tone),
 		MaxTokens:         1024,
 		Temperature:       0.3,
 		RepetitionPenalty: 1.15,

internal/llm/prompts.go

@@ -8,7 +8,7 @@ const checkpointSystemPrompt = `You are a warm, encouraging writing assistant he
 	`Analyze the text below and identify up to 5 issues: grammar errors, unnatural phrasing, ` +
 	`incorrect idiom usage, or unclear sentences that are common ESL patterns.
 
-Be specific, friendly, and explain WHY each suggestion improves the writing.
+Be specific, friendly, and explain WHY each suggestion improves the writing.%s
 
 Respond ONLY with valid JSON. No preamble, no markdown fences. Format:
 {
@@ -24,11 +24,32 @@ Respond ONLY with valid JSON. No preamble, no markdown fences. Format:
 
 If the writing looks good, return: {"suggestions": []}`
 
+// toneGuidance returns a sentence steering the checkpoint toward the writer's
+// chosen tone, or "" for the neutral default. The clause is appended to the
+// checkpoint instructions so the model's phrasing suggestions fit the target
+// register (e.g. an academic essay vs a casual journal). Unknown values fall
+// back to no steering, so a stray tone string is harmless.
+func toneGuidance(tone string) string {
+	clause, ok := map[string]string{
+		"academic":     "formal, academic, and objective — suited to a school essay or research paper",
+		"professional": "polished and professional — suited to a workplace email or report",
+		"casual":       "relaxed, friendly, and conversational",
+		"humorous":     "light, playful, and good-humored",
+		"creative":     "vivid, expressive, and imaginative — suited to a story or personal narrative",
+		"persuasive":   "confident and persuasive — suited to an argument or opinion piece",
+	}[tone]
+	if !ok {
+		return ""
+	}
+	return "\n\nThe writer wants this document to read as " + clause + ". When phrasing could " +
+		"be improved, prefer suggestions that fit that tone, and gently flag wording that clashes with it."
+}
+
 // CheckpointMessages builds the message array for a grammar checkpoint over the
-// given (already-truncated) document text.
-func CheckpointMessages(contentText string) []Message {
+// given (already-truncated) document text, steered toward the document's tone.
+func CheckpointMessages(contentText, tone string) []Message {
 	return []Message{
-		{Role: "system", Content: checkpointSystemPrompt},
+		{Role: "system", Content: fmt.Sprintf(checkpointSystemPrompt, toneGuidance(tone))},
 		{Role: "user", Content: contentText},
 	}
 }
@@ -99,3 +120,48 @@ Keep responses concise (2-4 sentences). This is a chat, not an essay. Be encoura
 func AskPetalSystemPrompt(original, replacement, suggestionType, explanation, paragraph string) string {
 	return fmt.Sprintf(askPetalSystemTemplate, original, replacement, suggestionType, explanation, paragraph)
 }
+
+// rewriteSystemTemplate drives the "say it more naturally" / tone-rewrite tool.
+// The writer selects a passage and picks a style; the model rewrites that
+// passage in place. The instruction is deliberately strict about returning ONLY
+// the rewritten passage so the result can be dropped straight into the editor —
+// no quotes, no preamble, no commentary to strip.
+const rewriteSystemTemplate = `You are Petal, a warm English writing assistant helping someone who speaks English ` +
+	`as a second language. Rewrite the passage the user sends so that it %s, while preserving its original ` +
+	`meaning. Fix any grammar mistakes and awkward phrasing along the way. Keep it about the same length — ` +
+	`do not add new ideas, explanations, or commentary.
+
+Respond with ONLY the rewritten passage. No quotation marks around it, no preamble, no notes — just the ` +
+	`rewritten English text, ready to drop back into the document.`
+
+// styleGuidance maps a rewrite style onto the clause describing the target
+// register. "natural" is the default "say it more naturally" action; the rest
+// mirror the document-tone vocabulary (see toneGuidance / the ToneSelect UI).
+// An unknown style falls back to the natural rewrite.
+func styleGuidance(style string) string {
+	switch style {
+	case "academic":
+		return "reads as formal, academic English suited to a school essay or research paper"
+	case "professional":
+		return "reads as polished, professional English suited to a workplace email or report"
+	case "casual":
+		return "sounds relaxed, friendly, and conversational"
+	case "humorous":
+		return "has a light, playful, good-humored tone"
+	case "creative":
+		return "is vivid, expressive, and imaginative"
+	case "persuasive":
+		return "is confident and persuasive"
+	default: // "natural"
+		return "sounds natural and fluent, the way a native English speaker would naturally say it"
+	}
+}
+
+// RewriteMessages builds the message array for a tone-rewrite: the styled system
+// instruction plus the passage to rewrite as the user turn.
+func RewriteMessages(text, style string) []Message {
+	return []Message{
+		{Role: "system", Content: fmt.Sprintf(rewriteSystemTemplate, styleGuidance(style))},
+		{Role: "user", Content: text},
+	}
+}

internal/llm/rewrite.go

@@ -0,0 +1,46 @@
+package llm
+
+import (
+	"context"
+	"strings"
+)
+
+// RewriteMaxRunes caps how much selected text a single rewrite will accept. A
+// rewrite is a focused "fix this sentence/paragraph" action, not a whole-doc
+// pass — bounding it keeps latency sane and the model on-task. The handler
+// rejects longer selections before calling the model.
+const RewriteMaxRunes = 2000
+
+// RunRewrite rewrites a selected passage in the requested style (e.g. "natural",
+// "academic"). It is a one-shot Complete — the result is shown as a preview the
+// writer accepts or discards, so we want the whole rewrite before rendering.
+func RunRewrite(ctx context.Context, client LLMClient, text, style string) (string, error) {
+	out, err := client.Complete(ctx, CompletionRequest{
+		Messages:          RewriteMessages(text, style),
+		MaxTokens:         1024,
+		Temperature:       0.7,
+		TopP:              0.9,
+		RepetitionPenalty: 1.1,
+	})
+	if err != nil {
+		return "", err
+	}
+	return cleanRewrite(out), nil
+}
+
+// cleanRewrite trims the model's output down to just the rewritten passage. The
+// prompt asks for no quotes or preamble, but small instruct models occasionally
+// wrap the answer in matching quotes — strip a single surrounding pair so the
+// text drops cleanly into the editor.
+func cleanRewrite(s string) string {
+	s = strings.TrimSpace(s)
+	if len(s) >= 2 {
+		first, last := s[0], s[len(s)-1]
+		if (first == '"' && last == '"') ||
+			(first == '\'' && last == '\'') ||
+			(strings.HasPrefix(s, "“") && strings.HasSuffix(s, "”")) {
+			s = strings.TrimSpace(strings.Trim(s, "\"'“”"))
+		}
+	}
+	return s
+}

internal/llm/voice.go

@@ -16,7 +16,10 @@ const VoiceInterval = 20 * time.Second
 // for a Tier-1 voice pass and parses the JSON result. It reuses the checkpoint's
 // tolerant parser and a larger token budget, since one pass may flag several
 // passages. Each flag carries a null replacement (awareness-only).
-func RunVoice(ctx context.Context, client LLMClient, contentText string) ([]RawSuggestion, error) {
+// The tone argument is accepted for a uniform pass signature but ignored: voice
+// consistency is judged against the document's own established voice, not an
+// externally-chosen register.
+func RunVoice(ctx context.Context, client LLMClient, contentText, _ string) ([]RawSuggestion, error) {
 	raw, err := client.Complete(ctx, CompletionRequest{
 		Messages:          VoiceMessages(contentText),
 		MaxTokens:         2048,

internal/suggestions/handlers.go

@@ -44,6 +44,7 @@ func New(database *db.DB, client llm.LLMClient) *Handler {
 func (h *Handler) RegisterDocRoutes(r chi.Router) {
 	r.Post("/{id}/check", h.check)
 	r.Post("/{id}/voice", h.voice)
+	r.Post("/{id}/rewrite", h.rewrite)
 	r.Get("/{id}/suggestions", h.listForDoc)
 }
 
@@ -69,8 +70,9 @@ func (h *Handler) voice(w http.ResponseWriter, r *http.Request) {
 }
 
 // pass is the signature shared by the grammar checkpoint and the voice pass:
-// given the document text it returns the model's raw suggestions.
-type pass func(ctx context.Context, client llm.LLMClient, contentText string) ([]llm.RawSuggestion, error)
+// given the document text and the document's tone it returns the model's raw
+// suggestions. The voice pass ignores tone (see llm.RunVoice).
+type pass func(ctx context.Context, client llm.LLMClient, contentText, tone string) ([]llm.RawSuggestion, error)
 
 // runPass is the shared body for both LLM passes. It loads the document text,
 // enforces the pass's per-document rate limit, runs the model, swaps in the
@@ -79,11 +81,11 @@ type pass func(ctx context.Context, client llm.LLMClient, contentText string) ([
 func (h *Handler) runPass(w http.ResponseWriter, r *http.Request, limiter *llm.RateLimiter, run pass, scope pendingScope) {
 	docID := chi.URLParam(r, "id")
 
-	var contentText string
+	var contentText, tone string
 	err := h.DB.QueryRow(
-		`SELECT content_text FROM documents WHERE id = ? AND user_id = ?`,
+		`SELECT content_text, tone FROM documents WHERE id = ? AND user_id = ?`,
 		docID, db.LocalUserID,
-	).Scan(&contentText)
+	).Scan(&contentText, &tone)
 	if errors.Is(err, sql.ErrNoRows) {
 		errorJSON(w, http.StatusNotFound, "document not found")
 		return
@@ -111,7 +113,7 @@ func (h *Handler) runPass(w http.ResponseWriter, r *http.Request, limiter *llm.R
 		return
 	}
 
-	raw, err := run(r.Context(), h.Client, contentText)
+	raw, err := run(r.Context(), h.Client, contentText, tone)
 	if err != nil {
 		errorJSON(w, http.StatusBadGateway, "llm pass failed: "+err.Error())
 		return

internal/suggestions/rewrite.go

@@ -0,0 +1,76 @@
+package suggestions
+
+import (
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+
+	"gitea.parodia.dev/drwily/petal/internal/db"
+	"gitea.parodia.dev/drwily/petal/internal/llm"
+)
+
+// rewriteRequest is the body the selection bubble posts: the selected passage
+// and the target style ("natural", "academic", …). The text is the client's
+// live selection — unlike a checkpoint, there is nothing to anchor server-side,
+// so the rewrite is stateless and never persisted (the editor applies it
+// directly, and the version history captures the resulting document change).
+type rewriteRequest struct {
+	Text  string `json:"text"`
+	Style string `json:"style"`
+}
+
+type rewriteResponse struct {
+	Rewrite string `json:"rewrite"`
+}
+
+// rewrite runs a one-shot tone-rewrite over a selected passage and returns the
+// rewritten text for the editor to preview. The document id scopes the request
+// to the owner (and reserves room to feed document context to the model later),
+// even though the passage itself rides in the body.
+func (h *Handler) rewrite(w http.ResponseWriter, r *http.Request) {
+	docID := chi.URLParam(r, "id")
+
+	var body rewriteRequest
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		errorJSON(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	text := strings.TrimSpace(body.Text)
+	if text == "" {
+		errorJSON(w, http.StatusBadRequest, "no text to rewrite")
+		return
+	}
+	if len([]rune(text)) > llm.RewriteMaxRunes {
+		errorJSON(w, http.StatusBadRequest, "selection too long to rewrite")
+		return
+	}
+
+	// Scope to the owner so a stray id can't drive rewrites against another
+	// user's document (and 404 cleanly when it doesn't exist).
+	var exists int
+	err := h.DB.QueryRow(
+		`SELECT 1 FROM documents WHERE id = ? AND user_id = ?`,
+		docID, db.LocalUserID,
+	).Scan(&exists)
+	if errors.Is(err, sql.ErrNoRows) {
+		errorJSON(w, http.StatusNotFound, "document not found")
+		return
+	}
+	if err != nil {
+		serverError(w, err)
+		return
+	}
+
+	out, err := llm.RunRewrite(r.Context(), h.Client, text, body.Style)
+	if err != nil {
+		errorJSON(w, http.StatusBadGateway, "rewrite failed: "+err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusOK, rewriteResponse{Rewrite: out})
+}

internal/suggestions/rewrite_test.go

@@ -0,0 +1,79 @@
+package suggestions
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"strings"
+	"testing"
+
+	"gitea.parodia.dev/drwily/petal/internal/llm"
+)
+
+// recordingClient captures the last Complete request so the rewrite test can
+// assert the styled system prompt and the selected passage reached the model.
+type recordingClient struct {
+	response string
+	last     llm.CompletionRequest
+}
+
+func (c *recordingClient) Complete(_ context.Context, req llm.CompletionRequest) (string, error) {
+	c.last = req
+	return c.response, nil
+}
+
+func (c *recordingClient) Stream(_ context.Context, _ llm.CompletionRequest) (<-chan string, error) {
+	ch := make(chan string)
+	close(ch)
+	return ch, nil
+}
+
+func TestRewrite(t *testing.T) {
+	// The model wraps its answer in quotes; cleanRewrite should strip them.
+	client := &recordingClient{response: `"I have two apples."`}
+	srv, docID, _ := newTestServer(t, client)
+
+	rec := do(t, srv, http.MethodPost, "/docs/"+docID+"/rewrite",
+		`{"text":"I has two apple.","style":"academic"}`)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("rewrite: code=%d body=%s", rec.Code, rec.Body)
+	}
+	var resp rewriteResponse
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if resp.Rewrite != "I have two apples." {
+		t.Fatalf("rewrite = %q, want the de-quoted text", resp.Rewrite)
+	}
+
+	// The passage rode in as the user turn, and the style steered the system turn.
+	msgs := client.last.Messages
+	if len(msgs) != 2 || msgs[0].Role != "system" || msgs[1].Role != "user" {
+		t.Fatalf("unexpected message shape: %+v", msgs)
+	}
+	if msgs[1].Content != "I has two apple." {
+		t.Fatalf("passage not forwarded: %q", msgs[1].Content)
+	}
+	if !strings.Contains(msgs[0].Content, "academic") {
+		t.Fatalf("system prompt missing academic style guidance:\n%s", msgs[0].Content)
+	}
+}
+
+func TestRewriteEmptyText(t *testing.T) {
+	client := &recordingClient{response: "anything"}
+	srv, docID, _ := newTestServer(t, client)
+	rec := do(t, srv, http.MethodPost, "/docs/"+docID+"/rewrite", `{"text":"   ","style":"natural"}`)
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("empty text: want 400, got %d", rec.Code)
+	}
+}
+
+func TestRewriteUnknownDoc(t *testing.T) {
+	client := &recordingClient{response: "anything"}
+	srv, _, _ := newTestServer(t, client)
+	rec := do(t, srv, http.MethodPost, "/docs/does-not-exist/rewrite",
+		`{"text":"hello there","style":"natural"}`)
+	if rec.Code != http.StatusNotFound {
+		t.Fatalf("unknown doc: want 404, got %d", rec.Code)
+	}
+}

scripts/build_gloss.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python3
+"""Build the embedded English->Chinese gloss dataset from ECDICT.
+
+Petal shows an instant Chinese gloss when the writer (an English-as-a-second-
+language user whose first language is Mandarin) hovers or right-clicks a word.
+The gloss is served offline from a small map compiled into the Go binary, the
+same way the English definitions/synonyms are (see internal/lexicon).
+
+Source: ECDICT (https://github.com/skywind3000/ECDICT), MIT-licensed. We keep
+only common single words that carry a Chinese translation, trim each gloss to a
+couple of senses, and drop the noisy "[网络]" (internet-slang) lines — the result
+gzips to a few MB, in line with the other lexicon assets.
+
+Usage:
+    curl -sL https://raw.githubusercontent.com/skywind3000/ECDICT/master/ecdict.csv -o ecdict.csv
+    python3 scripts/build_gloss.py ecdict.csv internal/lexicon/data/gloss.json.gz
+"""
+import csv
+import gzip
+import json
+import re
+import sys
+
+# Frequency gate: keep a word only if ECDICT ranks it in the BNC or COCA
+# frequency lists (frq/bnc > 0). That bounds the asset to the words an ESL
+# writer actually meets, dropping the long tail of archaic/technical headwords.
+# Words below this rank but present nowhere in the frequency lists are skipped.
+MAX_RANK = 50000
+
+# A gloss is at most this many sense-lines and characters, so the hover bubble
+# stays a glance, not a wall of text.
+MAX_SENSES = 3
+MAX_CHARS = 80
+
+# Single English word: letters, with internal apostrophe/hyphen (so "don't",
+# "well-being" survive but multi-word phrases and codes are dropped).
+WORD_RE = re.compile(r"^[a-z][a-z'\-]*[a-z]$|^[a-z]$")
+
+# Tag lines we drop from a translation: "[网络]" is crowd-sourced internet slang,
+# "[俚]" slang, "[古]" archaic — none help an ESL writer pick everyday meaning.
+DROP_TAG_RE = re.compile(r"^\[(网络|俚|古|罕|废)\]")
+
+
+def clean_gloss(translation: str) -> str:
+    """Trim an ECDICT translation to a compact, glanceable Chinese gloss."""
+    # ECDICT separates senses with a literal backslash-n; normalize to real
+    # newlines (and tolerate genuine newlines) before splitting.
+    translation = translation.replace("\\n", "\n")
+    senses = []
+    for line in translation.split("\n"):
+        line = line.strip()
+        if not line or DROP_TAG_RE.match(line):
+            continue
+        senses.append(line)
+        if len(senses) >= MAX_SENSES:
+            break
+    gloss = "；".join(senses)
+    if len(gloss) > MAX_CHARS:
+        gloss = gloss[:MAX_CHARS].rstrip("；，;, ") + "…"
+    return gloss
+
+
+def rank(row: dict) -> int:
+    """Best (lowest, non-zero) frequency rank across COCA and BNC."""
+    ranks = []
+    for key in ("frq", "bnc"):
+        try:
+            v = int(row.get(key) or 0)
+        except ValueError:
+            v = 0
+        if v > 0:
+            ranks.append(v)
+    return min(ranks) if ranks else 0
+
+
+def main(src: str, dst: str) -> None:
+    out: dict[str, str] = {}
+    kept_rank: dict[str, int] = {}
+    with open(src, newline="", encoding="utf-8") as f:
+        for row in csv.DictReader(f):
+            word = (row.get("word") or "").strip().lower()
+            translation = (row.get("translation") or "").strip()
+            if not word or not translation or not WORD_RE.match(word):
+                continue
+            r = rank(row)
+            if r == 0 or r > MAX_RANK:
+                continue
+            gloss = clean_gloss(translation)
+            if not gloss:
+                continue
+            # On a duplicate headword keep the more frequent (lower-rank) entry.
+            if word in kept_rank and kept_rank[word] <= r:
+                continue
+            out[word] = gloss
+            kept_rank[word] = r
+
+    payload = json.dumps(out, ensure_ascii=False, separators=(",", ":")).encode("utf-8")
+    with gzip.open(dst, "wb", compresslevel=9) as gz:
+        gz.write(payload)
+    print(f"{len(out)} words -> {dst} ({len(payload)} bytes json)")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 3:
+        sys.exit("usage: build_gloss.py <ecdict.csv> <out.json.gz>")
+    main(sys.argv[1], sys.argv[2])

web/package-lock.json

@@ -28,7 +28,8 @@
         "dictionary-en": "^4.0.0",
         "tailwindcss": "^4.0.0",
         "typescript": "^5.7.3",
-        "vite": "^6.1.0"
+        "vite": "^6.1.0",
+        "vitest": "^4.1.9"
       }
     },
     "node_modules/@babel/code-frame": {
@@ -1178,6 +1179,13 @@
         "win32"
       ]
     },
+    "node_modules/@standard-schema/spec": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/@standard-schema/spec/-/spec-1.1.0.tgz",
+      "integrity": "sha512-l2aFy5jALhniG5HgqrD6jXLi/rUWrKvqN/qJx6yoJsgKhblVd+iqqU4RCXavm/jPityDo5TCvKMnpjKnOriy0w==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@tailwindcss/node": {
       "version": "4.3.1",
       "resolved": "https://registry.npmjs.org/@tailwindcss/node/-/node-4.3.1.tgz",
@@ -1934,6 +1942,24 @@
         "@babel/types": "^7.28.2"
       }
     },
+    "node_modules/@types/chai": {
+      "version": "5.2.3",
+      "resolved": "https://registry.npmjs.org/@types/chai/-/chai-5.2.3.tgz",
+      "integrity": "sha512-Mw558oeA9fFbv65/y4mHtXDs9bPnFMZAL/jxdPFUpOHHIXX91mcgEHbS5Lahr+pwZFR8A7GQleRWeI6cGFC2UA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/deep-eql": "*",
+        "assertion-error": "^2.0.1"
+      }
+    },
+    "node_modules/@types/deep-eql": {
+      "version": "4.0.2",
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+    },
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@@ -2010,12 +2036,135 @@
         "vite": "^4.2.0 || ^5.0.0 || ^6.0.0 || ^7.0.0"
       }
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+      "license": "MIT",
+      "dependencies": {
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+        "@types/chai": "^5.2.2",
+        "@vitest/spy": "4.1.9",
+        "@vitest/utils": "4.1.9",
+        "chai": "^6.2.2",
+        "tinyrainbow": "^3.1.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/mocker": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/mocker/-/mocker-4.1.9.tgz",
+      "integrity": "sha512-EVkXzBjrPGM+cK8/ANWgBrkUCfJfb38/EfTSO8h7pWvKkyPkpWxvR7BkD2MyItMF62C97zAEoqdpUixwR/e+Rw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/spy": "4.1.9",
+        "estree-walker": "^3.0.3",
+        "magic-string": "^0.30.21"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "msw": "^2.4.9",
+        "vite": "^6.0.0 || ^7.0.0 || ^8.0.0"
+      },
+      "peerDependenciesMeta": {
+        "msw": {
+          "optional": true
+        },
+        "vite": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/@vitest/pretty-format": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/pretty-format/-/pretty-format-4.1.9.tgz",
+      "integrity": "sha512-s0iufns3iIFitdgm+YR7g1whCAaGtXz459VS9/PqyKDEEFgYIhsHOQmXgIgDuYCt7DeQmiZT0Qe2OA2p4ZPu5A==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "tinyrainbow": "^3.1.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/runner": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/runner/-/runner-4.1.9.tgz",
+      "integrity": "sha512-KXLMDtc7oe70+3mJfGrPUWPesswH+3sTxAMAMl8DG7I8IUQT4XW718dY5ID3vPUcmlu27CcKfY4P3h3I29SLJg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/utils": "4.1.9",
+        "pathe": "^2.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/snapshot": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/snapshot/-/snapshot-4.1.9.tgz",
+      "integrity": "sha512-Jc7RKGNBo8Z28WYIm0Niej4xdSPByRf6mU58VpHQkd6Zh05rlnA+twjbK5HyeIGHxrzsc3mJgS43uM0CZKzaIA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.1.9",
+        "@vitest/utils": "4.1.9",
+        "magic-string": "^0.30.21",
+        "pathe": "^2.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/spy": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/spy/-/spy-4.1.9.tgz",
+      "integrity": "sha512-fHpsS6mIi+PiEW+vcRVOMkX1oSaPKne3VOclSFICPcGOmfKgXPU5iAah+wcNcj2xPrCCmfq99IDGf+EojhhvhA==",
+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/utils": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-4.1.9.tgz",
+      "integrity": "sha512-A51o8ymO5PpqlWNnBP9ZHPXDIpuMtTLlGSjN7la4US+LJzoUMyhwjA5QXlm39JexgwHKW4Xjs8Z2d3dLCXOeuA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.1.9",
+        "convert-source-map": "^2.0.0",
+        "tinyrainbow": "^3.1.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
     "node_modules/argparse": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-2.0.1.tgz",
       "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==",
       "license": "Python-2.0"
     },
+    "node_modules/assertion-error": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
+      "integrity": "sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
     "node_modules/baseline-browser-mapping": {
       "version": "2.10.40",
       "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.10.40.tgz",
@@ -2084,6 +2233,16 @@
       ],
       "license": "CC-BY-4.0"
     },
+    "node_modules/chai": {
+      "version": "6.2.2",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-6.2.2.tgz",
+      "integrity": "sha512-NUPRluOfOiTKBKvWPtSD4PhFvWCqOi0BGStNWs57X9js7XGTprSmFoz5F0tWhR4WPjNeR9jXqdC7/UpSJTnlRg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/convert-source-map": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-2.0.0.tgz",
@@ -2176,6 +2335,13 @@
         "url": "https://github.com/fb55/entities?sponsor=1"
       }
     },
+    "node_modules/es-module-lexer": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-2.1.0.tgz",
+      "integrity": "sha512-n27zTYMjYu1aj4MjCWzSP7G9r75utsaoc8m61weK+W8JMBGGQybd43GstCXZ3WNmSFtGT9wi59qQTW6mhTR5LQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/esbuild": {
       "version": "0.25.12",
       "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.25.12.tgz",
@@ -2240,6 +2406,26 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/estree-walker": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-3.0.3.tgz",
+      "integrity": "sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/estree": "^1.0.0"
+      }
+    },
+    "node_modules/expect-type": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/expect-type/-/expect-type-1.4.0.tgz",
+      "integrity": "sha512-KfYbmpRm0VbLjEvVa9yGwCi9GI34xvi7A/HXYWQO65CSD2u3MczUJSuwXKFIxlGsgBQizV9q5J9NHj4VG0n+pA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=12.0.0"
+      }
+    },
     "node_modules/fast-deep-equal": {
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
@@ -2746,12 +2932,33 @@
         "is-buffer": "^2.0.0"
       }
     },
+    "node_modules/obug": {
+      "version": "2.1.3",
+      "resolved": "https://registry.npmjs.org/obug/-/obug-2.1.3.tgz",
+      "integrity": "sha512-9miFgM2OFba7hB+pRgvtV84pYTBaoTHohvmIgiRt6dRIzbwEOIaNaP+dIlGs2fNFoB0SeISs0Jz5WFVRid6Xyg==",
+      "dev": true,
+      "funding": [
+        "https://github.com/sponsors/sxzz",
+        "https://opencollective.com/debug"
+      ],
+      "license": "MIT",
+      "engines": {
+        "node": ">=12.20.0"
+      }
+    },
     "node_modules/orderedmap": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/orderedmap/-/orderedmap-2.1.1.tgz",
       "integrity": "sha512-TvAWxi0nDe1j/rtMcWcIj94+Ffe6n7zhow33h40SKxmsmozs6dz/e+EajymfoFcHd7sxNn8yHM8839uixMOV6g==",
       "license": "MIT"
     },
+    "node_modules/pathe": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/pathe/-/pathe-2.0.3.tgz",
+      "integrity": "sha512-WUjGcAqP1gQacoQe+OBJsFA7Ld4DyXuUIjZ5cc75cLHvJ7dtNsTugphxIADwspS+AraAUePCKrSVtPLFj/F88w==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/picocolors": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
@@ -3103,6 +3310,13 @@
         "semver": "bin/semver.js"
       }
     },
+    "node_modules/siginfo": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
+      "integrity": "sha512-ybx0WO1/8bSBLEWXZvEd7gMW3Sn3JFlW3TvX1nREbDLRNQNaeNN8WK0meBwPdAaOI7TtRRRJn/Es1zhrrCHu7g==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -3113,6 +3327,20 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/stackback": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
+      "integrity": "sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/std-env": {
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/std-env/-/std-env-4.1.0.tgz",
+      "integrity": "sha512-Rq7ybcX2RuC55r9oaPVEW7/xu3tj8u4GeBYHBWCychFtzMIr86A7e3PPEBPT37sHStKX3+TiX/Fr/ACmJLVlLQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/tailwindcss": {
       "version": "4.3.1",
       "resolved": "https://registry.npmjs.org/tailwindcss/-/tailwindcss-4.3.1.tgz",
@@ -3134,6 +3362,23 @@
         "url": "https://opencollective.com/webpack"
       }
     },
+    "node_modules/tinybench": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/tinybench/-/tinybench-2.9.0.tgz",
+      "integrity": "sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/tinyexec": {
+      "version": "1.2.4",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-1.2.4.tgz",
+      "integrity": "sha512-SHf/r48b7vOrjve9PxJo3MN5v5yuyjHvdUcrQffT3WXMUfnGmHDVbC4k3sHJaJTgZCwpUplIaAo5ANtMyp3YHg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/tinyglobby": {
       "version": "0.2.17",
       "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.17.tgz",
@@ -3151,6 +3396,16 @@
         "url": "https://github.com/sponsors/SuperchupuDev"
       }
     },
+    "node_modules/tinyrainbow": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-3.1.0.tgz",
+      "integrity": "sha512-Bf+ILmBgretUrdJxzXM0SgXLZ3XfiaUuOj/IKQHuTXip+05Xn+uyEYdVg0kYDipTBcLrCVyUzAPz7QmArb0mmw==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.0.0"
+      }
+    },
     "node_modules/tippy.js": {
       "version": "6.3.7",
       "resolved": "https://registry.npmjs.org/tippy.js/-/tippy.js-6.3.7.tgz",
@@ -3295,12 +3550,119 @@
         }
       }
     },
+    "node_modules/vitest": {
+      "version": "4.1.9",
+      "resolved": "https://registry.npmjs.org/vitest/-/vitest-4.1.9.tgz",
+      "integrity": "sha512-nE3/LEyc0z87uHYLZebqCUOaJr2hdtuPp7BQ4BosVFnfltxgAvMG08NyrSGlPpOUWvR27c5flSmYFTNr78L9GQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/expect": "4.1.9",
+        "@vitest/mocker": "4.1.9",
+        "@vitest/pretty-format": "4.1.9",
+        "@vitest/runner": "4.1.9",
+        "@vitest/snapshot": "4.1.9",
+        "@vitest/spy": "4.1.9",
+        "@vitest/utils": "4.1.9",
+        "es-module-lexer": "^2.0.0",
+        "expect-type": "^1.3.0",
+        "magic-string": "^0.30.21",
+        "obug": "^2.1.1",
+        "pathe": "^2.0.3",
+        "picomatch": "^4.0.3",
+        "std-env": "^4.0.0-rc.1",
+        "tinybench": "^2.9.0",
+        "tinyexec": "^1.0.2",
+        "tinyglobby": "^0.2.15",
+        "tinyrainbow": "^3.1.0",
+        "vite": "^6.0.0 || ^7.0.0 || ^8.0.0",
+        "why-is-node-running": "^2.3.0"
+      },
+      "bin": {
+        "vitest": "vitest.mjs"
+      },
+      "engines": {
+        "node": "^20.0.0 || ^22.0.0 || >=24.0.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "@edge-runtime/vm": "*",
+        "@opentelemetry/api": "^1.9.0",
+        "@types/node": "^20.0.0 || ^22.0.0 || >=24.0.0",
+        "@vitest/browser-playwright": "4.1.9",
+        "@vitest/browser-preview": "4.1.9",
+        "@vitest/browser-webdriverio": "4.1.9",
+        "@vitest/coverage-istanbul": "4.1.9",
+        "@vitest/coverage-v8": "4.1.9",
+        "@vitest/ui": "4.1.9",
+        "happy-dom": "*",
+        "jsdom": "*",
+        "vite": "^6.0.0 || ^7.0.0 || ^8.0.0"
+      },
+      "peerDependenciesMeta": {
+        "@edge-runtime/vm": {
+          "optional": true
+        },
+        "@opentelemetry/api": {
+          "optional": true
+        },
+        "@types/node": {
+          "optional": true
+        },
+        "@vitest/browser-playwright": {
+          "optional": true
+        },
+        "@vitest/browser-preview": {
+          "optional": true
+        },
+        "@vitest/browser-webdriverio": {
+          "optional": true
+        },
+        "@vitest/coverage-istanbul": {
+          "optional": true
+        },
+        "@vitest/coverage-v8": {
+          "optional": true
+        },
+        "@vitest/ui": {
+          "optional": true
+        },
+        "happy-dom": {
+          "optional": true
+        },
+        "jsdom": {
+          "optional": true
+        },
+        "vite": {
+          "optional": false
+        }
+      }
+    },
     "node_modules/w3c-keyname": {
       "version": "2.2.8",
       "resolved": "https://registry.npmjs.org/w3c-keyname/-/w3c-keyname-2.2.8.tgz",
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       "license": "MIT"
     },
+    "node_modules/why-is-node-running": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/why-is-node-running/-/why-is-node-running-2.3.0.tgz",
+      "integrity": "sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "siginfo": "^2.0.0",
+        "stackback": "0.0.2"
+      },
+      "bin": {
+        "why-is-node-running": "cli.js"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/yallist": {
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       "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.1.1.tgz",

web/package.json

@@ -6,7 +6,9 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@tiptap/extension-character-count": "^2.11.5",
@@ -29,6 +31,7 @@
     "dictionary-en": "^4.0.0",
     "tailwindcss": "^4.0.0",
     "typescript": "^5.7.3",
-    "vite": "^6.1.0"
+    "vite": "^6.1.0",
+    "vitest": "^4.1.9"
   }
 }

web/src/App.tsx

@@ -1,10 +1,14 @@
 import { useCallback, useEffect, useRef, useState } from 'react'
-import { api, type DocSummary, type Document, type Suggestion } from './api/client'
+import { api, type DocSummary, type Document, type Suggestion, type Tag, type TagColor } from './api/client'
 import { useAutoSave } from './hooks/useAutoSave'
 import { useCheckpoint } from './hooks/useCheckpoint'
 import { useSpellChecker } from './hooks/useSpellChecker'
+import { useTags } from './hooks/useTags'
 import { DocList } from './components/DocList/DocList'
 import { EditorCore, type EditorChange } from './components/Editor/EditorCore'
+import { ToneSelect } from './components/Editor/ToneSelect'
+import { ExportMenu } from './components/Export/ExportMenu'
+import { HistoryPanel } from './components/History/HistoryPanel'
 import { StatusBar } from './components/StatusBar/StatusBar'
 import { PetalCompanion } from './components/Companion/PetalCompanion'
 import { UpdateBanner } from './components/UpdateBanner/UpdateBanner'
@@ -16,41 +20,128 @@ export default function App() {
   const [currentDoc, setCurrentDoc] = useState<Document | null>(null)
   const [title, setTitle] = useState('')
   const [wordCount, setWordCount] = useState(0)
+  // The current document's target tone (steers checkpoint advice) and its live
+  // plain text (drives the expanded writing-stats panel in the StatusBar).
+  const [tone, setTone] = useState('general')
+  const [docText, setDocText] = useState('')
   const [ready, setReady] = useState(false)
   // Distraction-free mode: entered on editor focus, collapses the doc-list
   // sidebar. Escape or a click outside the editor canvas restores it.
   const [focusMode, setFocusMode] = useState(false)
+  // Mobile drawer: below the tablet breakpoint the sidebar is an overlay toggled
+  // by the header hamburger. Ignored on wide screens (sidebar is always in-flow).
+  const [drawerOpen, setDrawerOpen] = useState(false)
   const canvasRef = useRef<HTMLDivElement>(null)
   // Monotonic counters the companion watches to react to writing + accepts.
   const [editTick, setEditTick] = useState(0)
   const [acceptTick, setAcceptTick] = useState(0)
+  // History drawer visibility, and an epoch bumped on restore to force the
+  // editor to remount with the restored content (its initialContent is read
+  // only on mount).
+  const [historyOpen, setHistoryOpen] = useState(false)
+  const [editorEpoch, setEditorEpoch] = useState(0)
+
+  // Live mirrors of the current doc's editable fields so the "discard blank
+  // drafts on navigation" logic can read the latest values without rebuilding
+  // callbacks on every keystroke.
+  const currentDocRef = useRef(currentDoc)
+  const titleRef = useRef(title)
+  const wordCountRef = useRef(wordCount)
+  currentDocRef.current = currentDoc
+  titleRef.current = title
+  wordCountRef.current = wordCount
+
+  // A throwaway blank draft: no words and still the default/empty title. We
+  // delete these on navigation rather than leave orphan "Untitled" docs behind.
+  const isBlankDraft = useCallback(() => {
+    const t = titleRef.current.trim()
+    return wordCountRef.current === 0 && (t === '' || t === 'Untitled')
+  }, [])
 
   const { status, schedule, saveNow } = useAutoSave(currentDoc?.id ?? null)
   const {
     suggestions,
     checking,
     voicing,
+    llmDown,
     schedule: scheduleCheckpoint,
     runVoice,
     removeSuggestion,
   } = useCheckpoint(currentDoc?.id ?? null)
   // Browser-side spell checker — loads the en-US dictionary once per session.
   const { checker: spellChecker, addWord } = useSpellChecker()
+  // The tag roster (with counts). Assignments live on the doc summaries below.
+  const { tags: tagRoster, refresh: refreshTags, createTag } = useTags()
 
   // Patch a summary in the sidebar list (optimistic title / word-count updates).
   const patchSummary = useCallback((id: string, patch: Partial<DocSummary>) => {
     setDocs((prev) => prev.map((d) => (d.id === id ? { ...d, ...patch } : d)))
   }, [])
 
+  // Attach or detach a tag on a document, updating the sidebar optimistically and
+  // refreshing the roster so its counts stay current. Tags are kept sorted by
+  // name to match the server's ordering.
+  const setDocTag = useCallback(
+    async (docId: string, tag: Tag, attach: boolean) => {
+      setDocs((prev) =>
+        prev.map((d) => {
+          if (d.id !== docId) return d
+          const without = d.tags.filter((t) => t.id !== tag.id)
+          const next = attach ? [...without, tag] : without
+          next.sort((a, b) => a.name.localeCompare(b.name, undefined, { sensitivity: 'base' }))
+          return { ...d, tags: next }
+        }),
+      )
+      try {
+        if (attach) await api.assignTag(docId, tag.id)
+        else await api.unassignTag(docId, tag.id)
+        void refreshTags()
+      } catch (err) {
+        console.error('tag assignment failed', err)
+        void refreshTags()
+      }
+    },
+    [refreshTags],
+  )
+
+  const handleToggleTag = useCallback(
+    (docId: string, tag: Tag) => {
+      const doc = docs.find((d) => d.id === docId)
+      const has = doc?.tags.some((t) => t.id === tag.id) ?? false
+      void setDocTag(docId, tag, !has)
+    },
+    [docs, setDocTag],
+  )
+
+  const handleCreateTag = useCallback(
+    async (docId: string, name: string, color: TagColor) => {
+      const tag = await createTag(name, color)
+      if (tag) void setDocTag(docId, tag, true)
+    },
+    [createTag, setDocTag],
+  )
+
   const openDoc = useCallback(
     async (id: string) => {
+      setDrawerOpen(false) // close the mobile drawer when a doc is chosen
+      // Decide the leaving doc's fate before any await mutates state.
+      const leaving = currentDocRef.current
+      const leavingBlank = isBlankDraft()
       await saveNow() // flush any pending edits to the doc we're leaving
       const doc = await api.getDoc(id)
       setCurrentDoc(doc)
       setTitle(doc.title)
       setWordCount(doc.word_count)
+      setTone(doc.tone || 'general')
+      setDocText(doc.content_text)
+      // Leaving an untouched blank draft for a different doc? Drop it silently
+      // (best-effort cleanup — a 404 just means it's already gone).
+      if (leaving && leaving.id !== id && leavingBlank) {
+        api.deleteDoc(leaving.id).catch(() => {})
+        setDocs((prev) => prev.filter((d) => d.id !== leaving.id))
+      }
     },
-    [saveNow],
+    [saveNow, isBlankDraft],
   )
 
   // Initial load: fetch the list, opening the first doc (or creating one).
@@ -63,11 +154,13 @@ export default function App() {
         let list = await api.listDocs()
         if (list.length === 0) {
           const fresh = await api.createDoc()
-          list = [{ id: fresh.id, title: fresh.title, word_count: 0, updated_at: fresh.updated_at }]
+          list = [{ id: fresh.id, title: fresh.title, word_count: 0, updated_at: fresh.updated_at, tags: [] }]
           setDocs(list)
           setCurrentDoc(fresh)
           setTitle(fresh.title)
           setWordCount(0)
+          setTone(fresh.tone || 'general')
+          setDocText('')
         } else {
           setDocs(list)
           await openDoc(list[0].id)
@@ -81,16 +174,21 @@ export default function App() {
   }, [openDoc])
 
   const handleCreate = useCallback(async () => {
+    // Already sitting on a fresh blank draft? Reuse it instead of stacking
+    // another empty "Untitled" on top.
+    if (currentDocRef.current && isBlankDraft()) return
     await saveNow()
     const fresh = await api.createDoc()
     setDocs((prev) => [
-      { id: fresh.id, title: fresh.title, word_count: 0, updated_at: fresh.updated_at },
+      { id: fresh.id, title: fresh.title, word_count: 0, updated_at: fresh.updated_at, tags: [] },
       ...prev,
     ])
     setCurrentDoc(fresh)
     setTitle(fresh.title)
     setWordCount(0)
-  }, [saveNow])
+    setTone(fresh.tone || 'general')
+    setDocText('')
+  }, [saveNow, isBlankDraft])
 
   const handleDelete = useCallback(
     async (id: string) => {
@@ -104,6 +202,8 @@ export default function App() {
             setCurrentDoc(null)
             setTitle('')
             setWordCount(0)
+            setTone('general')
+            setDocText('')
           }
         }
         return remaining
@@ -126,6 +226,7 @@ export default function App() {
   const handleEditorChange = useCallback(
     (change: EditorChange) => {
       setWordCount(change.word_count)
+      setDocText(change.content_text)
       setEditTick((n) => n + 1)
       if (currentDoc) {
         patchSummary(currentDoc.id, { word_count: change.word_count })
@@ -136,6 +237,20 @@ export default function App() {
     [currentDoc, patchSummary, schedule, scheduleCheckpoint],
   )
 
+  // Changing the tone persists it and re-runs the checkpoint so Petal's advice
+  // re-tunes to the new register. The auto-save (1.5s) lands before the
+  // checkpoint debounce (4s), so the server reads the updated tone.
+  const handleToneChange = useCallback(
+    (value: string) => {
+      setTone(value)
+      if (currentDoc) {
+        schedule({ tone: value })
+        scheduleCheckpoint()
+      }
+    },
+    [currentDoc, schedule, scheduleCheckpoint],
+  )
+
   // Accept applies the replacement in the editor (handled in EditorCore) and
   // marks the suggestion accepted; dismiss just rejects it. Both drop it locally.
   const handleAccept = useCallback(
@@ -151,6 +266,21 @@ export default function App() {
     [removeSuggestion],
   )
 
+  // After restoring a version, swap the restored doc into the editor. Bumping
+  // editorEpoch remounts EditorCore so it picks up the restored content.
+  const handleRestored = useCallback(
+    (doc: Document) => {
+      setCurrentDoc(doc)
+      setTitle(doc.title)
+      setWordCount(doc.word_count)
+      setTone(doc.tone || 'general')
+      setDocText(doc.content_text)
+      patchSummary(doc.id, { title: doc.title, word_count: doc.word_count })
+      setEditorEpoch((n) => n + 1)
+    },
+    [patchSummary],
+  )
+
   // Escape always restores the sidebar while in distraction-free mode.
   useEffect(() => {
     if (!focusMode) return
@@ -183,24 +313,47 @@ export default function App() {
     <div className="flex h-full flex-col">
       <header
         onMouseDown={handleChromeDown}
-        className="flex h-12 shrink-0 items-center gap-2 px-5"
+        className="petal-no-print flex h-12 shrink-0 items-center gap-2 px-5"
         style={{ borderBottom: '1px solid var(--color-border)' }}
       >
+        <button
+          type="button"
+          aria-label="Toggle document list"
+          onClick={() => {
+            setFocusMode(false)
+            setDrawerOpen((v) => !v)
+          }}
+          className="petal-sidebar-toggle petal-tap-sm -ml-2 mr-1 items-center justify-center text-xl"
+          style={{ borderRadius: 'var(--radius-pill)', width: 36, height: 36, color: 'var(--color-plum)' }}
+        >
+          ☰
+        </button>
         <span className="text-xl">🌸</span>
         <span className="text-lg font-extrabold text-plum">Petal</span>
       </header>
 
-      <div className="flex min-h-0 flex-1">
-        <div className={`petal-sidebar shrink-0${focusMode ? ' petal-sidebar-hidden' : ''}`}>
+      <div className="relative flex min-h-0 flex-1">
+        <div
+          className={`petal-no-print petal-sidebar shrink-0${focusMode ? ' petal-sidebar-hidden' : ''}${drawerOpen ? ' petal-drawer-open' : ''}`}
+        >
           <DocList
             docs={docs}
+            roster={tagRoster}
             selectedId={currentDoc?.id ?? null}
             onSelect={openDoc}
             onCreate={handleCreate}
             onDelete={handleDelete}
+            onToggleTag={handleToggleTag}
+            onCreateTag={handleCreateTag}
           />
         </div>
 
+        <div
+          className={`petal-no-print petal-scrim${drawerOpen ? ' petal-scrim-show' : ''}`}
+          onClick={() => setDrawerOpen(false)}
+          aria-hidden
+        />
+
         <main className="flex min-w-0 flex-1 flex-col">
           {currentDoc ? (
             <>
@@ -209,16 +362,41 @@ export default function App() {
                 className="flex flex-1 flex-col overflow-y-auto px-6 py-8"
               >
                 <div ref={canvasRef} className="mx-auto flex w-full max-w-[720px] flex-1 flex-col">
+                  <div className="mb-5 flex items-center gap-3">
                     <input
                       value={title}
                       onChange={(e) => handleTitleChange(e.target.value)}
                       placeholder="Untitled"
                       aria-label="Document title"
-                    className="mb-5 w-full bg-transparent text-3xl font-extrabold text-plum focus:outline-none"
+                      className="min-w-0 flex-1 bg-transparent text-3xl font-extrabold text-plum focus:outline-none"
                       style={{ fontFamily: 'var(--font-ui)' }}
                     />
+                    <div className="petal-no-print shrink-0">
+                      <ToneSelect value={tone} onChange={handleToneChange} />
+                    </div>
+                    <button
+                      type="button"
+                      onClick={() => setHistoryOpen(true)}
+                      aria-label="Version history"
+                      title="Browse and restore earlier versions"
+                      className="petal-no-print inline-flex h-9 shrink-0 items-center gap-1.5 whitespace-nowrap px-3 text-sm font-bold"
+                      style={{
+                        borderRadius: 'var(--radius-pill)',
+                        background: 'var(--color-surface)',
+                        color: 'var(--color-plum)',
+                        boxShadow: 'var(--shadow-soft)',
+                      }}
+                    >
+                      <span aria-hidden>🕘</span>
+                      <span>历史</span>
+                      <span style={{ color: 'var(--color-muted)' }}>· History</span>
+                    </button>
+                    <div className="petal-no-print">
+                      <ExportMenu docId={currentDoc.id} />
+                    </div>
+                  </div>
                   <EditorCore
-                    key={currentDoc.id}
+                    key={`${currentDoc.id}:${editorEpoch}`}
                     docId={currentDoc.id}
                     initialContent={currentDoc.content}
                     onChange={handleEditorChange}
@@ -233,12 +411,14 @@ export default function App() {
                   />
                 </div>
               </div>
-              <div onMouseDown={handleChromeDown}>
+              <div className="petal-no-print" onMouseDown={handleChromeDown}>
                 <StatusBar
                   wordCount={wordCount}
+                  text={docText}
                   saveStatus={status}
                   checking={checking}
                   voicing={voicing}
+                  llmDown={llmDown}
                 />
               </div>
             </>
@@ -253,14 +433,25 @@ export default function App() {
         </main>
       </div>
 
+      {historyOpen && currentDoc && (
+        <HistoryPanel
+          docId={currentDoc.id}
+          onClose={() => setHistoryOpen(false)}
+          onRestored={handleRestored}
+        />
+      )}
+
       {updateAvailable && <UpdateBanner />}
 
+      <div className="petal-no-print">
         <PetalCompanion
           wordCount={wordCount}
           saveStatus={status}
           editTick={editTick}
           acceptTick={acceptTick}
+          text={docText}
         />
       </div>
+    </div>
   )
 }

web/src/api/client.ts

@@ -1,11 +1,34 @@
 // Thin fetch wrappers for the Petal backend. Everything lives under /api, which
 // Vite proxies to the Go server in dev and the binary serves directly in prod.
 
+// A tag's palette key, mapped to a CSS color on the frontend. Mirrors the
+// backend TagColor* constants; unknown values render as rose.
+export type TagColor = 'rose' | 'mint' | 'peach' | 'lavender' | 'sky' | 'honey'
+
+export interface Tag {
+  id: string
+  name: string
+  color: TagColor
+  doc_count?: number // present only in the tag-roster listing
+}
+
 export interface DocSummary {
   id: string
   title: string
   word_count: number
   updated_at: string
+  tags: Tag[]
+}
+
+// One cross-document search hit. `snippet` is plain text with the matched span
+// wrapped in the 
… sentinels (see splitSnippet) for highlighting.
+export interface SearchResult {
+  id: string
+  title: string
+  word_count: number
+  updated_at: string
+  snippet: string
+  tags: Tag[]
 }
 
 export interface Document {
@@ -14,6 +37,7 @@ export interface Document {
   title: string
   content: string // Tiptap JSON (stringified)
   content_text: string // flattened plain text
+  tone: string // target writing tone; steers LLM advice
   word_count: number
   created_at: string
   updated_at: string
@@ -25,11 +49,51 @@ export interface DocUpdate {
   title?: string
   content?: string
   content_text?: string
+  tone?: string
   word_count?: number
 }
 
+// One sense of a word from the offline dictionary.
+export interface WordMeaning {
+  part_of_speech: string
+  definition: string
+  example?: string
+}
+
+// The offline lookup for one word: a Chinese gloss, a few definition senses, and
+// a list of synonyms. Any of these may be empty when the word isn't a headword.
+export interface WordInfo {
+  word: string
+  gloss: string // Chinese translation; '' when the word isn't in the gloss set
+  definitions: WordMeaning[]
+  synonyms: string[]
+}
+
+// The lightweight Chinese-only gloss behind the inline hover/select tooltip.
+export interface Gloss {
+  word: string
+  gloss: string
+}
+
 export type SuggestionType = 'grammar' | 'phrasing' | 'idiom' | 'clarity' | 'voice'
 
+// A point-in-time snapshot of a document. List responses omit the heavy
+// content/content_text fields; they arrive only on getVersion (preview/restore).
+export interface DocumentVersion {
+  id: string
+  doc_id: string
+  title: string
+  content?: string
+  content_text?: string
+  word_count: number
+  kind: 'auto' | 'manual' | 'pre_restore'
+  created_at: string
+}
+
+// Downloadable export formats. PDF is handled client-side via the browser's
+// print dialog (CJK-safe, no server-side font embedding).
+export type ExportFormat = 'md' | 'html' | 'txt' | 'docx'
+
 // A single LLM-proposed edit. `original` is the source of truth for placement —
 // the editor re-anchors by matching this string in the live document (spec
 // Note #6); from_pos/to_pos are server-side advisory only. `replacement` is
@@ -83,11 +147,109 @@ export const api = {
   dismissSuggestion: (id: string) =>
     req<void>(`/suggestions/${id}/dismiss`, { method: 'POST' }),
 
+  // Version history. listVersions returns metadata only (no bodies); getVersion
+  // loads one full snapshot for preview; snapshotDoc takes an explicit restore
+  // point; restoreVersion copies a snapshot back onto the live doc (capturing a
+  // pre_restore safety copy server-side first) and returns the restored doc.
+  listVersions: (id: string) => req<DocumentVersion[]>(`/docs/${id}/versions`),
+  getVersion: (id: string, vid: string) =>
+    req<DocumentVersion>(`/docs/${id}/versions/${vid}`),
+  snapshotDoc: (id: string) =>
+    req<DocumentVersion>(`/docs/${id}/versions`, { method: 'POST' }),
+  restoreVersion: (id: string, vid: string) =>
+    req<Document>(`/docs/${id}/versions/${vid}/restore`, { method: 'POST' }),
+
+  // Download URL for an exported document (md/html/txt/docx). Used as an <a
+  // href download> target so the browser handles the file save.
+  exportUrl: (id: string, format: ExportFormat) =>
+    `/api/docs/${id}/export?format=${format}`,
+
+  // Offline word lookup (gloss + definition + synonyms) for the right-click popover.
+  lookupWord: (word: string) => req<WordInfo>(`/word/${encodeURIComponent(word)}`),
+  // Lightweight Chinese-only gloss for the inline hover/select tooltip — instant
+  // and offline, so it fires on hover without spinning up the heavier lookup.
+  glossWord: (word: string) => req<Gloss>(`/gloss/${encodeURIComponent(word)}`),
+  // Tone-rewrite: rewrites a selected passage in the given style ('natural',
+  // 'academic', …) and returns the rewritten text for an in-editor preview. Not
+  // persisted — the editor applies it directly on accept.
+  rewriteSelection: (docId: string, text: string, style: string) =>
+    req<{ rewrite: string }>(`/docs/${docId}/rewrite`, {
+      method: 'POST',
+      body: JSON.stringify({ text, style }),
+    }),
+
+  // Cross-document full-text search (title + body). Returns hits with a
+  // highlighted snippet. Empty query returns []. Encodes the term for the URL.
+  search: (q: string) => req<SearchResult[]>(`/search?q=${encodeURIComponent(q)}`),
+
+  // Tags. listTags returns the roster with per-tag document counts; createTag is
+  // idempotent on name (returns the existing tag if it already exists);
+  // updateTag recolors/renames; deleteTag removes it (assignments cascade).
+  // assignTag/unassignTag link a tag to one document.
+  listTags: () => req<Tag[]>('/tags'),
+  createTag: (name: string, color: TagColor) =>
+    req<Tag>('/tags', { method: 'POST', body: JSON.stringify({ name, color }) }),
+  updateTag: (id: string, patch: { name?: string; color?: TagColor }) =>
+    req<Tag>(`/tags/${id}`, { method: 'PATCH', body: JSON.stringify(patch) }),
+  deleteTag: (id: string) => req<void>(`/tags/${id}`, { method: 'DELETE' }),
+  assignTag: (docId: string, tagId: string) =>
+    req<void>(`/docs/${docId}/tags`, { method: 'POST', body: JSON.stringify({ tag_id: tagId }) }),
+  unassignTag: (docId: string, tagId: string) =>
+    req<void>(`/docs/${docId}/tags/${tagId}`, { method: 'DELETE' }),
+
   // Current deployed build id — changes whenever a new frontend ships. The
   // app polls this to offer a refresh. Bypasses any cache so the answer is live.
   version: () => req<{ version: string }>('/version', { cache: 'no-store' }),
 }
 
+// The sentinel characters the server wraps a search match in (\x01 … \x02). Used
+// by splitSnippet to render the matched span highlighted.
+export const SNIPPET_HL_START = String.fromCharCode(1)
+export const SNIPPET_HL_END = String.fromCharCode(2)
+
+// splitSnippet breaks a server snippet into ordered { text, hit } segments so the
+// UI can bold the matched span(s) without dangerously setting innerHTML.
+export function splitSnippet(snippet: string): { text: string; hit: boolean }[] {
+  const out: { text: string; hit: boolean }[] = []
+  let rest = snippet
+  for (;;) {
+    const start = rest.indexOf(SNIPPET_HL_START)
+    if (start < 0) {
+      if (rest) out.push({ text: rest, hit: false })
+      break
+    }
+    if (start > 0) out.push({ text: rest.slice(0, start), hit: false })
+    const end = rest.indexOf(SNIPPET_HL_END, start + 1)
+    if (end < 0) {
+      // Unterminated (shouldn't happen) — emit the remainder plainly.
+      out.push({ text: rest.slice(start + 1), hit: false })
+      break
+    }
+    out.push({ text: rest.slice(start + 1, end), hit: true })
+    rest = rest.slice(end + 1)
+  }
+  return out
+}
+
+// tagColorVar maps a tag color key to its CSS custom property. Unknown keys fall
+// back to the rose accent, matching the backend's coercion.
+export function tagColorVar(color: TagColor | string): string {
+  switch (color) {
+    case 'mint':
+      return 'var(--color-mint)'
+    case 'peach':
+      return 'var(--color-peach)'
+    case 'lavender':
+      return 'var(--color-lavender)'
+    case 'sky':
+      return 'var(--color-sky)'
+    case 'honey':
+      return 'var(--color-honey)'
+    default:
+      return 'var(--color-accent)'
+  }
+}
+
 // One turn in an Ask Petal conversation. History lives only in the component —
 // the server is stateless and re-injects the suggestion context every request.
 export interface ChatMessage {

web/src/components/Companion/PetalCompanion.tsx

@@ -9,6 +9,7 @@ interface Props {
   saveStatus: SaveStatus
   editTick: number
   acceptTick: number
+  text: string
 }
 
 // Emoji placeholder per mood, used for any mood a companion has no Lottie for.
@@ -26,8 +27,14 @@ const STORAGE_KEY = 'petal.companion'
 // useCompanion and shows a Mandarin-first speech bubble for cheers, tips, and
 // break reminders. Clicking the mascot opens a picker to switch companions
 // (the choice persists in localStorage).
-export function PetalCompanion({ wordCount, saveStatus, editTick, acceptTick }: Props) {
-  const { mood, bubble, dismiss } = useCompanion({ wordCount, saveStatus, editTick, acceptTick })
+export function PetalCompanion({ wordCount, saveStatus, editTick, acceptTick, text }: Props) {
+  const { mood, bubble, dismiss, holdBubble, releaseBubble } = useCompanion({
+    wordCount,
+    saveStatus,
+    editTick,
+    acceptTick,
+    text,
+  })
 
   const [companionId, setCompanionId] = useState<string>(() => {
     try {
@@ -136,6 +143,8 @@ export function PetalCompanion({ wordCount, saveStatus, editTick, acceptTick }:
         <div
           role="status"
           onClick={dismiss}
+          onMouseEnter={holdBubble}
+          onMouseLeave={releaseBubble}
           className="petal-bubble pointer-events-auto max-w-[260px] cursor-pointer p-3 pr-3.5"
           style={{
             background: 'var(--color-surface)',

web/src/components/Companion/prose.test.ts

@@ -0,0 +1,250 @@
+import { describe, it, expect } from 'vitest'
+import { analyzeProse } from './prose'
+
+// These tests pin the rules-based prose checker's behavior. For an ESL writer a
+// *wrong* nudge costs trust faster than a missed one earns it, so every rule is
+// tested in two directions: a true-positive case that must fire, and at least
+// one near-miss "guard" case that must stay silent. Sentences are padded past
+// the 8-word floor that analyzeProse needs before it offers advice.
+
+const rulesFor = (text: string) => analyzeProse(text).map((h) => h.rule)
+
+// Assert a given rule appears among the hints for this text.
+function expectRule(text: string, rule: string) {
+  expect(rulesFor(text), `expected "${rule}" for: ${text}`).toContain(rule)
+}
+
+// Assert the text produces no hints at all (false-positive guard).
+function expectClean(text: string) {
+  expect(analyzeProse(text), `expected no hints for: ${text}`).toEqual([])
+}
+
+describe('analyzeProse — floor', () => {
+  it('stays quiet on very short drafts (under 8 English words)', () => {
+    expect(analyzeProse('he go now')).toEqual([])
+  })
+
+  it('returns hints highest-priority first', () => {
+    // This 36-word run-on also contains a lowercase "i"; run-on must lead.
+    const hints = analyzeProse(
+      'yesterday i walked all the way to the market and i bought apples and oranges and i saw my friend there and we talked and laughed and walked back home together in the warm afternoon sun.',
+    )
+    expect(hints[0].rule).toBe('runon')
+    expect(hints.map((h) => h.rule)).toContain('cap-i')
+  })
+})
+
+describe('run-ons', () => {
+  it('flags a long, comma-heavy sentence', () => {
+    expectRule(
+      'I went to the market and I bought some apples and then I saw my friend and we talked for a while and after that we went to the cafe and ordered coffee and cake together.',
+      'runon',
+    )
+  })
+
+  it('leaves a normal sentence alone', () => {
+    expectClean('The garden was quiet in the morning and the rain fell softly on the leaves.')
+  })
+})
+
+describe('comma splices', () => {
+  it('flags two independent clauses joined by a comma', () => {
+    expectRule('I finished the report, I sent it to my boss right away today.', 'splice')
+  })
+
+  it('catches a splice with a verb not on any list', () => {
+    expectRule('The garden was quiet in the morning, she poured a cup of tea slowly.', 'splice')
+  })
+
+  it('does not flag an introductory transition (However, …)', () => {
+    expectClean('However, we decided to stay home and rest for the entire weekend.')
+  })
+
+  it('does not flag an introductory phrase (After dinner, …)', () => {
+    expectClean('After dinner, I went home and read a book until I fell asleep.')
+  })
+
+  it('does not flag a pronoun list after a comma', () => {
+    expectClean('We invited my brother, you and your sister to the dinner party.')
+  })
+})
+
+describe('unclear antecedents', () => {
+  it('flags a vague "This + verb" opener after a prior sentence', () => {
+    expectRule(
+      'We changed the whole schedule last week. This makes everyone confused about the new times.',
+      'antecedent',
+    )
+  })
+
+  it('leaves "This" alone when it names its noun', () => {
+    expectClean(
+      'We changed the whole schedule last week. This new schedule confuses everyone about the times.',
+    )
+  })
+})
+
+describe('oxford comma', () => {
+  it('flags a 3-item noun list missing the serial comma', () => {
+    expectRule('My mother, my father and my sister came to visit us last summer.', 'oxford')
+  })
+
+  it('flags a verb-phrase list missing the serial comma', () => {
+    expectRule('We cleaned the kitchen, washed the dishes and took out the trash.', 'oxford')
+  })
+
+  it('does not flag a list that already has the serial comma', () => {
+    expectClean('I bought apples, bananas, and oranges at the store this morning.')
+  })
+
+  it('does not flag a compound predicate as a list', () => {
+    expectClean('After dinner, I went home and read a book until I fell asleep.')
+  })
+})
+
+describe('a / an', () => {
+  it('flags "a" before a vowel sound', () => {
+    expectRule('She found a umbrella and a old book on the table by the window.', 'article')
+  })
+
+  it('flags "an" before a consonant sound', () => {
+    expectRule('He gave me an book and an pencil to use during the long exam.', 'article')
+  })
+
+  it('respects sound exceptions (a university, an hour)', () => {
+    expectClean('He is a university student and it took an hour to arrive here.')
+  })
+})
+
+describe('uncountable plurals', () => {
+  it('flags a pluralized mass noun', () => {
+    expectRule('She gave me many informations about the new job opening today.', 'uncountable')
+  })
+
+  it('leaves the singular mass noun alone', () => {
+    expectClean('He shared some useful advice and helped me with my homework tonight.')
+  })
+})
+
+describe('capitalization of proper nouns', () => {
+  it('flags lowercase languages and days', () => {
+    expectRule('I am learning english and french during my free time every week.', 'propercap')
+    expectRule('We will meet on monday to discuss the final project together soon.', 'propercap')
+  })
+
+  it('does not flag ambiguous homographs (may, march)', () => {
+    expectClean('They may visit in the spring and march through the old town square.')
+  })
+
+  it('leaves already-capitalized proper nouns alone', () => {
+    expectClean('I will study English and Chinese together this coming summer break here.')
+  })
+})
+
+describe('subject–verb agreement', () => {
+  it('flags a bare verb after he/she/it', () => {
+    expectRule('My brother is busy but he go to the gym every single morning.', 'sva')
+    expectRule('She have a lovely garden full of roses behind her small house.', 'sva')
+  })
+
+  it('flags a sentence-initial subject too', () => {
+    expectRule('It make me happy whenever the sun comes out after the rain.', 'sva')
+  })
+
+  it('does not flag causative/perception frames (let it go, make it work)', () => {
+    expectClean('Please let it go and try to enjoy the rest of your day.')
+    expectClean('We should make it work before the big meeting tomorrow afternoon.')
+  })
+})
+
+describe('plural after a number', () => {
+  it('flags a singular noun after a cardinal number', () => {
+    expectRule('I bought three apple and some bread at the market this morning.', 'plural')
+  })
+
+  it('does not flag an adjective between number and noun', () => {
+    expectClean('We adopted two small dogs from the shelter near our apartment today.')
+  })
+
+  it('does not flag irregular plurals (five people)', () => {
+    expectClean('There were five people waiting patiently outside in the cold morning rain.')
+  })
+
+  it('does not flag an already-plural noun', () => {
+    expectClean('She has two cats and they sleep all day long on the couch.')
+  })
+})
+
+describe('double determiner', () => {
+  it('flags a stacked article + possessive', () => {
+    expectRule('Please put the my book back on the shelf when you finish it.', 'doubledet')
+  })
+})
+
+describe('there is + plural', () => {
+  it('flags "there is" with a plural quantifier', () => {
+    expectRule('There is many reasons to visit the coast during the warm months.', 'thereis')
+  })
+
+  it('does not flag "there is some" with a mass noun', () => {
+    expectClean('There is some water left in the bottle if you are thirsty now.')
+  })
+})
+
+describe('its / it’s', () => {
+  it("flags it's used as a possessive", () => {
+    expectRule("The cat licked it's own paw while sitting quietly by the window.", 'its')
+  })
+
+  it('flags its used where "it is" is meant', () => {
+    expectRule('I think its a wonderful idea to travel together next year sometime.', 'its')
+  })
+
+  it('leaves correct possessive "its" alone', () => {
+    expectClean('The dog wagged its tail happily when we came home that evening.')
+  })
+})
+
+describe('than / then', () => {
+  it('flags a comparative followed by "then"', () => {
+    expectRule('This cake tastes much better then the one we made last weekend.', 'than')
+  })
+
+  it('leaves sequential "then" alone', () => {
+    expectClean('We ate dinner and then we watched a long movie on the sofa.')
+  })
+})
+
+describe('comma after a transition', () => {
+  it('flags a sentence-initial transition with no comma', () => {
+    expectRule('However we decided to stay home and rest for the whole weekend.', 'introcomma')
+  })
+
+  it('does not flag a sequence word (Then …)', () => {
+    expectClean('Then we walked to the park and fed the ducks by the pond.')
+  })
+})
+
+describe('spacing around punctuation', () => {
+  it('flags a missing space after a comma', () => {
+    expectRule('I like apples,bananas and grapes from the little shop down the street.', 'space-after')
+  })
+
+  it('flags a space before punctuation', () => {
+    expectRule('She smiled warmly , then walked away without saying a single word today.', 'space-punct')
+  })
+
+  it('does not flag thousands separators in numbers', () => {
+    expectClean('The list had 1,000 items and cost us about 2,500 dollars in total.')
+  })
+})
+
+describe('capitalization basics', () => {
+  it('flags a lowercase standalone "i"', () => {
+    expectRule('Yesterday i walked to the store and bought milk, eggs, and bread.', 'cap-i')
+  })
+
+  it('flags a sentence that does not start with a capital', () => {
+    expectRule('The sun set slowly. it was a beautiful evening down by the river.', 'cap-sentence')
+  })
+})

web/src/components/Companion/prose.ts

@@ -0,0 +1,577 @@
+// Rules-based prose checker — NO LLM. This is the companion's "smart" side: it
+// reads the writer's actual text and surfaces one gentle, context-aware grammar
+// or style note at a time, the way an attentive tutor leaning over her shoulder
+// would. Every rule here is intentionally conservative: a wrong nudge erodes
+// trust far faster than a missed one earns it, so we only speak up when a
+// pattern is a high-confidence, genuinely-common English mistake.
+//
+// Each finding becomes a Mandarin-first bubble Line (see tips.ts), often quoting
+// a short slice of her own sentence so the advice clearly belongs to *this*
+// paragraph and not a generic tip jar.
+
+import type { Line } from './tips'
+
+export interface ProseHint extends Line {
+  // Stable, content-derived id so the same untouched sentence isn't re-flagged
+  // every cadence; the companion remembers recently-shown ids.
+  id: string
+  // Rule family, used to vary advice (don't show the same kind twice in a row).
+  rule: string
+}
+
+// ── small text helpers ──────────────────────────────────────────────────────
+
+const ENGLISH_WORD_RE = /[A-Za-z]+(?:['’-][A-Za-z]+)*/g
+
+// Split into sentence-ish chunks (text + leading punctuation trimmed). Mirrors
+// the SENTENCE_RE terminators used elsewhere, including CJK fullwidth forms.
+function sentences(text: string): string[] {
+  const out: string[] = []
+  const re = /[^.!?。！？]+[.!?。！？]*/g
+  let m: RegExpExecArray | null
+  while ((m = re.exec(text))) {
+    const s = m[0].trim()
+    if (s) out.push(s)
+  }
+  return out
+}
+
+// First few words of a sentence, as an anchor we can quote back to her.
+function anchor(s: string, n = 6): string {
+  const words = s.split(/\s+/).slice(0, n).join(' ')
+  return words.length < s.length ? `${words}…` : words
+}
+
+// Cheap, stable hash → short id suffix, so ids stay stable across recomputes but
+// change the moment she edits the offending text.
+function key(s: string): string {
+  return s.toLowerCase().replace(/\s+/g, ' ').trim().slice(0, 48)
+}
+
+// ── individual rules ────────────────────────────────────────────────────────
+// Each rule pushes at most a couple of findings; the caller shows one at a time.
+
+// Run-on / overly long sentences — the single most common readability problem
+// for ESL writers, who often chain clauses that a period would serve better.
+function runOns(text: string, out: ProseHint[]) {
+  let found = 0
+  for (const s of sentences(text)) {
+    if (found >= 2) break
+    const words = s.match(ENGLISH_WORD_RE)?.length ?? 0
+    const commas = (s.match(/,/g) ?? []).length
+    const longRun = words >= 32
+    const commaHeavy = words >= 24 && commas >= 2
+    if (longRun || commaHeavy) {
+      found++
+      out.push({
+        id: `runon:${key(s)}`,
+        rule: 'runon',
+        zh: '这句话有点长啦，分成两三句会更清楚 🌸',
+        en: `This one runs long — try splitting it: “${anchor(s)}”`,
+      })
+    }
+  }
+}
+
+// Comma splice — two independent clauses joined by only a comma. We look for a
+// comma immediately followed by a subject pronoun + a finite verb, which is a
+// strong, low-false-positive signal of a spliced second clause.
+// A comma, then a subject pronoun starting a fresh clause, then its verb. We no
+// longer whitelist verbs (that lost too many real splices) — instead we take any
+// word after the pronoun and reject the function words that signal it *isn't* a
+// new clause (a conjunction/preposition list like “she and I”, “it of course”).
+const SPLICE_RE = /[a-z]\w*,\s+(I|we|they|he|she|it|you)\s+([a-z]+)\b/g
+const SPLICE_NONVERB = new Set([
+  'and', 'or', 'but', 'nor', 'yet', 'so', 'to', 'too', 'also', 'of', 'in', 'on',
+  'at', 'for', 'with', 'as', 'who', 'whom', 'which', 'that', 'than', 'then',
+  'will', // “…, I will, …” is usually an aside, not a clean splice
+])
+
+// First words that signal the lead is an *introductory* element (transition,
+// subordinate clause, or adverbial phrase), where a following “, subject verb”
+// is correct punctuation — not a splice. Guards against “However, we left.” and
+// “After dinner, I went home.”
+const INTRO_LEAD = new Set([
+  'after', 'before', 'when', 'while', 'although', 'though', 'because', 'since',
+  'if', 'as', 'until', 'unless', 'whenever', 'wherever', 'whereas', 'however',
+  'therefore', 'moreover', 'furthermore', 'nevertheless', 'nonetheless',
+  'meanwhile', 'consequently', 'otherwise', 'besides', 'instead', 'finally',
+  'first', 'firstly', 'second', 'secondly', 'next', 'then', 'later', 'eventually',
+  'afterwards', 'anyway', 'yesterday', 'today', 'tomorrow', 'honestly',
+  'actually', 'suddenly', 'sometimes', 'usually', 'often', 'also', 'still',
+  'now', 'here', 'there', 'well', 'yes', 'no', 'fortunately', 'unfortunately',
+  'surprisingly', 'clearly', 'obviously', 'basically', 'generally', 'initially',
+  'recently', 'currently', 'sadly', 'luckily', 'hopefully', 'frankly',
+  'personally', 'overall', 'soon', 'once', 'during', 'in', 'on', 'at', 'for',
+  'with', 'without', 'by', 'from', 'despite', 'throughout', 'given', 'regarding',
+])
+
+// A genuine comma splice has an *independent clause* before the comma. We
+// approximate that by requiring the lead to be ≥3 words and not begin with an
+// introductory word — short or transition-led leads are intro phrases, not
+// spliced clauses. Precision over recall: a wrong nudge costs more than a miss.
+function commaSplices(text: string, out: ProseHint[]) {
+  let found = 0
+  for (const s of sentences(text)) {
+    if (found >= 2) break
+    SPLICE_RE.lastIndex = 0
+    let m: RegExpExecArray | null
+    while ((m = SPLICE_RE.exec(s)) && found < 2) {
+      const commaIdx = s.indexOf(',', m.index)
+      const lead = s.slice(0, commaIdx).trim()
+      const words = lead.split(/\s+/).filter(Boolean)
+      const firstWord = words[0]?.toLowerCase().replace(/[^a-z]/g, '') ?? ''
+      if (words.length < 3 || INTRO_LEAD.has(firstWord)) continue
+      if (SPLICE_NONVERB.has(m[2].toLowerCase())) continue
+      found++
+      out.push({
+        id: `splice:${key(m[0])}`,
+        rule: 'splice',
+        zh: '这里用逗号连了两句话，可以改成句号，或加个 “and / but”。',
+        en: `Two sentences joined by a comma: “…${m[0].trim()}…” — use a period or add a joining word.`,
+      })
+    }
+  }
+}
+
+// Unclear antecedent — a sentence that opens with This/That/These/Those riding
+// straight into a verb, with no noun naming what it points back to. Only flag
+// when there's a prior sentence (so an antecedent is actually in question).
+const ANTECEDENT_RE =
+  /^(This|That|These|Those)\s+(is|are|was|were|will|would|can|could|should|makes?|made|means?|shows?|showed|gives?|gave|causes?|caused|creates?|created|leads?|led|results?|happens?|happened|helps?|helped)\b/
+
+function antecedents(text: string, out: ProseHint[]) {
+  const list = sentences(text)
+  let found = 0
+  for (let i = 1; i < list.length && found < 2; i++) {
+    const s = list[i]
+    const m = s.match(ANTECEDENT_RE)
+    if (m) {
+      found++
+      out.push({
+        id: `antecedent:${key(s)}`,
+        rule: 'antecedent',
+        zh: `“${m[1]}” 指代不太清楚，最好点明它指的是什么（比如 “${m[1]} idea / change…”）。`,
+        en: `“${m[1]}” here is a little vague — name what it refers to.`,
+      })
+    }
+  }
+}
+
+// Oxford comma — a 3+ item list ending “… X and Y” with no comma before the
+// conjunction. Guarded by a clause-starter stoplist so we don't mistake a
+// compound clause (“…, but she and I…”) for a list.
+const OXFORD_RE = /(\w+),\s+([\w'’-]+(?:\s+[\w'’-]+){0,2})\s+(and|or)\s+[\w'’-]+/g
+const CLAUSE_STARTERS = new Set([
+  'but', 'so', 'because', 'which', 'who', 'that', 'when', 'while', 'if',
+  'although', 'though', 'since', 'as', 'and', 'or', 'nor', 'yet', 'then',
+  'however', 'whereas',
+  // Subject pronouns signal a clause, not a list item (“…, I went home and…”).
+  'i', 'you', 'he', 'she', 'it', 'we', 'they',
+])
+
+function oxford(text: string, out: ProseHint[]) {
+  let m: RegExpExecArray | null
+  let found = 0
+  OXFORD_RE.lastIndex = 0
+  while ((m = OXFORD_RE.exec(text)) && found < 1) {
+    const firstWord = m[2].split(/\s+/)[0]?.toLowerCase() ?? ''
+    if (CLAUSE_STARTERS.has(firstWord)) continue
+    found++
+    out.push({
+      id: `oxford:${key(m[0])}`,
+      rule: 'oxford',
+      zh: '列举三样以上时，在 “and / or” 前也加个逗号会更清楚（牛津逗号）。',
+      en: `In a list, a comma before “${m[3]}” keeps it clear: “a, b, ${m[3]} c”.`,
+    })
+  }
+}
+
+// a vs. an — chosen by the *sound* of the next word. We work only on lowercase
+// words (sidestepping proper nouns / acronyms) and keep sound-exception lists.
+const A_BEFORE_VOWEL_RE = /\ba\s+([aeiou][a-z]+)\b/g
+// Vowel-spelled but consonant-sounding → “a” is correct, don't flag.
+const CONSONANT_SOUND_RE = /^(uni|use|usu|util|euro?|eul|ewe|once|one|ubiqu|unanim)/
+const AN_BEFORE_CONSONANT_RE = /\ban\s+([b-df-hj-np-tv-z][a-z]+)\b/g
+// Consonant-spelled but vowel-sounding (silent h) → “an” is correct, don't flag.
+const VOWEL_SOUND_RE = /^(hour|honest|honou?r|heir|homage)/
+
+function articles(text: string, out: ProseHint[]) {
+  let m: RegExpExecArray | null
+  let found = 0
+  A_BEFORE_VOWEL_RE.lastIndex = 0
+  while ((m = A_BEFORE_VOWEL_RE.exec(text)) && found < 1) {
+    if (CONSONANT_SOUND_RE.test(m[1])) continue
+    found++
+    out.push({
+      id: `article-an:${key(m[1])}`,
+      rule: 'article',
+      zh: `元音开头的词前用 “an”：“an ${m[1]}”。`,
+      en: `Before a vowel sound, use “an”: “an ${m[1]}”.`,
+    })
+  }
+  AN_BEFORE_CONSONANT_RE.lastIndex = 0
+  while ((m = AN_BEFORE_CONSONANT_RE.exec(text)) && found < 2) {
+    if (VOWEL_SOUND_RE.test(m[1])) continue
+    found++
+    out.push({
+      id: `article-a:${key(m[1])}`,
+      rule: 'article',
+      zh: `辅音开头的词前用 “a”：“a ${m[1]}”。`,
+      en: `Before a consonant sound, use “a”: “a ${m[1]}”.`,
+    })
+  }
+}
+
+// Doubled word — “the the”, “is is”. Excludes the handful of doublings that can
+// be legitimate (“the fact that that happened”, “she had had enough”).
+const DOUBLE_RE = /\b([A-Za-z]+)\s+\1\b/gi
+const LEGIT_DOUBLES = new Set(['that', 'had'])
+
+function doubles(text: string, out: ProseHint[]) {
+  let m: RegExpExecArray | null
+  let found = 0
+  DOUBLE_RE.lastIndex = 0
+  while ((m = DOUBLE_RE.exec(text)) && found < 1) {
+    const w = m[1].toLowerCase()
+    if (LEGIT_DOUBLES.has(w)) continue
+    found++
+    out.push({
+      id: `double:${key(m[0])}`,
+      rule: 'double',
+      zh: `“${m[1]}” 好像写了两遍，检查一下哦。`,
+      en: `“${m[1]} ${m[1]}” — looks like a word got doubled.`,
+    })
+  }
+}
+
+// Lowercase standalone “I”. Conservative: only when bounded by spaces / line
+// edge, to avoid tangling with “i.e.” and the like.
+const LOWER_I_RE = /(?:^|\s)i(?=\s|$)/m
+
+function pronounI(text: string, out: ProseHint[]) {
+  if (LOWER_I_RE.test(text)) {
+    out.push({
+      id: 'cap-i',
+      rule: 'cap-i',
+      zh: '英文里的 “I”（我）任何时候都要大写哦。',
+      en: 'In English, “I” is always written as a capital letter.',
+    })
+  }
+}
+
+// Sentence not starting with a capital. We look after a terminator, and ignore
+// CJK sentences (she writes Mandarin too — those don't take Latin capitals).
+const LOWER_START_RE = /[.!?]\s+([a-z])/
+
+function sentenceCaps(text: string, out: ProseHint[]) {
+  if (LOWER_START_RE.test(text)) {
+    out.push({
+      id: 'cap-sentence',
+      rule: 'cap-sentence',
+      zh: '每个句子的开头，用大写字母开始吧。',
+      en: 'Start each new sentence with a capital letter.',
+    })
+  }
+}
+
+// A stray space *before* punctuation (a common habit carried from CJK spacing).
+const SPACE_BEFORE_PUNCT_RE = /[A-Za-z] +([,;:!?]|\.(?!\.))/
+
+function spaceBeforePunct(text: string, out: ProseHint[]) {
+  if (SPACE_BEFORE_PUNCT_RE.test(text)) {
+    out.push({
+      id: 'space-punct',
+      rule: 'space-punct',
+      zh: '标点前面不用空格，逗号、句号紧跟在前一个词后面就好。',
+      en: 'No space before punctuation — it tucks right against the word.',
+    })
+  }
+}
+
+// ── Chinese-L1 interference rules (Tier 1) ──────────────────────────────────
+// Mandarin lacks plural inflection, articles, and verb agreement, so these
+// patterns are the predictable places that grammar "leaks" into her English.
+// All are closed-list or strong-signal to keep false positives near zero.
+
+// Mass nouns that Mandarin speakers very commonly pluralize. These words are
+// essentially never valid with a trailing “s”, so the list is its own guard.
+const UNCOUNTABLE_PLURAL_RE =
+  /\b(informations|advices|knowledges|equipments|furnitures|homeworks|softwares|hardwares|luggages|baggages|sceneries|machineries)\b/i
+
+function uncountables(text: string, out: ProseHint[]) {
+  const m = UNCOUNTABLE_PLURAL_RE.exec(text)
+  UNCOUNTABLE_PLURAL_RE.lastIndex = 0
+  if (m) {
+    const singular = m[1].replace(/s$/i, '')
+    out.push({
+      id: `uncountable:${m[1].toLowerCase()}`,
+      rule: 'uncountable',
+      zh: `“${m[1]}” 是不可数名词，不用加 s，写 “${singular}” 就好。`,
+      en: `“${m[1]}” is uncountable — drop the “s”: just “${singular}”.`,
+    })
+  }
+}
+
+// Languages, nationalities, days, and months are proper nouns in English but
+// not in Mandarin, so they're routinely left lowercase. We list only the
+// unambiguous ones — “may/march/august/china/turkey/polish” are skipped because
+// they're also ordinary lowercase words and would misfire.
+const PROPER_NOUNS =
+  'monday|tuesday|wednesday|thursday|friday|saturday|sunday|' +
+  'january|february|april|june|july|september|october|november|december|' +
+  'english|chinese|mandarin|cantonese|japanese|korean|french|spanish|german|' +
+  'italian|russian|portuguese|arabic|vietnamese|thai|american|british|canadian|' +
+  'australian|mexican|brazilian|european'
+// Case-sensitive (lowercase-only) so already-capitalized words aren't flagged.
+const PROPER_NOUN_RE = new RegExp(`\\b(${PROPER_NOUNS})\\b`)
+
+function properCaps(text: string, out: ProseHint[]) {
+  const m = PROPER_NOUN_RE.exec(text)
+  if (m) {
+    const fixed = m[1][0].toUpperCase() + m[1].slice(1)
+    out.push({
+      id: `propercap:${m[1]}`,
+      rule: 'propercap',
+      zh: `语言、国籍、星期和月份在英文里要大写：“${fixed}”。`,
+      en: `Languages, days, and months are capitalized in English: “${fixed}”.`,
+    })
+  }
+}
+
+// Third-person singular verb form, for the agreement rule's suggestion.
+function third(verb: string): string {
+  const v = verb.toLowerCase()
+  const irregular: Record<string, string> = { have: 'has', do: 'does', go: 'goes' }
+  if (irregular[v]) return irregular[v]
+  if (/[^aeiou]y$/.test(v)) return v.slice(0, -1) + 'ies'
+  if (/(s|x|z|ch|sh)$/.test(v)) return v + 'es'
+  return v + 's'
+}
+
+// Subject–verb agreement after he/she/it: a bare (base-form) verb where the
+// third-person “-s” form is required. We skip the causative/perception frames
+// (“let it go”, “make it work”, “help it grow”) where the bare verb is correct.
+const SVA_BASE =
+  'go|have|do|make|like|want|need|know|think|say|see|feel|get|take|come|give|' +
+  'run|play|work|live|look|seem|become|bring|buy|find|keep|leave|tell|try|call|' +
+  'move|turn|put|mean|show|use|love|hope|wish|believe|understand|remember|enjoy'
+// The preceding word is optional so a sentence-initial subject (“She have…”)
+// still matches; when present it lets us skip causative/perception frames.
+const SVA_RE = new RegExp(`(?:(\\w+)\\s+)?\\b(he|she|it)\\s+(${SVA_BASE})\\b`, 'gi')
+const CAUSATIVE = new Set([
+  'let', 'lets', 'make', 'makes', 'made', 'help', 'helps', 'helped', 'watch',
+  'watches', 'watched', 'see', 'sees', 'saw', 'hear', 'heard', 'have', 'has',
+  'had', 'let’s', "let's",
+])
+
+function subjectVerbAgreement(text: string, out: ProseHint[]) {
+  let m: RegExpExecArray | null
+  let found = 0
+  SVA_RE.lastIndex = 0
+  while ((m = SVA_RE.exec(text)) && found < 2) {
+    if (m[1] && CAUSATIVE.has(m[1].toLowerCase())) continue
+    found++
+    const fixed = third(m[3])
+    out.push({
+      id: `sva:${m[2].toLowerCase()}:${m[3].toLowerCase()}`,
+      rule: 'sva',
+      zh: `主语是 he/she/it 时，动词要加 -s：“${m[2]} ${fixed}”。`,
+      en: `After he/she/it the verb takes “-s”: “${m[2]} ${fixed}”.`,
+    })
+  }
+}
+
+// Singular noun after a cardinal number (“three apple”). Adjectives between the
+// number and noun would misfire (“two small dogs”), so we only flag when the
+// candidate is followed by a clause boundary — a verb, preposition, article, or
+// punctuation — which means it's the noun itself, not a modifier.
+const NUMBER_NOUN_RE =
+  /\b(two|three|four|five|six|seven|eight|nine|ten)\s+([a-z]{3,})\b(?=\s*(?:[.,!?;:]|$|\s(?:is|are|was|were|and|or|but|that|which|who|in|on|at|to|for|with|will|can|could|would|should|the|a|an)\b))/g
+// Irregular plurals / mass nouns that are correct without an “s”.
+const NON_S_PLURAL = new Set([
+  'people', 'children', 'men', 'women', 'fish', 'deer', 'sheep', 'feet', 'teeth',
+  'mice', 'geese', 'police', 'staff', 'series', 'species', 'aircraft', 'cattle',
+  'hundred', 'thousand', 'million', 'billion', 'dozen', 'percent',
+])
+
+function pluralAfterNumber(text: string, out: ProseHint[]) {
+  let m: RegExpExecArray | null
+  let found = 0
+  NUMBER_NOUN_RE.lastIndex = 0
+  while ((m = NUMBER_NOUN_RE.exec(text)) && found < 1) {
+    const noun = m[2].toLowerCase()
+    if (noun.endsWith('s') || NON_S_PLURAL.has(noun)) continue
+    found++
+    out.push({
+      id: `plural:${key(m[0])}`,
+      rule: 'plural',
+      zh: `“${m[1]}” 后面的名词要用复数：“${m[1]} ${m[2]}s”。`,
+      en: `After “${m[1]}”, the noun is plural: “${m[1]} ${m[2]}s”.`,
+    })
+  }
+}
+
+// Two stacked determiners (“the my book”, “a the”) — Mandarin uses a bare
+// possessive, so the article often gets stacked on top. One of the two must go.
+const DOUBLE_DET_RE =
+  /\b(a|an|the)\s+(a|an|the|my|your|his|her|its|our|their)\b/gi
+
+function doubleDeterminer(text: string, out: ProseHint[]) {
+  const m = DOUBLE_DET_RE.exec(text)
+  DOUBLE_DET_RE.lastIndex = 0
+  if (m) {
+    out.push({
+      id: `doubledet:${key(m[0])}`,
+      rule: 'doubledet',
+      zh: `“${m[1]} ${m[2]}” 用了两个限定词，留一个就好（比如去掉 “${m[1]}”）。`,
+      en: `“${m[1]} ${m[2]}” stacks two determiners — keep just one.`,
+    })
+  }
+}
+
+// “there is” with a plural quantifier → should be “there are”. We trigger only
+// on clearly-plural cues (skip “some/any”, which are fine with singular mass
+// nouns: “there is some water”).
+const THERE_IS_RE =
+  /\bthere(?:\s+is|'s|’s)\s+(many|several|numerous|various|few|two|three|four|five|six|seven|eight|nine|ten)\b/i
+
+function thereIsPlural(text: string, out: ProseHint[]) {
+  const m = THERE_IS_RE.exec(text)
+  THERE_IS_RE.lastIndex = 0
+  if (m) {
+    out.push({
+      id: `thereis:${m[1].toLowerCase()}`,
+      rule: 'thereis',
+      zh: `后面是复数时用 “there are”：“there are ${m[1]}…”。`,
+      en: `With a plural, use “there are”: “there are ${m[1]}…”.`,
+    })
+  }
+}
+
+// ── confusables (Tier 2) ─────────────────────────────────────────────────────
+
+// its / it's — only the two unambiguous directions: “it's own” (always its own)
+// and “its a/an” (the possessive can't take an article → it's a/an).
+const ITS_OWN_RE = /\bit's\s+own\b/i
+const ITS_ARTICLE_RE = /\bits\s+(a|an)\b/i
+
+function itsConfusion(text: string, out: ProseHint[]) {
+  if (ITS_OWN_RE.test(text)) {
+    out.push({
+      id: 'its-own',
+      rule: 'its',
+      zh: '“it’s” = “it is”；表示“它的”要用 “its”，所以是 “its own”。',
+      en: '“it’s” means “it is” — the possessive is “its”: “its own”.',
+    })
+    return
+  }
+  const m = ITS_ARTICLE_RE.exec(text)
+  ITS_ARTICLE_RE.lastIndex = 0
+  if (m) {
+    out.push({
+      id: 'its-article',
+      rule: 'its',
+      zh: `这里应该是 “it’s ${m[1]}”（it is），“its” 是“它的”。`,
+      en: `Here it should be “it’s ${m[1]}” (it is); “its” means belonging to it.`,
+    })
+  }
+}
+
+// Comparative + “then” where “than” is meant (“better then”, “more then”). We
+// use an explicit comparative list rather than a generic “-er” pattern, which
+// would snag “after then”, “however”, “remember”, etc.
+const COMPARATIVES =
+  'better|more|less|rather|worse|greater|other|older|younger|bigger|smaller|' +
+  'larger|faster|slower|higher|lower|cheaper|stronger|weaker|easier|harder|' +
+  'earlier|later|sooner|longer|shorter|taller|richer|poorer|happier|safer'
+const THAN_THEN_RE = new RegExp(`\\b(${COMPARATIVES})\\s+then\\b`, 'i')
+
+function thanThen(text: string, out: ProseHint[]) {
+  const m = THAN_THEN_RE.exec(text)
+  if (m) {
+    out.push({
+      id: `than:${m[1].toLowerCase()}`,
+      rule: 'than',
+      zh: `比较的时候用 “than”，不是 “then”：“${m[1]} than”。`,
+      en: `For comparisons use “than”, not “then”: “${m[1]} than”.`,
+    })
+  }
+}
+
+// A transition word opening a sentence with no comma after it (“However we…”).
+// Limited to conjunctive adverbs that strongly want the comma — sequence words
+// like “Then/First/Finally” are left out (their comma is optional).
+const INTRO_RE =
+  /^(However|Therefore|Moreover|Furthermore|Nevertheless|Nonetheless|Meanwhile|Consequently|In addition|In conclusion|As a result|On the other hand|For example|For instance)\s+[A-Za-z]/
+
+function introComma(text: string, out: ProseHint[]) {
+  let found = false
+  for (const s of sentences(text)) {
+    const m = s.match(INTRO_RE)
+    if (m) {
+      out.push({
+        id: `introcomma:${m[1].toLowerCase()}`,
+        rule: 'introcomma',
+        zh: `开头的过渡词后面加个逗号：“${m[1]}, …”。`,
+        en: `Put a comma after the opening transition: “${m[1]}, …”.`,
+      })
+      found = true
+      break
+    }
+  }
+  return found
+}
+
+// Missing space *after* a comma or sentence period (“apple,banana”, “end.Next”).
+// The comma case requires letters on both sides so numbers like 1,000 are safe;
+// the period case requires a real word boundary so “e.g.”/“U.S.” are skipped.
+const NO_SPACE_COMMA_RE = /[A-Za-z],[A-Za-z]/
+const NO_SPACE_PERIOD_RE = /[a-z]{2,}\.[A-Z][a-z]/
+
+function spaceAfterPunct(text: string, out: ProseHint[]) {
+  if (NO_SPACE_COMMA_RE.test(text) || NO_SPACE_PERIOD_RE.test(text)) {
+    out.push({
+      id: 'space-after',
+      rule: 'space-after',
+      zh: '逗号、句号后面要空一格，再接下一个词。',
+      en: 'Add a space after a comma or period before the next word.',
+    })
+  }
+}
+
+// ── orchestration ───────────────────────────────────────────────────────────
+
+// Rules run in priority order — the ones the writer cares most about first, so
+// that when several fire at once the companion leads with the weightiest note.
+const RULES: Array<(text: string, out: ProseHint[]) => void> = [
+  runOns,
+  commaSplices,
+  antecedents,
+  oxford,
+  articles,
+  uncountables,
+  properCaps,
+  subjectVerbAgreement,
+  pluralAfterNumber,
+  doubleDeterminer,
+  thereIsPlural,
+  itsConfusion,
+  thanThen,
+  introComma,
+  doubles,
+  pronounI,
+  sentenceCaps,
+  spaceBeforePunct,
+  spaceAfterPunct,
+]
+
+// analyzeProse returns context-aware hints, highest-priority first. It bails on
+// text too short to advise on (mid-thought drafts shouldn't get picked apart).
+export function analyzeProse(text: string): ProseHint[] {
+  const englishWords = text.match(ENGLISH_WORD_RE)?.length ?? 0
+  if (englishWords < 8) return []
+  const out: ProseHint[] = []
+  for (const rule of RULES) rule(text, out)
+  return out
+}

web/src/components/Companion/tips.ts

@@ -17,7 +17,8 @@ export const ENCOURAGEMENTS: Line[] = [
   { zh: '嗯嗯，这样清楚多了 👍', en: 'Mm, that’s much clearer.' },
 ]
 
-// Gentle, periodic writing/ESL tips. Surfaced only when nothing else is showing.
+// Gentle, generic writing/ESL tips — the fallback when the rules-based prose
+// checker (prose.ts) finds nothing concrete to point at in her current text.
 export const TIPS: Line[] = [
   { zh: '小贴士：英文句子短一点，会更清楚哦。', en: 'Tip: shorter English sentences often read clearer.' },
   { zh: '别忘了冠词 “the” 和 “a” 哦。', en: "Don't forget articles like “the” and “a”." },

web/src/components/Companion/useCompanion.ts

@@ -11,6 +11,7 @@ import {
   pick,
   type Line,
 } from './tips'
+import { analyzeProse } from './prose'
 
 // The kitten's expression. Maps to a Lottie animation when assets are present,
 // otherwise to an emoji placeholder (see PetalCompanion).
@@ -28,6 +29,9 @@ interface Signals {
   // suggestion — lets the companion react without a full event bus.
   editTick: number
   acceptTick: number
+  // The document's plain text, used by the rules-based prose checker to offer
+  // context-aware writing notes instead of only generic tips.
+  text: string
 }
 
 // Timing knobs (ms). Tuned to feel present but never naggy.
@@ -35,14 +39,29 @@ const IDLE_MS = 75_000 // no edits → kitten naps
 const BREAK_MS = 25 * 60_000 // continuous writing → suggest a break
 const TIP_MIN_GAP = 4 * 60_000 // at most one spontaneous tip per this window
 const PROACTIVE_GAP = 40_000 // floor between any two unsolicited bubbles
-const BUBBLE_MS = 6_500 // how long a bubble lingers
-const CHEER_MS = 4_500 // shorter for quick cheers
+// How long a bubble lingers. These are *floors* — readBubbleMs extends them by
+// how much there is to read, since she reads both the Mandarin and the English
+// (and tips now quote a slice of her own sentence, so they run longer).
+const BUBBLE_MS = 9_000 // baseline for a tip / break
+const CHEER_MS = 6_000 // a short cheer still needs a beat in two languages
+const READ_MS_PER_CHAR = 45 // ~22 chars/sec, generous for a bilingual read
+const MAX_BUBBLE_MS = 20_000 // cap so a long quote can't pin the bubble forever
+const HOVER_GRACE_MS = 3_000 // lingers this long after she stops hovering
 const now = () => Date.now()
 
+// Reading time for a bubble: a base floor by tone, stretched by the combined
+// length of the Mandarin + English lines so denser advice stays up long enough
+// to actually finish reading.
+function readBubbleMs(b: Bubble): number {
+  const base = b.tone === 'cheer' ? CHEER_MS : BUBBLE_MS
+  const chars = b.zh.length + b.en.length
+  return Math.min(MAX_BUBBLE_MS, base + chars * READ_MS_PER_CHAR)
+}
+
 // useCompanion is the behavior engine: it watches writing signals and decides
 // when the kitten speaks, what mood it shows, and how to pace itself so the
 // companion feels alive without interrupting. UI-agnostic — returns state only.
-export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Signals) {
+export function useCompanion({ wordCount, saveStatus, editTick, acceptTick, text }: Signals) {
   const [mood, setMood] = useState<Mood>('idle')
   const [bubble, setBubble] = useState<Bubble | null>(null)
 
@@ -54,6 +73,15 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Si
   const nextMilestone = useRef(0) // index into MILESTONES
   const sleeping = useRef(false)
 
+  // Latest text for the prose checker, read lazily by the heartbeat (kept in a
+  // ref so per-keystroke changes don't re-arm the interval).
+  const textRef = useRef(text)
+  textRef.current = text
+  // Recently-surfaced hint ids, so the same untouched sentence isn't re-flagged
+  // each cadence. A small ring — old ids age out and may resurface later.
+  const recentHints = useRef<string[]>([])
+  const lastRule = useRef<string>('')
+
   const bubbleTimer = useRef<ReturnType<typeof setTimeout>>(undefined)
   const moodTimer = useRef<ReturnType<typeof setTimeout>>(undefined)
 
@@ -71,11 +99,30 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Si
     setMood(opts?.celebrate ? 'celebrate' : 'talking')
     clearTimeout(bubbleTimer.current)
     clearTimeout(moodTimer.current)
-    const dur = b.tone === 'cheer' ? CHEER_MS : BUBBLE_MS
+    const dur = readBubbleMs(b)
     bubbleTimer.current = setTimeout(() => setBubble(null), dur)
     moodTimer.current = setTimeout(() => setMood('idle'), dur)
   }, [bubble])
 
+  // Choose the next spontaneous tip. Prefer a real, context-aware note from the
+  // rules-based prose checker (it's actionable and clearly about *her* writing);
+  // fall back to a generic encouragement-style tip when the text reads clean or
+  // every finding was shown recently. Avoids repeating a finding or the same
+  // rule family back-to-back so the companion never feels like a broken record.
+  const nextTip = useCallback((): Bubble => {
+    const hints = analyzeProse(textRef.current)
+    const fresh = hints.find(
+      (h) => !recentHints.current.includes(h.id) && h.rule !== lastRule.current,
+    )
+    const hint = fresh ?? hints.find((h) => !recentHints.current.includes(h.id))
+    if (hint) {
+      lastRule.current = hint.rule
+      recentHints.current = [hint.id, ...recentHints.current].slice(0, 8)
+      return { zh: hint.zh, en: hint.en, tone: 'tip' }
+    }
+    return { ...pick(TIPS), tone: 'tip' }
+  }, [])
+
   const dismiss = useCallback(() => {
     clearTimeout(bubbleTimer.current)
     clearTimeout(moodTimer.current)
@@ -83,6 +130,21 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Si
     setMood('idle')
   }, [])
 
+  // Pause the auto-dismiss while she hovers a bubble — so a longer note never
+  // vanishes mid-read. Releasing leaves it up for a short, fixed grace so it
+  // doesn't linger forever once she looks away.
+  const holdBubble = useCallback(() => {
+    clearTimeout(bubbleTimer.current)
+    clearTimeout(moodTimer.current)
+  }, [])
+
+  const releaseBubble = useCallback(() => {
+    clearTimeout(bubbleTimer.current)
+    clearTimeout(moodTimer.current)
+    bubbleTimer.current = setTimeout(() => setBubble(null), HOVER_GRACE_MS)
+    moodTimer.current = setTimeout(() => setMood('idle'), HOVER_GRACE_MS)
+  }, [])
+
   // Opening hello (once), after a short beat so it doesn't race the first paint.
   useEffect(() => {
     const id = setTimeout(() => say({ ...GREETING, tone: 'tip' }), 1200)
@@ -161,14 +223,15 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Si
         return
       }
 
-      // Otherwise an occasional tip.
+      // Otherwise an occasional tip — context-aware when her text gives us
+      // something concrete to gently point at, generic warmth otherwise.
       if (t - lastTip.current > TIP_MIN_GAP) {
         lastTip.current = t
-        say({ ...pick(TIPS), tone: 'tip' }, { proactive: true })
+        say(nextTip(), { proactive: true })
       }
     }, 10_000)
     return () => clearInterval(id)
-  }, [bubble, say])
+  }, [bubble, say, nextTip])
 
   useEffect(
     () => () => {
@@ -178,5 +241,5 @@ export function useCompanion({ wordCount, saveStatus, editTick, acceptTick }: Si
     [],
   )
 
-  return { mood, bubble, dismiss }
+  return { mood, bubble, dismiss, holdBubble, releaseBubble }
 }

web/src/components/DocList/DocList.tsx

@@ -1,26 +1,71 @@
-import type { DocSummary } from '../../api/client'
+import { useMemo, useState } from 'react'
+import type { DocSummary, Tag, TagColor } from '../../api/client'
 import { DocListItem } from './DocListItem'
+import { SearchBox } from './SearchBox'
+import { TagChip } from './TagChip'
 
 interface Props {
   docs: DocSummary[]
+  roster: Tag[]
   selectedId: string | null
   onSelect: (id: string) => void
   onCreate: () => void
   onDelete: (id: string) => void
+  onToggleTag: (docId: string, tag: Tag) => void
+  onCreateTag: (docId: string, name: string, color: TagColor) => void
 }
 
-// DocList is the 260px sidebar: the document browser plus a New button.
-export function DocList({ docs, selectedId, onSelect, onCreate, onDelete }: Props) {
+// DocList is the sidebar: a cross-document search box, a tag filter bar, the New
+// button, and the document browser (each row showing its tag chips).
+export function DocList({
+  docs,
+  roster,
+  selectedId,
+  onSelect,
+  onCreate,
+  onDelete,
+  onToggleTag,
+  onCreateTag,
+}: Props) {
+  // Active tag filter (null = show all). Cleared automatically if the tag
+  // disappears from the roster.
+  const [filterId, setFilterId] = useState<string | null>(null)
+  const activeFilter = filterId && roster.some((t) => t.id === filterId) ? filterId : null
+
+  const filtered = useMemo(
+    () => (activeFilter ? docs.filter((d) => d.tags.some((t) => t.id === activeFilter)) : docs),
+    [docs, activeFilter],
+  )
+
+  // Only surface tags that are actually in use, so the filter bar stays tidy.
+  const usedTags = useMemo(() => roster.filter((t) => (t.doc_count ?? 0) > 0), [roster])
+
   return (
     <aside
-      className="flex h-full w-[260px] flex-col gap-2 p-3"
+      className="flex h-full w-[280px] flex-col gap-2 p-3"
       style={{ borderRight: '1px solid var(--color-border)' }}
     >
+      <SearchBox onSelect={onSelect} />
+
+      {usedTags.length > 0 && (
+        <div className="flex flex-wrap gap-1 pb-0.5">
+          {usedTags.map((t) => (
+            <TagChip
+              key={t.id}
+              tag={t}
+              count={t.doc_count}
+              active={activeFilter === t.id}
+              onClick={() => setFilterId((cur) => (cur === t.id ? null : t.id))}
+            />
+          ))}
+        </div>
+      )}
+
       <button
         type="button"
         onClick={onCreate}
-        className="flex items-center justify-center gap-2 py-2.5 text-sm font-bold text-white"
-        style={{ borderRadius: 'var(--radius-pill)', background: 'var(--color-accent)' }}
+        className="petal-tap flex items-center justify-center gap-2 text-sm font-bold text-white"
+        style={{ minHeight: 44, borderRadius: 'var(--radius-pill)', background: 'var(--color-accent)' }}
         onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-accent-hover)')}
         onMouseLeave={(e) => (e.currentTarget.style.background = 'var(--color-accent)')}
       >
@@ -28,18 +73,21 @@ export function DocList({ docs, selectedId, onSelect, onCreate, onDelete }: Prop
       </button>
 
       <div className="flex flex-1 flex-col gap-0.5 overflow-y-auto">
-        {docs.length === 0 ? (
+        {filtered.length === 0 ? (
           <p className="px-3 py-6 text-center text-xs" style={{ color: 'var(--color-muted)' }}>
-            No documents yet.
+            {activeFilter ? 'No documents with this tag.' : 'No documents yet.'}
           </p>
         ) : (
-          docs.map((doc) => (
+          filtered.map((doc) => (
             <DocListItem
               key={doc.id}
               doc={doc}
               active={doc.id === selectedId}
+              roster={roster}
               onSelect={() => onSelect(doc.id)}
               onDelete={() => onDelete(doc.id)}
+              onToggleTag={onToggleTag}
+              onCreateTag={onCreateTag}
             />
           ))
         )}

web/src/components/DocList/DocListItem.tsx

@@ -1,25 +1,43 @@
-import type { DocSummary } from '../../api/client'
+import { useState } from 'react'
+import type { DocSummary, Tag, TagColor } from '../../api/client'
+import { TagChip } from './TagChip'
+import { TagPicker } from './TagPicker'
 
 interface Props {
   doc: DocSummary
   active: boolean
+  roster: Tag[]
   onSelect: () => void
   onDelete: () => void
+  onToggleTag: (docId: string, tag: Tag) => void
+  onCreateTag: (docId: string, name: string, color: TagColor) => void
 }
 
-// One row in the sidebar: title + word count, a delete affordance on hover, and
-// a rose wash when it's the open document.
-export function DocListItem({ doc, active, onSelect, onDelete }: Props) {
+// One row in the sidebar: title + word count, its tag chips, a tag affordance and
+// a delete affordance on hover, and a rose wash when it's the open document.
+export function DocListItem({
+  doc,
+  active,
+  roster,
+  onSelect,
+  onDelete,
+  onToggleTag,
+  onCreateTag,
+}: Props) {
+  const [picking, setPicking] = useState(false)
+  const assignedIds = new Set(doc.tags.map((t) => t.id))
+
   return (
     <div
       onClick={onSelect}
-      className="group flex cursor-pointer items-center gap-2 px-3 py-2.5"
+      className="group relative flex cursor-pointer flex-col gap-1 px-3 py-2.5"
       style={{
         borderRadius: 'var(--radius-card)',
         background: active ? 'var(--color-surface)' : 'transparent',
         boxShadow: active ? 'var(--shadow-soft)' : 'none',
       }}
     >
+      <div className="flex items-center gap-2">
         <div className="min-w-0 flex-1">
           <div
             className="truncate text-sm font-semibold"
@@ -31,6 +49,22 @@ export function DocListItem({ doc, active, onSelect, onDelete }: Props) {
             {doc.word_count} {doc.word_count === 1 ? 'word' : 'words'}
           </div>
         </div>
+
+        {/* Tag + delete affordances: always reachable on touch (no hover), fade in
+            on hover for the pointer experience. */}
+        <button
+          type="button"
+          aria-label="Tag document"
+          title="Tags"
+          onClick={(e) => {
+            e.stopPropagation()
+            setPicking((v) => !v)
+          }}
+          className="petal-row-action flex h-7 w-7 shrink-0 items-center justify-center text-sm"
+          style={{ borderRadius: 'var(--radius-pill)', color: 'var(--color-muted)' }}
+        >
+          🏷️
+        </button>
         <button
           type="button"
           aria-label="Delete document"
@@ -38,11 +72,30 @@ export function DocListItem({ doc, active, onSelect, onDelete }: Props) {
             e.stopPropagation()
             onDelete()
           }}
-        className="flex h-6 w-6 shrink-0 items-center justify-center text-base opacity-0 group-hover:opacity-100"
+          className="petal-row-action flex h-7 w-7 shrink-0 items-center justify-center text-base"
           style={{ borderRadius: 'var(--radius-pill)', color: 'var(--color-muted)' }}
         >
           ×
         </button>
+
+        {picking && (
+          <TagPicker
+            roster={roster}
+            assignedIds={assignedIds}
+            onToggle={(t) => onToggleTag(doc.id, t)}
+            onCreate={(name, color) => onCreateTag(doc.id, name, color)}
+            onClose={() => setPicking(false)}
+          />
+        )}
+      </div>
+
+      {doc.tags.length > 0 && (
+        <div className="flex flex-wrap gap-1">
+          {doc.tags.map((t) => (
+            <TagChip key={t.id} tag={t} onRemove={() => onToggleTag(doc.id, t)} />
+          ))}
+        </div>
+      )}
     </div>
   )
 }

web/src/components/DocList/SearchBox.tsx

@@ -0,0 +1,145 @@
+import { useEffect, useRef, useState } from 'react'
+import { api, splitSnippet, type SearchResult } from '../../api/client'
+
+interface Props {
+  // Called when a result is chosen — opens that document.
+  onSelect: (id: string) => void
+}
+
+const DEBOUNCE_MS = 220
+
+// SearchBox is the cross-document finder at the top of the sidebar. Typing
+// debounces a full-text query; results drop in below with a highlighted snippet.
+// Clearing (× or empty) returns the sidebar to the normal document list.
+export function SearchBox({ onSelect }: Props) {
+  const [q, setQ] = useState('')
+  const [results, setResults] = useState<SearchResult[] | null>(null)
+  const [busy, setBusy] = useState(false)
+  const runRef = useRef(0)
+  const debounceRef = useRef<ReturnType<typeof setTimeout>>(undefined)
+
+  useEffect(() => {
+    clearTimeout(debounceRef.current)
+    const term = q.trim()
+    if (!term) {
+      setResults(null)
+      setBusy(false)
+      return
+    }
+    setBusy(true)
+    const run = ++runRef.current
+    debounceRef.current = setTimeout(async () => {
+      try {
+        const hits = await api.search(term)
+        if (run === runRef.current) setResults(hits)
+      } catch (err) {
+        console.error('search failed', err)
+        if (run === runRef.current) setResults([])
+      } finally {
+        if (run === runRef.current) setBusy(false)
+      }
+    }, DEBOUNCE_MS)
+    return () => clearTimeout(debounceRef.current)
+  }, [q])
+
+  const clear = () => {
+    setQ('')
+    setResults(null)
+  }
+
+  return (
+    <div className="flex flex-col gap-1.5">
+      <div className="relative">
+        <span
+          aria-hidden
+          className="pointer-events-none absolute left-3 top-1/2 -translate-y-1/2 text-sm"
+          style={{ color: 'var(--color-muted)' }}
+        >
+          🔍
+        </span>
+        <input
+          value={q}
+          onChange={(e) => setQ(e.target.value)}
+          placeholder="搜索 · Search"
+          aria-label="Search documents"
+          className="petal-tap w-full bg-transparent pl-9 pr-8 text-sm focus:outline-none"
+          style={{
+            height: 40,
+            borderRadius: 'var(--radius-pill)',
+            border: '1px solid var(--color-border)',
+            background: 'var(--color-surface)',
+            color: 'var(--color-plum)',
+          }}
+        />
+        {q && (
+          <button
+            type="button"
+            aria-label="Clear search"
+            onClick={clear}
+            className="absolute right-2 top-1/2 flex h-6 w-6 -translate-y-1/2 items-center justify-center"
+            style={{ borderRadius: 'var(--radius-pill)', color: 'var(--color-muted)' }}
+          >
+            ×
+          </button>
+        )}
+      </div>
+
+      {results !== null && (
+        <div className="petal-search-results flex flex-col gap-0.5">
+          {busy && results.length === 0 ? (
+            <p className="px-2 py-3 text-center text-xs" style={{ color: 'var(--color-muted)' }}>
+              查找中… · Searching…
+            </p>
+          ) : results.length === 0 ? (
+            <p className="px-2 py-3 text-center text-xs" style={{ color: 'var(--color-muted)' }}>
+              没有找到 · No matches
+            </p>
+          ) : (
+            results.map((r) => (
+              <button
+                key={r.id}
+                type="button"
+                onClick={() => onSelect(r.id)}
+                className="petal-tap flex flex-col items-start gap-0.5 px-3 py-2 text-left"
+                style={{ borderRadius: 'var(--radius-card)' }}
+                onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+                onMouseLeave={(e) => (e.currentTarget.style.background = 'transparent')}
+              >
+                <span
+                  className="w-full truncate text-sm font-bold"
+                  style={{ color: 'var(--color-plum)' }}
+                >
+                  {r.title || 'Untitled'}
+                </span>
+                {r.snippet && (
+                  <span
+                    className="line-clamp-2 text-xs"
+                    style={{ color: 'var(--color-muted)', lineHeight: 1.4 }}
+                  >
+                    {splitSnippet(r.snippet).map((seg, i) =>
+                      seg.hit ? (
+                        <mark
+                          key={i}
+                          style={{
+                            background: 'color-mix(in srgb, var(--color-accent) 35%, white)',
+                            color: 'var(--color-plum)',
+                            borderRadius: 3,
+                            padding: '0 1px',
+                          }}
+                        >
+                          {seg.text}
+                        </mark>
+                      ) : (
+                        <span key={i}>{seg.text}</span>
+                      ),
+                    )}
+                  </span>
+                )}
+              </button>
+            ))
+          )}
+        </div>
+      )}
+    </div>
+  )
+}

web/src/components/DocList/TagChip.tsx

@@ -0,0 +1,75 @@
+import { tagColorVar, type Tag } from '../../api/client'
+
+interface Props {
+  tag: Tag
+  // When set, renders an interactive chip (filter toggle); `active` fills it.
+  onClick?: () => void
+  active?: boolean
+  // When set, shows a small × to remove the tag (used on document rows).
+  onRemove?: () => void
+  // Optional trailing count (used in the filter bar).
+  count?: number
+  size?: 'sm' | 'md'
+}
+
+// TagChip is the pill used everywhere a tag appears: on document rows, in the
+// filter bar, and in the assign popover. The palette color tints a soft wash; a
+// filled variant marks an active filter. Keeps tap targets comfortable on touch.
+export function TagChip({ tag, onClick, active, onRemove, count, size = 'sm' }: Props) {
+  const color = tagColorVar(tag.color)
+  const interactive = !!onClick
+  const pad = size === 'md' ? '0.3rem 0.7rem' : '0.12rem 0.5rem'
+  const font = size === 'md' ? '0.8rem' : '0.7rem'
+
+  return (
+    <span
+      onClick={
+        onClick
+          ? (e) => {
+              e.stopPropagation()
+              onClick()
+            }
+          : undefined
+      }
+      className={`petal-tag-chip inline-flex items-center gap-1 whitespace-nowrap font-bold${interactive ? ' cursor-pointer' : ''}`}
+      style={{
+        borderRadius: 'var(--radius-pill)',
+        padding: pad,
+        fontSize: font,
+        lineHeight: 1.2,
+        background: active ? color : 'color-mix(in srgb, ' + color + ' 22%, white)',
+        color: active ? 'white' : 'var(--color-plum)',
+        border: `1px solid ${active ? color : 'color-mix(in srgb, ' + color + ' 45%, white)'}`,
+      }}
+    >
+      <span
+        aria-hidden
+        className="inline-block shrink-0"
+        style={{
+          width: 7,
+          height: 7,
+          borderRadius: 'var(--radius-pill)',
+          background: active ? 'white' : color,
+        }}
+      />
+      {tag.name}
+      {typeof count === 'number' && (
+        <span style={{ opacity: 0.7, fontWeight: 700 }}>{count}</span>
+      )}
+      {onRemove && (
+        <button
+          type="button"
+          aria-label={`Remove ${tag.name}`}
+          onClick={(e) => {
+            e.stopPropagation()
+            onRemove()
+          }}
+          className="ml-0.5 inline-flex items-center justify-center"
+          style={{ color: 'inherit', opacity: 0.65, fontSize: '0.85em', lineHeight: 1 }}
+        >
+          ×
+        </button>
+      )}
+    </span>
+  )
+}

web/src/components/DocList/TagPicker.tsx

@@ -0,0 +1,139 @@
+import { useEffect, useRef, useState } from 'react'
+import { tagColorVar, type Tag, type TagColor } from '../../api/client'
+
+const COLORS: TagColor[] = ['rose', 'mint', 'peach', 'lavender', 'sky', 'honey']
+
+interface Props {
+  roster: Tag[]
+  assignedIds: Set<string>
+  onToggle: (tag: Tag) => void
+  onCreate: (name: string, color: TagColor) => void
+  onClose: () => void
+}
+
+// TagPicker is the small popover for managing one document's tags: tap an
+// existing tag to attach/detach it, or type a new name (with a color swatch) to
+// create-and-attach. Closes on outside click or Escape.
+export function TagPicker({ roster, assignedIds, onToggle, onCreate, onClose }: Props) {
+  const [name, setName] = useState('')
+  const [color, setColor] = useState<TagColor>('rose')
+  const ref = useRef<HTMLDivElement>(null)
+
+  useEffect(() => {
+    const onDown = (e: PointerEvent) => {
+      if (!ref.current?.contains(e.target as Node)) onClose()
+    }
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') onClose()
+    }
+    // Defer so the opening click doesn't immediately close it.
+    const id = setTimeout(() => document.addEventListener('pointerdown', onDown), 0)
+    document.addEventListener('keydown', onKey)
+    return () => {
+      clearTimeout(id)
+      document.removeEventListener('pointerdown', onDown)
+      document.removeEventListener('keydown', onKey)
+    }
+  }, [onClose])
+
+  const submit = () => {
+    const n = name.trim()
+    if (!n) return
+    onCreate(n, color)
+    setName('')
+  }
+
+  return (
+    <div
+      ref={ref}
+      onClick={(e) => e.stopPropagation()}
+      className="petal-tag-picker absolute z-20 flex w-60 flex-col gap-2 p-3"
+      style={{
+        top: 'calc(100% + 4px)',
+        right: 0,
+        borderRadius: 'var(--radius-card)',
+        background: 'var(--color-surface)',
+        boxShadow: 'var(--shadow-soft)',
+        border: '1px solid var(--color-border)',
+      }}
+    >
+      <div className="text-xs font-bold" style={{ color: 'var(--color-muted)' }}>
+        标签 · Tags
+      </div>
+
+      {roster.length > 0 && (
+        <div className="flex max-h-40 flex-wrap gap-1.5 overflow-y-auto">
+          {roster.map((t) => {
+            const on = assignedIds.has(t.id)
+            const c = tagColorVar(t.color)
+            return (
+              <button
+                key={t.id}
+                type="button"
+                onClick={() => onToggle(t)}
+                className="petal-tap inline-flex items-center gap-1 whitespace-nowrap text-xs font-bold"
+                style={{
+                  borderRadius: 'var(--radius-pill)',
+                  padding: '0.25rem 0.6rem',
+                  background: on ? c : 'color-mix(in srgb, ' + c + ' 18%, white)',
+                  color: on ? 'white' : 'var(--color-plum)',
+                  border: `1px solid ${on ? c : 'color-mix(in srgb, ' + c + ' 40%, white)'}`,
+                }}
+              >
+                {on && <span aria-hidden>✓</span>}
+                {t.name}
+              </button>
+            )
+          })}
+        </div>
+      )}
+
+      <div className="flex flex-col gap-1.5 pt-1" style={{ borderTop: '1px solid var(--color-border)' }}>
+        <div className="flex items-center gap-1.5">
+          {COLORS.map((c) => (
+            <button
+              key={c}
+              type="button"
+              aria-label={`Color ${c}`}
+              onClick={() => setColor(c)}
+              className="petal-tap-sm"
+              style={{
+                width: 18,
+                height: 18,
+                borderRadius: 'var(--radius-pill)',
+                background: tagColorVar(c),
+                border: color === c ? '2px solid var(--color-plum)' : '2px solid transparent',
+              }}
+            />
+          ))}
+        </div>
+        <div className="flex items-center gap-1.5">
+          <input
+            value={name}
+            onChange={(e) => setName(e.target.value)}
+            onKeyDown={(e) => {
+              if (e.key === 'Enter') submit()
+            }}
+            placeholder="新标签 · New tag"
+            aria-label="New tag name"
+            className="petal-tap min-w-0 flex-1 bg-transparent px-2.5 text-sm focus:outline-none"
+            style={{
+              height: 34,
+              borderRadius: 'var(--radius-input)',
+              border: '1px solid var(--color-border)',
+              color: 'var(--color-plum)',
+            }}
+          />
+          <button
+            type="button"
+            onClick={submit}
+            className="petal-tap-sm shrink-0 px-3 text-sm font-bold text-white"
+            style={{ height: 34, borderRadius: 'var(--radius-pill)', background: 'var(--color-accent)' }}
+          >
+            ＋
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}

web/src/components/Editor/EditorCore.tsx

@@ -10,7 +10,11 @@ import { SuggestionCard } from './SuggestionCard'
 import { SuggestionHighlight, setSuggestions, findRange } from './SuggestionHighlight'
 import { SpellCheck, setSpellChecker, wordAt } from './SpellCheck'
 import { MisspellCard } from './MisspellCard'
-import type { Suggestion } from '../../api/client'
+import { WordCard } from './WordCard'
+import { GlossTip } from './GlossTip'
+import { SelectionBubble } from './SelectionBubble'
+import { RewritePreview, type RewriteStatus } from './RewritePreview'
+import { api, type Suggestion, type WordInfo } from '../../api/client'
 import type { SpellChecker } from '../../hooks/useSpellChecker'
 
 export interface EditorChange {
@@ -50,6 +54,19 @@ interface MisspellState {
   left: number
 }
 
+// The open right-click word popover (definition + synonyms), or null. `info` is
+// null while the offline lookup is in flight (`loading`); the card shows a
+// looking-up state until it resolves.
+interface WordInfoState {
+  word: string
+  from: number
+  to: number
+  top: number
+  left: number
+  loading: boolean
+  info: WordInfo | null
+}
+
 // A tiny CSS-only confetti burst played at an accept. Four palette-colored dots
 // spray up-and-out from a point; each reads its direction from --dx/--dy.
 const CONFETTI_DOTS = [
@@ -92,6 +109,39 @@ interface HoverState {
   left: number
 }
 
+// The inline hover gloss: the word under the resting pointer, its Chinese
+// translation, the PM range it covers (to dedupe re-fetches), and where to anchor.
+interface GlossState {
+  word: string
+  gloss: string
+  from: number
+  to: number
+  top: number
+  left: number
+}
+
+// A non-empty text selection that the rewrite bubble hovers over.
+interface SelectionState {
+  from: number
+  to: number
+  text: string
+  top: number
+  left: number
+}
+
+// An in-flight or completed tone-rewrite preview, pinned over the selection it
+// came from. `from`/`to` are the PM range the accepted rewrite replaces.
+interface RewriteState {
+  from: number
+  to: number
+  original: string
+  style: string
+  top: number
+  left: number
+  status: RewriteStatus
+  rewrite: string
+}
+
 // EditorCore is the Tiptap instance: StarterKit formatting plus underline, text
 // alignment, a placeholder, character counting, and the suggestion-highlight
 // decoration layer. Hovering a highlight opens its SuggestionCard.
@@ -112,6 +162,10 @@ export function EditorCore({
   const [hover, setHover] = useState<HoverState | null>(null)
   // The open spelling popover (click a red-underlined word), or null.
   const [misspell, setMisspell] = useState<MisspellState | null>(null)
+  // The open right-click word popover (definition + synonyms), or null.
+  const [wordInfo, setWordInfo] = useState<WordInfoState | null>(null)
+  // Token to discard a word lookup whose popover has since closed/changed.
+  const wordReqRef = useRef(0)
   // Transient confetti burst played at the last accept location.
   const [confetti, setConfetti] = useState<{ top: number; left: number } | null>(null)
   const confettiTimer = useRef<ReturnType<typeof setTimeout>>(undefined)
@@ -120,6 +174,15 @@ export function EditorCore({
   // While the Ask Petal panel is expanded the card is pinned: the hover-close
   // timer is suppressed so chatting doesn't dismiss it. A click outside closes.
   const [pinned, setPinned] = useState(false)
+  // Inline hover gloss (rest the pointer on a word → its Chinese meaning).
+  const [gloss, setGloss] = useState<GlossState | null>(null)
+  const glossTimer = useRef<ReturnType<typeof setTimeout>>(undefined)
+  const glossReqRef = useRef(0)
+  // The rewrite affordances: a bubble over the current selection, and the
+  // preview that replaces it once a style is chosen.
+  const [selection, setSelection] = useState<SelectionState | null>(null)
+  const [rewrite, setRewrite] = useState<RewriteState | null>(null)
+  const rewriteReqRef = useRef(0)
 
   const editor = useEditor({
     extensions: [
@@ -137,14 +200,40 @@ export function EditorCore({
     },
     onFocus: () => onFocusMode?.(),
     onUpdate: ({ editor }) => {
-      // Any edit shifts positions, stranding the spelling popover's anchor.
+      // Any edit shifts positions, stranding the popover anchors.
       setMisspell(null)
+      setWordInfo(null)
+      setGloss(null)
+      setSelection(null)
+      // A stale rewrite preview points at a range that just moved — drop it.
+      rewriteReqRef.current++
+      setRewrite(null)
       onChange({
         content: JSON.stringify(editor.getJSON()),
         content_text: editor.getText(),
         word_count: editor.storage.characterCount.words(),
       })
     },
+    onSelectionUpdate: ({ editor }) => {
+      // A selection supersedes the hover gloss; an empty one clears the bubble.
+      setGloss(null)
+      const { from, to, empty } = editor.state.selection
+      const wrapper = wrapperRef.current
+      if (empty || !wrapper) {
+        setSelection(null)
+        return
+      }
+      const text = editor.state.doc.textBetween(from, to, ' ').trim()
+      if (!text) {
+        setSelection(null)
+        return
+      }
+      const start = editor.view.coordsAtPos(from)
+      const wrapRect = wrapper.getBoundingClientRect()
+      const left = Math.max(0, Math.min(start.left - wrapRect.left, wrapper.clientWidth - 360))
+      const top = start.top - wrapRect.top
+      setSelection({ from, to, text, top, left })
+    },
   })
 
   // When the selected document changes, swap in its content without emitting an
@@ -154,6 +243,11 @@ export function EditorCore({
     editor.commands.setContent(parseDoc(initialContent) ?? '', false)
     setHover(null)
     setMisspell(null)
+    setWordInfo(null)
+    setGloss(null)
+    setSelection(null)
+    rewriteReqRef.current++
+    setRewrite(null)
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [docId, editor])
 
@@ -186,6 +280,8 @@ export function EditorCore({
         Math.min(elRect.left - wrapRect.left, wrapper.clientWidth - cardWidth),
       )
       const top = elRect.bottom - wrapRect.top + 6
+      // A suggestion card and the word popover shouldn't stack.
+      setWordInfo(null)
       setHover((prev) => {
         // Moving to a different highlight resets any Ask Petal pin.
         if (prev && prev.suggestion.id !== suggestion.id) setPinned(false)
@@ -266,8 +362,17 @@ export function EditorCore({
   // Click a red-underlined word to open its spelling popover, anchored under the
   // word. posAtCoords→wordAt resolves the exact PM span (robust to the same
   // misspelling appearing elsewhere); nspell supplies the corrections.
+  //
+  // Tapping an AI-suggestion highlight also opens its card here — on touch there's
+  // no hover, so the tap is the only way in (mouse users still get hover).
   const handleSpellClick = useCallback(
     (e: React.MouseEvent) => {
+      const suggestionEl = (e.target as HTMLElement).closest('.petal-suggestion') as HTMLElement | null
+      if (suggestionEl) {
+        const id = suggestionEl.getAttribute('data-suggestion-id')
+        if (id) openCardFor(id, suggestionEl)
+        return
+      }
       if (!editor || !spellChecker) return
       const target = (e.target as HTMLElement).closest('.petal-misspelling') as HTMLElement | null
       if (!target) return
@@ -284,9 +389,10 @@ export function EditorCore({
       const top = elRect.bottom - wrapRect.top + 6
       // Opening a spelling popover supersedes any AI-suggestion hover card.
       closeCard()
+      setWordInfo(null)
       setMisspell({ ...range, suggestions: spellChecker.suggest(range.word), top, left })
     },
-    [editor, spellChecker, closeCard],
+    [editor, spellChecker, closeCard, openCardFor],
   )
 
   const replaceMisspelling = useCallback(
@@ -304,6 +410,209 @@ export function EditorCore({
     setMisspell(null)
   }, [misspell, onAddWord])
 
+  // Right-click a word to look it up: resolve the exact word span under the
+  // pointer, anchor a popover beneath it, and kick off the offline lookup. The
+  // card opens immediately in a loading state and fills in when the (local)
+  // lookup returns. Right-clicking off any word falls through to the native menu.
+  const handleContextMenu = useCallback(
+    (e: React.MouseEvent) => {
+      if (!editor) return
+      const coords = editor.view.posAtCoords({ left: e.clientX, top: e.clientY })
+      if (!coords) return
+      const range = wordAt(editor.state.doc, coords.pos)
+      if (!range) return
+      const wrapper = wrapperRef.current
+      if (!wrapper) return
+      e.preventDefault()
+      // Anchor under the word itself (not the click point) so the card lines up
+      // with the text the way the spelling popover does.
+      const start = editor.view.coordsAtPos(range.from)
+      const end = editor.view.coordsAtPos(range.to)
+      const wrapRect = wrapper.getBoundingClientRect()
+      const cardWidth = 300
+      const left = Math.max(0, Math.min(start.left - wrapRect.left, wrapper.clientWidth - cardWidth))
+      const top = end.bottom - wrapRect.top + 6
+      // Opening a word lookup supersedes any suggestion/spelling card.
+      closeCard()
+      setMisspell(null)
+      const token = ++wordReqRef.current
+      setWordInfo({ word: range.word, from: range.from, to: range.to, top, left, loading: true, info: null })
+      api
+        .lookupWord(range.word)
+        .then((info) => {
+          if (token === wordReqRef.current) {
+            setWordInfo((w) => (w ? { ...w, loading: false, info } : null))
+          }
+        })
+        .catch((err) => {
+          console.error('word lookup failed', err)
+          if (token === wordReqRef.current) {
+            setWordInfo((w) => (w ? { ...w, loading: false, info: null } : null))
+          }
+        })
+    },
+    [editor, closeCard],
+  )
+
+  const replaceWord = useCallback(
+    (synonym: string) => {
+      if (editor && wordInfo) {
+        editor.chain().focus().insertContentAt({ from: wordInfo.from, to: wordInfo.to }, synonym).run()
+      }
+      setWordInfo(null)
+    },
+    [editor, wordInfo],
+  )
+
+  // Hover gloss: rest the pointer on an English word and, after a short delay,
+  // show its Chinese meaning from the offline gloss dataset. Suppressed while a
+  // selection, preview, or another popover is active, or over a word that has its
+  // own affordance (a suggestion highlight / a misspelling).
+  const handleMouseMove = useCallback(
+    (e: React.MouseEvent) => {
+      if (!editor) return
+      if (selection || rewrite || misspell || wordInfo || pinned) return
+      if (!editor.state.selection.empty) return
+      const t = e.target as HTMLElement
+      const clear = () => {
+        clearTimeout(glossTimer.current)
+        glossReqRef.current++
+        setGloss(null)
+      }
+      if (t.closest('.petal-suggestion') || t.closest('.petal-misspelling')) {
+        clear()
+        return
+      }
+      const coords = editor.view.posAtCoords({ left: e.clientX, top: e.clientY })
+      if (!coords) {
+        clear()
+        return
+      }
+      const range = wordAt(editor.state.doc, coords.pos)
+      if (!range) {
+        clear()
+        return
+      }
+      // Already showing this exact word — leave it be (no flicker on micro-moves).
+      if (gloss && gloss.from === range.from && gloss.to === range.to) return
+      clearTimeout(glossTimer.current)
+      const token = ++glossReqRef.current
+      glossTimer.current = setTimeout(() => {
+        api
+          .glossWord(range.word)
+          .then((g) => {
+            if (token !== glossReqRef.current) return
+            const wrapper = wrapperRef.current
+            if (!g.gloss || !wrapper) {
+              setGloss(null)
+              return
+            }
+            const start = editor.view.coordsAtPos(range.from)
+            const end = editor.view.coordsAtPos(range.to)
+            const wrapRect = wrapper.getBoundingClientRect()
+            const left = Math.max(0, Math.min(start.left - wrapRect.left, wrapper.clientWidth - 280))
+            const top = end.bottom - wrapRect.top + 6
+            setGloss({ word: range.word, gloss: g.gloss, from: range.from, to: range.to, top, left })
+          })
+          .catch(() => {
+            if (token === glossReqRef.current) setGloss(null)
+          })
+      }, 350)
+    },
+    [editor, selection, rewrite, misspell, wordInfo, pinned, gloss],
+  )
+
+  // Leaving the editor surface drops any pending/shown gloss.
+  const handleMouseLeave = useCallback(() => {
+    clearTimeout(glossTimer.current)
+    glossReqRef.current++
+    setGloss(null)
+  }, [])
+
+  // runRewrite fires the LLM rewrite for a captured range + style and tracks it
+  // through loading → ready/error. A request token discards a response whose
+  // preview has since been cancelled or superseded.
+  const runRewrite = useCallback(
+    (from: number, to: number, original: string, style: string, top: number, left: number) => {
+      const token = ++rewriteReqRef.current
+      setRewrite({ from, to, original, style, top, left, status: 'loading', rewrite: '' })
+      api
+        .rewriteSelection(docId, original, style)
+        .then((res) => {
+          if (token === rewriteReqRef.current) {
+            setRewrite((r) => (r ? { ...r, status: 'ready', rewrite: res.rewrite } : null))
+          }
+        })
+        .catch((err) => {
+          console.error('rewrite failed', err)
+          if (token === rewriteReqRef.current) {
+            setRewrite((r) => (r ? { ...r, status: 'error' } : null))
+          }
+        })
+    },
+    [docId],
+  )
+
+  // Picking a style in the selection bubble: capture the selection's range +
+  // text, anchor a preview below it, and kick off the rewrite.
+  const handleRewrite = useCallback(
+    (style: string) => {
+      if (!editor || !selection) return
+      const wrapper = wrapperRef.current
+      if (!wrapper) return
+      const start = editor.view.coordsAtPos(selection.from)
+      const end = editor.view.coordsAtPos(selection.to)
+      const wrapRect = wrapper.getBoundingClientRect()
+      const left = Math.max(0, Math.min(start.left - wrapRect.left, wrapper.clientWidth - 340))
+      const top = end.bottom - wrapRect.top + 6
+      setSelection(null)
+      setGloss(null)
+      runRewrite(selection.from, selection.to, selection.text, style, top, left)
+    },
+    [editor, selection, runRewrite],
+  )
+
+  const acceptRewrite = useCallback(() => {
+    if (editor && rewrite && rewrite.rewrite) {
+      editor.chain().focus().insertContentAt({ from: rewrite.from, to: rewrite.to }, rewrite.rewrite).run()
+    }
+    rewriteReqRef.current++
+    setRewrite(null)
+  }, [editor, rewrite])
+
+  const cancelRewrite = useCallback(() => {
+    rewriteReqRef.current++
+    setRewrite(null)
+  }, [])
+
+  const retryRewrite = useCallback(() => {
+    if (rewrite) runRewrite(rewrite.from, rewrite.to, rewrite.original, rewrite.style, rewrite.top, rewrite.left)
+  }, [rewrite, runRewrite])
+
+  // A pointer-down outside the rewrite preview dismisses it.
+  useEffect(() => {
+    if (!rewrite) return
+    const onDown = (e: MouseEvent) => {
+      if ((e.target as HTMLElement).closest('.petal-rewrite-card')) return
+      rewriteReqRef.current++
+      setRewrite(null)
+    }
+    document.addEventListener('mousedown', onDown)
+    return () => document.removeEventListener('mousedown', onDown)
+  }, [rewrite])
+
+  // A pointer-down outside the word popover (and not on another word, which would
+  // reopen it via the context menu) closes it.
+  useEffect(() => {
+    if (!wordInfo) return
+    const onDown = (e: MouseEvent) => {
+      if ((e.target as HTMLElement).closest('.petal-word-card')) return
+      setWordInfo(null)
+    }
+    document.addEventListener('mousedown', onDown)
+    return () => document.removeEventListener('mousedown', onDown)
+  }, [wordInfo])
+
   // A pointer-down outside the popover (and not on another misspelling, which
   // would reopen it) closes the spelling card.
   useEffect(() => {
@@ -320,6 +629,7 @@ export function EditorCore({
   useEffect(() => () => {
     clearTimeout(closeTimer.current)
     clearTimeout(confettiTimer.current)
+    clearTimeout(glossTimer.current)
   }, [])
 
   // While pinned (Ask Petal open), a pointer-down outside the card closes it —
@@ -333,6 +643,20 @@ export function EditorCore({
     return () => document.removeEventListener('mousedown', onDown)
   }, [pinned, closeCard])
 
+  // Touch has no hover, so the card is opened by a tap and can't close itself on
+  // mouse-leave. Whenever a card is open, a pointer-down outside both the card and
+  // any highlight dismisses it. Excluding `.petal-suggestion` lets a tap on
+  // another highlight reopen for that one (via the click handler) without flicker.
+  useEffect(() => {
+    if (!hover) return
+    const onDown = (e: PointerEvent) => {
+      const t = e.target as HTMLElement
+      if (!t.closest('.petal-suggestion-card') && !t.closest('.petal-suggestion')) closeCard()
+    }
+    document.addEventListener('pointerdown', onDown)
+    return () => document.removeEventListener('pointerdown', onDown)
+  }, [hover, closeCard])
+
   return (
     <div className="flex flex-1 flex-col">
       <Toolbar editor={editor} onVoiceCheck={onVoiceCheck} voicing={voicing} />
@@ -341,10 +665,41 @@ export function EditorCore({
         className="relative flex-1"
         onMouseOver={handleMouseOver}
         onMouseOut={handleMouseOut}
+        onMouseMove={handleMouseMove}
+        onMouseLeave={handleMouseLeave}
         onClick={handleSpellClick}
+        onContextMenu={handleContextMenu}
       >
         <EditorContent editor={editor} className="h-full" />
         {confetti && <Confetti top={confetti.top} left={confetti.left} />}
+        {gloss && <GlossTip gloss={gloss.gloss} style={{ top: gloss.top, left: gloss.left }} />}
+        {selection && !rewrite && (
+          <SelectionBubble
+            style={{ top: selection.top, left: selection.left, transform: 'translateY(calc(-100% - 8px))' }}
+            onRewrite={handleRewrite}
+          />
+        )}
+        {rewrite && (
+          <RewritePreview
+            style={rewrite.style}
+            status={rewrite.status}
+            original={rewrite.original}
+            rewrite={rewrite.rewrite}
+            cardStyle={{ top: rewrite.top, left: rewrite.left }}
+            onAccept={acceptRewrite}
+            onCancel={cancelRewrite}
+            onRetry={retryRewrite}
+          />
+        )}
+        {wordInfo && (
+          <WordCard
+            word={wordInfo.word}
+            info={wordInfo.info}
+            loading={wordInfo.loading}
+            style={{ top: wordInfo.top, left: wordInfo.left }}
+            onReplace={replaceWord}
+          />
+        )}
         {misspell && (
           <MisspellCard
             word={misspell.word}

web/src/components/Editor/GlossTip.tsx

@@ -0,0 +1,32 @@
+// GlossTip is the inline hover gloss: rest the pointer on an English word and a
+// small bubble shows its Chinese meaning, pulled instantly from the offline
+// gloss dataset. It's a pure reading aid — pointer-events are off so it never
+// steals hover or blocks a click, and it sits just under the word. Bilingual
+// chrome elsewhere puts zh first; here the gloss IS the content (the word is
+// already on screen), so the bubble shows only the 中文.
+
+interface Props {
+  gloss: string
+  style: React.CSSProperties
+}
+
+export function GlossTip({ gloss, style }: Props) {
+  return (
+    <div
+      className="petal-gloss-tip pointer-events-none absolute z-20 px-2.5 py-1.5 text-sm"
+      role="tooltip"
+      style={{
+        maxWidth: 280,
+        background: 'var(--color-plum)',
+        color: 'var(--color-surface)',
+        borderRadius: 'var(--radius-input)',
+        boxShadow: 'var(--shadow-soft)',
+        lineHeight: 1.35,
+        fontFamily: "'Nunito','PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif",
+        ...style,
+      }}
+    >
+      {gloss}
+    </div>
+  )
+}

web/src/components/Editor/RewritePreview.tsx

@@ -0,0 +1,136 @@
+import { REWRITE_STYLES } from './SelectionBubble'
+
+// RewritePreview shows the result of a tone-rewrite before it touches the
+// document: the writer's original passage, the model's rewrite beneath it, and
+// accept/cancel. It mirrors the SuggestionCard's warm, bilingual chrome. While
+// the model runs it shows a breathing dot; on failure it offers a gentle retry.
+
+export type RewriteStatus = 'loading' | 'ready' | 'error'
+
+interface Props {
+  style: string // the chosen rewrite style key (for the header label)
+  status: RewriteStatus
+  original: string
+  rewrite: string
+  cardStyle: React.CSSProperties
+  onAccept: () => void
+  onCancel: () => void
+  onRetry: () => void
+}
+
+const CJK = "'Nunito','PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif"
+
+export function RewritePreview({
+  style,
+  status,
+  original,
+  rewrite,
+  cardStyle,
+  onAccept,
+  onCancel,
+  onRetry,
+}: Props) {
+  const meta = REWRITE_STYLES.find((s) => s.value === style) ?? REWRITE_STYLES[0]
+
+  return (
+    <div
+      className="petal-rewrite-card absolute z-30 p-3.5 text-sm"
+      role="dialog"
+      aria-label="Rewrite preview"
+      onMouseDown={(e) => e.stopPropagation()}
+      style={{
+        width: 340,
+        background: 'var(--color-surface)',
+        border: '1px solid var(--color-border)',
+        borderRadius: 'var(--radius-card)',
+        boxShadow: 'var(--shadow-soft)',
+        fontFamily: CJK,
+        ...cardStyle,
+      }}
+    >
+      <div className="flex items-center gap-1.5">
+        <span
+          className="inline-flex items-center gap-1 rounded-full px-2.5 py-0.5 text-xs font-bold"
+          style={{ background: 'var(--color-accent)', color: 'var(--color-plum)' }}
+        >
+          <span aria-hidden>{meta.emoji}</span>
+          {meta.zh} · {meta.en}
+        </span>
+        <span className="text-xs font-semibold" style={{ color: 'var(--color-muted)' }}>
+          改写 · Rewrite
+        </span>
+      </div>
+
+      {/* Original passage, dimmed — what's being replaced. */}
+      <p
+        className="mt-3 leading-snug"
+        style={{ color: 'var(--color-muted)', textDecoration: 'line-through', textDecorationColor: 'var(--color-border)' }}
+      >
+        {original}
+      </p>
+
+      {status === 'loading' && (
+        <div className="mt-3 inline-flex items-center gap-1.5" style={{ color: 'var(--color-muted)' }}>
+          <span
+            className="petal-checkpoint-dot inline-block h-2 w-2 rounded-full"
+            style={{ background: 'var(--color-accent)' }}
+            aria-hidden
+          />
+          改写中… · Rewriting…
+        </div>
+      )}
+
+      {status === 'error' && (
+        <div className="mt-3">
+          <p className="leading-snug" style={{ color: 'var(--color-muted)' }}>
+            改写失败，请再试一次 · Couldn’t rewrite — try again
+          </p>
+          <div className="mt-2.5 flex justify-end gap-2">
+            <button
+              type="button"
+              onClick={onCancel}
+              className="rounded-full px-3 py-1 text-xs font-semibold"
+              style={{ background: 'var(--color-surface-alt)', color: 'var(--color-plum)' }}
+            >
+              取消 · Cancel
+            </button>
+            <button
+              type="button"
+              onClick={onRetry}
+              className="rounded-full px-3 py-1 text-xs font-bold"
+              style={{ background: 'var(--color-accent)', color: 'var(--color-plum)' }}
+            >
+              重试 · Retry
+            </button>
+          </div>
+        </div>
+      )}
+
+      {status === 'ready' && (
+        <>
+          <p className="mt-2 leading-snug" style={{ color: 'var(--color-plum)' }}>
+            {rewrite}
+          </p>
+          <div className="mt-3 flex justify-end gap-2">
+            <button
+              type="button"
+              onClick={onCancel}
+              className="rounded-full px-3 py-1 text-xs font-semibold"
+              style={{ background: 'var(--color-surface-alt)', color: 'var(--color-plum)' }}
+            >
+              取消 · Cancel
+            </button>
+            <button
+              type="button"
+              onClick={onAccept}
+              className="rounded-full px-3 py-1 text-xs font-bold"
+              style={{ background: 'var(--color-accent)', color: 'var(--color-plum)' }}
+            >
+              用这个 · Use this
+            </button>
+          </div>
+        </>
+      )}
+    </div>
+  )
+}

web/src/components/Editor/SelectionBubble.tsx

@@ -0,0 +1,85 @@
+// SelectionBubble floats above a text selection and offers to rewrite it: a
+// prominent "✨ 更自然 Say it naturally" action plus the tone vocabulary (学术,
+// 轻松, …) mirrored from the document-tone picker. Picking one hands the style up
+// to EditorCore, which calls the LLM and shows a preview. Buttons use
+// onMouseDown→preventDefault so clicking them doesn't collapse the selection
+// before the handler captures its range.
+
+export interface RewriteStyle {
+  value: string
+  emoji: string
+  zh: string
+  en: string
+}
+
+// 'natural' is the default "say it more naturally" rewrite; the rest mirror the
+// llm styleGuidance keys (and the ToneSelect labels) so the two stay in step.
+export const REWRITE_STYLES: RewriteStyle[] = [
+  { value: 'natural', emoji: '✨', zh: '更自然', en: 'Natural' },
+  { value: 'academic', emoji: '🎓', zh: '学术', en: 'Academic' },
+  { value: 'professional', emoji: '💼', zh: '专业', en: 'Professional' },
+  { value: 'casual', emoji: '☕', zh: '轻松', en: 'Casual' },
+  { value: 'humorous', emoji: '😄', zh: '幽默', en: 'Humorous' },
+  { value: 'creative', emoji: '🎨', zh: '创意', en: 'Creative' },
+  { value: 'persuasive', emoji: '📣', zh: '说服', en: 'Persuasive' },
+]
+
+interface Props {
+  style: React.CSSProperties
+  onRewrite: (style: string) => void
+}
+
+const CJK = "'Nunito','PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif"
+
+export function SelectionBubble({ style, onRewrite }: Props) {
+  const [natural, ...tones] = REWRITE_STYLES
+
+  return (
+    <div
+      className="petal-selection-bubble absolute z-30 flex max-w-[360px] flex-wrap items-center gap-1.5 p-2"
+      role="toolbar"
+      aria-label="Rewrite the selection"
+      onMouseDown={(e) => e.preventDefault()} // keep the editor selection
+      style={{
+        background: 'var(--color-surface)',
+        border: '1px solid var(--color-border)',
+        borderRadius: 'var(--radius-pill)',
+        boxShadow: 'var(--shadow-soft)',
+        fontFamily: CJK,
+        ...style,
+      }}
+    >
+      <button
+        type="button"
+        onClick={() => onRewrite(natural.value)}
+        className="inline-flex h-8 items-center gap-1.5 whitespace-nowrap px-3 text-sm font-bold"
+        style={{ borderRadius: 'var(--radius-pill)', background: 'var(--color-accent)', color: 'var(--color-plum)' }}
+        title="Rewrite the selection to sound more natural"
+      >
+        <span aria-hidden>{natural.emoji}</span>
+        <span>{natural.zh}</span>
+        <span className="font-semibold" style={{ color: 'var(--color-plum)', opacity: 0.7 }}>
+          {natural.en}
+        </span>
+      </button>
+
+      <span className="mx-0.5 h-5 w-px shrink-0" style={{ background: 'var(--color-border)' }} />
+
+      {tones.map((t) => (
+        <button
+          key={t.value}
+          type="button"
+          onClick={() => onRewrite(t.value)}
+          className="inline-flex h-8 items-center gap-1 whitespace-nowrap px-2.5 text-sm font-semibold"
+          style={{ borderRadius: 'var(--radius-pill)', background: 'var(--color-surface-alt)', color: 'var(--color-plum)' }}
+          onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-lavender)')}
+          onMouseLeave={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+          title={`Rewrite in a ${t.en.toLowerCase()} tone`}
+        >
+          <span aria-hidden>{t.emoji}</span>
+          <span>{t.zh}</span>
+        </button>
+      ))}
+    </div>
+  )
+}

web/src/components/Editor/ToneSelect.tsx

@@ -0,0 +1,119 @@
+import { useEffect, useRef, useState } from 'react'
+
+// ToneSelect lets the writer set the document's target tone, which steers the
+// grammar-checkpoint LLM toward the right register (an academic essay vs a casual
+// journal). A small custom dropdown (not a native <select>) so it can carry the
+// bilingual zh·en labels and emoji that match Petal's chrome — the writer uses
+// Mandarin and English. The `value` strings mirror the backend's tone keys.
+
+export interface ToneOption {
+  value: string
+  emoji: string
+  zh: string
+  en: string
+}
+
+// Keep these `value`s in sync with llm.toneGuidance on the server. 'general'
+// means no steering (Petal's default friendly ESL advice).
+export const TONES: ToneOption[] = [
+  { value: 'general', emoji: '🌸', zh: '通用', en: 'General' },
+  { value: 'academic', emoji: '🎓', zh: '学术', en: 'Academic' },
+  { value: 'professional', emoji: '💼', zh: '专业', en: 'Professional' },
+  { value: 'casual', emoji: '☕', zh: '轻松', en: 'Casual' },
+  { value: 'humorous', emoji: '😄', zh: '幽默', en: 'Humorous' },
+  { value: 'creative', emoji: '🎨', zh: '创意', en: 'Creative' },
+  { value: 'persuasive', emoji: '📣', zh: '说服', en: 'Persuasive' },
+]
+
+interface Props {
+  value: string
+  onChange: (value: string) => void
+}
+
+export function ToneSelect({ value, onChange }: Props) {
+  const [open, setOpen] = useState(false)
+  const ref = useRef<HTMLDivElement>(null)
+  const current = TONES.find((t) => t.value === value) ?? TONES[0]
+
+  // Click outside closes the menu.
+  useEffect(() => {
+    if (!open) return
+    const onDown = (e: MouseEvent) => {
+      if (!ref.current?.contains(e.target as Node)) setOpen(false)
+    }
+    document.addEventListener('mousedown', onDown)
+    return () => document.removeEventListener('mousedown', onDown)
+  }, [open])
+
+  return (
+    <div ref={ref} className="relative shrink-0">
+      <button
+        type="button"
+        aria-label="Document tone"
+        aria-haspopup="listbox"
+        aria-expanded={open}
+        onClick={() => setOpen((o) => !o)}
+        className="inline-flex h-9 items-center gap-1.5 whitespace-nowrap px-3 text-sm font-bold"
+        style={{
+          borderRadius: 'var(--radius-pill)',
+          background: 'var(--color-surface)',
+          color: 'var(--color-plum)',
+          boxShadow: 'var(--shadow-soft)',
+        }}
+        title="Set the tone — Petal tailors its advice to match"
+      >
+        <span aria-hidden>{current.emoji}</span>
+        <span>{current.zh}</span>
+        <span style={{ color: 'var(--color-muted)' }}>· {current.en}</span>
+        <span aria-hidden style={{ color: 'var(--color-muted)' }}>
+          ⌄
+        </span>
+      </button>
+
+      {open && (
+        <div
+          role="listbox"
+          className="petal-word-card absolute right-0 z-30 mt-1.5 p-1.5"
+          style={{
+            width: 200,
+            background: 'var(--color-surface)',
+            border: '1px solid var(--color-border)',
+            borderRadius: 'var(--radius-card)',
+            boxShadow: 'var(--shadow-soft)',
+          }}
+        >
+          {TONES.map((t) => {
+            const active = t.value === value
+            return (
+              <button
+                key={t.value}
+                type="button"
+                role="option"
+                aria-selected={active}
+                onClick={() => {
+                  onChange(t.value)
+                  setOpen(false)
+                }}
+                className="flex w-full items-center gap-2 rounded-xl px-2.5 py-1.5 text-left text-sm font-semibold"
+                style={{
+                  background: active ? 'var(--color-surface-alt)' : 'transparent',
+                  color: 'var(--color-plum)',
+                }}
+                onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+                onMouseLeave={(e) =>
+                  (e.currentTarget.style.background = active ? 'var(--color-surface-alt)' : 'transparent')
+                }
+              >
+                <span aria-hidden>{t.emoji}</span>
+                <span>{t.zh}</span>
+                <span className="font-normal" style={{ color: 'var(--color-muted)' }}>
+                  {t.en}
+                </span>
+              </button>
+            )
+          })}
+        </div>
+      )}
+    </div>
+  )
+}

web/src/components/Editor/WordCard.tsx

@@ -0,0 +1,130 @@
+import type { WordInfo } from '../../api/client'
+
+// WordCard is the right-click popover for any word: its dictionary definition(s)
+// on top and tappable synonym pills below. Clicking a synonym replaces the word
+// in place. Both datasets are offline, so this opens instantly and fills in as
+// the (local) lookup returns. Labels are bilingual (zh-first, en subtitle) to
+// match the rest of Petal's chrome — the writer uses Mandarin and English.
+
+interface Props {
+  word: string
+  info: WordInfo | null
+  loading: boolean
+  style: React.CSSProperties
+  onReplace: (synonym: string) => void
+}
+
+export function WordCard({ word, info, loading, style, onReplace }: Props) {
+  const definitions = info?.definitions ?? []
+  const synonyms = info?.synonyms ?? []
+  const gloss = info?.gloss ?? ''
+  const empty = !loading && !gloss && definitions.length === 0 && synonyms.length === 0
+
+  return (
+    <div
+      role="dialog"
+      aria-label={`Definition and synonyms for ${word}`}
+      className="petal-word-card absolute z-20 p-3.5 text-sm"
+      style={{
+        width: 300,
+        maxHeight: 340,
+        overflowY: 'auto',
+        background: 'var(--color-surface)',
+        border: '1px solid var(--color-border)',
+        borderRadius: 'var(--radius-card)',
+        boxShadow: 'var(--shadow-soft)',
+        ...style,
+      }}
+    >
+      <div className="flex items-center gap-1.5">
+        <span
+          className="inline-flex items-center rounded-full px-2.5 py-0.5 text-xs font-bold"
+          style={{ background: 'var(--color-lavender)', color: 'var(--color-plum)' }}
+        >
+          词语 · Word
+        </span>
+        <span className="font-bold" style={{ color: 'var(--color-plum)' }}>
+          {word}
+        </span>
+      </div>
+
+      {/* Chinese gloss first — it's what the Mandarin-speaking writer reaches for. */}
+      {gloss && (
+        <p
+          className="mt-2.5 leading-snug"
+          style={{
+            color: 'var(--color-plum)',
+            fontFamily: "'Nunito','PingFang SC','Microsoft YaHei','Noto Sans CJK SC',sans-serif",
+          }}
+        >
+          {gloss}
+        </p>
+      )}
+
+      {loading && (
+        <div className="mt-3 inline-flex items-center gap-1.5" style={{ color: 'var(--color-muted)' }}>
+          <span
+            className="petal-checkpoint-dot inline-block h-2 w-2 rounded-full"
+            style={{ background: 'var(--color-accent)' }}
+            aria-hidden
+          />
+          查找中… · Looking up…
+        </div>
+      )}
+
+      {definitions.length > 0 && (
+        <div className="mt-3 space-y-2">
+          <p className="text-xs font-bold" style={{ color: 'var(--color-muted)' }}>
+            释义 · Definition
+          </p>
+          <ol className="space-y-1.5">
+            {definitions.map((m, i) => (
+              <li key={i} className="leading-snug" style={{ color: 'var(--color-plum)' }}>
+                {m.part_of_speech && (
+                  <span className="mr-1 italic" style={{ color: 'var(--color-accent-hover)' }}>
+                    {m.part_of_speech}
+                  </span>
+                )}
+                {m.definition}
+                {m.example && (
+                  <span className="mt-0.5 block italic" style={{ color: 'var(--color-muted)' }}>
+                    “{m.example}”
+                  </span>
+                )}
+              </li>
+            ))}
+          </ol>
+        </div>
+      )}
+
+      {synonyms.length > 0 && (
+        <div className="mt-3">
+          <p className="mb-1.5 text-xs font-bold" style={{ color: 'var(--color-muted)' }}>
+            近义词 · Synonyms <span className="font-normal">(点击替换 · tap to swap)</span>
+          </p>
+          <div className="flex flex-wrap gap-1.5">
+            {synonyms.map((s) => (
+              <button
+                key={s}
+                type="button"
+                onClick={() => onReplace(s)}
+                className="rounded-full px-3 py-1 text-xs font-semibold"
+                style={{ background: 'var(--color-surface-alt)', color: 'var(--color-plum)' }}
+                onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-accent)')}
+                onMouseLeave={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+              >
+                {s}
+              </button>
+            ))}
+          </div>
+        </div>
+      )}
+
+      {empty && (
+        <p className="mt-3 leading-snug" style={{ color: 'var(--color-muted)' }}>
+          没有找到这个词 · Nothing found for this word
+        </p>
+      )}
+    </div>
+  )
+}

web/src/components/Export/ExportMenu.tsx

@@ -0,0 +1,120 @@
+import { useEffect, useRef, useState } from 'react'
+import { api, type ExportFormat } from '../../api/client'
+
+// ExportMenu is the "get your writing out of Petal" dropdown. File formats are
+// plain <a download> links to the server's export endpoint (which sets the
+// Content-Disposition filename, CJK and all). "Print / Save as PDF" calls the
+// browser print dialog against the print stylesheet, so PDF stays CJK-safe with
+// no server-side font embedding. Bilingual zh·en labels match Petal's chrome.
+
+interface FormatOption {
+  format: ExportFormat
+  emoji: string
+  zh: string
+  en: string
+}
+
+const FORMATS: FormatOption[] = [
+  { format: 'docx', emoji: '📄', zh: 'Word 文档', en: 'Word (.docx)' },
+  { format: 'md', emoji: '📝', zh: 'Markdown', en: 'Markdown (.md)' },
+  { format: 'html', emoji: '🌐', zh: '网页', en: 'Web page (.html)' },
+  { format: 'txt', emoji: '🧾', zh: '纯文本', en: 'Plain text (.txt)' },
+]
+
+interface Props {
+  docId: string
+}
+
+export function ExportMenu({ docId }: Props) {
+  const [open, setOpen] = useState(false)
+  const ref = useRef<HTMLDivElement>(null)
+
+  useEffect(() => {
+    if (!open) return
+    const onDown = (e: MouseEvent) => {
+      if (!ref.current?.contains(e.target as Node)) setOpen(false)
+    }
+    document.addEventListener('mousedown', onDown)
+    return () => document.removeEventListener('mousedown', onDown)
+  }, [open])
+
+  return (
+    <div ref={ref} className="relative shrink-0">
+      <button
+        type="button"
+        aria-label="Export document"
+        aria-haspopup="menu"
+        aria-expanded={open}
+        onClick={() => setOpen((o) => !o)}
+        className="inline-flex h-9 items-center gap-1.5 whitespace-nowrap px-3 text-sm font-bold"
+        style={{
+          borderRadius: 'var(--radius-pill)',
+          background: 'var(--color-surface)',
+          color: 'var(--color-plum)',
+          boxShadow: 'var(--shadow-soft)',
+        }}
+        title="Save or print your writing"
+      >
+        <span aria-hidden>⬇</span>
+        <span>导出</span>
+        <span style={{ color: 'var(--color-muted)' }}>· Export</span>
+      </button>
+
+      {open && (
+        <div
+          role="menu"
+          className="petal-word-card absolute right-0 z-30 mt-1.5 p-1.5"
+          style={{
+            width: 220,
+            background: 'var(--color-surface)',
+            border: '1px solid var(--color-border)',
+            borderRadius: 'var(--radius-card)',
+            boxShadow: 'var(--shadow-soft)',
+          }}
+        >
+          {FORMATS.map((f) => (
+            <a
+              key={f.format}
+              role="menuitem"
+              href={api.exportUrl(docId, f.format)}
+              download
+              onClick={() => setOpen(false)}
+              className="flex w-full items-center gap-2 rounded-xl px-2.5 py-1.5 text-left text-sm font-semibold no-underline"
+              style={{ color: 'var(--color-plum)' }}
+              onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+              onMouseLeave={(e) => (e.currentTarget.style.background = 'transparent')}
+            >
+              <span aria-hidden>{f.emoji}</span>
+              <span>{f.zh}</span>
+              <span className="font-normal" style={{ color: 'var(--color-muted)' }}>
+                {f.en}
+              </span>
+            </a>
+          ))}
+
+          <div className="my-1 h-px" style={{ background: 'var(--color-border)' }} />
+
+          <button
+            type="button"
+            role="menuitem"
+            onClick={() => {
+              setOpen(false)
+              // Defer so the menu unmounts before the print dialog snapshots.
+              setTimeout(() => window.print(), 50)
+            }}
+            className="flex w-full items-center gap-2 rounded-xl px-2.5 py-1.5 text-left text-sm font-semibold"
+            style={{ background: 'transparent', color: 'var(--color-plum)' }}
+            onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+            onMouseLeave={(e) => (e.currentTarget.style.background = 'transparent')}
+          >
+            <span aria-hidden>🖨️</span>
+            <span>打印 / PDF</span>
+            <span className="font-normal" style={{ color: 'var(--color-muted)' }}>
+              Print / PDF
+            </span>
+          </button>
+        </div>
+      )}
+    </div>
+  )
+}

web/src/components/History/HistoryPanel.tsx

@@ -0,0 +1,230 @@
+import { useCallback, useEffect, useState } from 'react'
+import { api, type Document, type DocumentVersion } from '../../api/client'
+
+// HistoryPanel is the "time machine" drawer: every snapshot Petal kept of this
+// document, newest first, with a one-click preview and restore. It's the safety
+// net that makes trusting Petal with real writing reasonable — a bad edit or a
+// regretted rewrite is always recoverable, and restoring is itself undoable
+// (the server keeps a pre_restore copy). Bilingual, zh-first, to match chrome.
+
+interface Props {
+  docId: string
+  onClose: () => void
+  // Called after a successful restore with the freshly-restored document so the
+  // editor can reload it.
+  onRestored: (doc: Document) => void
+}
+
+// kindLabel maps a snapshot kind to its bilingual badge + accent color.
+const KIND: Record<DocumentVersion['kind'], { zh: string; en: string; color: string }> = {
+  manual: { zh: '保存点', en: 'Saved point', color: 'var(--color-accent)' },
+  auto: { zh: '自动', en: 'Auto', color: 'var(--color-muted)' },
+  pre_restore: { zh: '恢复前', en: 'Before restore', color: 'var(--color-lavender)' },
+}
+
+// relativeTime renders a UTC timestamp as a gentle "x minutes ago" string.
+function relativeTime(iso: string): string {
+  const then = new Date(iso).getTime()
+  const secs = Math.max(0, Math.round((Date.now() - then) / 1000))
+  if (secs < 60) return 'just now · 刚刚'
+  const mins = Math.round(secs / 60)
+  if (mins < 60) return `${mins} min ago · ${mins} 分钟前`
+  const hrs = Math.round(mins / 60)
+  if (hrs < 24) return `${hrs} hr ago · ${hrs} 小时前`
+  const days = Math.round(hrs / 24)
+  return `${days} day${days > 1 ? 's' : ''} ago · ${days} 天前`
+}
+
+export function HistoryPanel({ docId, onClose, onRestored }: Props) {
+  const [versions, setVersions] = useState<DocumentVersion[] | null>(null)
+  const [error, setError] = useState(false)
+  const [selected, setSelected] = useState<DocumentVersion | null>(null)
+  const [preview, setPreview] = useState<DocumentVersion | null>(null)
+  const [busy, setBusy] = useState(false)
+
+  const load = useCallback(async () => {
+    setError(false)
+    try {
+      setVersions(await api.listVersions(docId))
+    } catch {
+      setError(true)
+    }
+  }, [docId])
+
+  useEffect(() => {
+    void load()
+  }, [load])
+
+  // Escape closes the drawer.
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') onClose()
+    }
+    window.addEventListener('keydown', onKey)
+    return () => window.removeEventListener('keydown', onKey)
+  }, [onClose])
+
+  const choose = useCallback(
+    async (v: DocumentVersion) => {
+      setSelected(v)
+      setPreview(null)
+      try {
+        setPreview(await api.getVersion(docId, v.id))
+      } catch {
+        setPreview(null)
+      }
+    },
+    [docId],
+  )
+
+  const restore = useCallback(async () => {
+    if (!selected) return
+    setBusy(true)
+    try {
+      const doc = await api.restoreVersion(docId, selected.id)
+      onRestored(doc)
+      onClose()
+    } catch {
+      setBusy(false)
+    }
+  }, [docId, selected, onRestored, onClose])
+
+  return (
+    <div className="petal-no-print fixed inset-0 z-40 flex justify-end">
+      {/* Backdrop */}
+      <div
+        className="absolute inset-0"
+        style={{ background: 'rgba(61, 46, 57, 0.18)' }}
+        onClick={onClose}
+      />
+
+      <aside
+        className="relative flex h-full w-full max-w-[380px] flex-col"
+        style={{
+          background: 'var(--color-surface)',
+          borderLeft: '1px solid var(--color-border)',
+          boxShadow: 'var(--shadow-soft)',
+        }}
+      >
+        <header
+          className="flex items-center justify-between px-5 py-4"
+          style={{ borderBottom: '1px solid var(--color-border)' }}
+        >
+          <div>
+            <div className="text-base font-extrabold text-plum">历史 · History</div>
+            <div className="text-xs" style={{ color: 'var(--color-muted)' }}>
+              Every saved moment — nothing is ever lost 🌸
+            </div>
+          </div>
+          <button
+            type="button"
+            aria-label="Close history"
+            onClick={onClose}
+            className="flex h-8 w-8 items-center justify-center rounded-full text-lg"
+            style={{ color: 'var(--color-muted)' }}
+            onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-surface-alt)')}
+            onMouseLeave={(e) => (e.currentTarget.style.background = 'transparent')}
+          >
+            ✕
+          </button>
+        </header>
+
+        <div className="min-h-0 flex-1 overflow-y-auto px-3 py-3">
+          {error ? (
+            <div className="px-2 py-6 text-center text-sm" style={{ color: 'var(--color-muted)' }}>
+              Couldn’t load history just now.
+              <button onClick={load} className="ml-1 font-bold text-plum underline">
+                Try again
+              </button>
+            </div>
+          ) : versions === null ? (
+            <div className="px-2 py-6 text-center text-sm" style={{ color: 'var(--color-muted)' }}>
+              Loading…
+            </div>
+          ) : versions.length === 0 ? (
+            <div className="px-2 py-8 text-center text-sm" style={{ color: 'var(--color-muted)' }}>
+              No snapshots yet. Keep writing — Petal saves restore points as you go.
+            </div>
+          ) : (
+            <ul className="flex flex-col gap-1.5">
+              {versions.map((v) => {
+                const k = KIND[v.kind]
+                const active = selected?.id === v.id
+                return (
+                  <li key={v.id}>
+                    <button
+                      type="button"
+                      onClick={() => choose(v)}
+                      className="flex w-full flex-col gap-1 rounded-2xl px-3 py-2.5 text-left"
+                      style={{
+                        background: active ? 'var(--color-surface-alt)' : 'transparent',
+                        border: `1px solid ${active ? 'var(--color-border)' : 'transparent'}`,
+                      }}
+                      onMouseEnter={(e) =>
+                        (e.currentTarget.style.background = 'var(--color-surface-alt)')
+                      }
+                      onMouseLeave={(e) =>
+                        (e.currentTarget.style.background = active
+                          ? 'var(--color-surface-alt)'
+                          : 'transparent')
+                      }
+                    >
+                      <div className="flex items-center justify-between gap-2">
+                        <span className="truncate text-sm font-bold text-plum">{v.title || 'Untitled'}</span>
+                        <span
+                          className="shrink-0 rounded-full px-2 py-0.5 text-[10px] font-bold"
+                          style={{ background: k.color, color: '#fff' }}
+                        >
+                          {k.zh} · {k.en}
+                        </span>
+                      </div>
+                      <div className="flex items-center justify-between gap-2 text-xs" style={{ color: 'var(--color-muted)' }}>
+                        <span>{relativeTime(v.created_at)}</span>
+                        <span>{v.word_count} words</span>
+                      </div>
+                    </button>
+                  </li>
+                )
+              })}
+            </ul>
+          )}
+        </div>
+
+        {selected && (
+          <div
+            className="shrink-0 px-4 py-3"
+            style={{ borderTop: '1px solid var(--color-border)', background: 'var(--color-surface-alt)' }}
+          >
+            <div className="mb-2 text-xs font-bold" style={{ color: 'var(--color-muted)' }}>
+              预览 · Preview
+            </div>
+            <div
+              className="mb-3 max-h-32 overflow-y-auto whitespace-pre-wrap rounded-xl px-3 py-2 text-sm"
+              style={{
+                background: 'var(--color-surface)',
+                color: 'var(--color-plum)',
+                fontFamily: 'var(--font-body)',
+              }}
+            >
+              {preview ? preview.content_text || '(empty)' : 'Loading…'}
+            </div>
+            <button
+              type="button"
+              onClick={restore}
+              disabled={busy}
+              className="w-full rounded-full py-2.5 text-sm font-extrabold text-white disabled:opacity-60"
+              style={{ background: 'var(--color-accent)' }}
+              onMouseEnter={(e) => (e.currentTarget.style.background = 'var(--color-accent-hover)')}
+              onMouseLeave={(e) => (e.currentTarget.style.background = 'var(--color-accent)')}
+            >
+              {busy ? 'Restoring…' : '恢复这个版本 · Restore this version'}
+            </button>
+            <div className="mt-1.5 text-center text-[11px]" style={{ color: 'var(--color-muted)' }}>
+              Your current draft is saved first, so this is undoable.
+            </div>
+          </div>
+        )}
+      </aside>
+    </div>
+  )
+}

web/src/components/StatusBar/StatsPanel.tsx

@@ -0,0 +1,81 @@
+import { useMemo } from 'react'
+import { computeStats, gradeBand } from './stats'
+
+// StatsPanel is the popover that opens above the word count: a small grid of
+// writing statistics computed from the live document. Bilingual zh·en labels to
+// match Petal's chrome. Reading level shows a friendly band, not just a number.
+
+interface Props {
+  text: string
+  wordCount: number
+}
+
+interface Row {
+  zh: string
+  en: string
+  value: string
+}
+
+export function StatsPanel({ text, wordCount }: Props) {
+  const rows = useMemo<Row[]>(() => {
+    const s = computeStats(text, wordCount)
+    const band = gradeBand(s.gradeLevel)
+    const fmt = (n: number, d = 0) =>
+      n.toLocaleString(undefined, { minimumFractionDigits: d, maximumFractionDigits: d })
+    return [
+      { zh: '字数', en: 'Words', value: fmt(s.words) },
+      { zh: '字符', en: 'Characters', value: fmt(s.characters) },
+      { zh: '句子', en: 'Sentences', value: fmt(s.sentences) },
+      { zh: '段落', en: 'Paragraphs', value: fmt(s.paragraphs) },
+      { zh: '页数', en: 'Pages', value: `~${fmt(Math.max(s.pages, s.words > 0 ? 0.1 : 0), 1)}` },
+      { zh: '阅读时间', en: 'Reading time', value: readingTime(s.readingTimeMin) },
+      { zh: '平均词长', en: 'Avg word length', value: `${fmt(s.avgWordLength, 1)}` },
+      { zh: '词汇丰富度', en: 'Word variety', value: `${fmt(s.variety * 100)}%` },
+      {
+        zh: '阅读难度',
+        en: 'Reading level',
+        value: s.words > 0 ? `${band.en} · ${fmt(s.gradeLevel, 1)}` : '—',
+      },
+    ]
+  }, [text, wordCount])
+
+  return (
+    <div
+      role="dialog"
+      aria-label="Writing statistics"
+      className="petal-word-card absolute bottom-7 left-0 z-30 p-3.5"
+      style={{
+        width: 268,
+        background: 'var(--color-surface)',
+        border: '1px solid var(--color-border)',
+        borderRadius: 'var(--radius-card)',
+        boxShadow: 'var(--shadow-soft)',
+        color: 'var(--color-plum)',
+      }}
+    >
+      <p className="mb-2 text-xs font-bold" style={{ color: 'var(--color-muted)' }}>
+        写作统计 · Writing stats
+      </p>
+      <dl className="space-y-1.5">
+        {rows.map((r) => (
+          <div key={r.en} className="flex items-baseline justify-between gap-3 text-sm">
+            <dt style={{ color: 'var(--color-muted)' }}>
+              <span className="font-semibold" style={{ color: 'var(--color-plum)' }}>
+                {r.zh}
+              </span>{' '}
+              {r.en}
+            </dt>
+            <dd className="font-bold tabular-nums">{r.value}</dd>
+          </div>
+        ))}
+      </dl>
+    </div>
+  )
+}
+
+// readingTime renders minutes as a friendly "< 1 min" / "N min" string.
+function readingTime(min: number): string {
+  if (min <= 0) return '0 min'
+  if (min < 1) return '< 1 min'
+  return `${Math.round(min)} min`
+}

web/src/components/StatusBar/StatusBar.tsx

@@ -1,12 +1,19 @@
+import { useEffect, useRef, useState } from 'react'
 import type { SaveStatus } from '../../hooks/useAutoSave'
+import { StatsPanel } from './StatsPanel'
 
 interface Props {
   wordCount: number
+  // Live plain text of the document, for the expanded stats panel.
+  text: string
   saveStatus: SaveStatus
   // True while a grammar checkpoint is in flight — shows the breathing rose dot.
   checking: boolean
   // True while a whole-document voice pass runs — shows a breathing honey dot.
   voicing: boolean
+  // True when Petal can't reach its LLM helper — shows a gentle, reassuring note
+  // (the writing still saves locally, so this is awareness, not an error).
+  llmDown: boolean
 }
 
 const SAVE_LABEL: Record<SaveStatus, string> = {
@@ -20,16 +27,44 @@ const SAVE_LABEL: Record<SaveStatus, string> = {
 // StatusBar is the slim footer: word count on the left, save state and the
 // grammar-checkpoint indicator on the right. The checkpoint dot is a soft rose
 // circle that breathes while a check is in flight (spec → Signature animations).
-export function StatusBar({ wordCount, saveStatus, checking, voicing }: Props) {
+export function StatusBar({ wordCount, text, saveStatus, checking, voicing, llmDown }: Props) {
   const label = SAVE_LABEL[saveStatus]
+  // The expanded stats panel toggles open when the word count is clicked.
+  const [statsOpen, setStatsOpen] = useState(false)
+  const statsRef = useRef<HTMLDivElement>(null)
+
+  useEffect(() => {
+    if (!statsOpen) return
+    const onDown = (e: MouseEvent) => {
+      if (!statsRef.current?.contains(e.target as Node)) setStatsOpen(false)
+    }
+    document.addEventListener('mousedown', onDown)
+    return () => document.removeEventListener('mousedown', onDown)
+  }, [statsOpen])
+
   return (
     <footer
       className="flex h-9 shrink-0 items-center gap-3 px-6 text-xs"
       style={{ borderTop: '1px solid var(--color-border)', color: 'var(--color-muted)' }}
     >
-      <span>
+      <div className="relative" ref={statsRef}>
+        <button
+          type="button"
+          onClick={() => setStatsOpen((o) => !o)}
+          aria-haspopup="dialog"
+          aria-expanded={statsOpen}
+          className="rounded-full px-1.5 py-0.5 font-semibold transition-colors"
+          style={{ color: statsOpen ? 'var(--color-accent-hover)' : 'inherit' }}
+          onMouseEnter={(e) => (e.currentTarget.style.color = 'var(--color-accent-hover)')}
+          onMouseLeave={(e) =>
+            (e.currentTarget.style.color = statsOpen ? 'var(--color-accent-hover)' : 'inherit')
+          }
+          title="Writing stats"
+        >
           {wordCount} {wordCount === 1 ? 'word' : 'words'}
-      </span>
+        </button>
+        {statsOpen && <StatsPanel text={text} wordCount={wordCount} />}
+      </div>
       {checking && (
         <>
           <span aria-hidden>·</span>
@@ -54,6 +89,20 @@ export function StatusBar({ wordCount, saveStatus, checking, voicing }: Props) {
           </span>
         </>
       )}
+      {llmDown && !checking && !voicing && (
+        <>
+          <span aria-hidden>·</span>
+          <span
+            className="inline-flex items-center gap-1.5"
+            title="Petal can't reach its writing helper right now — your text is still saved."
+            style={{ color: 'var(--color-honey)' }}
+          >
+            <span aria-hidden>🌙</span>
+            <span>小助手在休息</span>
+            <span style={{ opacity: 0.75 }}>· Petal's helper is resting · 文字已保存</span>
+          </span>
+        </>
+      )}
       {label && (
         <>
           <span aria-hidden>·</span>

web/src/components/StatusBar/stats.ts

@@ -0,0 +1,92 @@
+// Writing statistics computed from the document's plain text. These power the
+// expanded stats panel that opens when the writer clicks the word count. The
+// reading-level formulas are English-centric (Flesch); a document mixing in
+// Mandarin still gets sensible counts, with the level treated as approximate.
+
+export interface WritingStats {
+  words: number
+  characters: number
+  charactersNoSpaces: number
+  sentences: number
+  paragraphs: number
+  pages: number
+  avgWordLength: number // letters per English word
+  uniqueWords: number
+  variety: number // type-token ratio, 0–1 (unique ÷ total English words)
+  readingTimeMin: number
+  gradeLevel: number // Flesch–Kincaid grade
+}
+
+// English word tokens (letters with internal apostrophes/hyphens) — used for the
+// letter-length, syllable, and variety measures, which only make sense for
+// alphabetic words.
+const ENGLISH_WORD_RE = /[A-Za-z]+(?:['’-][A-Za-z]+)*/g
+// Sentence terminators, including the CJK fullwidth forms.
+const SENTENCE_RE = /[.!?。！？]+/g
+// Words per page (a rough double-spaced manuscript page) and reading speed.
+const WORDS_PER_PAGE = 250
+const WORDS_PER_MINUTE = 200
+
+// countSyllables is the common vowel-group heuristic: count vowel runs, drop a
+// trailing silent "e"/"es"/"ed", and floor at one. Not perfect, but plenty
+// accurate for an at-a-glance reading level.
+function countSyllables(word: string): number {
+  const w = word.toLowerCase().replace(/[^a-z]/g, '')
+  if (w.length === 0) return 0
+  if (w.length <= 3) return 1
+  const trimmed = w.replace(/(?:[^laeiouy]es|ed|[^laeiouy]e)$/, '').replace(/^y/, '')
+  const groups = trimmed.match(/[aeiouy]{1,2}/g)
+  return groups ? groups.length : 1
+}
+
+export function computeStats(text: string, wordCount: number): WritingStats {
+  const trimmed = text.trim()
+  const characters = [...text].length
+  const charactersNoSpaces = text.replace(/\s/g, '').length
+
+  const sentenceMatches = trimmed.match(SENTENCE_RE)
+  const sentences = sentenceMatches ? sentenceMatches.length : trimmed ? 1 : 0
+
+  const paragraphBlocks = trimmed.split(/\n{2,}/).filter((p) => p.trim().length > 0)
+  const paragraphs = paragraphBlocks.length
+
+  const englishWords = trimmed.match(ENGLISH_WORD_RE) ?? []
+  const letters = englishWords.reduce((sum, w) => sum + w.length, 0)
+  const avgWordLength = englishWords.length > 0 ? letters / englishWords.length : 0
+
+  const unique = new Set(englishWords.map((w) => w.toLowerCase()))
+  const uniqueWords = unique.size
+  const variety = englishWords.length > 0 ? uniqueWords / englishWords.length : 0
+
+  const syllables = englishWords.reduce((sum, w) => sum + countSyllables(w), 0)
+  // Flesch–Kincaid grade level; needs at least one sentence and word to be real.
+  let gradeLevel = 0
+  if (englishWords.length > 0 && sentences > 0) {
+    gradeLevel =
+      0.39 * (englishWords.length / sentences) + 11.8 * (syllables / englishWords.length) - 15.59
+    if (gradeLevel < 0) gradeLevel = 0
+  }
+
+  return {
+    words: wordCount,
+    characters,
+    charactersNoSpaces,
+    sentences,
+    paragraphs,
+    pages: wordCount / WORDS_PER_PAGE,
+    avgWordLength,
+    uniqueWords,
+    variety,
+    readingTimeMin: wordCount / WORDS_PER_MINUTE,
+    gradeLevel,
+  }
+}
+
+// gradeBand turns a Flesch–Kincaid grade into a friendly bilingual descriptor —
+// far more useful to an ESL writer than a bare number.
+export function gradeBand(grade: number): { zh: string; en: string } {
+  if (grade <= 5) return { zh: '简单', en: 'Easy' }
+  if (grade <= 8) return { zh: '标准', en: 'Standard' }
+  if (grade <= 12) return { zh: '偏难', en: 'Fairly hard' }
+  return { zh: '较难', en: 'Advanced' }
+}

web/src/hooks/useCheckpoint.ts

@@ -13,6 +13,11 @@ export function useCheckpoint(docId: string | null) {
   const [checking, setChecking] = useState(false)
   // True while a whole-document voice pass is in flight (explicit user action).
   const [voicing, setVoicing] = useState(false)
+  // True when the last LLM pass couldn't reach the model (server 502 or network
+  // error). Drives a gentle, reassuring "helper is resting" note — the writing
+  // itself still saves fine, so this is awareness, not an error. Cleared on the
+  // next success or doc switch.
+  const [llmDown, setLlmDown] = useState(false)
 
   const debounceRef = useRef<ReturnType<typeof setTimeout>>(undefined)
   const docIdRef = useRef(docId)
@@ -30,9 +35,11 @@ export function useCheckpoint(docId: string | null) {
       const fresh = await api.checkDoc(id)
       if (run === runRef.current && id === docIdRef.current) {
         setSuggestions(fresh)
+        setLlmDown(false)
       }
     } catch (err) {
       console.error('checkpoint failed', err)
+      if (run === runRef.current) setLlmDown(true)
     } finally {
       if (run === runRef.current) setChecking(false)
     }
@@ -50,9 +57,11 @@ export function useCheckpoint(docId: string | null) {
       const full = await api.voiceDoc(id)
       if (run === runRef.current && id === docIdRef.current) {
         setSuggestions(full)
+        setLlmDown(false)
       }
     } catch (err) {
       console.error('voice pass failed', err)
+      if (run === runRef.current) setLlmDown(true)
     } finally {
       if (run === runRef.current) setVoicing(false)
     }
@@ -72,6 +81,7 @@ export function useCheckpoint(docId: string | null) {
     setSuggestions([])
     setChecking(false)
     setVoicing(false)
+    setLlmDown(false)
     if (!docId) return
     let cancelled = false
     void (async () => {
@@ -94,5 +104,5 @@ export function useCheckpoint(docId: string | null) {
     setSuggestions((prev) => prev.filter((s) => s.id !== id))
   }, [])
 
-  return { suggestions, checking, voicing, schedule, runVoice, removeSuggestion }
+  return { suggestions, checking, voicing, llmDown, schedule, runVoice, removeSuggestion }
 }

web/src/hooks/useTags.ts

@@ -0,0 +1,63 @@
+import { useCallback, useEffect, useState } from 'react'
+import { api, type Tag, type TagColor } from '../api/client'
+
+// useTags owns the user's tag roster (the full set the writer has created, with
+// per-tag document counts). Document↔tag assignments live in App alongside the
+// document list; this hook is just the roster plus create/recolor/delete and a
+// refresh used to keep counts current after an assignment changes.
+export function useTags() {
+  const [tags, setTags] = useState<Tag[]>([])
+
+  const refresh = useCallback(async () => {
+    try {
+      setTags(await api.listTags())
+    } catch (err) {
+      console.error('failed to load tags', err)
+    }
+  }, [])
+
+  useEffect(() => {
+    void refresh()
+  }, [refresh])
+
+  // Create (or reuse) a tag, returning it. The roster is refreshed so the new
+  // tag appears with a zero count.
+  const createTag = useCallback(
+    async (name: string, color: TagColor): Promise<Tag | null> => {
+      try {
+        const tag = await api.createTag(name, color)
+        await refresh()
+        return tag
+      } catch (err) {
+        console.error('failed to create tag', err)
+        return null
+      }
+    },
+    [refresh],
+  )
+
+  const recolorTag = useCallback(
+    async (id: string, color: TagColor) => {
+      // Optimistic recolor; refresh reconciles.
+      setTags((prev) => prev.map((t) => (t.id === id ? { ...t, color } : t)))
+      try {
+        await api.updateTag(id, { color })
+      } catch (err) {
+        console.error('failed to recolor tag', err)
+        void refresh()
+      }
+    },
+    [refresh],
+  )
+
+  const deleteTag = useCallback(async (id: string) => {
+    setTags((prev) => prev.filter((t) => t.id !== id))
+    try {
+      await api.deleteTag(id)
+    } catch (err) {
+      console.error('failed to delete tag', err)
+    }
+  }, [])
+
+  return { tags, refresh, createTag, recolorTag, deleteTag }
+}

web/src/index.css

@@ -156,6 +156,25 @@ button, a, input {
   animation: petal-suggestion-in 200ms ease both;
 }
 
+/* --- Word lookup popover ----------------------------------------------------
+   Right-click a word for its dictionary definition and synonyms. Same soft card
+   treatment as the spelling popover; synonym pills swap the word on click. */
+.petal-word-card {
+  animation: petal-suggestion-in 200ms ease both;
+}
+
+/* --- ESL superpowers (Phase 9) ----------------------------------------------
+   Inline Chinese gloss on hover (a small dark tooltip under the word), and the
+   selection rewrite bubble + its preview card. All share the soft pop-in. The
+   gloss tip fades in a touch faster — it's a fleeting reading aid, not a panel. */
+.petal-gloss-tip {
+  animation: petal-suggestion-in 140ms ease both;
+}
+.petal-selection-bubble,
+.petal-rewrite-card {
+  animation: petal-suggestion-in 200ms ease both;
+}
+
 /* --- Accept confetti --------------------------------------------------------
    A tiny CSS-only burst played where a suggestion is accepted: four colored
    dots spray up-and-out, then fade. No JS animation — each dot reads its
@@ -262,3 +281,131 @@ button, a, input {
   0%, 100% { opacity: 0.4; }
   50%      { opacity: 1; }
 }
+
+/* --- Organization & search (Phase 10) --------------------------------------
+   Tag chips, the search results list, and per-row affordances. The row actions
+   (tag / delete) fade in on hover for pointer users but are always visible on
+   touch (no hover) — see the coarse-pointer block below. */
+.petal-tag-chip {
+  transition: background 160ms ease, color 160ms ease, transform 160ms ease;
+}
+.petal-search-results {
+  animation: petal-suggestion-in 160ms ease both;
+}
+.petal-tag-picker {
+  animation: petal-suggestion-in 160ms ease both;
+}
+.petal-row-action {
+  opacity: 0;
+  transition: opacity 160ms ease, background 160ms ease;
+}
+.group:hover .petal-row-action,
+.petal-row-action:focus-visible {
+  opacity: 1;
+}
+.petal-row-action:hover {
+  background: var(--color-surface-alt);
+}
+/* Clamp a search snippet to two lines. */
+.line-clamp-2 {
+  display: -webkit-box;
+  -webkit-line-clamp: 2;
+  line-clamp: 2;
+  -webkit-box-orient: vertical;
+  overflow: hidden;
+}
+
+/* --- Touch & tablet polish --------------------------------------------------
+   On coarse pointers (tablets, phones) there's no hover, so make tap targets
+   comfortable and reveal affordances that would otherwise be hover-only. */
+@media (pointer: coarse) {
+  .petal-tap {
+    min-height: 44px;
+  }
+  .petal-tap-sm {
+    min-height: 36px;
+  }
+  /* Row actions can't rely on hover — keep them visible and roomy. */
+  .petal-row-action {
+    opacity: 1;
+    height: 36px;
+    width: 36px;
+  }
+  /* Bigger, easier-to-hit suggestion/word/tag pills. */
+  .petal-tag-chip {
+    padding-top: 0.25rem;
+    padding-bottom: 0.25rem;
+  }
+}
+
+/* --- Responsive sidebar (narrow screens) ------------------------------------
+   Below the tablet breakpoint the sidebar becomes an overlay drawer toggled by a
+   hamburger in the header, instead of a permanent column. A scrim sits behind it.
+   On wide screens the toggle + scrim are hidden and the sidebar is in-flow. */
+.petal-sidebar-toggle {
+  display: none;
+}
+.petal-scrim {
+  display: none;
+}
+@media (max-width: 768px) {
+  .petal-sidebar-toggle {
+    display: inline-flex;
+  }
+  .petal-sidebar {
+    position: fixed;
+    top: 48px; /* below the 12-height header */
+    bottom: 0;
+    left: 0;
+    z-index: 30;
+    background: var(--color-bg);
+    box-shadow: var(--shadow-soft);
+  }
+  /* On mobile the sidebar is hidden by default; the drawer-open class slides it
+     in. (Distraction-free's petal-sidebar-hidden still wins to keep it closed.) */
+  .petal-sidebar:not(.petal-drawer-open) {
+    width: 0;
+    transform: translateX(-24px);
+    opacity: 0;
+    pointer-events: none;
+  }
+  .petal-scrim.petal-scrim-show {
+    display: block;
+    position: fixed;
+    inset: 48px 0 0 0;
+    z-index: 20;
+    background: rgba(61, 46, 57, 0.18);
+  }
+}
+
+/* Print / Save-as-PDF: strip every bit of app chrome and editing decoration so
+   only the title and the writing itself reach the page. This is Petal's PDF
+   path — it uses the browser's own fonts, so CJK renders correctly with no
+   server-side font embedding. */
+@media print {
+  .petal-no-print,
+  .petal-sidebar,
+  .petal-suggestion-card,
+  .petal-misspell-card,
+  .petal-gloss-tip,
+  .petal-selection-bubble,
+  .petal-rewrite-card,
+  .petal-confetti,
+  .petal-companion {
+    display: none !important;
+  }
+  html, body, #root {
+    height: auto !important;
+    overflow: visible !important;
+    background: #fff !important;
+  }
+  /* Drop the in-editor highlight underlines/tints — they're guidance, not ink. */
+  .petal-suggestion,
+  .petal-misspelling {
+    background: none !important;
+    text-decoration: none !important;
+    border-bottom: none !important;
+  }
+  /* Let the writing use the full page width. */
+  .max-w-\[720px\] { max-width: none !important; }
+}