petal/UX_REVIEW_2026-07-27.md

# Petal UX review — 2026-07-27 (implementation doc)

**Origin:** a hands-on browser session against the live VPS deploy
(petal.parodia.dev) on a 1517×810 desktop viewport, deliberately writing
ESL-style English, accepting/undoing suggestions, using Ask Petal, the
right-click dictionary, the Garden, History, and the doc-type menu. Goal:
close the gap to Grammarly's *feel* (latency, stability, proximity of
feedback) without its cost or surveillance.

**How to use this doc:** each item has symptom/repro, likely code location,
proposed fix, and acceptance criteria. Items are ordered by
value-for-effort. Where the session couldn't confirm root cause, that is
said explicitly — verify before building. The product *why* behind Petal
lives in `SUGGESTIONS.md`; execution phases in `BUILD_PLAN.md`. Nothing here
contradicts them; this is polish on the existing loop.

**What was verified working well (don't regress):** error coverage and
explanation quality across two check rounds; bilingual (en+zh) card
explanations; Ask Petal follow-up answers; instant right-click dictionary
with TTS + slow-replay; Garden sprouting; autosave + History snapshots;
kitten cheers on accept; clean console throughout.

---

## 0. DONE this session — kitten yields to cards

The corner mascot's halo sat on top of the bottom rail cards, History-panel
footer controls, and the Garden counter, blocking reading and clicks.

**Implemented (this commit):** when any `.petal-rail-card` overlaps the
mascot badge, the kitten fades to 15% opacity, shrinks 10% toward its
corner (standalone `scale` property, so it composes with the bob
animation's `transform`), and goes `pointer-events: none` so clicks pass
through. It wakes (full size/opacity) while its speech bubble or the
companion picker is open, or when cards no longer overlap.

- `web/src/components/Companion/useCardOverlap.ts` — rect-intersection
  hook, rAF-throttled on scroll/resize + 500 ms poll.
- `web/src/components/Companion/PetalCompanion.tsx` — `faded` wiring.
- `web/src/index.css` — `.petal-companion-faded`, transition.

**Follow-up — DONE.** The overlap check now watches
`.petal-rail-card, [role="dialog"][aria-modal="true"]`. Matching the modal
role rather than each panel's class covers History and Garden today (both
already render `role="dialog" aria-modal="true"` drawers) and any future
drawer for free, with no selector list to keep in sync.

Two refinements the original note didn't anticipate:

- The hook now reports `{ cards, modal }` separately. A card overlap still
  lets the kitten wake for a bubble; a **modal overlap yields
  unconditionally** — a cheer isn't worth covering the panel she just
  opened on purpose.
- The speech bubble is its own layer, so fading the badge didn't hide it.
  It's now held back explicitly while a panel is open, and reappears when
  she closes it (`useCompanion` keeps it in state).

Verified against the live build: with History open, the drawer overlaps the
badge rect and the "📜 写作证明 · Writing passport" control sits under the
mascot — the exact defect. The new selector trips on it.

- `useCardOverlap.ts` — `CardOverlap` return type, modal selector, identity
  guard so the 500 ms poll doesn't re-render on every tick.
- `PetalCompanion.tsx` — `crowded.modal || (crowded.cards && …)`, bubble gate.

---

## 1. Bug: redo does not re-apply an accepted suggestion — NOT REPRODUCIBLE

**Status (2026-07-27, follow-up session):** investigated against the live
VPS build with the ProseMirror history plugin state read directly
(`done.eventCount` / `undone.eventCount`) and `view.dispatch` hooked to log
every transaction. **Redo works in every path tried** — including the exact
repro below, on the same Idiom card. Closing this unless it resurfaces with
a tighter repro.

Paths tried, all correct (accept → `done` +1; undo → `done` −1, `undone` 1,
text reverts; redo → replacement restored):

- accept → undo → redo pressed immediately
- accept → undo → **18 s pause so the full re-check lands** → redo
- accept with the editor never focused → undo → redo

The doc's hypothesis — that the re-check wipes the redo stack — was tested
directly and is **false**: across the pause, the only doc-changing
transaction was the undo itself (`metaHistory: true`); the re-check's
transactions are all decoration-only (`docChanged: false`), which
prosemirror-history ignores. `canRedo` stayed `true` throughout.

One real trap that likely explains the original report: **keyboard undo
only works when focus is in the editor.** Clicking Accept in the rail moves
focus to the Accept button; `handleAccept`'s `chain().focus()` normally
returns it, but that only runs when `findRange` locates the original span —
if the span isn't found, focus stays on the button and Ctrl+Z/Ctrl+Shift+Z
silently do nothing. Worth hardening regardless of this item.

**Still real, found while investigating:** after undo, the suggestion is
already marked accepted server-side, so the card doesn't reliably come back
for the text that's now showing again. In one run the "for buy some apple"
card was gone while the erroneous text was visible; in another the card did
return (re-merged into a wider span). This is the second half of this item's
own acceptance criterion and belongs with item 2's stable identity work.

**Original repro (could not reproduce):** accept a suggestion (text
updates), press Ctrl+Z (text reverts — correct), press Ctrl+Shift+Z →
nothing happens. Observed on the Idiom card "by foots → on foot".

**Where to look:** `EditorCore.handleAccept`
(`web/src/components/Editor/EditorCore.tsx` ~line 556) applies via
`editor.chain().focus().insertContentAt(range, s.replacement).run()`, which
*is* a normal history transaction — so the break is probably downstream:
after the undo, the parent `onAccept`/re-check flow may dispatch a
transaction that clears the redo stack (any doc-touching tr wipes redo), or
the accepted suggestion's server-side state makes the recheck rewrite
content. Root cause was **not** confirmed in the session — instrument
first.

**Acceptance:** accept → undo → redo restores the replacement; the
suggestion card state stays consistent with whichever text is showing.

## 2. Suggestion stability: stop regenerating the world on every accept

The biggest feel gap vs Grammarly. Today every accept (and every edit)
triggers a full-document `POST /api/docs/:id/check`; all remaining cards
vanish and re-arrive seconds later, spans re-merge into different shapes,
and the LLM re-words every explanation each round (the "weather were" card
carried three different explanations in one session). It reads as
instability, doubles the pause after each accept, and burns qwen3.5 tokens.

**Proposed fix (server + client):**
- Split the doc into sentences (or paragraphs) and hash each. On re-check,
  send only chunks whose hash changed since the last check; suggestions on
  unchanged chunks are returned from cache byte-identical, including the
  explanation text. `internal/suggestions/handlers.go` is the entry point.
- Give suggestions stable identity across checks: key on
  (chunk hash, original span, replacement) so an untouched suggestion keeps
  its `id`, and the client keeps the existing card DOM instead of
  remounting (no vanish/reappear).
- Client: on accept, remove that one card optimistically and leave the rest
  untouched while the changed-chunk recheck runs.

**Acceptance:** accepting one suggestion never changes the text, wording,
or position of any other card; re-check traffic after a one-sentence edit
contains only that sentence's chunk; explanations are stable across rounds.

### 2 — DONE (fourth session). Server-side; the client needed nothing.

Both halves shipped, and they turned out to be one idea. The root cause of
the vanish/reappear was structural: **every pass deleted its whole family
and re-inserted it**, so each round minted new row ids. The rail keys its
cards on `suggestion.id`, so a full remount was guaranteed — new id, new
`created_at` (hence the re-fired arrival chime), and a freshly-worded
explanation from a model that re-reasons every time it's asked.

**Implemented:**

- `chunk.go` — splits the document into sentences and hashes each. Newlines
  always break; ASCII terminators need trailing whitespace (so `3.50` and
  `Ms.` stay whole); `。！？` break outright, since Chinese runs sentences
  together with no space and she writes both languages in one document. The
  hash normalizes quotes and whitespace runs through the existing
  `normalizeForDedup`, so the editor's constant quote rewriting and a
  reflowed paragraph cost nothing. Identity is the hash, not the position —
  insert a paragraph at the top and every sentence below keeps its cards.
- `reconcile.go` — passes now *reconcile* rather than replace. A row on a
  sentence this pass didn't ask about is kept untouched; a row whose
  sentence is gone is dropped; a row on a sentence that was re-read survives
  only if the model proposed the same edit again, keeping its id,
  `created_at` and its **original explanation**. Re-proposals are matched on
  `(original, replacement)` normalized — not on type, so a re-labelled edit
  keeps the label she's already reading.
- `checked_chunks` (migration `0014`) records which sentences a family has
  read. The grammar checkpoint asks only about the difference. **When
  nothing changed it doesn't call the model at all** — and doesn't consume
  its rate-limit slot, so an idle check can't throttle the next real edit.
- The tone is folded into a sentence's hash, so switching doc type still
  re-reads every line: the same sentence gets different advice as an
  academic essay than as a journal entry, and cached advice was written for
  the old register.
- `replaceMechanics` reconciles too. This mattered more than expected: the
  rule pack fires 250 ms after a keystroke (item 3b), so it was re-minting
  every local card's id several times a sentence.

**Deliberately not done:**

- Only the grammar checkpoint is chunked. Voice is a property of the
  document as a whole — a sentence isn't inconsistent with itself — and the
  collocation coach is a button she presses asking for a fresh read. Both
  still read everything, but both now reconcile, so they keep their ids.
- No client change. With stable ids the existing code already does what the
  item asked for: the rail keeps its card DOM, an expanded card survives a
  re-check, and the chime (which keys on id) stops re-firing for advice she
  is already reading. The one-card optimistic removal on accept was already
  there.

**Sentences the model can't be trusted to have read.** Two guards the plan
didn't anticipate, both found while writing the tests: a finding is
attributed to a sentence the model was *actually shown* before falling back
to the whole document (a short span like "the the" can occur twice, and
crediting the cached copy would drop it); and a cached row whose quoted span
no longer matches byte-for-byte is dropped *and* its sentence re-opened,
rather than caching advice the frontend can't anchor.

**Verified on the running binary**, not just in tests — per the handoff's
own advice. Against a stand-in model server: three checks over a two-
sentence document, editing only the second. The model received exactly
`She goes to market yesterday.` and never saw the first sentence; the
untouched card kept its id and its first explanation across all three
rounds; the fixed sentence's card was dropped; the idle re-check made zero
model calls. Mechanics identity confirmed the same way (a finding kept its
row id while its span moved).

Coverage: `chunk_test.go` (splitting, CJK, decimals, cosmetic churn) and
`stability_test.go` (untouched cards keep id + explanation, unchanged
document skips the model, deleted sentence drops its card, tone change
re-opens everything, mechanics rows keep identity). Two existing tests
changed contract deliberately — `TestFickleEditsSuppressed` and
`TestCollocationPassCoexists` both re-checked a document nobody had edited,
which is now a no-op; they edit the text between passes, as she always does.

## 3. Perceived latency: mask the LLM round-trip

Measured ~8–15 s from typing-stop to cards, with only a small "Checking…"
in the status bar. Two independent levers, both worth doing:

- **Incremental surfacing.** Stream/deliver per-chunk results as each
  sentence finishes checking instead of one batch at the end (pairs
  naturally with item 2's chunking). Status bar shows a live count:
  "Found 3 so far…".
- **Instant local rules layer.** A tiny deterministic pass that underlines
  the classics with zero network: a/an before vowel sound, plural after
  some/many/three…, he/she/it + verb-s, common mass nouns ("an
  information"). Petal's ethos (see `SUGGESTIONS.md`: LLM is garnish, plain
  code essential) fits this exactly. Note `grammarLite.test.ts` already
  exists under `web/src/components/Companion/` — check whether a rules
  engine is already half-built before writing a new one. Local hits render
  immediately with a modest style, then get confirmed/enriched (or
  withdrawn) when the LLM pass lands.

**Acceptance:** an obvious error like "a apple" underlines in <100 ms
offline; during a full check, at least one card appears before the last
chunk finishes; the status bar shows a running count.

### 3b — DONE (third session). The rules existed; the latency didn't.

Scoped against the code as the handoff advised, and the handoff was right:
`prose.ts` already carries every rule this item asks for — `articles`
(a/an), `pluralAfterNumber`, `subjectVerbAgreement`, `uncountables` — and
they already surface as real cards via the `mechanics` family. Nothing to
write there. The gap was purely *when* they render: `mechanicsFindings` ran
only inside `runCheck`, behind the same 4000 ms checkpoint debounce as the
LLM, and only reached the screen via the server's reply. So a free,
instant, offline-capable detection was being delivered at network speed on
an LLM-shaped delay.

**Implemented:**
- `useCheckpoint.ts` — the rule pack gets its own `FAST_MS = 250` fuse,
  separate from the 4 s checkpoint. It renders its findings as
  *provisional* suggestions with no network at all, then persists them; the
  server's reply is authoritative and clears the provisional set. If the
  reply never comes (offline, server down) the cards simply stay — which is
  the point of a rule pack.
- Provisional cards carry a `local:<original> <replacement>` id. The merge
  matches on wording, not position, so a card can't flicker into a
  duplicate of its own persisted twin while she types around it.
- `resolveServerId` maps a card to the row the API can act on, awaiting the
  in-flight submit if she accepts inside that window — so an early accept
  still records the keep and plants its word in the garden instead of being
  silently dropped. Null means no row exists (offline); the edit has landed
  regardless.
- Findings she actions while provisional are remembered client-side
  (`actionedRef`), because the detector has no memory between runs. The
  server already keeps the equivalent record for persisted rows.
- `runCheck` no longer re-submits mechanics for text the fast pass already
  filed; it's now a catch-up path for when that submit failed.
- `App.tsx` — accept/dismiss go through `resolveServerId`; the arrival
  chime keys rule-pack cards by wording so one finding doesn't chime twice
  (once provisional, once persisted).

**Deliberately not done:** no distinct "modest style" for unconfirmed local
hits. The rail renders LLM and rule-pack cards identically on purpose (see
the note on `Suggestion.source` in `client.ts`), and a provisional card now
lives for one LAN round-trip. Styling it differently would be a visible
regression against an existing decision, not polish.

**Still open from item 3:** the incremental-surfacing half (per-chunk LLM
results) and the running count in the status bar — both belong with item 2's
chunking and item 8's status-bar summary.

## 4. Rail scrolls away from the text

With ~7 cards the rail is taller than the viewport; scrolling to reach
lower cards scrolls the document text fully off-screen, severing the
card↔sentence connection.

**Proposed fix:** keep the editor column sticky/pinned while the rail
(`web/src/components/Editor/SuggestionRail.tsx`, `.petal-rail` in
`index.css`) scrolls in its own `overflow-y: auto` container. Preserve the
existing anchor-to-highlight layout for cards that fit; the container only
takes over when the stack exceeds the viewport.

**Acceptance:** with 10+ suggestions, the flagged text stays visible while
scrolling the card list; hover-linking still highlights the right span.

### 4 — DONE (fifth session). The cards weren't distant; they were unreachable.

Measured on the live build before touching anything, and the item understates
its own bug. Her open document: **four cards, 173 px each, all anchored inside
126 px of text** — the stack resolved to tops 4 / 189 / 374 / 559, so ~714 px
of cards beside four lines of prose. And because `.petal-rail` is
`position: absolute`, none of that counts as layout height: the page reported
`scrollHeight === clientHeight`, **no scroll container at all**. On the review's
810 px viewport the lower cards weren't merely severed from their sentence,
they were off-screen with no way to scroll to them. That is the real defect,
and it is why the item read as a scrolling problem.

**Implemented:**

- `SuggestionRail.tsx` — the stack reports how far it reaches (`onExtent`),
  computed in the same pass that resolves the collision-avoided tops.
- `EditorCore.tsx` — the wrapper takes `minHeight: railExtent + 24`, so the
  space the cards occupy becomes real, scrollable page. `minHeight` never
  shrinks the column, so a rail that fits beside its text changes nothing.
- The prose moved into its own box, pinned with `position: sticky` while the
  stack overhangs it, so scrolling down to reach the lower cards no longer
  carries every sentence off the top. The offset is `min(0, port − content)`:
  prose shorter than the viewport pins at the top; **taller prose pins by its
  bottom edge**, so the last lines — the ones the overhanging cards flag —
  stay visible rather than the first.
- The extent is cleared when the last card goes, or the window narrows past
  the rail's threshold; otherwise the column keeps the height of a stack that
  no longer exists.

**A trap worth recording.** That prose box must be left at its natural height.
The first version kept the existing `h-full`, so it measured the wrapper — which
this change had just grown to the stack's height — and reported the cards'
height back as the text's own. `railExtent > contentH` was then never true and
the pin could never trip. It typechecked, looked right, and did nothing; only
measuring the running page caught it (`proseHeight: 1424` for a two-line
document).

**Verified in a real browser at the review's own 1517×810**, driving the local
build with the rule pack from item 3b — which needs no model, so eight cards
appear offline in one paragraph. All three branches exercised:

- *Overhang, short prose* — 8 cards, stack 1400 px, prose 95 px. Page gained
  675 px of scroll where it previously had none; scrolled to the end, the last
  card sits fully in view (770–926) **and the prose is still on screen** (80–175).
- *Overhang, tall prose* — port 225 px, prose 347 px → `top: −146px`. Ordinary
  scrolling is untouched (at `scrollTop` 200 the text moves normally with the
  page); only at the overhang does it pin, bottom-anchored, last lines visible.
- *No overhang* — the port stays unscrollable and nothing moves.

Hover-linking re-checked on the last card, the one this fix made reachable at
all: it glows the right span ("It make"), the span is on screen, the card lifts.

**Known limit, not fixed.** The overlays anchored in wrapper coordinates (gloss
tip, selection bubble, word/misspell cards, confetti) rely on the invariant
noted at `recomputeRail` — "stable under scroll since text and wrapper scroll
together" — which the pin breaks. They are still placed correctly when opened,
because their coordinates come from live rects; they drift only if she scrolls
*while one is open* *and* the column is pinned, i.e. inside the overhang. Left
alone rather than papered over; if it ever bites, the fix is to close or
re-anchor them on scroll.

**Deliberately not done:** no compaction of the cards. Making crowded cards
drop to a one-line form is the obvious way to shorten the stack, and it is
wrong here — the explanation *is* the teaching, and hiding it from an ESL
writer to save vertical space trades the product's purpose for tidiness. Ten
cards cannot sit beside four lines of text; the answer is to make the overhang
navigable, not to shrink what each card says.

## 5. Mixed-language spans: offer translation, don't ignore

**Status (follow-up session): premise partly wrong — re-scope before
building.** On the live build the same sentence *does* now produce a card:
a **Clarity** card reading 我想说这句话但是不知道用英语怎么说。 → "I want to
say this sentence but do…". So the span is detected and an English
rendering is already generated; what's missing is only the *framing* — it's
labeled Clarity rather than a first-class 翻译 · Translate type, so the
flagship moment reads as a tidy-up. Re-scope this item from "detect and
translate" to "give it its own type, label, and card treatment", which is
much cheaper than the plan below. The original observation follows.

Typed mid-document: 我想说这句话但是不知道用英语怎么说。 ("I want to say
this but don't know how in English") — Petal produced **no card at all**.
The pair model (`SUGGESTIONS.md` §1: user may type in either language,
Petal infers direction) says this should be the flagship moment.

**Proposed fix:** during chunking (item 2), detect spans in the pair's X
language inside an English context (CJK detection already exists for
spellcheck exclusion — see `web/src/components/Editor/SpellCheck.ts`).
Emit a new suggestion type `translate` whose replacement is the English
rendering, card labeled 翻译 · Translate, with the usual
Accept / Ask Petal. Accept replaces the span (keep the original as the
card's strikethrough line so she can still see what she wrote).

**Acceptance:** a Chinese sentence inside an English doc yields a Translate
card within one check cycle; accepting swaps in the English; an
English-only doc and a Chinese-only doc are unaffected.

## 6. Ask Petal answers: bilingual, and room to read

The card's *explanation* is bilingual, but the Ask Petal *answer* came back
English-only, rendered in a small scrollable box inside the card.

**Proposed fix:** prompt the answer path
(`internal/suggestions/chat*.go` / `AskPetal.tsx`) to reply in both pair
languages (native first, mirroring the bubble pattern in
`PetalCompanion.tsx`); let the answer area grow to the card's width with a
sane max-height (~50vh) before scrolling.

**Acceptance:** an Ask Petal answer shows 中文 + English; a 3-paragraph
answer is readable without scrolling a ~100 px box.

## 7. Inline popover at the underline (verify, then strengthen)

Grammarly's core gesture is click-the-word → popup at the word.
`EditorCore.tsx` already has a `hover` card anchored to highlights (see
`handleAccept`'s fallback burst position), and the rail wires
`activeId`/`onHover` both ways — so part of this exists. The session
experience on a wide (1517 px) screen was still: click underline → the
*far-right* rail card expands, ~400 px of eye travel.

**Task:** confirm the hover card appears on click as well as hover, that it
offers Accept + a one-line reason + "more" (expanding the rail card), and
that hover-linking (card ↔ span glow) works in both directions. Fix
whichever half is missing.

**Acceptance:** clicking an underline shows an anchored mini-popover with
Accept, without needing the rail; hovering a rail card glows its span and
vice versa.

## 8. Smaller items (each small, do opportunistically)

- **Accept All per category.** Five tense fixes = five clicks today. Add
  "Accept all Grammar (5)" per category header in the rail, one undo step
  for the batch. Acceptance: batch-accept applies all, single Ctrl+Z
  reverts the batch.
- **Keyboard flow.** Tab/Shift+Tab (or n/p) cycles underlines with the
  popover open; Enter accepts, Esc dismisses popover. Acceptance: a doc
  can be fully triaged without the mouse.
- **Dismissal persistence.** Untested in session: does a dismissed (✕)
  suggestion stay dismissed after the next full re-check? With item 2's
  stable identity, store dismissed keys per doc and filter server-side.
  Acceptance: dismiss → edit elsewhere → recheck → the dismissed card does
  not return.
- **Status-bar summary.** "3 petals to polish 🌸 · 三片花瓣待打磨" next to
  the word count — the gentle version of Grammarly's score. No numeric
  grade, per the north star. Acceptance: count updates live with the rail.

---

## Explicit non-goals (from this review)

- No document score/grade, no streaks-pressure — the Garden and kitten
  already carry motivation warmly.
- No browser-extension-style everywhere-checking; Petal is the writing
  place.
- The doc-type dropdown's translucent look during open was **animation
  mid-fade, not a bug** — leave it.

---

## Handoff — state as of 2026-07-27, second session

**Shipped and live.** `main` is at the merge
`Merge fix/companion-yields-to-cards`, pushed to gitea, and the VPS is
rebuilt on it (`git pull && docker compose up -d --build`, all five
containers healthy). Working tree clean.

Note that deploy carried **two** commits: the item 0 fade (written in the
first session, never deployed) and this session's panel follow-up. So the
kitten only started yielding to rail cards in production with this push —
if you're comparing against memory of the live site, that's why.

**Done:** item 0 and its follow-up. **Closed without code:** item 1 (not
reproducible) and item 5's original premise (re-scoped, much cheaper now).
**Untouched:** items 2, 3, 4, 6, 7, 8.

*(Third session: item 3b done — see the subsection under item 3. Item 3's
incremental-surfacing half remains. Untouched: 2, 4, 6, 7, 8.)*

*(Fourth session: item 2 done — see the subsection under it. **Neither 3b
nor 2 is deployed yet**: both sit on unmerged topic branches
(`feat/instant-local-rules`, then `feat/stable-suggestions` stacked on it)
and `main` is still at `ba06d90`. Untouched: 4, 6, 7, 8. Item 3's
incremental-surfacing half is now cheap — the chunking it was waiting on
exists — but it needs streaming, which the current `/check` shape doesn't
do.)*

*(Fifth session: item 4 done — see the subsection under it. Still nothing
deployed: `main` remains at `ba06d90`, and 3b → 2 → 4 are now three stacked
topic branches. **Merging and deploying that stack is the obvious next move**
— three sessions of work she hasn't seen. Untouched: 6, 7, 8, item 3's
incremental half, and item 5's re-scoped Translate card type.)*

*(Sixth session: **the stack is merged and live.** Items 3b, 2 and 4 went to
`main` as one `--no-ff` merge (`963fc17`), pushed to gitea, and the VPS is
rebuilt on it — all five containers healthy, frontend build
`014b43cdf44f`, migration `0014` (`checked_chunks`) applied cleanly on the
real database. Green before merging: `go test ./...`, `tsc --noEmit`, 195
vitest tests. So the three sessions of work she hasn't seen, she can now
see. Untouched: 6, 7, 8, item 3's incremental half, item 5's re-scoped
Translate card type.)*

**Suggested next (sixth session onward):** items 6, 7, 8 are all untouched
and all small; item 5's re-scoped Translate card type is the cheapest
*visible* win (see its Status note — the span is already detected and
already rendered in English, it's only mislabeled as Clarity), and
`internal/suggestions/translate.go` already exists — read it before
designing a new type. Item 3's incremental-surfacing half now has the
chunking it was waiting on, but still needs streaming, which the current
`/check` response shape doesn't do.

*The advice below was written for the second session and is kept for its
reading list, not its recommendation: item 3b is done and deployed.* It was
**largely already built, in `main`**, and the item as written didn't know
that. Before touching the rules engine, read:

- `web/src/components/Companion/prose.ts` — the deterministic rules engine,
  client-side, already the single source of non-LLM detection. Sibling
  tests: `prose.test.ts`, `grammarLite.test.ts`.
- Commit `96f68a9` ("Add deterministic mechanics suggestion family,
  rule-based, no LLM"). Applyable rules already emit exact-span
  `original -> replacement` fixes that surface as suggestion cards, under
  a `mechanics` family persisted via `POST /docs/{id}/mechanics`;
  awareness-only rules (run-ons, splices) stay companion bubbles, and the
  companion hides fix-bearing hints so a span is never both.
- Commit `9d2501a` ("Suppress fickle re-edits of sentences the user already
  settled") — a partial item 2 that also already shipped.

So item 3b's real remaining work is probably not "write the rules" but
"make the existing local hits render *immediately*, before the LLM pass,
with a modest style" — i.e. the latency/ordering half of the item, plus
whatever rules `prose.ts` is missing. Scope it against the code, not
against the item text.

Item 5 likewise: `internal/suggestions/translate.go` already exists — read
it before designing a `translate` suggestion type.

(An earlier draft of this handoff claimed those two commits sat on
unmerged branches. They don't; both are in `main`. That came from
misreading `git branch -vv` tracking info as merge status.)

**Verification technique, for whoever picks up items 2/3/7.** Claims about
editor behaviour in this doc should be checked against the running build,
not reasoned about from source — item 1 looked airtight on paper and was
wrong. Against a production bundle there's no exposed editor handle, so:
walk up from `.ProseMirror` to the nearest `__reactFiber$` key, breadth-
first through the fiber tree for an object with `.view`/`.state`/
`.commands`/`.schema` — that's the Tiptap editor. From there
`editor.can().redo()`, the prosemirror-history plugin state
(`done.eventCount` / `undone.eventCount`), and a wrapper around
`view.dispatch` logging `tr.docChanged` are enough to settle most
"does the editor really do X" questions in a couple of minutes.

**Housekeeping:** every topic branch in the repo was fully merged into
`main` and they have all been deleted, locally and on origin. Testing
item 1 meant accepting suggestions on her live document;
the one residual edit was reverted ("on foot" → "by foots") and the doc
text is as it was found, but the History panel now shows several extra
auto-snapshots from that session.