Update README: !explain, paywall/Wayback fallback, explainer package

README.md

@@ -9,6 +9,8 @@ A Matrix news bot that ingests RSS feeds from curated sources, classifies storie
 - **Semantic deduplication** — GUID exact match + LLM-based cross-source duplicate detection
 - **Metered release** — per-channel post queues with minimum interval (5min) and burst cap (3/30min)
 - **Reaction tracking** — records emoji reactions on posts for classifier tuning
+- **`!explain` via ❓ reaction** — react with `❓` (or `❔ ⁉ 🤔 ?`) on any post; Pete fetches the article body and replies in-thread with a 3-bullet Ollama-generated TL;DR
+- **Paywall detection** — if an article's visible body text is below threshold, Pete swaps in a Wayback Machine snapshot URL for both the lead image and the posted link
 - **FTS5 search** — full-text search across headlines and ledes
 - **Image validation** — HEAD-based checks filter tracking pixels, uploads valid images via MXC
 
@@ -80,13 +82,15 @@ Set `PETE_PASSWORD` in your environment or a `.env` file for the Matrix password
 ## Architecture
 
 ```
-RSS Feed → Poller → GUID Dedup → Store → Classifier → Semantic Dedup → Image Validate → Queue → Matrix
-                                            ↓
-                                    Direct Route (no LLM)
-                                         or
-                                    Ollama /api/chat (Tier 1 routing)
-                                         or
-                                    Keyword Gating → Ollama (Tier 2)
+RSS Feed → Poller → GUID Dedup → Canonical/Headline Dedup → Article Fetch → Store → Classifier → Semantic Dedup → Image Validate → Queue → Matrix
+                                                                ↓                       ↓
+                                                    Paywall? → Wayback           Direct Route (no LLM)
+                                                                                       or
+                                                                                  Ollama /api/chat (Tier 1 routing)
+                                                                                       or
+                                                                                  Keyword Gating → Ollama (Tier 2)
+
+Posted message ← ❓ reaction → Explainer → Article Fetch → Ollama summary → Threaded reply
 ```
 
 ### Packages
@@ -97,8 +101,9 @@ RSS Feed → Poller → GUID Dedup → Store → Classifier → Semantic Dedup
 | `internal/storage` | SQLite with WAL, FTS5, all queries |
 | `internal/ingestion` | Per-source RSS polling, feed parsing, image validation |
 | `internal/classifier` | Ollama client, Tier 1/2 prompts, JSON repair, keyword gating |
-| `internal/matrix` | Password auth with device persistence, posting, reaction listener |
-| `internal/poster` | Per-channel metered release queue, reaction tracking |
+| `internal/matrix` | Password auth with device persistence, posting, threaded replies, reaction listener |
+| `internal/poster` | Per-channel metered release queue, reaction tracking, callback hook |
+| `internal/explainer` | ❓-reaction → article fetch → Ollama summary → threaded reply |
 
 ## Post Format