feat(skill): add WhatsApp reactions skill (emoji reactions + status tracker) (#509)

* feat(skill): add reactions skill (emoji reactions + status tracker)

* refactor(reactions): minimize overlays per upstream review

Address gavrielc's review on qwibitai/nanoclaw#509:
- SKILL.md: remove all inline code, follow add-telegram/add-whatsapp pattern (465→79 lines)
- Rebuild overlays as minimal deltas against upstream/main base
- ipc-mcp-stdio.ts: upstream base + only react_to_message tool (8% delta)
- ipc.ts: upstream base + only reactions delta (14% delta)
- group-queue.test.ts: upstream base + isActive tests only (5% delta)
- Remove group-queue.ts overlay (isActive provided by container-hardening)
- Remove group-queue.ts from manifest modifies list

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/add-reactions/SKILL.md

@@ -0,0 +1,103 @@
+---
+name: add-reactions
+description: Add WhatsApp emoji reaction support — receive, send, store, and search reactions.
+---
+
+# Add Reactions
+
+This skill adds emoji reaction support to NanoClaw's WhatsApp channel: receive and store reactions, send reactions from the container agent via MCP tool, and query reaction history from SQLite.
+
+## Phase 1: Pre-flight
+
+### Check if already applied
+
+Read `.nanoclaw/state.yaml`. If `reactions` is in `applied_skills`, skip to Phase 3 (Verify). The code changes are already in place.
+
+## Phase 2: Apply Code Changes
+
+Run the skills engine to apply this skill's code package. The package files are in this directory alongside this SKILL.md.
+
+### Apply the skill
+
+```bash
+npx tsx scripts/apply-skill.ts .claude/skills/add-reactions
+```
+
+This deterministically:
+- Adds `scripts/migrate-reactions.ts` (database migration for `reactions` table with composite PK and indexes)
+- Adds `src/status-tracker.ts` (forward-only emoji state machine for message lifecycle signaling, with persistence and retry)
+- Adds `src/status-tracker.test.ts` (unit tests for StatusTracker)
+- Adds `container/skills/reactions/SKILL.md` (agent-facing documentation for the `react_to_message` MCP tool)
+- Modifies `src/db.ts` — adds `Reaction` interface, `reactions` table schema, `storeReaction`, `getReactionsForMessage`, `getMessagesByReaction`, `getReactionsByUser`, `getReactionStats`, `getLatestMessage`, `getMessageFromMe`
+- Modifies `src/channels/whatsapp.ts` — adds `messages.reaction` event handler, `sendReaction()`, `reactToLatestMessage()` methods
+- Modifies `src/types.ts` — adds optional `sendReaction` and `reactToLatestMessage` to `Channel` interface
+- Modifies `src/ipc.ts` — adds `type: 'reaction'` IPC handler with group-scoped authorization
+- Modifies `src/index.ts` — wires `sendReaction` dependency into IPC watcher
+- Modifies `src/group-queue.ts` — `GroupQueue` class for per-group container concurrency with retry
+- Modifies `container/agent-runner/src/ipc-mcp-stdio.ts` — adds `react_to_message` MCP tool exposed to container agents
+- Records the application in `.nanoclaw/state.yaml`
+
+### Run database migration
+
+```bash
+npx tsx scripts/migrate-reactions.ts
+```
+
+### Validate code changes
+
+```bash
+npm test
+npm run build
+```
+
+All tests must pass and build must be clean before proceeding.
+
+## Phase 3: Verify
+
+### Build and restart
+
+```bash
+npm run build
+```
+
+Linux:
+```bash
+systemctl --user restart nanoclaw
+```
+
+macOS:
+```bash
+launchctl kickstart -k gui/$(id -u)/com.nanoclaw
+```
+
+### Test receiving reactions
+
+1. Send a message from your phone
+2. React to it with an emoji on WhatsApp
+3. Check the database:
+
+```bash
+sqlite3 store/messages.db "SELECT * FROM reactions ORDER BY timestamp DESC LIMIT 5;"
+```
+
+### Test sending reactions
+
+Ask the agent to react to a message via the `react_to_message` MCP tool. Check your phone — the reaction should appear on the message.
+
+## Troubleshooting
+
+### Reactions not appearing in database
+
+- Check NanoClaw logs for `Failed to process reaction` errors
+- Verify the chat is registered
+- Confirm the service is running
+
+### Migration fails
+
+- Ensure `store/messages.db` exists and is accessible
+- If "table reactions already exists", the migration already ran — skip it
+
+### Agent can't send reactions
+
+- Check IPC logs for `Unauthorized IPC reaction attempt blocked` — the agent can only react in its own group's chat
+- Verify WhatsApp is connected: check logs for connection status