Merge pull request 'feat(plugins): P5-003 Telegram channel plugin' (#93) from feat/p5-telegram-plugin into main

docs/scratchpads/p5-003-telegram-plugin.md

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+# Scratchpad — P5-003 Telegram Plugin
+
+## Objective
+
+Implement `@mosaic/telegram-plugin` by matching the established Discord plugin pattern with Telegraf + socket.io-client, add package docs, and pass package typecheck/lint.
+
+## Requirements Source
+
+- docs/PRD.md: Phase 5 remote control / Telegram plugin
+- docs/TASKS.md: P5-003
+- User task brief dated 2026-03-13
+
+## Plan
+
+1. Inspect Discord plugin behavior and package conventions
+2. Add Telegram runtime dependencies if missing
+3. Implement Telegram plugin with matching gateway event flow
+4. Add README usage documentation
+5. Run package typecheck and lint
+6. Run code review and remediate findings
+7. Commit, push, open PR, notify, remove worktree
+
+## TDD Rationale
+
+ASSUMPTION: No existing telegram package test harness or fixture coverage makes package-level TDD
+disproportionate for this plugin scaffold task. Validation will rely on typecheck, lint, and
+manual structural parity with the Discord plugin.
+
+## Risks
+
+- Telegram API typings may differ from Discord’s event shapes and require narrower guards.
+- Socket event payloads may already include `role` in shared gateway expectations.
+
+## Progress Log
+
+- 2026-03-13: Loaded Mosaic/global/repo guidance, mission files, Discord reference implementation, and Telegram package scaffold.
+- 2026-03-13: Added `telegraf` and `socket.io-client` to `@mosaic/telegram-plugin`.
+- 2026-03-13: Implemented Telegram message forwarding, gateway streaming accumulation, response chunking, and package README.
+
+## Verification Evidence
+
+- `pnpm --filter @mosaic/telegram-plugin typecheck` → pass
+- `pnpm --filter @mosaic/telegram-plugin lint` → pass
+- `pnpm typecheck` → pass
+- `pnpm lint` → pass
+
+## Review
+
+- Automated uncommitted review wrapper was invoked for the current delta.
+- Manual review completed against Discord parity, gateway event contracts, and package docs; no additional blockers found.