[Feat] One forum topic per task in Topics-enabled Telegram supergroups

[daniel-lxs]

What

Telegram has no threads in plain chats — but Topics-enabled supergroups do, and all our plumbing was already thread-aware (message_thread_id → communicationThreadId). This turns that on: when a task launches outside any topic in a forum chat, the bot creates a forum topic named after the request and moves the task's life there.

• The job's communicationThreadId points at the new topic, so follow-ups typed in the topic queue to the job and worker replies land there (they re-anchor to the in-topic started card).
• The started card (Follow Task / ✖️ Cancel) posts inside the topic; a pointer reply with an Open topic deep link is left next to the launch message so it's discoverable.
• The group's topic list becomes a task list — the closest Telegram gets to Slack threads.

Behavior boundaries

• Launch from inside an existing topic → stays in that topic (no nesting).
• Plain groups / DMs / missing manage-topics right / API failure → falls back to today's chat-scoped behavior; the task is never dropped.
• Works with routing confirmation: the Yes/Nope card stays where the user asked; the topic is created at actual launch (Yes click, picker pick, or auto-confirm).

Setup required (per group, one-time)

Create a group → enable Topics in group settings → add the bot as admin with "Manage topics". Same install-shaped setup as a Slack workspace.

Changes

• TelegramCommunicationProvider.createForumTopic; is_forum on the chat schema.
• launchTelegramTask topic creation + reply re-anchoring (setLatestInboundMessageId) + pointer message; chatIsForum threaded through routing-confirmation pending state and auto-confirm.
• Mock harness: forumTopics state, createForumTopic route, and real-Telegram forum semantics (unknown message_thread_id in a forum chat 400s; createForumTopic on a non-forum chat 400s).

Testing

• 201 tests pass across the telegram / mcp / communication suites (5 new: topic-per-task launch, in-topic entry no-nesting, creation-failure fallback, harness topic round-trip + rejections). Typecheck, lint, knip, knowledge-check clean on the current develop base (isolated worktree).
• Live end-to-end through the mock harness against the dev stack: mention in General → Yes on the routing card → topic "fix the flaky login test in the web app" created, started card posted inside it, Open-topic pointer in General, task canceled from the in-topic card (cloud job 85: communicationThreadId = 3, canceled).

Docs

.agent-guidance/features/telegram-integration.md (inbound flow + parity notes) and the mock-telegram-testing scenario catalog (new scenario 6, harness forum semantics).

🤖 Generated with Claude Code

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Reviewing the PR now. Follow