This feature allows different topics within a Telegram forum supergroup to route
to different agents, each with isolated workspace, memory, and sessions.
Key changes:
- Add agentId field to TelegramTopicConfig type for per-topic routing
- Add zod validation for agentId in topic config schema
- Implement routing logic to re-derive session key with topic's agent
- Add debug logging for topic agent overrides
- Add unit tests for routing behavior (forum topics + DM topics)
- Add config validation tests
- Document feature in docs/channels/telegram.md
This builds on the approach from PR #31513 by @Sid-Qin with additional fixes
for security (preserved account fail-closed guard) and test coverage.
Closes#31473
58bc9a241b
