fix: skip discussion tool when already in a topic

[lishuceo]

Summary

• When a user @mentions the bot inside an existing Feishu topic (话题), the bot was creating a new discussion thread instead of replying in the existing topic
• Root cause: discussionMcp tool was unconditionally injected into the Chat Agent, even when eventThreadId was already present
• Fix: only inject discussionMcp when eventThreadId is absent (message is in main chat, not in a topic)

Test plan

• In a Feishu group, create a topic, then @bot in the topic — should reply in-thread without creating a new discussion card
• In main chat area, @bot with a complex question — should still be able to create a discussion thread via the tool

🤖 Generated with Claude Code

[claude]

Claude finished @lishuceo's task in 42s —— View job

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Review of PR #146

• Check for previous review comments — none found
• Read changed file and diff
• Analyze changes
• Post review

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✅ Approved — Clean, minimal fix that correctly addresses the bug.

Analysis:

The change conditionally skips discussionMcp creation when eventThreadId is present (i.e., the message is already inside a topic thread). Two parts work together:

1. Line 1749-1757: discussionMcp is set to null when eventThreadId exists, avoiding unnecessary MCP server creation.
2. Line 1788: The spread ...(discussionMcp ? { additionalMcpServers: ... } : {}) cleanly omits the property when null, which is safe because executor.ts:117 declares additionalMcpServers as optional and the usage at executor.ts:425 is guarded by an if check.

Verified:

• eventThreadId is consistently used throughout the function to distinguish topic vs. main-chat context (session keys, reply targets, conversation storage) — this change follows the same established pattern
• No resource leaks — createDiscussionMcpServer is simply not called, so nothing needs cleanup
• No impact on the main-chat flow — when eventThreadId is absent, behavior is identical to before

No issues found. LGTM.