Summary

• preserve Feishu forum/topic thread context when inbound messages omit thread_id
• derive thread context from upper_message_id first, then parent_id, but only for forum chats
• add regression tests to lock in forum thread inference and prove regular group replies are not misclassified as threads

Problem

Part of #7734 reports that messages sent inside an existing Feishu topic can still trigger Hermes replies that start a new topic instead of staying inside the current one.

The adapter only propagated message.thread_id into source.thread_id. In Feishu forum chats, that field is not reliably present on every inbound message, so the downstream gateway lost the thread context and sent follow-up replies without reply_in_thread=True.

Fix

• add _resolve_inbound_thread_id() in gateway/platforms/feishu.py
• keep explicit thread_id when Feishu provides it
• for forum chats only, fall back to upper_message_id, then parent_id
• leave regular group messages unchanged so ordinary replies do not become synthetic threads

Scope

This PR addresses the topic-threading half of #7734. The interactive authorization-card button error discussed in that issue appears to depend on Feishu callback permissions / account capabilities and is intentionally out of scope here.

Testing

• python3 -m py_compile gateway/platforms/feishu.py tests/gateway/test_feishu.py
• uv run --extra dev pytest -o addopts='' tests/gateway/test_feishu.py -k 'thread_context or replies_in_thread_when_thread_metadata_present or fetches_reply_to_text'

Notes

• uv run --extra dev pytest -o addopts='' tests/gateway/test_feishu.py -q still hits one pre-existing mock-builder failure on current main (test_build_event_handler_registers_reaction_and_card_processors) unrelated to this change.

Platform Tested

• macOS 15.x (Apple Silicon)

Contribution Guide Notes

• Reviewed CONTRIBUTING.md and checked for existing open PRs before submitting this scoped change.
• Ran the targeted verification commands listed above for this PR. I have not claimed a full repo-wide pytest tests/ -q pass unless explicitly noted.