- Guard the thread-id-as-chat_id normalization to Discord only; Slack
and Telegram adapters use parent_channel as chat_id for thread messages,
so the unconditional version broke their handoff keys.
- Apply the same Discord-specific guard to _seed_cron_thread_session in
cron/scheduler.py (sibling site with the same bug, docstring said
'Mirrors _process_handoff').
- Replace the change-detector test with contract tests that verify the
actual invariant: Discord handoff key == organic thread key, Slack
handoff key still uses parent channel (non-regression).
A CLI→Discord handoff creates a dedicated thread and re-binds the CLI
session to it. It built the destination SessionSource with
chat_id = home.chat_id (the PARENT channel) while marking it
chat_type="thread" with thread_id set.
But platform adapters build organic in-thread messages with
chat_id = <thread id> (see the Discord adapter's on_message and
_build_thread_event paths). build_session_key therefore produced two
different keys for the same thread:
handoff: agent:main:<platform>🧵{parent}:{thread}
organic: agent:main:<platform>🧵{thread}:{thread}
So the next real user reply in the handoff thread resolved to a
DIFFERENT session_key and spawned a fresh session instead of continuing
the handed-off one — observed as a stray auto-titled session plus a
session_search fallback (the new session had no prior context).
Fix: for a thread destination, key on the thread's own id so the
synthetic handoff turn and later user replies share one session_key,
matching how adapters key organic in-thread messages.
Adds tests/gateway/test_handoff_thread_session_key.py, which asserts the
handoff key is byte-identical to the organic in-thread key (fails on the
old parent-channel keying, passes on the fix).
kshitij
Alejandro Moreno