Analytics drops late subagent activity after parent turn has already terminated

Affected version

Windows Codex Desktop OpenAI.Codex 26.901.5280.0, bundled codex-cli 0.153.4.

Summary

In a completed multi-agent session, a child subagent finished after the parent turn that spawned/waited on it had already terminated on a usage limit. The child's FINAL_ANSWER was delivered while the parent thread had started a new turn.

Codex accepted the inter-agent communication and continued normally, but codex_analytics::reducer emitted:

dropping sub-agent activity tool count update: missing turn state

with the old terminated parent turn id.

This appears to lose the collaboration/subagent tool-count analytics for a valid late child completion.

Observed ordering

1. Parent thread has turn A running with a subagent.
2. Turn A terminates (in this reproduction because of a usage-limit error).
3. Parent thread starts turn B.
4. The child finishes and sends FINAL_ANSWER back to the parent path.
5. Codex logs receipt of InterAgentCommunication from the child during turn B.
6. The analytics reducer immediately warns that it is dropping the sub-agent activity tool-count update because turn A's state is missing.
7. Turn B continues and completes normally.

The warning in this reproduction referenced turn A, not the currently running turn B.

Impact

I did not observe an execution failure from this warning. The impact appears limited to analytics correctness: a legitimate late subagent activity/tool-count update is discarded after the originating parent turn has already been evicted from reducer state.

Current source

The current default branch still contains this explicit warning-and-return path in codex-rs/analytics/src/reducer.rs:

tracing::warn!(
    thread_id = %notification.thread_id,
    turn_id = %notification.turn_id,
    "dropping sub-agent activity tool count update: missing turn state"
);
return;

So this does not appear specific to the installed 0.153.4 binary.

Expected behavior

Late subagent activity that is still valid and delivered to the parent thread should either:

• retain enough terminal turn metadata to attribute the collaboration tool count to its originating turn, or
• be attributed through a defined late-event path without silently losing the count.

At minimum, the reducer should have regression coverage for a subagent activity notification arriving after the originating parent turn has completed/failed but while the parent thread remains active.

Additional notes

• The child result itself was delivered successfully; this report is specifically about analytics reduction.
• I searched for the exact warning text in open/closed issues and found no matching report.
• No private prompt, repository content, credentials, or user data is included here.

Start in codex-rs/analytics/src/reducer.rs at the warning-and-return path for a missing turn state, then trace how InterAgentCommunication activity updates are associated with parent turns. Add regression coverage for a late notification after the originating turn completes or fails while the parent thread remains active, and verify the valid subagent tool count is no longer silently dropped.