[App][Subagents] Long-running command card disappears after child-thread rebind; output deltas are dropped

What version of the Codex App are you using (From “About Codex” dialog)?

26.727.51351 (build 6119)

What subscription do you have?

ChatGPT Pro

What platform is your computer?

Darwin 25.5.0 arm64 arm

What issue are you seeing?

When a sub-agent runs a long-lived command that streams progress and is polled until completion, the Codex Desktop Subagents panel can omit the entire Ran a command card. The backend command completes successfully and the raw session contains the command plus every output chunk, but the child thread UI shows only the initial assistant message and the final JSON/result message.

The Desktop log for one affected child recorded 31 instances of:

Dropping commandExecution/outputDelta for missing item

The same child initially logged:

Received turn/started for unknown conversation

The app then performed thread/read and logged Rebinding placeholder latest turn to incoming event, but the active commandExecution item was not restored. All subsequent progress deltas referenced a missing command item, so no command card or live output could be rendered.

The command itself was healthy: its raw session showed the initial invocation, repeated polling calls, progress from 0% through 100%, exit code 0, and the final artifact. Only the renderer presentation was missing.

What steps can reproduce the bug?

1. Open Codex Desktop on macOS.
2. Start a task that spawns a single sub-agent.
3. Have that sub-agent execute a command that runs longer than the initial tool yield and prints periodic progress, so the command continues as a process session and is polled. A minimal equivalent is:

python -u -c 'import time; [(print(f"progress {i}/24", flush=True), time.sleep(10)) for i in range(1, 25)]'

1. Keep the Subagents panel open and inspect the child thread while the command runs.
2. After completion, inspect the child thread and the Desktop log.

Observed result:

• The child thread displays its starting assistant message and final result.
• No Ran a command card is displayed.
• The raw session contains the command and all progress/output.
• The Desktop log repeatedly reports Dropping commandExecution/outputDelta for missing item for the command item.

Short commands that return within one tool call do not reliably reproduce this. The failure is easier to observe when execution exceeds the first yield and produces multiple streamed/polled output deltas.

Session and conversation identifiers are omitted from this public report. Redacted correlated excerpts can be provided if needed.

What is the expected behavior?

The child thread should display its Ran a command card and append streamed output throughout execution.

If the renderer receives a child event before the child conversation is registered, it should queue/replay the event or fully reconstruct the turn and its active command items during thread/read/rebind. Rebinding the turn must not leave later commandExecution/outputDelta events pointing to a missing item.

Additional information

This appears related to #23292 and especially #32737, but the visible failure here is narrower: the child completes normally and remains visible, while only its command/tool card and streamed command output are lost.

Version comparison from the same machine:

• Codex App release 26.727.40816: an affected long-running rollout dropped 11 command output events.
• Codex App release 26.727.51351 (build 6119): an affected long-running rollout dropped 31 command output events.

Therefore the issue is still present in 26.727.51351. Changing the workspace directory and creating multiple sequential sub-agents were investigated and are not required triggers. The stronger correlation is a newly hydrated child thread running a long-lived command with repeated output deltas.

Privacy: project paths, prompts containing user data, command arguments, conversation IDs, session IDs, and task artifacts have been omitted.