[macOS] Fatal remote compaction v2: expected one compaction output item, got 2 from 2; task stalls

What version of the Codex App are you using?

Installed desktop app: 26.908.70816 (build 9275).
Bundled Codex runtime: codex-cli 0.154.0-alpha.6.2.
These versions were read from the local installation when preparing this report.

What subscription do you have?

Not included in this public report.

What platform is your computer?

macOS 26.4.1 (build 25E253), arm64.

What issue are you seeing?

During a long-running Codex conversation, remote compaction fails with this exact error:

Error running remote compact task: Fatal error: remote compaction v2 expected exactly one compaction output item, got 2 from 2 output items

The user experiences this as Codex freezing / losing progress and being unable to continue the task reliably. Actual deletion of persisted history or files has not been confirmed; this report concerns the fatal compaction failure and interrupted task continuity.

What steps can reproduce the bug?

Observed context, not a deterministic minimal reproduction:

1. Work in an existing long-running Codex conversation with substantial conversation and tool history.
2. When a remote compaction attempt occurs, it fails with the exact error above.
3. The ongoing workflow is interrupted and task continuity becomes unreliable.

Whether this specific attempt was automatic or manually triggered is not yet confirmed. The failing request payload and the two returned output items have not been captured in this report.

What is the expected behavior?

Compaction should preserve the conversation state and allow work to continue. If the compaction response does not satisfy the expected output contract, Codex should preserve the last valid state and provide a recoverable, actionable error rather than leave the task apparently stuck.

Please investigate why the remote compaction v2 path returned two compaction output items while the consumer expected exactly one, and ensure failed compaction cannot discard task progress.

Additional information

Related but different reports: #30018 and #32646 describe zero compaction output items from two output items. This report specifically concerns two compaction output items from two output items.

The error and user-visible impact are user-reported; installed app/runtime/OS versions were checked locally. No deterministic reproduction or backend root cause has been independently verified.

No customer data, conversation transcript, credentials, infrastructure identifiers, or raw logs are attached.

Start by tracing the remote compaction v2 path that handles the reported "expected exactly one compaction output item" error and inspect how multiple returned items are processed. Reproduce with a long-running conversation if possible, then verify that an invalid response preserves the last valid state and leaves the task recoverable; no source files or tests are named in the report.