codex exec non interactive mode prints duplicate output

Hi! I can take this one. I’ll reproduce the duplicate output in and propose a focused fix with tests.

Opened a fix PR: https://github.com/openai/codex/pull/12828

It suppresses duplicate final output in interactive terminals while preserving stdout output for piped/CI usage.

Thanks for the policy clarification — understood on invite-only code contributions.\n\nFor maintainers’ convenience, here is the technical rationale for the fix I tested for #12566:\n\n- Root cause: in , the final assistant message is emitted once during handling (stderr), and then emitted again in (stdout), which causes visible duplication in interactive terminal runs.\n- Proposed behavior: keep stdout emission only for non-interactive contexts (pipes/CI), where machine-readable final output is expected.\n- Implementation detail: gate the final stdout print on using .\n- Safety:\n - Interactive TTY: no duplicate human-visible output.\n - Piped/non-interactive mode: final stdout output preserved for scripts and CI workflows.\n- Tests added: helper-level tests for to lock behavior.\n\nPatch reference (fork branch/commit):\n- commit: https://github.com/pdonizete/codex/commit/912fc3966\n- branch compare: https://github.com/pdonizete/codex/compare/main...pdonizete:fix/12566-exec-duplicate-output\n\nIf this aligns with project direction, I’d be happy to provide the same change via an invited PR route.

Thanks for the policy clarification — understood on invite-only code contributions.

For maintainers’ convenience, here is the technical rationale for the fix I tested for #12566:

• Root cause: in codex-rs/exec/src/event_processor_with_human_output.rs, the final assistant message is emitted once during EventMsg::AgentMessage handling (stderr), and then emitted again in print_final_output() (stdout), which causes visible duplication in interactive terminal runs.
• Proposed behavior: keep stdout emission only for non-interactive contexts (pipes/CI), where machine-readable final output is expected.
• Implementation detail: gate the final stdout print on !stdout.is_terminal() using std::io::IsTerminal.
• Safety:
• Interactive TTY: no duplicate human-visible output.
• Piped/non-interactive mode: final stdout output preserved for scripts and CI workflows.
• Tests added: helper-level tests for (message present/absent) x (tty/non-tty) to lock behavior.

Patch reference (fork branch/commit):

• commit: https://github.com/pdonizete/codex/commit/912fc3966
• branch compare: https://github.com/pdonizete/codex/compare/main...pdonizete:fix/12566-exec-duplicate-output

If this aligns with project direction, I’d be happy to provide the same change via an invited PR route.

Thanks for the bug report. And @pdonizete, thanks for the analysis — it was spot on.

This will be fixed in the next release.

Thanks — I appreciate it. I’m glad my analysis was helpful and that the fix is now in.
I’ll verify on my side once the next release is out.

Closing as resolved in current releases.