Allow harness-generated timing to be omitted from model-visible tool results

Environment and scope

• Observed Codex version: 0.150.1
• Interfaces: direct CLI and clients using codex app-server
• This appears to be shared core behavior rather than platform-specific behavior

Problem

Codex adds its own elapsed-time metadata to model-facing tool results, for example:

Wall time: 835 seconds

This value is generated by Codex. It is not command stdout, stderr, or MCP tool-returned content. I need a supported way to prevent it from entering model context.

This is an information-boundary requirement, not merely a model-behavior complaint. Even if every model ignored the value, I would still want Codex not to disclose it.

This request concerns explicit timing generated by Codex. It does not attempt to prevent indirect inference of latency or remove timing emitted by the underlying command or tool.

Long blocking calls are normal in my workflow and must be repeated. Models sometimes treat the reported duration as a reason to abandon that workflow. This illustrates the impact, but it is not required to reproduce the underlying issue.

Implementation confirmation

The timing is added while constructing model-facing results, not only while rendering the UI.

In the current 0.152.0 source:

• Exec results place response_text() into the model response item, while response_header() unconditionally adds Wall time.
• MCP results response_payload() prepends Wall time to the function-call output.
• Code-mode exec results include wall_time_seconds.

Requested behavior

Provide a supported configuration or model-input policy that omits Codex-generated elapsed-time metadata from model-accessible tool results.

When enabled:

• Codex-generated timing must be absent from model input and persisted or replayed conversation history.
• The policy must cover direct exec, MCP, model-accessible code-mode results, and elapsed timing in abort results.
• Command stdout, stderr, exit status, errors, tool status, and tool-returned content must remain unchanged.
• Timing emitted by the underlying command or MCP tool must not be filtered.
• Operator-facing timing must remain available through client events, the UI, logs, tracing, and telemetry.
• The policy must be honored by direct CLI sessions and threads created through codex app-server.

Hiding timing only in the UI is insufficient. Omission must occur before model-input and conversation-history construction.

The existing behavior may remain available for compatibility. The exact configuration name is not important; a global setting inherited by app-server threads would satisfy the request.

Start in codex-rs/core/src/tools/context.rs, especially response_header(), response_payload(), and the code-mode result handling linked in the issue. Trace how these results enter model input and persisted or replayed history, including abort results and app-server threads. Done means an opt-in policy omits Codex-generated timing across all listed result paths while preserving command and tool output plus operator-facing timing.