Codex: SessionStart systemMessage renders as a yellow warning: (reads like an error every session)

[spde]

What happens

On Codex, every SessionStart shows ponytail's mode as a yellow warning: line:

• SessionStart hook (completed)
  warning: PONYTAIL:FULL
  hook context: PONYTAIL MODE ACTIVE — level: full

Ponytail is working correctly, but the warning: styling reads as an error every session — a small adoption paper-cut. (Screenshot available.)

Root cause — ponytail-side, distinct from #331 / openai/codex#16933

This is not the #331 case (Codex rendering additionalContext). This specific line comes from ponytail's own systemMessage in the isCodex branch of hooks/ponytail-runtime.js:

const output = { systemMessage: `PONYTAIL:${mode.toUpperCase()}` };

Codex maps a hook systemMessage to a Warning entry, and the presence of any Warning entry also drops the completed-hook bullet from green to neutral (see codex tui/src/history_cell/hook_cell.rs: the warning: prefix on the Warning kind, and hook_completed_bullet greening the bullet only when no Warning entry is present). The additionalContext "hook context:" line is a separate Context entry and is untouched.

Because it's ponytail's own systemMessage, it's fully in ponytail's control — unlike #331.

Fix

The Qoder branch right below already ships hookSpecificOutput minus systemMessage, so there's precedent for a silent mode signal. Dropping systemMessage on Codex:

• removes the warning: line,
• flips the completed-hook bullet to green (success),
• keeps every state visible via the hook context: line — PONYTAIL MODE ACTIVE — level: <mode> when on, PONYTAIL MODE OFF when off (the off path passes that context too), since Codex renders additionalContext (Ponytail instructions are printed on codex session start #331).

So there's no loss of visibility — only the alarming styling goes. After the change the isCodex branch becomes identical to isQoder; happy to dedup them in the PR if you'd prefer.

PR incoming. tests/hooks.test.js currently asserts the systemMessage values, so those move with the change.

[vinitgirdhar]

Hello can you assign me this issue?

[AlexAgo83]

I can confirm this affects Codex CLI 0.147.0 on macOS with Ponytail 4.9.0.

Observed on every new session:

SessionStart hook (failed)
  error: hook exited with code 1

UserPromptSubmit hook (failed)
  error: hook exited with code 1

The Ponytail hook scripts themselves ran successfully when invoked directly. Applying the change from PR #606 locally — removing the Codex systemMessage while preserving hookSpecificOutput.additionalContext — fixed both events:

SessionStart hook (completed)
  hook context: PONYTAIL MODE ACTIVE — level: full

A normal prompt then completed without a UserPromptSubmit hook error.

This seems broader than the warning-only presentation described in the issue: under this Codex version, systemMessage can surface as actual hook failures. Merging #606 would fix the problem.