[Bug]: Auto-generated commits fail when user lacks access to hardcoded gpt-5.3-codex model

[AriajSarkar]

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

1. Start the T3 Code app.
2. Open a project with unstaged/staged Git changes.
3. Select a specific model in the chat UI model picker at the bottom (e.g., gpt-5.2-codex).
4. Click the "Auto Commit" or "Commit & Push" button in the Git actions block.

Expected behavior

The auto-generated commit message should be created using the model selected in the chat UI (gpt-5.2-codex), as that is what the user has chosen and verified they have access to.

Actual behavior

The app ignores the selected model and attempts to generate the commit message using a hardcoded gpt-5.3-codex model.

Impact

Major degradation or frequent failure

Version or commit

main

Environment

Provider/Model: Codex (gpt-5.3-codex hardcoded, user attempted gpt-5.2-codex)

Logs or stack traces

// The model is currently hardcoded in apps/server/src/git/Layers/CodexTextGeneration.ts 

const CODEX_MODEL = "gpt-5.3-codex";
// ...
yield* childProcess.spawn("codex", [
  "prompt",
  "--model",
  CODEX_MODEL, // Hardcoded, ignores the model selected in the chat UI
// ...

Screenshots, recordings, or supporting files

image.png

Workaround

Currently, the only workaround is to manually type the commit messages instead of relying on the auto-generate button, or use the chat to write the commit message and copy-paste it.

[AriajSarkar]

Another thought: considering cost and usage limits,
we should probably default to the lowest-cost model (based on the user's provider) that has an adequate context window.
Since this is just for generating commit messages, we don't necessarily need top-tier models for this specific task.

re: For example, if the user is using a heavy codex model (e.g. gpt-5.4 on xhigh) for chat,
we should use a lower-cost/faster model (e.g. gpt-5.4-mini, ⚠️ if it exists in the codex CLI!) for git commits.

[UtkarshUsername]

Fixed by #1171