Multi-line git commit messages use literal “\n” instead of newlines

What version of Codex is running?

codex-cli 0.23.0

Which model were you using?

gpt-5 medium

What platform is your computer?

Darwin 24.6.0 arm64 arm

What steps can reproduce the bug?

Steps To Reproduce

• In Codex CLI, ask the agent to “commit with a multi-line message” and it runs:
• git commit -m "Subject\n\nBody"
• View the commit in git log or on GitHub; it displays “\n” instead of actual newlines.

What is the expected behavior?

Expected

• Multi-line messages render with real newlines:
• Subject line
• Blank line
• Body text on following lines

What do you see instead?

Actual

• Commit message contains literal “\n” characters.

Additional information

Impact

• Reduces readability of commit history and violates conventional commit formatting (subject line + blank line + body).

Workarounds

• Use a temp file and -F:
• cat > .git/COMMIT_MSG_TMP << 'MSG'
• <message with real newlines>
• MSG
• git commit -F .git/COMMIT_MSG_TMP

Proposed Fix

• Default behavior: when a message contains line breaks or needs a body, always write it to a temp file and use git commit -F <file>.
• Add a small helper in the agent:
• Detect “\n” or multi-line content in the requested message.
• Serialise to a temp file (e.g., .git/COMMIT_MSG_TMP), then run git commit -F.
• Clean up the temp file afterward.
• Training:
• Update training or prompts to avoid recommending embedded “\n” in -m args.

Acceptance Criteria

• Any commit created by the agent with multi-line content renders correctly with real newlines in git log and on GitHub.
• No occurrences of literal “\n” in recent commit messages produced by the agent in test scenarios.