feat(codex): add user-global Codex CLI instructions

[kurone-kito]

Summary

Adds home/dot_codex/AGENTS.md so chezmoi deploys a user-global
Codex CLI instructions file at ~/.codex/AGENTS.md, bringing
Codex CLI to parity with the already-deployed Copilot CLI
user-global file (home/dot_copilot/copilot-instructions.md →
~/.copilot/copilot-instructions.md).

The new file preserves the same five sections used by the
canonical Copilot user-global file — repository-precedence
preamble, Conversation, Commit rules (with the full P/C/A/U
signing fallback ladder), Coding standards, and Guardrails — and
adapts the wording for Codex CLI's interaction model (intent-based
pause/continue wording rather than Copilot's product-specific
"Agent mode" / "Plan mode" terms).

Closes #131
Roadmap #130

Test plan

• npx markdownlint-cli2 "home/dot_codex/AGENTS.md" — 0 errors
• npx cspell home/dot_codex/AGENTS.md — 0 issues
• tests/bash/helpers/bats-core/bin/bats tests/bash/ — 212 / 212
• pwsh -c "Invoke-Pester tests/powershell/ -Output Detailed" — Linux baseline: 182 passed, 0 failed, 33 skipped (Windows-only scopes auto-skipped)
• Lint workflow on this PR — green
• Test workflow on this PR — green
• After merge, chezmoi diff shows ~/.codex/AGENTS.md will be added

Signing path

GPG was attempted first (configured default; key
DFC46A0ADEE2FC635163CD5431D6D754C1D839D1) and failed with
category (P) pinentry — PINENTRY_LAUNCHED was emitted, then
gpg reported signing failed: タイムアウトです (Timeout).
Category (P) prohibits the gpg-agent restart step, so the commit
was routed straight to the project-blessed git commit-ssh alias
(SSH key ~/.ssh/id_ed25519-kito.pub, transient
gpg.format=ssh invocation). GitHub may show the commit as
Unverified if that SSH key is not registered as a signing
key on the maintainer's GitHub profile; that is expected
best-effort behavior for SSH signing.

Out-of-scope

• home/dot_codex/config.toml is intentionally untouched.
• Sibling tracks land separately:
  • feat(claude): add user-global Claude Code memory file #132 — feat(claude): add user-global Claude Code memory file
  • feat(gemini): add user-global Gemini CLI instructions #133 — feat(gemini): add user-global Gemini CLI instructions
  • docs(ai-strategy): document the user-global instructions layer #134 — docs(ai-strategy): document the user-global instructions layer

Summary by CodeRabbit

• Chores
  • Added internal development guidelines documentation for code maintainers and AI agents.

---

Note: This release contains no end-user-visible changes. Updates are limited to internal development standards and processes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 356d4a9a-ac6a-41df-8db8-b37688cef4f5

📥 Commits

Reviewing files that changed from the base of the PR and between e4b8ca9 and 9b0ed84.

📒 Files selected for processing (1)

• home/dot_codex/AGENTS.md

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📝 Walkthrough

Walkthrough

This PR adds home/dot_codex/AGENTS.md, a new configuration file that provides repository-wide default instructions for Codex AI agent sessions. The file establishes global guidelines for conversation language, commit message formatting, commit signing with a bounded fallback ladder, coding standards, and operational safety constraints.

Changes

Codex AI Agent Instructions

Layer / File(s)

Summary

User-global agent guidelines home/dot_codex/AGENTS.md

New file defining default behaviors for Codex CLI agents: defers to repository-specific instructions; specifies conversation language (match user's language, English for code/docs); Conventional Commits rules with atomic, lowercase imperative subjects; commit signing with bounded GPG attempt, classification-based gpg-agent restart, SSH fallback with key discovery, and unsigned final fallback; coding standards (LF line endings, no trailing whitespace, final newline, lowercase-hyphenated filenames); guardrails (no unauthorized community-doc edits, no false test success claims).

Possibly related issues

• #131 (feat: add user-global Codex CLI instructions) — This PR directly implements the objectives outlined in issue #131, adding the complete home/dot_codex/AGENTS.md file with all required sections, signing fallback ladder, and guardrails as specified.
• #130 (dotfiles-roadmap: user-global-ai-symmetrization) — This PR is part of the parent roadmap that tracks parity between user-global AI agent instruction files.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A codex of codes for our AI friend,
Clear signals and rules from start to end,
Commits signed with care, standards so bright,
The dotfiles now guide the agent just right! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title is concise and directly describes the main change: adding a user-global Codex CLI instructions file, aligning with the PR's core objective.
Description check	✅ Passed	PR description is comprehensive with clear summary, test plan results, signing path explanation, and scope clarification, exceeding template requirements.
Linked Issues check	✅ Passed	PR successfully addresses all requirements from issue #131: AGENTS.md file created with repository-precedence preamble, Conversation, Commit rules with full signing fallback ladder, Coding standards, and Guardrails sections adapted for Codex CLI.
Out of Scope Changes check	✅ Passed	PR adds only the required home/dot_codex/AGENTS.md file and intentionally leaves home/dot_codex/config.toml untouched; no out-of-scope changes detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue/131-feat-codex-add-user-global-codex-cli

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[Copilot]

Pull request overview

This PR adds a user-global Codex CLI instructions file so Codex picks up consistent defaults (conversation language, Conventional Commits, signing fallback ladder, coding standards, guardrails) across repositories that lack their own AGENTS.md. It mirrors the existing Copilot CLI user-global file for parity.

Changes:

• Add home/dot_codex/AGENTS.md deployed by chezmoi to ~/.codex/AGENTS.md.
• Adapt Copilot-specific "Agent mode" / "Plan mode" wording to intent-based phrasing for Codex CLI.

[kurone-kito]

claude-code-8e8ebc52: review triage snapshot — IDD automation marker. Do not edit.

[kurone-kito]

Acknowledged — recording the auto-no-action review for the IDD pre-merge unreplied-comment evidence check.

[kurone-kito]

E6 dispositions — PATH B (advisory)

Both items in ReviewItems_snapshot for head 9b0ed84 carry no actionable feedback and are recorded as PATH B advisory rejections so the F2 disposition-evidence gate is satisfied.

• copilot-pull-request-reviewer review at 2026-05-19T00:03:41Z: Rejected — review body is a pull-request overview only; no actionable findings, no change requests, no inline suggestions.
• coderabbitai comment at 2026-05-19T00:02:51Z: Rejected — body explicitly states "No actionable comments were generated in the recent review."

E2 critique pass on the same snapshot returned 0 additional findings (acceptance criteria of #131 satisfied; required CI checks all green; no scope drift).

[kurone-kito]

claude-code-8e8ebc52: review triage snapshot (refreshed post-disposition) — IDD automation marker. Do not edit.