feat(gemini): add user-global Gemini CLI instructions

[kurone-kito]

Summary

Adds home/dot_gemini/GEMINI.md so chezmoi deploys a user-global
Gemini CLI instructions file at ~/.gemini/GEMINI.md, bringing
Gemini CLI to parity with the already-deployed Copilot CLI, Codex
CLI, and Claude Code user-global files.

The new file preserves the same five sections — repository-precedence
preamble, Conversation, Commit rules (with the full P/C/A/U signing
fallback ladder), Coding standards, and Guardrails — adapted for
Gemini CLI's interaction model (intent-based wording in place of the
Copilot product-specific "Agent mode" / "Plan mode" terms).

Closes #133
Roadmap #130

Test plan

• npx markdownlint-cli2 "home/dot_gemini/GEMINI.md" — 0 errors
• npx cspell home/dot_gemini/GEMINI.md — 0 issues
• tests/bash/helpers/bats-core/bin/bats tests/bash/ — 212/212
• pwsh -c "Invoke-Pester tests/powershell/ -Output Detailed" — 182 passed, 0 failed, 33 skipped
• Lint + Test workflow on this PR — CI green on required checks

Signing path

GPG attempt 1 (category P pinentry — PINENTRY_LAUNCHED then
timeout). Category (P) prohibits the gpg-agent restart, so routed
directly to the project-blessed git commit-ssh alias (attempt 2).

Out-of-scope

• Sibling track: docs(ai-strategy): document the user-global instructions layer #134 docs(ai-strategy)

Summary by CodeRabbit

• Documentation
  • Added repository documentation with guidelines for code standards, commit message conventions, and development practices.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR introduces home/dot_gemini/GEMINI.md, a new user-global instruction file for Gemini CLI interactions. The document establishes default conversation behavior, Conventional Commits formatting with a comprehensive signing failure recovery ladder, coding standards for line endings and whitespace, and guardrails against false claims about command execution. Repository-specific instructions override these defaults when present.

Changes

Gemini CLI user-global instructions

Layer / File(s)	Summary
Scope and conversation defaults home/dot_gemini/GEMINI.md	File introduction defers to repository-specific instructions, and conversation policy specifies language-matching behavior and English documentation standards.
Commit rules with signing failure ladder home/dot_gemini/GEMINI.md	Conventional Commits formatting combined with a five-step signing failure recovery workflow: categorization, bounded gpg-agent restart, SSH fallback with key discovery, SSH best-effort treatment, and unsigned-commit final fallback with cause reporting.
Coding standards and guardrails home/dot_gemini/GEMINI.md	Line-ending, whitespace, and naming conventions, plus guardrails against unauthorized community-document modification and false claims about command/test execution.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• Roadmap: Symmetrize user-global AI agent instructions #130 — This PR directly implements the roadmap's Track C objective by adding user-global Gemini CLI instructions with conversation policy, Conventional Commits rules, and the complete signing-fallback ladder.
• feat(codex): add user-global Codex CLI instructions #131 — Related issue proposing similar repository-level agent instructions covering the same structural sections (conversation, commits with signing ladder, coding standards, guardrails).

Possibly related PRs

• kurone-kito/dotfiles#136 — Adds parallel repository documentation files defining commit rules, Git signing failure ladders, and guardrails under the same dot-directory instruction pattern.
• kurone-kito/dotfiles#135 — Adds complementary agent instruction files with matching structure, including the same five-step signing-failure ladder and guardrails about not claiming commands/tests ran when they didn't.

Poem

🐰 A rabbit drafts commands with care,
GPG keys and signing layers fair,
From Gemini's global wisdom flows—
No false claims of tests that don't run, one knows.
Standards set, guardrails in place, the dotfiles grow! 🌿

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	PR description includes comprehensive details but template structure is minimal; clarity on completeness against repository standards is uncertain.	Ensure description format aligns with repository contribution guidelines; verify all required sections per CONTRIBUTING.md are included.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title clearly summarizes the main change: adding a Gemini CLI instructions file, which aligns with the changeset.
Linked Issues check	✅ Passed	PR addresses all acceptance criteria from issue #133: file created at correct location, signing fallback ladder included, markdown/spell checks pass, and existing tests unchanged.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to creating home/dot_gemini/GEMINI.md per issue #133; no unrelated modifications 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/133-feat-gemini-add-user-global-gemini-cli

---

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

[coderabbitai]

🧹 Nitpick comments (1)

home/dot_gemini/GEMINI.md (1)

45-140: ⚡ Quick win

Keep the signing ladder as five numbered steps for contract parity.

Line 45 frames a bounded ladder, but Lines 120-140 continue numbering as steps 6-8. That drifts from the “same five steps” objective and makes cross-file parity with the Copilot instruction set harder to validate. Consider keeping only five numbered steps and moving 6-8 into sub-bullets or a non-numbered “Notes/Reporting” subsection.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@home/dot_gemini/GEMINI.md` around lines 45 - 140, The numbered “ladder” in
the "Prefer signed commits" section currently continues past five steps (steps
6–8); change it so the ladder is exactly five numbered steps (keep items 1–5
as-is) and move the content currently labeled 6 ("Treat SSH signing as
best-effort"), 7 ("Unsigned commit is the accepted final fallback"), and 8
("Always report which path was taken") into a non-numbered "Notes" or
"Reporting" subsection (or convert them to sub-bullets) under the same header;
update the text around the ladder header and any references to ensure the unique
phrases "Prefer signed commits", the numbered steps 1–5, and the specific lines
beginning with "Treat SSH signing as best-effort", "Unsigned commit is the
accepted final fallback", and "Always report which path was taken" are relocated
and reflowed so the document only shows five numbered steps followed by the new
Notes/Reporting block.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@home/dot_gemini/GEMINI.md`:
- Around line 45-140: The numbered “ladder” in the "Prefer signed commits"
section currently continues past five steps (steps 6–8); change it so the ladder
is exactly five numbered steps (keep items 1–5 as-is) and move the content
currently labeled 6 ("Treat SSH signing as best-effort"), 7 ("Unsigned commit is
the accepted final fallback"), and 8 ("Always report which path was taken") into
a non-numbered "Notes" or "Reporting" subsection (or convert them to
sub-bullets) under the same header; update the text around the ladder header and
any references to ensure the unique phrases "Prefer signed commits", the
numbered steps 1–5, and the specific lines beginning with "Treat SSH signing as
best-effort", "Unsigned commit is the accepted final fallback", and "Always
report which path was taken" are relocated and reflowed so the document only
shows five numbered steps followed by the new Notes/Reporting block.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 7129d95b-3650-437c-bd47-3d41dbcd49ee

📥 Commits

Reviewing files that changed from the base of the PR and between 7b4292c and 3565180.

📒 Files selected for processing (1)

• home/dot_gemini/GEMINI.md

[Copilot]

Pull request overview

Adds a new user-global Gemini CLI instructions file under home/ so chezmoi deploys a consistent baseline guidance set to ~/.gemini/GEMINI.md, aligning Gemini CLI with the existing user-global instruction surfaces for other agents.

Changes:

• Add home/dot_gemini/GEMINI.md with repository-precedence guidance, conversation policy, Conventional Commits rules, the bounded signing fallback ladder, coding standards defaults, and guardrails.

[kurone-kito]

claude-code-73ed18fc: review triage snapshot — IDD automation marker. Do not edit.

[kurone-kito]

Acknowledged — recording the auto-no-action review for the F2 unreplied-comment evidence check.

[kurone-kito]

E6 dispositions — PATH A and PATH B

PATH A (reviewer feedback, Rejected):

• copilot-pull-request-reviewer inline thread at home/dot_gemini/GEMINI.md line 106: Rejected — the reviewer suggested adding ~/.ssh/id_ed25519 as an example of what NOT to do, matching the reference Copilot file. However, issue feat(gemini): add user-global Gemini CLI instructions #133's acceptance criteria explicitly requires "No fixed ~/.ssh/id_ed25519 path is named." The omission is intentional; the phrase "never assume a fixed key path, and never invent one" conveys the constraint without naming a common default path. Thread resolved.

PATH B (advisory, Rejected):

• coderabbitai review at 2026-05-19T02:04:30Z: Rejected — no actionable changes requested; review body describes the PR accurately.
• coderabbitai comment at 2026-05-19T02:04:28Z: Rejected — auto-generated "no actionable comments" summary; acknowledged above.

E2 critique pass returned 0 additional findings.

[kurone-kito]

claude-code-73ed18fc: review triage snapshot (final pre-merge) — IDD automation marker. Do not edit.