feat: add frontend LOC ratchet warnings

[Astro-Han]

Summary

• Adds a frontend-architecture CI job that writes the frontend inventory JSON and runs LOC ratchet warnings.
• Extends script/frontend-inventory.mjs with a warn-only --check-baseline mode for touched production frontend files above >500 / >200 LOC.
• Updates the frontend architecture manifest with the current LOC baseline and CI-stage wording.

Why

#688 needs executable frontend governance in separate slices. LOC is the smallest first slice because the inventory script and manifest already exist; this PR makes that signal visible in CI without turning LOC into a hard merge gate or touching UI rewrite code.

Related Issue

Refs #688.

Human Review Status

Pending. A human should make the final merge decision after reviewing the final diff and verification evidence.

Review Focus

Please check that the new CI job is scoped as warn-only LOC governance, that it is wired into ci / check as an infrastructure signal, and that this PR does not expand into dependency boundary or cognitive-complexity work.

Risk Notes

• LOC warnings are advisory only in this slice; they do not reduce existing large files and do not block oversized touched files yet.
• The CI job fetches full history so git diff can compare PR base/head reliably.
• No visible UI, packaging, permissions, dependency, or platform behavior changes.

How To Verify

Frontend inventory JSON: passed, summary produced schemaVersion=1 with productionOver500=19 and productionOver200=81
LOC warn dry run: passed, origin/dev..HEAD had 0 changed frontend files and 0 touched production warnings
Focused tests: passed, 11 tests / 0 failures in packages/opencode test/github/frontend-inventory.test.ts and test/github/ci-workflow.test.ts
Diff check: passed, git diff --check reported no whitespace errors

Screenshots or Recordings

Not required; no visible UI changes.

Checklist

• Human review status is stated above as pending, approved, or not required
• I linked the related issue, or stated why there is no issue
• This PR has type, primary area, and priority labels, or I requested maintainer labeling
• I described the review focus and any meaningful risks
• I listed the relevant verification steps and the key result for each
• I did not introduce unrelated refactors, dependencies, generated files, or file changes beyond the stated scope
• I manually checked visible UI or copy changes when needed, with screenshots or recordings
• I considered macOS and Windows impact for platform, packaging, updater, signing, paths, shell, or permissions changes
• I called out docs, release notes, dependencies, permissions, credentials, deletion behavior, generated content, or local file changes when relevant
• I reviewed the final diff for unrelated changes and suspicious dependency changes
• I am targeting dev, and my PR title and commit messages use Conventional Commits in English

Summary by CodeRabbit

• New Features

  • Added frontend code size monitoring to the CI pipeline. The system now warns when modified production files exceed size thresholds (>200 and >500 lines of code).

• Tests

  • Added test coverage for the new code size monitoring functionality.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 4e21f55f-5a64-403a-985f-303cc1bc3a97

📥 Commits

Reviewing files that changed from the base of the PR and between 5633009 and 4e94c6d.

📒 Files selected for processing (1)

• packages/opencode/test/github/frontend-inventory.test.ts

📝 Walkthrough

Walkthrough

This PR implements a frontend architecture LOC baseline ratchet that runs as a warn-only CI check. The script gains --check-baseline mode to detect production files exceeding LOC thresholds, a new CI job runs the checks, tests cover the behavior, and governance documentation is updated.

Changes

Frontend LOC baseline ratchet with warn-only CI checks

Layer / File(s)	Summary
Baseline checking script implementation script/frontend-inventory.mjs	Parses --check-baseline, --base, and --head CLI arguments. Implements listChangedFrontendFiles(base, head) to detect modified production files via git diff, checkBaseline(inventory, {base, head}) to identify files exceeding >200 and >500 LOC thresholds, and githubWarning(record, threshold) to format GitHub Actions warning annotations.
CI workflow job and result integration \.github/workflows/ci\.yml	Adds new frontend-architecture job that installs dependencies, generates a frontend inventory JSON artifact, and runs baseline LOC checks with BASE_SHA/HEAD_SHA. Wires the job into the aggregate check job's needs, captures its result via FRONTEND_ARCHITECTURE_RESULT env var, and treats non-success results as CI failures with failure reason output.
CI workflow test coverage packages/opencode/test/github/ci-workflow\.test\.ts	Introduces constant frontendArchitectureJobName and adds test case validating the new job's docs-only gating, required workflow actions (checkout, setup-node, setup-bun, cache), script execution, SHA env wiring, and inclusion in check.needs. Updates existing aggregate test to include the job in expected check.needs ordering and assert FRONTEND_ARCHITECTURE_RESULT env propagation in the validation step.
Frontend inventory baseline test packages/opencode/test/github/frontend-inventory\.test\.ts	New Bun test suite that sets up a temporary git repository, creates and modifies an oversized frontend TypeScript file exceeding LOC threshold, runs frontend-inventory script with --check-baseline against base/head commits, and asserts successful exit, "Frontend LOC ratchet warnings" output, and GitHub-style ::warning annotations referencing the threshold violation.
Governance manifest and documentation \.github/frontend-architecture-manifest\.md	Updates manifest header to "LOC warn-only CI slice" with new baseline commit. Expands inventory command instructions to include baseline-diff check before markdown generation. Regenerates baseline inventory summary with updated tracked/ratchet file counts and owner lane distribution. Rewrites ratchet stages to specify warn-on-threshold behavior for PR-added production files above >500/>200 LOC. Updates production burn-down list with new file entries and owner lane assignments. Marks Governance PR as "complete" and adds new "LOC warn-only CI PR" row with verification commands and "in progress" status.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• Astro-Han/pawwork#667: Directly extends the frontend-inventory.mjs script and governance baseline from PR #667 by implementing --check-baseline mode with base-head diff detection and ratchet warning logic.
• Astro-Han/pawwork#125: Overlaps on .github/workflows/ci.yml modifications to the aggregate check job's dependency contract and corresponding test assertions on check.needs and result env passing.

Suggested labels

app

Poem

🐰 A rabbit hops through baselines true,
Counting LOC in every view.
Warnings echo, clean and kind,
No hard fail—just peace of mind!
The frontend glows with ratchet's grace, 🎯✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title 'feat: add frontend LOC ratchet warnings' clearly and specifically describes the main change: adding LOC ratchet warning functionality to the frontend architecture.
Description check	✅ Passed	The PR description is comprehensive and follows the template well, including all key sections: Summary, Why, Related Issue, Human Review Status, Review Focus, Risk Notes, How To Verify, Screenshots/Recordings, and a completed Checklist.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ 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 codex/i688-loc-ratchet

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[gemini-code-assist]

Code Review

This pull request implements a warn-only CI check for frontend architecture governance. The frontend-inventory.mjs script is updated to support baseline comparisons using git diff, enabling it to issue warnings for touched production files that exceed 200 or 500 Lines of Code (LOC). Additionally, the GitHub Actions workflow now includes a frontend-architecture job, and new tests have been added to verify the script's reporting logic and CI integration. The architecture manifest has also been updated to reflect the latest baseline metrics and project status. I have no feedback to provide.

[github-actions]

Suggested priority: P2 (includes non-doc, non-test paths outside the low-risk bucket).

P1/P0 are reserved for maintainer confirmation. Please relabel manually if this is a release blocker, security issue, data-loss risk, or updater/runtime failure.

[coderabbitai]

Actionable comments posted: 1

🤖 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.

Inline comments:
In `@packages/opencode/test/github/frontend-inventory.test.ts`:
- Around line 23-29: Replace the manual temp-repo creation in the test
(mkdtempSync, git init/config calls) with the shared tmpdir fixture: use "await
using tmpdir({ git: true }) as workspace" (imported from fixture/fixture.ts) to
obtain a git-initialized workspace and automatic cleanup, then copy
inventoryScript into path.join(workspace, "frontend-inventory.mjs") and create
the packages/app/src dir as before; remove the explicit git(...) calls and the
manual mkdtempSync to rely on the fixture-managed repo and root commit.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 60a23f6f-6440-4454-85dc-4b4a84e970a8

📥 Commits

Reviewing files that changed from the base of the PR and between c3e9319 and 5633009.

📒 Files selected for processing (5)

• .github/frontend-architecture-manifest.md
• .github/workflows/ci.yml
• packages/opencode/test/github/ci-workflow.test.ts
• packages/opencode/test/github/frontend-inventory.test.ts
• script/frontend-inventory.mjs