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MIP-0072: A Gemini review on request, by adding the Gemini reviewer
Status Partially implemented (tasks 1–2 of 3 — marola-dev/marola-devkit#19, marola-dev/marola-devkit#24; task 3 in six of seven repos, §5.4). Missing: marola-corpus's caller (marola-dev/marola-corpus#5) and the team's Read on marola-app, marola-ml and marola-corpus (task H). Issues #546, #641. Tasks: docs/MIPs/MIP-0072.tasks.md
Author Claude, for M. Hoffmann
Created 2026-09-30; revised 2026-10-06 to the design that shipped
Phase 0 (dev-loop; no user-facing surface)
Related GEMINI-CODE-ASSIST.md (#400, the hosted product this replaces for now), DEV-FLOW.md §5 route 4, MIP-0060 (§5.5 reserved a hosted review for a human go-ahead), MIP-0070 (the devkit's reusable workflows)
Effort M: one reusable workflow and one script in marola-devkit, a ~15-line caller per repo, human-only org settings
Gain infra/dev-loop: one gesture anyone with triage access can make, from the PR sidebar or gh pr edit --add-reviewer, in every repo; cost/ops: $0 on the Gemini API free tier, no GCP project or billing account
Effort vs Gain do now
Depends on No MIP. No paid resource: the API key is a free AI Studio key with no billing attached
Blocked by none
Risk Google cuts the free tier (about 20 requests a day per model) or retires the default model; GEMINI_MODEL switches models without a release
Cost so far see each PR's Cost: trailers

1. Summary

Requesting the empty, visible org team marola-dev/gemini as a reviewer on any marola pull request starts a Gemini review. Each repo's .github/workflows/gemini.yml calls marola-devkit's reusable gemini-review.yml, which sends the diff to the Gemini API in one call, posts one review as the GitHub App marola-gemini-bot, and pushes one commit with the fixes it can apply safely. The PR merges once every repo has the caller (§5.4).

2. Motivation

The maintainer wants a review to start when someone adds "the Gemini reviewer" to a PR. The first draft of this MIP (2026-09-30) did that through Gemini Code Assist on GitHub. Google shut its consumer app down on 2026-07-17, and the enterprise install needs a GCP project with a billing account (GEMINI-CODE-ASSIST.md), which the cost gate in AGENTS.md would hold. Calling the Gemini API directly with a free AI Studio key needs neither, and the same workflow serves every repo from the devkit.

3. User-visible change

Before: no gesture asks for a review, and no Gemini comment exists on any marola PR.

After (PR timeline):

h0ffmann requested a review from marola-dev/gemini
github-actions removed the review request for marola-dev/gemini
marola-gemini-bot reviewed: one summary, ≤ 10 inline comments tagged [high]/[medium]/[low]
marola-gemini-bot pushed: fix: apply Gemini review findings   (same-repo PRs only)

From a terminal: gh pr edit <N> --add-reviewer marola-dev/gemini. Request it again after new commits for a fresh review. A fork PR gets the review and no fix commit.

4. Data sources and dependencies reviewed

  • A GitHub App cannot be requested as a reviewer, so a team stands in for the bot. A team is offered in the Reviewers box only when it has access to the repo; on 2026-10-06 the team had Read on marola, marola-site, marola-devkit and marola-oods, and requesting it on a marola-oods PR failed until it was added there (gh api repos/marola-dev/<repo>/teams).
  • The review_requested payload carries requested_team.slug, which the caller's if reads.
  • The free tier allows about 20 requests a day per model. An agent loop (run-gemini-cli) spent them on one PR in testing, so the design makes one API call per review.
  • pull_request_target runs the base branch's workflow with the repo's secrets. It is safe here because only someone with triage access can request a reviewer, and nothing from a fork's head is executed (§5.3).
  • A push with GITHUB_TOKEN starts no CI on the PR; a push with the App's installation token does. An App with no Workflows permission cannot push a change under .github/workflows/.

5. Design

5.1 The gesture

The team marola-dev/gemini: visible, no members, Read on every repo that calls the workflow. The workflow removes the team request first, so it can be requested again.

5.2 gemini-review.yml (marola-devkit)

One job. scripts/gemini_review.py review sends the diff, numbered by new-file line, with the repo's .gemini/styleguide.md and AGENTS.md, and asks for JSON. It keeps at most 10 comments GitHub accepts and posts one COMMENT review with suggestion blocks. gemini_review.py fix then applies a comment's fix only where its original text still matches, only in files the PR changed and never under .github/; the caller's check-command runs without the token; one commit carrying Tested:/Cost: (and any extra-trailers) is pushed. Inputs and secrets are in the devkit's 4-reference_workflows.

5.3 Fork PRs (marola-dev/marola-devkit#23)

The workspace is the base commit, so the style guide is the repo's own. The fork's head is checked out into .pr-head without credentials and read as text, and review --root .pr-head anchors the suggestions there. The fix step is skipped: the App cannot push to a fork.

5.4 Where it is wired

Repo Caller State
marola-devkit the reusable workflow plus its own gemini.yml (devkit-ref: ${{ github.sha }}) marola-dev/marola-devkit#19, #24, merged (v0.5.0)
marola gemini.yml #642, merged
marola-site gemini.yml with check-command: node scripts/site_check.js and MIP: none marola-dev/marola-site#52, merged
marola-app gemini.yml marola-dev/marola-app#37, merged
marola-ml gemini.yml marola-dev/marola-ml#15, merged
marola-oods gemini.yml marola-dev/marola-oods#6, merged
marola-corpus gemini.yml marola-dev/marola-corpus#5, open

Every caller pins @v0.5.0 with devkit-ref: v0.5.0 and triggers on pull_request_target.

5.5 Human-only settings (task H)

The org secrets GEMINI_API_KEY and GEMINI_APP_PRIVATE_KEY and the variable GEMINI_APP_ID, scoped to the repos above; the App installed on them with Contents and Pull requests read/write and no Workflows permission; the team with Read on each. The optional org variable GEMINI_MODEL overrides the default gemini-3.5-flash.

6. Scoring / safety impact

None. The review is advisory and touches no app code path.

7. Verification plan

  • Each caller passes actionlint in its repo's CI.
  • Live, on the devkit's own PRs: requesting the team posted a review and a fix commit whose push started CI (marola-dev/marola-devkit#19).
  • Live, a fork PR (marola-dev/marola-site#54): one review, no fix commit, nothing from the fork run.
  • Per repo: request marola-dev/gemini on any PR; the request disappears and a review appears.

8. Risks, limitations, and honest caveats

  • The free tier's daily quota is shared by every repo; a busy day runs out and the job fails until the next day.
  • One call cannot follow up: the review sees the diff, the style guide and AGENTS.md, not the rest of the repo.
  • Source leaves the org for Google's API, as Gemini Code Assist would have sent it.

9. Alternatives considered

  • Gemini Code Assist on GitHub (this MIP's first draft): needs a GCP project with billing since the consumer app's shutdown. GEMINI-CODE-ASSIST.md keeps the plan.
  • An agent loop (run-gemini-cli): spent the day's quota on a single PR.

11. Open questions

None open. The draft's questions on Code Assist's bot-comment filter and drafts no longer apply.