# ADR 041: Gemini Code Assist

- HTML version: https://robbiepalmer.me/projects/personal-site/adrs/041-gemini-code-assist
- Project: Personal Site (https://robbiepalmer.me/projects/personal-site.md)
- Status: Accepted
- Date: 2026-06-20

# Context

[ADR 009: CodeRabbit](/projects/personal-site/adrs/009-code-rabbit) records the decision to use automated AI review on Pull Requests and the broader reasons for keeping a review step in a solo-development workflow. This ADR does not repeat that rationale. It records why I added a second automated reviewer.

Relying on one review provider creates two risks:

1. **Review Blind Spots**: AI reviewers differ in the issues they notice and the recommendations they make. A single reviewer can repeatedly miss the same classes of problem.
2. **Provider Dependency**: A pricing, product, or availability change from CodeRabbit could remove the review step or slow down delivery while I evaluate a replacement.

Gemini Code Assist on GitHub has been available at no cost for public open-source repositories, making it possible to reduce these risks without adding a financial commitment.

# Decision

I will use **[Gemini Code Assist on GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code)** alongside CodeRabbit for automated code review on Pull Requests.

Gemini Code Assist is a complementary reviewer, not a replacement for CodeRabbit. The value comes from receiving an independent review from a different provider and model family. Its feedback often diverges from CodeRabbit's, increasing the chance that one reviewer identifies an issue or alternative that the other misses.

# Alternatives

## CodeRabbit Only

* **Pros**: Fewer review comments to process and only one service to configure.
* **Cons**: Concentrates review coverage and workflow continuity in one provider. A CodeRabbit pricing or product change could interrupt the review workflow and reduce delivery velocity.
* **Decision**: Rejected. Gemini Code Assist adds useful diversity at no cost for this public repository.

## Replace CodeRabbit with Gemini Code Assist

* **Pros**: Retains a single automated reviewer while avoiding dependence on CodeRabbit.
* **Cons**: Loses CodeRabbit's accumulated learnings and removes the diversity of feedback that justifies adopting Gemini Code Assist.
* **Decision**: Rejected. The services provide more value together than either provides alone.

# Consequences

## Positive

* **Diverse Feedback**: Independent reviewers surface different concerns, interpretations, and implementation options.
* **Reduced Provider Risk**: The review workflow is less exposed to pricing or availability changes from CodeRabbit.
* **Maintained Velocity**: If one reviewer becomes unavailable or uneconomical, the other can continue reviewing PRs while a replacement is evaluated.
* **No Additional Cost**: The consumer GitHub integration has been free for public open-source repositories.

## Negative

* **Additional Noise**: Two AI reviewers can produce duplicate, conflicting, or low-value comments that take time to assess.
* **No Guaranteed Consensus**: Agreement between two AI reviewers does not prove that a change is correct, and disagreement still requires human judgement.
* **Second Provider Dependency**: The approach reduces dependence on CodeRabbit but introduces dependence on Google's continued support for the integration.

# Planned Deprecation

Google has announced the **[sunset of the consumer version of Gemini Code Assist on GitHub](https://developers.google.com/gemini-code-assist/docs/deprecations/consumer-code-review)**. New consumer installations are blocked from June 18, 2026, and consumer code review activity will cease on July 17, 2026. The enterprise version is not affected.

This ADR remains **Accepted** while the existing installation continues to review Pull Requests. Unless the enterprise version is adopted, its status should change to **Deprecated** when consumer review activity ceases on July 17, 2026.

The enterprise GitHub integration is currently in Preview and requires Google Cloud billing, IAM configuration, and a Developer Connect connection in `us-east1`. Google does not publish product-specific pricing for it. Its uncertain post-preview cost and additional operational overhead make it unsuitable as a direct continuation of the original no-cost decision.

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