ci: enable CodeRabbit auto-review on PRs based on playground

[dcccrypto]

The gap

CodeRabbit auto-reviews only PRs whose base branch is the repository default (main). reviews.auto_review.base_branches defaults to an empty list, and this repo has no .coderabbit.yaml at all.

But the repo does almost all of its work against playground:

$ gh pr list --state merged --limit 15 --json baseRefName
playground: 13    main: 2

So in practice the large majority of PRs in this repo receive no automated review. Every one gets:

Review skipped — Auto reviews are disabled on base/target branches other than the default branch.

I found this while chasing review on #2451 / #2452 / #2453 — all three were skipped for exactly this reason, which is why they'd sat with zero review signal.

The change

One new file, four lines of config:

reviews:
  auto_review:
    base_branches:
      - "main"
      - "playground"

Key verified against the configuration reference: reviews.auto_review.base_branches, a list of regex patterns matched against the PR's base branch name. main is listed explicitly rather than relying on the implicit default, so the effective set is obvious from the file.

One thing I could not verify — please confirm on merge

The docs do not state which branch CodeRabbit reads .coderabbit.yaml from (PR base, head, or repo default). I checked the configuration reference and searched the docs; it's simply not specified.

That matters here because the file is landing on playground, not the default branch:

• If CodeRabbit reads config from the PR's base branch, this works as-is for the playground → PR flow.
• If it reads from the repository default branch, this also needs to land on main before it takes effect.

Recommend porting to main as well — it's harmless in either case, and it removes the ambiguity. Easy to confirm after merge: open any throwaway PR against playground and check whether CodeRabbit reviews it instead of skipping.

I did not want to quietly assume one behaviour and have this look like it worked when it hadn't.

Immediate unblock (already done)

@coderabbitai review posted manually on #2451, #2452 and #2453 — that path works regardless of this config, so those three have review running now.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
percolator-launch	Ready	Preview, Comment	Jul 21, 2026 5:10pm
percolator-mainnet	Ready	Preview, Comment	Jul 21, 2026 5:10pm
percolator-playground	Ready	Preview, Comment	Jul 21, 2026 5:10pm

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: e190f641-470f-475a-994f-7d3c6595d7d4

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci/coderabbit-review-playground-base

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