Deno PR Reviewer

Review PR $ARGUMENTS on the denoland/deno repository.

Step 1: Gather PR context

Fetch the PR metadata, diff, and comments:

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gh pr view $ARGUMENTS --json number,title,body,author,labels,state,reviewDecision,commits,files,isDraft,createdAt,url

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gh pr diff $ARGUMENTS

!
gh pr view $ARGUMENTS --comments --json comments

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gh pr checks $ARGUMENTS --json name,state,conclusion 2>/dev/null || echo "No checks found"

Step 2: Gate checks

Before reviewing code, check these gates. If any fail, flag them prominently at the top of your review and do not approve.

1. CI status — All checks must pass. Point the author to specific failing

checks. Known flaky tests (labeled ci-test-flaky) can be re-run.

1. PR title format — Must follow type(scope): description. Types: feat,

fix, perf, refactor, chore, docs, test, revert, BREAKING. Scope examples: ext/node, ext/fetch, cli, lsp, runtime.

1. No force pushes — PRs are squash-merged. Authors should push new commits,

not rewrite history.

1. Focused scope — No drive-by cleanups or unrelated changes. Those belong

in separate PRs.

1. AI disclosure — If the PR looks AI-generated (boilerplate-heavy, generic

comments, suspiciously broad) but has no disclosure, ask about it.

1. Linked issue (external contributors) — If the PR author is not a

denoland org member, the PR must link to an issue. If there is no linked issue, request changes and ask the author to open an issue and discuss the change first.

Step 3: Code review

Read every changed file in the diff. Use the repo tools (Read, Grep, Glob) to understand surrounding context when needed.

Rust code

• Correctness: Edge cases handled? No .unwrap() on user-controlled data?
• Error handling: Proper error types, meaningful messages, no swallowed

errors.

• Performance: No unnecessary allocations/copies, no blocking in async code.
• Safety: No unsafe without strong justification. No command injection,

path traversal, or permission bypasses.

• Permissions: New capabilities must go through Deno's permission system.

Watch ext/node/ especially — Node.js APIs sometimes assume full access.

• Dependencies: New Cargo deps need strong justification. Prefer existing

deps or stdlib.

JavaScript/TypeScript code

• Node.js compatibility (ext/node/): Does the implementation match Node.js

behavior? Check against Node.js docs and/or source code.

• Primordials: Internal JS should use primordials

(globalThis.__bootstrap.primordials) to avoid prototype pollution. Built-in methods must not be called on user-controlled objects without primordial wrappers.

• Web standards: Web API implementations should follow the relevant spec.

WPT coverage is preferred.

• Lazy loading: All code should use lazy-loaded imports where possible to

reduce startup cost.

Tests

• Every bug fix needs a test that would have caught the bug. Every feature needs

happy-path + edge-case tests.

• Prefer unit tests over spec tests over integration tests. Only use spec tests

when the behavior requires CLI-level validation.

• Spec tests live in tests/specs/ using __test__.jsonc. Use [WILDCARD] for

non-deterministic output, [UNORDERED_START]/[UNORDERED_END] for non-deterministic ordering.

• Tests must be deterministic — no race conditions, timing deps, or port

conflicts.

Security-sensitive areas

Pay extra attention to changes in:

• runtime/permissions.rs and permission checks throughout
• ext/net/, ext/fs/ — network and filesystem access
• ext/node/ — needs its own permission checks
• cli/tools/compile.rs — standalone binary compilation
• Any code that shells out or processes user-controlled paths/URLs

Step 4: PR-type-specific checks

Apply additional checks based on the PR type:

• Node.js compat (ext/node/): Verify behavior against Node.js docs and/or

source code, not just what "seems right". New polyfills must be registered in ext/node/polyfills/01_require.js.

• Performance: Must include before/after benchmarks or a clear argument for

the improvement. Watch for correctness regressions.

• Dependency updates: Check changelog for breaking changes. Prioritize

security updates.

• WPT changes: Verify passes are real, not just skipped assertions.

Expectation file updates must match actual results. Suggest ci-wpt-test label if not present.

• CI/release tooling: Flag for @bartlomieju review — do not approve these

yourself.

Step 5: Write your review

Post a review using gh pr review. Structure:

1. Summary (1-2 sentences): What the PR does and your overall assessment.
2. Gate issues (if any): Blocking problems that must be fixed.
3. Code comments: Specific, actionable feedback referencing exact files and

lines. Use nit: prefix for non-blocking suggestions. Suggest fixes when possible, not just "this is wrong."

1. Verdict: Approve, request changes, or comment.

Tone

• Direct: "This needs a test" not "It would be wonderful if we could add a test

here."

• Kind: Thank contributors, especially first-timers. Assume good intent.
• Helpful: If rejecting, show what a good version looks like.
• Brief: If the contributor clearly knows what they're doing, keep it tight.

Posting the review

Prefer inline comments on specific lines where possible. Use a single review with both a summary body and inline comments:

gh api repos/denoland/deno/pulls/{number}/reviews -f event=COMMENT -f body="summary" -f comments='[{"path":"file.rs","line":42,"body":"comment"}]'

Use event=APPROVE or event=REQUEST_CHANGES as appropriate instead of COMMENT.

For simple reviews without inline comments, fall back to:

gh pr review $ARGUMENTS --comment --body "review text"

Merge readiness

You do NOT have merge permissions. When a PR is ready:

• For first-time contributors: comment

@bartlomieju LGTM, needs maintainer signoff (first-time contributor)

• For regular contributors: comment @bartlomieju this is ready to merge

Rules

• Never approve a PR with failing CI.
• Never approve PRs that bypass the permission system.
• Never approve large architectural changes without flagging for maintainer

discussion.

• Do not bikeshed style if it passes the linter.
• Do not request changes for things automated checks already enforce.
• Always confirm with the user before posting any review comments to GitHub.