mz-pr-review

name	mz-pr-review
description	Perform a local code review of the current branch's changes against Materialize project standards. Trigger when the user says "review my code", "review my changes", "check my diff", "does this look ok", "what do you think of this PR", "code review", or asks you to look over changes before merging. Also trigger when the user passes a PR number and wants feedback on quality, style, or correctness.
argument-hint	["base-branch"]
allowed-tools	["Bash","Read","Grep","Glob","Task"]

Perform a local code review of the current branch's changes against Materialize project standards.

Steps

1. Parse arguments from: $ARGUMENTS — a PR number, base branch, or nothing.
2. Get the diff using the first method that works:
   • PR number given (e.g. 123): gh pr diff 123
   • git available: git diff <base>...HEAD (default base: main)
   • jj available: jj diff -r <revset> (default: diff from trunk)
3. Get the file list from the same diff (add --stat for git, --stat for jj, or gh pr diff 123 --stat for PR).
4. Review the diff against the checklists below.
5. Present findings organized as: Blocking, Strong suggestions, Nits.

Review checklist

The overall developer guide for reviewing changes is defined in doc/developer/guide-changes.md, always read and follow its guidance.

Tests

• Every behavior change has at least one new or modified test.
• SQL/query behavior → look for .slt in test/sqllogictest/.
• Wire/protocol behavior → look for .pt in test/pgtest/.
• Rust logic/types/APIs → add or extend a Rust unit test in the crate (e.g. #[cfg(test)] or tests/); run with cargo test -p mz-<crate>.
• Prefer testing observable behavior (SQL results, wire protocol) over implementation details.
• Red flag: behavior change with no test changes.
• For more testing guidelines, read doc/developer/guide-testing.md

Code style (Rust)

• Imports: std → external crates → crate::; one use per module; prefer crate:: over super:: in non-test code.
• Errors: Structured with thiserror; no bare anyhow!("..."). Display should not print full error chain.
• Async: Use ore::task::spawn / spawn_blocking, not raw tokio::spawn.
• Tests: #[mz_ore::test]; panic in tests rather than returning Result.

Code style (SQL)

• Keywords capitalized (SELECT, FROM); identifiers lowercase.
• No space between function name and (.

Error messages

• Primary: short, factual, lowercase first letter, no trailing punctuation.
• Detail/hint: complete sentences, capitalized, period.
• No "unable", "bad", "illegal", "unknown"; say what kind of object.

Sensitive data handling

• Types holding passwords, keys, tokens, or credentials should use mz_ore::secure::{SecureString, SecureVec} or zeroize::Zeroizing<T> (from mz_ore::secure).
• Sensitive types should not derive Clone or Debug (use custom Debug that redacts).
• Stack-local buffers holding derived keys, nonces, or HMAC outputs should be wrapped in Zeroizing<T>.
• See doc/developer/generated/ore/secure.md for full guidance and src/ssh-util/src/keys.rs for a reference implementation.

Architecture

• Simplicity: No incidental complexity; simplify redundant logic.
• No special casing: Prefer composable design over extra booleans/branches.
• Encapsulation: sql-parser = grammar only (no semantic validation); sql = planning + semantics.
• Dependencies: New crates must be justified.
• For more design guidelines read: doc/developer/best-practices.md

Polish

• No leftover // XXX, // FIXME, dbg!, println!, or commented-out code.
• No unrelated formatting changes in untouched code.
• New public items should have doc comments.

Release notes

• Any user-visible change to stable APIs needs a release note (imperative, "This release will…").

One semantic change rule

The PR should do one thing. If it spans multiple CODEOWNERS areas (e.g. sql-parser + sql planner), consider suggesting a split.

Rules

• Review the code, not the author. Explain the why behind suggestions.
• Use nit: for preferences where reasonable people could disagree.
• If the PR improves overall codebase health and blocking items are addressed, say so.
• Do NOT make any changes — this is read-only review.