Committing in Materialize

Read doc/developer/guide-changes.md for the full conventions on submitting and reviewing changes.

Pre-commit checklist

Before committing, run these and fix any warnings:

1. bin/fmt (formats all .rs, .py, and .proto files; takes no file arguments)
2. bin/lint (can error if tools are missing; use bin/ci-builder run stable bin/lint as an alternative)
3. cargo clippy --all-targets -- -D warnings

Do not manually update *.snap files. Use cargo test followed by cargo insta accept to update snapshot files. Rewrite datadriven test expectations with REWRITE=1 cargo test ....

PR titles and commit messages

Materialize uses squash merging, so the PR title becomes the commit subject on main.

• Use imperative mood: "Fix X" not "Fixed X" or "Fixes X".
• Be specific: "Fix panic in catalog sync when controller restarts" not "Fix bug".
• Prefix with area if helpful: adapter: , storage: , compute: , sql: .

Write a thorough PR description explaining the rationale for the change. Mention which tests were added or modified in the pull request description, but do not list which tests were run. Add release notes for user-visible changes (should complete "This release will...").

Issue tracking: Linear only for new issues

New issues are filed in Linear, never in the database-issues GitHub repo. database-issues is legacy. Its open issues are still valid to read, link, and close, so an existing database-issues#NNNN reference in code or a comment stays as it is.

Reference the Linear issue by its its key, e.g. Closes: SQL-450. Don't include the full URL containing the issue title.

When a change closes a legacy GitHub issue, Fixes database-issues#NNNN works for auto-closing.

Cargo.lock discipline

Never regenerate the entire Cargo.lock — bare cargo update bumps every semver-compatible dep and introduces unrelated breakage (e.g., osinfo pulling in objc2 on macOS, chrono-tz changing timezone data, serdepathtoerror changing error formats).

• Adding a dep or changing features: just cargo check. It updates only what's needed.
• Updating one crate: cargo update -p <crate> (add --precise <ver> to pin).
• After any Cargo.lock change, review the diff:

`` git diff Cargo.lock | grep '^[+-]version' | head -40 ` Pin back anything that moved unexpectedly: cargo update -p <crate> --precise <old-version>`.

• After rebase conflicts in Cargo.lock: resolve by taking HEAD's version then running cargo check (not cargo update). This preserves existing pins while adding only what the new commits require.

Git conventions

• Work against the main branch of MaterializeInc/materialize.
• Push branches to your fork.
• Pull requests target main on MaterializeInc/materialize.
• Each PR should contain one semantic change.

Splitting large branches

The repo is squash-merge-only: every PR lands as exactly one commit on main, however many commits it had internally. Keep each commit/PR under ~500 changed lines, split by concern, not by the chronology of how the code was written.

• Prefer GitHub's native stacked-PR support to land a chain of dependent PRs, where it's set up for the branch. Where it isn't, fall back to sequential landing, one PR at a time: cut a PR from the front, merge, git fetch upstream && git rebase upstream/main the remaining tail, repeat. Squash-only means merging an earlier PR always replaces its commits with one new commit, so any later branch still built on the old commits needs a rebase either way; sequential landing keeps that to one clean rebase per merge instead of compounding across an unmanaged chain.
• Land foundational or low-conflict commits (design docs, scaffolding, new deps) first. The longer a tail branch lives, the more likely a concurrent unrelated PR touches the same files and turns a clean rebase into a real conflict.
• To split one large diff into smaller commits, or squash a long messy history into fewer reviewable units, as an alternative to interactive rebase: git reset --soft <base> stages the full diff, then stage per group with git add <files> for a file-level split, or use git checkout <sha> -- . to reproduce an exact historical checkpoint's tree for a chronological squash. (Claude Code's Bash tool has no interactive terminal, so agents need this non-interactive form; use whichever you prefer by hand.) git checkout <sha> -- . only adds or updates paths present in <sha>, it never removes files that shouldn't exist yet at that checkpoint: compute the removal set first with comm -23 <(git ls-files|sort) <(git ls-tree -r --name-only <sha>|sort) and git rm -f those, or the checkpoint commit silently carries files from later history. Verify every checkpoint with git diff HEAD <sha> (must be empty) before moving to the next. Reattach already-clean commits on top with git rebase --onto <new-branch> <old-base> (also non-interactive).