| name | accesslint-diff |
| description | Diff a live page's accessibility violations against a baseline — by default compares uncommitted changes (stash-based), or pass --branch [<name>] to diff against a branch. Reports only new violations introduced, violations fixed, and pre-existing count. Use `scan` for a full audit with no diffing. |
| argument-hint | [--branch [<name>]] [target|url] |
| allowed-tools | Bash, Read, Glob, Grep, Skill, Task |
Default branch: !git symbolic-ref refs/remotes/origin/HEAD --short 2>/dev/null | sed 's|.*/||' || echo main
Report only what changed. Locate; don't fix.
Parse $ARGUMENTS: strip --branch <name> if present → branch mode (no value → the default branch above). The remainder is the target — a URL, a config target name, or empty for the default target from accesslint.config.json; if empty and no config, ask for a URL.
1. Audit
PORT=$(npx -y @accesslint/chrome@latest ensure | node -e 'process.stdin.on("data",d=>process.stdout.write(""+JSON.parse(d).port))')
Stash mode (default — uncommitted changes). Tell the user first: "Running in diff mode — stashing your changes to capture a baseline, then restoring. Your working tree will be fully restored." If git stash push fails, warn and exit.
git stash push -u -m "accesslint-diff-baseline"
npx -y @accesslint/cli@latest scan <target> --port "$PORT" --snapshot accesslint-diff --snapshot-dir /tmp --update-snapshot
git stash pop && sleep 2
npx -y @accesslint/cli@latest scan <target> --port "$PORT" --snapshot accesslint-diff --snapshot-dir /tmp --format json
Branch mode (--branch <name>). Tell the user first: "Diffing against <name> — checking out that branch to capture a baseline, then restoring. Your working tree will be fully restored."
Branch switching triggers a rebuild but not a browser reload — the CLI opens a fresh tab each time so it always reads the current build. Use --wait-for "<selector>" to gate the audit until the rebuild is ready; without it, warn the user that a slow build may yield a stale baseline.
git diff --quiet && git diff --cached --quiet || git stash push -u -m "accesslint-diff-branch"
git checkout <branch>
npx -y @accesslint/cli@latest scan <target> --port "$PORT" --snapshot accesslint-diff --snapshot-dir /tmp --update-snapshot [--wait-for "<selector>"]
git checkout - && git stash pop 2>/dev/null
npx -y @accesslint/cli@latest scan <target> --port "$PORT" --snapshot accesslint-diff --snapshot-dir /tmp --format json [--wait-for "<selector>"]
Pass --selector, --include-aaa to both runs.
2. Report
Accessibility diff — http://localhost:3000/ vs main (94 rules, live DOM)
2 new · 1 fixed · 4 pre-existing hidden
New — Critical
- color-contrast — 2.1:1 (needs 4.5:1), #bbb on #fff
where: main > p.subtitle fix: darken to #767676
Fixed
- img-alt — <img src="old.jpg"> (no longer present)
Each new violation: where (selector verbatim + file:line (symbol) if source present — never fabricate), evidence, fix (mechanical change or NEEDS HUMAN).
Don't edit. For fixes: apply mechanical ones then re-run accesslint:diff to verify; for bulk work hand off to accesslint:audit.
3. Tear down
npx -y @accesslint/chrome@latest stop --all
Gotchas
ensure always determines the port — never hardcode 9222.- CLI exit 2 = bad URL/target or page never loaded; check the dev server.
- A
<target> name resolves the same in both runs only if accesslint.config.json is stable across the stash/checkout — if your changes touch the config, pass an explicit URL instead.
- Stash mode:
sleep 2 covers most HMR cases; if baseline looks identical to current, add --wait-for "<selector>".
- Branch mode: no HMR — CLI opens a fresh tab each run.
--wait-for is the rebuild gate.
- Heavy DOM changes between runs cause selector drift — re-run with
accesslint:scan for the full picture.
