diff --git a/eslint.config.mjs b/eslint.config.mjs
index 9cf97333..f992bef5 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -51,7 +51,7 @@ export default [
     ],
     // Lint only changed lines. `diff/ci` diffs against the PR base but no-ops
     // when CI is unset, so it cannot replace `diff/diff` locally.
-    processor: process.env.CI ? 'diff/ci' : 'diff/diff',
+    ...(!process.env.LINT_ALL && { processor: process.env.CI ? 'diff/ci' : 'diff/diff' }),
     rules: {
       ...js.configs.recommended.rules,
       ...stylistic.configs.customize({
diff --git a/package.json b/package.json
index 7ef0fcc8..aee1ac4c 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
     "prepare": "husky",
     "setup": "sh scripts/setup.sh",
     "lint": "eslint",
+    "lint:all": "LINT_ALL=1 eslint",
     "lint:fix": "eslint --fix",
     "lint:verbose": "eslint --debug",
     "changeset": "sh scripts/changeset.sh",