diff --git a/lefthook.yml b/lefthook.yml
index 66f0edf..ce67689 100644
--- a/lefthook.yml
+++ b/lefthook.yml
@@ -5,13 +5,13 @@ pre-commit:
     commands:
         oxlint:
             glob: "*.{ts,tsx,js,jsx,mjs,cjs}"
-            run: npx oxlint {staged_files}
+            run: sh -c 'LEFTHOOK_FILES="$0" npm run check:oxlint' {staged_files}
         oxfmt:
             glob: "*.{ts,tsx,js,jsx,mjs,cjs}"
-            run: npx oxfmt --check {staged_files}
+            run: sh -c 'LEFTHOOK_FILES="$0" npm run check:oxfmt' {staged_files}
         cspell:
-            run: npx cspell {staged_files}
+            run: sh -c 'LEFTHOOK_FILES="$0" npm run check:cspell' {staged_files}
         sort-package-json:
-            run: npx sort-package-json --check
+            run: npm run check:package
         typecheck:
-            run: npx tsc --noEmit
\ No newline at end of file
+            run: npm run check:tsc
\ No newline at end of file
diff --git a/package.json b/package.json
index 14d44da..fb3eeb2 100644
--- a/package.json
+++ b/package.json
@@ -33,10 +33,10 @@
     "scripts": {
         "build": "tsc -p tsconfig.build.json",
         "check": "npm run check:oxlint && npm run check:oxfmt && npm run check:tsc && npm run check:cspell && npm run check:package && npm run check:outdated",
-        "check:cspell": "cspell .",
+        "check:cspell": "cspell lint ${LEFTHOOK_FILES:-.}",
         "check:outdated": "check-outdated --ignore-pre-releases --ignore-packages @oxfmt/binding-darwin-arm64,@oxfmt/binding-darwin-x64,@oxfmt/binding-linux-arm64-gnu,@oxfmt/binding-linux-arm64-musl,@oxfmt/binding-linux-x64-gnu,@oxfmt/binding-linux-x64-musl,@oxfmt/binding-win32-x64-msvc,@oxlint/binding-darwin-arm64,@oxlint/binding-darwin-x64,@oxlint/binding-linux-arm64-gnu,@oxlint/binding-linux-arm64-musl,@oxlint/binding-linux-x64-gnu,@oxlint/binding-linux-x64-musl,@oxlint/binding-win32-x64-msvc",
-        "check:oxfmt": "oxfmt --check src",
-        "check:oxlint": "oxlint src",
+        "check:oxfmt": "oxfmt --check ${LEFTHOOK_FILES:-src}",
+        "check:oxlint": "oxlint ${LEFTHOOK_FILES:-src}",
         "check:package": "sort-package-json --check",
         "check:tsc": "tsc --noEmit",
         "clean": "node -e \"fs.rmSync('dist', { recursive: true, force: true })\"",
@@ -84,4 +84,4 @@
     "publishConfig": {
         "access": "public"
     }
-}
+}
\ No newline at end of file
diff --git a/project-specs.md b/project-specs.md
index 7142c24..b4b41e7 100644
--- a/project-specs.md
+++ b/project-specs.md
@@ -38,15 +38,24 @@ typescript-lib-starter-tiny => https://github.com/tmueller/typescript-lib-starte
   `oxfmtrc`, `oxlintrc`, `sortpackagerc`, `EDITMSG`, `typescriptteam`,
   `gitmoji`, `dbaeumer`, `msvc`) and a few library names (`tslib`,
   `typefest`, `lefthook`).
-- **Lefthook**: Pre-commit checks (run in parallel, lefthook v2 schema):
-    - `min_version: 2.0.0`
-    - `pre-commit.commands.oxlint` — `npx oxlint {staged_files}` on
-      staged `*.{ts,tsx,js,jsx,mjs,cjs}` files
-    - `pre-commit.commands.oxfmt` — `npx oxfmt --check {staged_files}`
-      on staged `*.{ts,tsx,js,jsx,mjs,cjs}` files
-    - `pre-commit.commands.cspell` — `npx cspell {staged_files}`
-    - `pre-commit.commands.sort-package-json` — `npx sort-package-json --check`
-    - `pre-commit.commands.typecheck` — `npx tsc --noEmit`
+- **Lefthook**: Pre-commit checks (run in parallel, lefthook v2 schema).
+  Single source of truth for the underlying commands is in
+  `package.json#scripts`; the lefthook config only describes *what to
+  run on which files*. Hooks that should run on staged files
+  (`oxlint`, `oxfmt`, `cspell`) set the `LEFTHOOK_FILES` env var to
+  the staged-files list via a `sh -c` wrapper, and the npm script
+  uses `${LEFTHOOK_FILES:-<default>}` to default to the full project
+  when invoked manually:
+    - `pre-commit.commands.oxlint` (glob `*.{ts,tsx,js,jsx,mjs,cjs}`):
+      `sh -c 'LEFTHOOK_FILES="$0" npm run check:oxlint' {staged_files}`
+    - `pre-commit.commands.oxfmt` (glob `*.{ts,tsx,js,jsx,mjs,cjs}`):
+      `sh -c 'LEFTHOOK_FILES="$0" npm run check:oxfmt' {staged_files}`
+    - `pre-commit.commands.cspell`:
+      `sh -c 'LEFTHOOK_FILES="$0" npm run check:cspell' {staged_files}`
+    - `pre-commit.commands.sort-package-json`:
+      `npm run check:package` (no file args needed)
+    - `pre-commit.commands.typecheck`:
+      `npm run check:tsc` (no file args needed)
   `outdated` is intentionally NOT a pre-commit check (it can flag
   upstream patch releases that aren't actionable locally); it runs in
   CI and via the explicit `lefthook run outdated` command.
@@ -163,10 +172,18 @@ typescript-lib-starter-tiny => https://github.com/tmueller/typescript-lib-starte
 
 - `check`: Run all checks in order — `check:oxlint`, `check:oxfmt`,
   `check:tsc`, `check:cspell`, `check:package`, `check:outdated`.
-- `check:oxlint`: `oxlint src`.
-- `check:oxfmt`: `oxfmt --check src`.
+- `check:oxlint`: `oxlint ${LEFTHOOK_FILES:-src}` — lints `src/`
+  by default; when invoked from the lefthook pre-commit hook with
+  `LEFTHOOK_FILES` set to the staged-files list, lints only those
+  files. This is the single source of truth for the oxlint command
+  and is shared between the manual `npm run check` and the pre-commit
+  hook.
+- `check:oxfmt`: `oxfmt --check ${LEFTHOOK_FILES:-src}` — same
+  pattern as `check:oxlint` (whole `src/` by default, staged files
+  from lefthook).
 - `check:tsc`: `tsc --noEmit`.
-- `check:cspell`: `cspell .`.
+- `check:cspell`: `cspell lint ${LEFTHOOK_FILES:-.}` — walks the
+  project root by default; from lefthook, only the staged files.
 - `check:package`: `sort-package-json --check`.
 - `check:outdated`: `check-outdated --ignore-pre-releases --ignore-packages @oxfmt/binding-*,@oxlint/binding-*`. The oxc native bindings are declared as `optionalDependencies` so the correct one is selected per platform automatically; the `*`-platform bindings show as "not installed" on the current platform and are explicitly ignored here.