chore: lint only staged files in the pre-commit hook

AGENTS.md

@@ -334,7 +334,7 @@ Prettier: single quotes, trailing commas, 100-char width (120 for Markdown) —
 ### Git hooks
 
 - `.husky/commit-msg` → `commitlint --edit` (Conventional Commits enforced)
-- `.husky/pre-commit` → `dotgit/hooks/pre-commit-format.sh && dotgit/hooks/pre-commit-reject-binaries.py`
+- `.husky/pre-commit` → `dotgit/hooks/pre-commit-format.sh && dotgit/hooks/pre-commit-reject-binaries.py` (the format hook checks only the staged files with Prettier and ESLint, plus the SDK validators when `package/` is staged; CI runs the full `yarn lint`)
 - Root `postinstall` runs `husky`
 
 ### Commits

dotgit/hooks/pre-commit-format.sh

@@ -1,10 +1,61 @@
 #!/usr/bin/env bash
 
-set -e
+# Lints only the staged files, so a commit takes seconds instead of a full-repo `yarn lint`.
+# CI (check-pr.yml) still runs the full `yarn lint`.
 
-if ! yarn lint; then
-    yarn lint-fix
-    echo "some files were not formatted correctly (prettier/eslint) commit aborted!"
-    echo "your changes are still staged, you can accept formatting changes with git add or ignore them by adding --no-verify to git commit"
-    exit 1
+set -euo pipefail
+
+ROOT_DIR="$(git rev-parse --show-toplevel)"
+cd "$ROOT_DIR"
+
+PRETTIER="node_modules/.bin/prettier"
+ESLINT="node_modules/.bin/eslint"
+
+# Staged files that still exist (added, copied, modified, renamed). Bash 3.2 has no mapfile.
+staged=()
+while IFS= read -r -d '' file; do
+  staged+=("$file")
+done < <(git diff --cached --name-only --diff-filter=ACMR -z)
+
+if [ "${#staged[@]}" -eq 0 ]; then
+  exit 0
+fi
+
+lintable=()
+touches_package=false
+for file in "${staged[@]}"; do
+  case "$file" in
+    *.js | *.jsx | *.ts | *.tsx | *.mjs | *.cjs) lintable+=("$file") ;;
+  esac
+  case "$file" in
+    package/*) touches_package=true ;;
+  esac
+done
+
+run_checks() {
+  # --ignore-unknown: skip files Prettier has no parser for. .prettierignore still applies.
+  "$PRETTIER" --list-different --ignore-unknown "${staged[@]}" || return 1
+
+  if [ "${#lintable[@]}" -gt 0 ]; then
+    # --no-warn-ignored: files excluded by the ESLint config would otherwise count as warnings.
+    "$ESLINT" --max-warnings 0 --no-warn-ignored --cache --cache-location node_modules/.cache/eslint/ \
+      "${lintable[@]}" || return 1
+  fi
+
+  # Both validators only read the SDK package, and take about a second each.
+  if [ "$touches_package" = true ]; then
+    yarn workspace stream-chat-react-native-core validate-translations || return 1
+    yarn workspace stream-chat-react-native-core validate-entry-isolation || return 1
+  fi
+}
+
+if ! run_checks; then
+  "$PRETTIER" --write --ignore-unknown "${staged[@]}" >/dev/null || true
+  if [ "${#lintable[@]}" -gt 0 ]; then
+    "$ESLINT" --fix --no-warn-ignored --cache --cache-location node_modules/.cache/eslint/ \
+      "${lintable[@]}" >/dev/null || true
+  fi
+  echo "some files were not formatted correctly (prettier/eslint) commit aborted!"
+  echo "your changes are still staged, you can accept formatting changes with git add or ignore them by adding --no-verify to git commit"
+  exit 1
 fi

dotgit/hooks/pre-commit-reject-binaries.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import os
 import subprocess
 import sys