From 11d35910fd3b14da1a800fb1ae8828aeb079884f Mon Sep 17 00:00:00 2001
From: npeter83 <npeter83+claude@gmail.com>
Date: Sun, 4 Oct 2026 20:09:58 +0200
Subject: [PATCH] =?UTF-8?q?feat(tooling):=20lint-changed.sh=20=E2=80=94=20?=
 =?UTF-8?q?fast=20lint=20lanes=20on=20the=20uncommitted=20files,=20usable?=
 =?UTF-8?q?=20as=20a=20Stop=20hook?=
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---
 scripts/lint-changed.sh | 54 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 scripts/lint-changed.sh

diff --git a/scripts/lint-changed.sh b/scripts/lint-changed.sh
new file mode 100644
index 00000000..f4feb716
--- /dev/null
+++ b/scripts/lint-changed.sh
@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# The fast lint lanes on the uncommitted files only — ruff (check + format) on Python, eslint +
+# prettier on the frontend — for a check after every edit instead of a full gate run. It is a
+# convenience, never the gate: scripts/check.sh stays what a merge or a release requires.
+#
+#   bash scripts/lint-changed.sh          lint what `git status` shows as changed or new
+#   bash scripts/lint-changed.sh --hook   the same, as a Claude Code Stop hook: silent and exit 0 when
+#                                         clean; otherwise the findings on stderr and exit 2, which
+#                                         hands them back to the agent before it ends its turn
+#
+# Measured 2026-10-04: one cold eslint run (type-aware) takes 3.4–4.7 s, so this runs once per turn
+# (Stop), not after every edit — a warm daemon (eslint_d) would add a dependency and a stray process.
+set -u
+cd "$(dirname "$0")/.." || exit 2
+hook=0
+[ "${1:-}" = --hook ] && hook=1
+
+if [ "$hook" = 1 ]; then
+  # A Stop hook that blocked once is told so on the next stop; let that one through, or an unfixable
+  # finding would keep the agent in a loop.
+  grep -q '"stop_hook_active": *true' && exit 0
+fi
+
+mapfile -t changed < <(git status --porcelain --untracked-files=all | sed -E 's/^.. //; s/.* -> //' |
+  while read -r f; do [ -f "$f" ] && printf '%s\n' "$f"; done)
+py=() fe=()
+for f in "${changed[@]}"; do
+  case "$f" in
+    backend/*.py | scripts/*.py) py+=("$f") ;;
+    frontend/*.ts | frontend/*.tsx | frontend/*.js | frontend/*.mjs) fe+=("${f#frontend/}") ;;
+  esac
+done
+
+report="$(
+  if [ ${#py[@]} -gt 0 ]; then
+    python -m ruff check --quiet --config backend/ruff.toml "${py[@]}" 2>&1
+    python -m ruff format --check --quiet --config backend/ruff.toml "${py[@]}" 2>&1
+  fi
+  if [ ${#fe[@]} -gt 0 ]; then
+    (cd frontend && npx eslint --max-warnings 0 "${fe[@]}" 2>&1)
+    (cd frontend && npx prettier --check --log-level warn "${fe[@]}" 2>&1)
+  fi
+)"
+
+if [ -z "$report" ]; then
+  [ "$hook" = 1 ] || echo "lint-changed: clean (${#py[@]} py, ${#fe[@]} frontend)"
+  exit 0
+fi
+if [ "$hook" = 1 ]; then
+  printf 'lint-changed found problems in the uncommitted files:\n%s\n' "$report" >&2
+  exit 2
+fi
+printf '%s\n' "$report"
+exit 1