ci-mirror: split into ci-venv / ci-precommit / ci-pytest, pytest under xdist

The single ci-mirror manual hook took ~100 s (pre-commit --all-files plus a
serial clean-venv pytest, ~85 s), past the 60 s per-action cap. ci_mirror.sh
now takes a subcommand (venv|precommit|pytest|all; default all = the old
one-shot behaviour) and each step is its own manual hook, ordered so the
venv rebuild runs first in its own call. The clean-venv pytest runs
-n auto --dist worksteal; branch coverage stays at 100% (pytest-cov merges
the workers).

Measured (timeout 58): ci-venv 27.0 s cold / 0.1 s warm, ci-precommit
32.6 s, ci-pytest 12.6 s, flutter-test-coverage 46.5 s, web-coverage 1.7 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PAhbNszs5JKdtnD4uBi3xp

.pre-commit-config.yaml

@@ -179,9 +179,28 @@ repos:
 
   - repo: local
     hooks:
-      - id: ci-mirror
-        name: CI mirror (clean-venv pytest + pre-commit --all-files)
-        entry: bash scripts/ci_mirror.sh
+      # The CI mirror, one step per hook so each call stays under the 60 s
+      # action cap. Order matters: ci-venv (re)builds .ci-mirror-venv from
+      # requirements.txt when it changed, so ci-pytest only reuses it.
+      - id: ci-venv
+        name: CI mirror (clean requirements.txt venv)
+        entry: bash scripts/ci_mirror.sh venv
+        language: system
+        pass_filenames: false
+        always_run: true
+        require_serial: true
+        stages: [manual]
+      - id: ci-precommit
+        name: CI mirror (pre-commit --all-files)
+        entry: bash scripts/ci_mirror.sh precommit
+        language: system
+        pass_filenames: false
+        always_run: true
+        require_serial: true
+        stages: [manual]
+      - id: ci-pytest
+        name: CI mirror (clean-venv pytest, xdist)
+        entry: bash scripts/ci_mirror.sh pytest
         language: system
         pass_filenames: false
         always_run: true

scripts/ci_mirror.sh

@@ -18,6 +18,12 @@
 # Runs on demand (`scripts/check_gate_stamp.sh full`, pre-commit's manual
 # stage) and in CI. It left the pre-push path on 2026-09-20: 10+ minutes
 # per push under the resource cap, for work finish_auto.sh had just done.
+#
+# Usage: ci_mirror.sh [venv|precommit|pytest|all] [pytest args...]
+#   Each step is its own manual hook (ci-venv, ci-precommit, ci-pytest) so no
+#   single call outlives the 60 s action cap; `all` (the default) is the old
+#   one-shot behaviour. pytest runs under xdist (-n auto --dist worksteal):
+#   serial it was ~85 s, and pytest-cov merges the workers' coverage.
 # ============================================================================
 
 set -euo pipefail
@@ -80,15 +86,32 @@ run_precommit_all_files() {
 
 run_pytest_clean_venv() {
     log "pytest in the clean venv (mirrors the Tests workflow)"
-    "$VENV_DIR/bin/python" -m pytest "$@" || fail "pytest (clean requirements.txt venv)"
+    "$VENV_DIR/bin/python" -m pytest -n auto --dist worksteal "$@" \
+        || fail "pytest (clean requirements.txt venv)"
 }
 
 main() {
+    local mode="all"
+    case "${1:-}" in
+        venv | precommit | pytest | all) mode="$1"; shift ;;
+        *) ;;
+    esac
+
+    case "$mode" in
+        precommit) run_precommit_all_files; return ;;
+        *) ;;
+    esac
     require_file
     ensure_venv
-    run_precommit_all_files
-    run_pytest_clean_venv "$@"
-    log "all CI gates passed locally — safe to push"
+    case "$mode" in
+        venv) ;;
+        pytest) run_pytest_clean_venv "$@" ;;
+        *)
+            run_precommit_all_files
+            run_pytest_clean_venv "$@"
+            log "all CI gates passed locally — safe to push"
+            ;;
+    esac
 }
 
 main "$@"