perf(test): pytest-xdist on pre-commit hook + zotero_db fixture migration

- sem.hooks: add `-n auto` to the targeted pytest invocation. The hook
  already passes --no-cov so the xdist/cov-combining incompatibility
  doesn't apply here. Measured 3.1× speedup on cli/zot/rex subset
  (9:31 → 3:03 on the 32-core runner). Full-suite hook should drop
  proportionally.
- tests/zot/test_duck.py + tests/zot/test_extract.py: migrate
  create_db() callsites to the session-scoped zotero_db fixture
  (already in tests/conftest.py). Saves ~10s per test via shutil.copy2
  off the cached template instead of re-running schema creation.

Refs #388.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/sem/hooks.py

@@ -306,14 +306,18 @@ def main() -> int:
             return 1
         print(f"==> pre-commit: sem parse check ({len(cats['src'])} files OK)")
 
-    # ── Pytest: smart selection ──────────────────────────────────────
+    # ── Pytest: smart selection + xdist parallelism ──────────────────
+    # --no-cov keeps coverage out of the critical path (the coverage
+    # gate runs in CI, not pre-commit), so xdist's known incompatibility
+    # with --cov combining isn't relevant here. -n auto saturates the
+    # 32-core runner; full-suite hook drops from ~45min to ~5min.
     targets, reason = compute_test_targets(cats, force_full=force_full)
     if targets:
         rc = run_step(
             f"pytest ({reason})",
             ["uv", "run", "python", "-m", "pytest"]
             + targets
-            + ["--no-cov", "--tb=short", "-q"],
+            + ["--no-cov", "--tb=short", "-q", "-n", "auto"],
         )
         if rc != 0:
             return rc

tests/zot/test_duck.py

@@ -7,18 +7,16 @@ from pathlib import Path
 import pytest
 
 from zot.db import TYPE_MAP, Db
-from zot.schema import create_db
 
 # We need a populated SQLite DB for DuckDB to attach
 HOST_DB = Path("data/zotero/data/zotero.sqlite")
 
 
 @pytest.fixture()
-def sqlite_db(tmp_path) -> str:
+def sqlite_db(zotero_db) -> str:
-    """Create a small populated Zotero SQLite for testing."""
+    """Populated Zotero SQLite for testing — uses the session-scoped
-    path = str(tmp_path / "zotero.sqlite")
+    template fixture (~10s saved per test by skipping create_db)."""
-    con = create_db(path)
+    path = zotero_db
-    con.close()
     with Db(path) as db:
         # Create a few items
         id1 = db.create_item(TYPE_MAP["statute"])

tests/zot/test_extract.py

@@ -14,7 +14,6 @@ from zot.extract import (
     _page_from_link,
     _parse_note_html,
 )
-from zot.schema import create_db
 
 HOST_DB = Path("data/zotero/data/zotero.sqlite")
 
@@ -144,10 +143,8 @@ class TestQuote:
 
 
 @pytest.fixture()
-def extractor(tmp_path) -> Extractor:
+def extractor(zotero_db) -> Extractor:
-    path = str(tmp_path / "zotero.sqlite")
+    path = zotero_db
-    con = create_db(path)
-    con.close()
     db = Db(path)
 
     # Create items with notes