diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..11f0848
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,10 @@
+# AGENTS.md
+
+- Assume concurrent human/agent work; never revert or overwrite changes you did not author.
+- This repo processes model data into SQLite; watch query/transform cost, memory churn, and fixture representativeness.
+- Prefer minimal, behavior-proven changes; add regression coverage for bug fixes and use existing fixtures under `tests/fixtures` or `tests/data` when practical.
+- No breadcrumbs after deleting or moving code; remove the old code/comment instead of leaving relocation notes.
+- Use `uv sync --all-groups` for setup. For changed areas, run the narrow relevant check first; before broad handoff use `uv run prek run --show-diff-on-failure --color=always --all-files --hook-stage pre-push` when feasible.
+- Type-check package changes with `uv run ty check --output-format github ./src/plexosdb`.
+- Test package changes with `uv run pytest --cov --cov-report=xml`; benchmark-sensitive changes may need `uv run pytest benchmarks/ -k "not xlarge_300k" --benchmark-only --benchmark-json=benchmark-results.json --no-cov`.
+- Build docs for user/operator-facing documentation changes with `uv run sphinx-build docs/source/ docs/_build/`.
diff --git a/tests/test_plexosdb_copy_object.py b/tests/test_plexosdb_copy_object.py
index 51ccbe8..c2263bf 100644
--- a/tests/test_plexosdb_copy_object.py
+++ b/tests/test_plexosdb_copy_object.py
@@ -60,12 +60,8 @@ def test_copy_object_copies_date_from_and_date_to(db_base: PlexosDB):
         date_to=date_to,
     )
 
-    original_date_from = db.query(
-        "SELECT date FROM t_date_from WHERE data_id = ?", (original_data_id,)
-    )
-    original_date_to = db.query(
-        "SELECT date FROM t_date_to WHERE data_id = ?", (original_data_id,)
-    )
+    original_date_from = db.query("SELECT date FROM t_date_from WHERE data_id = ?", (original_data_id,))
+    original_date_to = db.query("SELECT date FROM t_date_to WHERE data_id = ?", (original_data_id,))
     assert original_date_from == [(date_from.isoformat(),)]
     assert original_date_to == [(date_to.isoformat(),)]
 
@@ -77,12 +73,8 @@ def test_copy_object_copies_date_from_and_date_to(db_base: PlexosDB):
     new_data_id = new_data_ids[0]
     assert new_data_id != original_data_id
 
-    copied_date_from = db.query(
-        "SELECT date FROM t_date_from WHERE data_id = ?", (new_data_id,)
-    )
-    copied_date_to = db.query(
-        "SELECT date FROM t_date_to WHERE data_id = ?", (new_data_id,)
-    )
+    copied_date_from = db.query("SELECT date FROM t_date_from WHERE data_id = ?", (new_data_id,))
+    copied_date_to = db.query("SELECT date FROM t_date_to WHERE data_id = ?", (new_data_id,))
     assert copied_date_from == [(date_from.isoformat(),)]
     assert copied_date_to == [(date_to.isoformat(),)]