fix: bound task identity ambiguity

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a053ff-1d6f-7fe2-ac1c-a6eb40a42a0c

tests/test_forge_projection.py

@@ -218,12 +218,21 @@ class _Row:
 class _FakeSession:
     """Stands in for AsyncSession: enough to prove intent without a database."""
 
-    def __init__(self, repo, rows, foreign=None, slug_clash=None, task_rows=None):
+    def __init__(
+        self,
+        repo,
+        rows,
+        foreign=None,
+        slug_clash=None,
+        task_rows=None,
+        task_collision_rows=None,
+    ):
         self._repo = repo
         self.rows = list(rows)
         self._foreign = list(foreign or [])
         self._slug_clash = list(slug_clash or [])
         self._task_rows = task_rows
+        self._task_collision_rows = list(task_collision_rows or [])
         self.added = []
         self.deleted = []
         self.committed = False
@@ -244,12 +253,14 @@ class _FakeSession:
             payload = rows
         elif update_only and self._calls == 3:
             payload = self._task_rows
+        elif update_only and self._calls == 4:
+            payload = self._task_collision_rows
         elif self._calls == 3:
             payload = self._foreign
         elif self._calls == 4:
             payload = self._slug_clash
         elif self._calls == 5:
-            payload = self._task_rows or []
+            payload = self._task_collision_rows
         else:
             payload = []
 
@@ -1129,3 +1140,124 @@ class TestExistingWorkplanTasks:
             derived=self._derived(("DEMO-WP-0001-T01", "Do it", "todo")),
         )
         assert orphan.status == "todo"
+
+    @pytest.mark.asyncio
+    async def test_duplicate_identity_inside_current_workplan_is_refused(self):
+        row = _Row(slug="demo-wp-0001", status="active", path="workplans/a.md")
+        first = _TaskRow("DEMO-WP-0001-T01", workplan_id=row.id)
+        second = _TaskRow("demo-wp-0001-t01", workplan_id=row.id)
+        session = _FakeSession(repo=_Repo(), rows=[row], task_rows=[first, second])
+        out = await fp.reset_repository_projection(
+            session,
+            "demo",
+            derived=self._derived(("DEMO-WP-0001-T01", "Do it", "todo")),
+        )
+        assert out.status == "refused"
+        assert out.refused[0]["reason"].startswith("current workplan contains duplicate")
+        assert session.added == []
+
+    @pytest.mark.asyncio
+    async def test_derived_task_uuid_held_elsewhere_is_refused_before_insert(self):
+        row = _Row(slug="demo-wp-0001", status="active", path="workplans/a.md")
+        derived = self._derived(("DEMO-WP-0001-T01", "Do it", "todo"))
+        holder = _TaskRow("DEMO-WP-0001-T01", workplan_id=__import__("uuid").uuid4())
+        holder.id = __import__("uuid").UUID(derived.workplans[0].tasks[0].uuid)
+        session = _FakeSession(
+            repo=_Repo(),
+            rows=[row],
+            task_rows=[],
+            task_collision_rows=[holder],
+        )
+        out = await fp.reset_repository_projection(session, "demo", derived=derived)
+        assert out.status == "refused"
+        assert out.refused[0]["reason"].startswith("task identity already belongs")
+        assert session.added == []
+
+    @pytest.mark.asyncio
+    async def test_tasks_on_retired_copy_do_not_block_current_projection(self):
+        from datetime import datetime, timezone
+
+        current = _Row(slug="demo-wp-0001", status="active", path="workplans/a.md")
+        current.id = __import__("uuid").UUID(fp.derived_record_uuid("DEMO-WP-0001"))
+        retired = _Row(
+            slug="demo-wp-0001@retired-20260831",
+            status="finished",
+            path="workplans/a.md",
+        )
+        retired.projection_retired_at = datetime.now(tz=timezone.utc)
+        task = _TaskRow("DEMO-WP-0001-T01", status="todo", workplan_id=current.id)
+        session = _FakeSession(repo=_Repo(), rows=[current, retired], task_rows=[task])
+        out = await fp.reset_repository_projection(
+            session,
+            "demo",
+            derived=self._derived(("DEMO-WP-0001-T01", "Do it", "todo")),
+        )
+        assert out.status in {"applied", "noop"}
+        assert out.refused == []
+
+
+def test_diff_reports_duplicate_current_task_identity_as_ambiguous():
+    derived = TestExistingWorkplanTasks()._derived(
+        ("DEMO-WP-0001-T01", "Do it", "todo")
+    )
+    workplan_id = derived.workplans[0].uuid
+    hub_workplans = [
+        {
+            "id": workplan_id,
+            "slug": "demo-wp-0001",
+            "status": "active",
+            "backing_relative_path": "workplans/a.md",
+        }
+    ]
+    hub_tasks = {
+        workplan_id: [
+            {
+                "id": "11111111-1111-4111-8111-111111111111",
+                "record_id": "DEMO-WP-0001-T01",
+                "title": "a",
+                "status": "todo",
+            },
+            {
+                "id": "22222222-2222-4222-8222-222222222222",
+                "record_id": "demo-wp-0001-t01",
+                "title": "b",
+                "status": "todo",
+            },
+        ]
+    }
+    diff = fp.diff_against_hub(derived, hub_workplans, hub_tasks)
+    assert diff.clean is False
+    assert diff.to_dict()["counts"]["ambiguous"] == 1
+    assert diff.ambiguous[0]["source"] == "hub"
+
+
+@pytest.mark.asyncio
+async def test_reset_refuses_duplicate_task_identity_in_forge_projection():
+    first = TestExistingWorkplanTasks()._derived(
+        ("SHARED-WP-0001-T01", "First", "todo")
+    ).workplans[0]
+    second = fp.DerivedWorkplan(
+        record_id="DEMO-WP-0002",
+        uuid=fp.derived_record_uuid("DEMO-WP-0002"),
+        title="Second",
+        status="active",
+        relative_path="workplans/b.md",
+        archived=False,
+        tasks=[
+            fp.DerivedTask(
+                record_id="SHARED-WP-0001-T01",
+                uuid=fp.derived_record_uuid("SHARED-WP-0001-T01"),
+                title="Second claim",
+                status="todo",
+                priority="medium",
+            )
+        ],
+    )
+    derived = fp.DerivedProjection(
+        repo_slug="demo", commit="c0ffee", workplans=[first, second]
+    )
+    session = _FakeSession(repo=_Repo(), rows=[])
+    out = await fp.reset_repository_projection(session, "demo", derived=derived)
+    assert out.status == "refused"
+    assert any(item.get("source") == "forge" for item in out.refused)
+    assert session.added == []