test(kanban): pin the review handoff of a card assigned to its own reviewer

The suite already covers the shape where assignee != reviewer
(test_review_handoff_without_live_run_attributes_run_to_implementer). The
mirror case -- a card created already assigned to its reviewer -- was the gap.

Asserts the honest provenance (no implementer, NULL run profile) and, more to
the point, that request_changes refuses instead of routing the rejection back
to the reviewer. Fails on the parent commit with implementer='reviewer-a'.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/hermes_cli/test_kanban_review_lifecycle.py

@@ -923,6 +923,37 @@ def test_review_handoff_without_live_run_attributes_run_to_implementer(kanban_ho
         assert _events(conn, tid, kind="review_requested")[0][1]["implementer"] == "worker"
 
 
+def test_review_handoff_of_card_assigned_to_its_reviewer_records_no_implementer(
+    kanban_home: Path,
+) -> None:
+    """A card created already assigned to its reviewer has no implementer to
+    record. Stamping the assignee made the payload read
+    ``implementer == reviewer``, and ``request_changes`` routes on that field —
+    so a rejection went back to the profile that wrote the findings. With no
+    live run and nothing but the reviewer on the row, the honest provenance is
+    *none*, and the rejection must refuse rather than misroute."""
+    with kbc.connect() as conn:
+        tid = kb.create_task(conn, title="already applied", assignee="reviewer-a")
+        assert kb.request_review(
+            conn, tid, summary="review this", reviewer="reviewer-a",
+        ) is True
+
+        ev = _events(conn, tid, kind="review_requested")[0][1]
+        assert ev["reviewer"] == "reviewer-a"
+        assert ev["implementer"] is None
+        run = conn.execute(
+            "SELECT profile, outcome FROM task_runs WHERE task_id = ? "
+            "ORDER BY id DESC LIMIT 1", (tid,),
+        ).fetchone()
+        assert (run["outcome"], run["profile"]) == ("review_requested", None)
+
+        claimed = kb.claim_review_task(conn, tid, claimer="reviewer-a")
+        assert claimed is not None
+        ok, reason = kb.request_changes(conn, tid, reason="found 3 issues")
+        assert ok is False
+        assert "implementer provenance" in (reason or "")
+
+
 def test_synthesized_run_for_unassigned_card_keeps_null_profile(kanban_home: Path) -> None:
     """A transition that does not name an actor still reads the card: an
     unassigned card's synthesized run carries ``profile=NULL`` (the actor