Finish STATE-WP-0069: retire legacy completion event and DELETE /workstreams

Stop dual-publishing org.statehub.workstream.completed; return 410 Gone for
legacy DELETE /workstreams/{id}. Migrate fix-consistency, MCP adhoc bootstrap,
and dashboard token summary to /workplans/. Add legacy-meter evidence capture
script and pytest snapshot; update docs and close out the workplan.

tests/test_legacy_meter.py

@@ -1,5 +1,10 @@
 from __future__ import annotations
 
+import json
+import os
+from datetime import datetime, timezone
+from pathlib import Path
+
 
 async def _create_domain(client, slug="legacy-domain", name="Legacy Domain"):
     r = await client.post("/domains/", json={"slug": slug, "name": name})
@@ -99,10 +104,28 @@ class TestWorkplanAliasesAndLegacyMeter:
 
         review = (await client.get("/legacy-meter/weekly-review")).json()
         assert review["activity_core_handoff"]["scheduler_owner"] == "activity-core"
+        assert review["activity_core_handoff"]["source_endpoint"] == "/legacy-meter/weekly-review"
+        assert "window_start" in review
+        assert "window_end" in review
+        assert isinstance(review["interfaces"], list)
+        assert isinstance(review["retirement_candidates"], list)
         candidates = _summary_by_key({"interfaces": review["retirement_candidates"]})
         assert "rest_api:GET /obsolete" in candidates
         assert candidates["rest_api:GET /obsolete"]["retirement_reason"] == "no measured usage in review window"
 
+        if os.environ.get("CAPTURE_LEGACY_METER_EVIDENCE"):
+            evidence_dir = Path(__file__).resolve().parents[1] / "docs" / "evidence"
+            evidence_dir.mkdir(parents=True, exist_ok=True)
+            today = datetime.now(tz=timezone.utc).strftime("%Y%m%d")
+            out = evidence_dir / f"legacy-meter-weekly-review-{today}.json"
+            payload = {
+                "captured_at": datetime.now(tz=timezone.utc).isoformat(),
+                "source": "pytest",
+                "workplan": "STATE-WP-0069",
+                "weekly_review": review,
+            }
+            out.write_text(json.dumps(payload, indent=2) + "\n", encoding="utf-8")
+
     async def test_recent_usage_blocks_weekly_retirement_candidate(self, client):
         r = await client.post("/legacy-meter/usage", json={
             "interface_key": "rest_api:GET /old-but-used",
@@ -122,7 +145,7 @@ class TestWorkplanAliasesAndLegacyMeter:
         assert item["retirement_candidate"] is False
         assert item["retirement_reason"] == "1 call(s) in review window"
 
-    async def test_legacy_completion_event_is_metered_and_workplan_event_is_preferred(self, client):
+    async def test_workplan_finish_does_not_meter_legacy_completion_event(self, client):
         await _create_domain(client)
         topic = await _create_topic(client)
         wp = await _create_workplan(client, topic["id"])
@@ -140,9 +163,26 @@ class TestWorkplanAliasesAndLegacyMeter:
         assert items["rest_api:PATCH /workstreams/{workstream_id}"]["window"]["components"] == {
             "old-client": 1
         }
-        event = items["event_subject:org.statehub.workstream.completed"]
-        assert event["interface"]["replacement_ref"] == "org.statehub.workplan.completed"
-        assert event["window"]["components"] == {"state-hub.events": 1}
+        assert items.get("event_subject:org.statehub.workstream.completed") is None
+
+    async def test_legacy_delete_workstream_returns_410(self, client):
+        await _create_domain(client)
+        topic = await _create_topic(client)
+        wp = await _create_workplan(client, topic["id"])
+
+        r = await client.delete(
+            f"/workstreams/{wp['id']}",
+            headers={"X-StateHub-Component": "old-archiver"},
+        )
+        assert r.status_code == 410
+        assert "retired" in r.json()["detail"]
+        assert r.headers["Deprecation"] == "true"
+        assert r.headers["X-StateHub-Replacement"] == "DELETE /workplans/{workplan_id}"
+
+        summary = (await client.get("/legacy-meter/summary")).json()
+        item = _summary_by_key(summary)["rest_api:DELETE /workstreams/{workstream_id}"]
+        assert item["window"]["calls"] == 1
+        assert item["window"]["components"] == {"old-archiver": 1}
 
     async def test_legacy_workstream_id_query_param_on_tasks_is_metered(self, client):
         await _create_domain(client)