feat(legacy-meter): meter MCP aliases and fix brief workstream_id label (STATE-WP-0070 T03/T04)

T03: MCP alias retirement gate was unstartable — deprecation notices existed
but no mcp:* interfaces were ever registered or metered. Add
_meter_legacy_mcp() posting /legacy-meter/usage (kind mcp_tool, component
state-hub.mcp) from create_workstream, list_workstreams, update_workstream,
update_workstream_status, and state://workstreams/{topic_slug}; register all
five phase-3 backlog keys so zero-window streaks accrue from today.

T04: trace residual POST /progress/ workstream_id (3 calls/8h, unknown) to
.custodian-brief.md labelling workplans "workstream_id:"; brief generator now
prints "workplan_id:". Briefs refresh on each repo's next fix-consistency run.

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

docs/workplan-terminology-legacy-retirement-backlog.md

@@ -57,6 +57,10 @@ Risk order: REST > MCP > events > dashboard prose > internal identifiers.
 | 3 | `mcp:update_workstream_status` | `update_workplan_status` | MCP | T03 |
 | 3 | `mcp:list_workstreams` | `list_workplans` | MCP | T03 |
 | 3 | `state://workstreams/{topic_slug}` | `state://workplans/{topic_slug}` (proposed) | MCP resource | T03 |
+
+Phase-3 MCP keys metered + registered 2026-07-10 (STATE-WP-0070 T03):
+`_meter_legacy_mcp()` records usage from the alias tools/resource; zero-window
+streaks accrue from registration.
 | 4 | ~~`event_subject:org.statehub.workstream.completed`~~ **retired** | `org.statehub.workplan.completed` | Event | T05 ✓ |
 | 5 | Dashboard nav label `Workstreams` | `Workplans` (URL compat retained) | Prose | T02 |
 | 5 | `dashboard/src/index.md` user-facing copy | workplan-first strings | Prose | T02 |

mcp_server/server.py

@@ -219,6 +219,38 @@ def _legacy_mcp_deprecation(*, tool: str | None = None, resource: str | None = N
     raise ValueError("tool or resource required")
 
 
+def _meter_legacy_mcp(*, tool: str | None = None, resource: str | None = None) -> None:
+    """Record legacy MCP alias usage on the legacy meter (best-effort).
+
+    Keys match docs/workplan-terminology-legacy-retirement-backlog.md phase 3
+    (`mcp:<tool_name>` / resource URI). Failures never surface to the caller —
+    the meter gates retirement, it must not break the aliased call itself.
+    """
+    if tool:
+        key = f"mcp:{tool}"
+        replacement = _LEGACY_MCP_TOOL_REPLACEMENTS[tool]
+    elif resource:
+        key = resource
+        replacement = _LEGACY_MCP_RESOURCE_REPLACEMENTS[resource]
+    else:
+        raise ValueError("tool or resource required")
+    try:
+        with _client() as c:
+            c.post(
+                "/legacy-meter/usage",
+                json={
+                    "interface_key": key,
+                    "interface_kind": "mcp_tool",
+                    "replacement_ref": replacement,
+                    "owner_component": "state-hub.mcp",
+                    "replacement_verified": True,
+                    "component_key": "state-hub.mcp",
+                },
+            )
+    except Exception:
+        pass
+
+
 def _attach_legacy_deprecation(tool_name: str, result_json: str) -> str:
     if tool_name not in _LEGACY_MCP_TOOL_REPLACEMENTS:
         return result_json
@@ -272,6 +304,7 @@ def resource_workplans(topic_slug: str) -> str:
 @mcp.resource("state://workstreams/{topic_slug}")
 def resource_workstreams(topic_slug: str) -> str:
     """Legacy resource alias — prefer state://workplans/{topic_slug}."""
+    _meter_legacy_mcp(resource="state://workstreams/{topic_slug}")
     topics = _get("/topics", {"status": "active"})
     match = next((t for t in topics if t["slug"] == topic_slug), None)
     if not match:
@@ -802,6 +835,7 @@ def create_workstream(
     planning_order: int | None = None,
 ) -> str:
     """DEPRECATED legacy alias — use create_workplan(repo_id=...) instead."""
+    _meter_legacy_mcp(tool="create_workstream")
     if not repo_id:
         return _json_result(_mcp_error("create_workstream", "repo_id is required"))
     return _create_workplan_impl(
@@ -1219,6 +1253,7 @@ def list_workstreams(
     slug: str | None = None,
 ) -> str:
     """DEPRECATED legacy alias — use list_workplans instead."""
+    _meter_legacy_mcp(tool="list_workstreams")
     return _attach_legacy_deprecation(
         "list_workstreams",
         list_workplans(
@@ -1249,6 +1284,7 @@ def update_workstream_status(
     workstream_id: str | None = None,
 ) -> str:
     """DEPRECATED legacy alias — use update_workplan_status instead."""
+    _meter_legacy_mcp(tool="update_workstream_status")
     parent_id = workplan_id or workstream_id
     if not parent_id:
         return _json_result(_mcp_error("update_workstream_status", "workplan_id is required"))
@@ -1289,6 +1325,7 @@ def update_workstream(
     status: str | None = None,
 ) -> str:
     """DEPRECATED legacy alias — use update_workplan instead."""
+    _meter_legacy_mcp(tool="update_workstream")
     parent_id = workplan_id or workstream_id
     if not parent_id:
         return _json_result(_mcp_error("update_workstream", "workplan_id is required"))

scripts/consistency_check.py

@@ -2099,7 +2099,7 @@ def _write_custodian_brief(api_base: str, repo_slug: str, repo_path: str) -> boo
             lines += [
                 "",
                 f"### {ws_title}",
-                f"Progress: {pct} done  |  workstream_id: `{ws_id}`",
+                f"Progress: {pct} done  |  workplan_id: `{ws_id}`",
             ]
 
             if open_tasks:

workplans/STATE-WP-0070-workplan-terminology-phase2-retirement.md

@@ -110,6 +110,15 @@ Remove `create_workstream`, `update_workstream`, `list_workstreams`,
 `update_workstream_status`, and `state://workstreams/{topic_slug}` when MCP
 procedure keys hit zero usage for seven windows. Keep `TOOLS.md` migration notes.
 
+Progress 2026-07-10: gate was unstartable — MCP alias usage was never metered
+(deprecation notices only, no `mcp:*` interfaces registered). Fixed:
+`_meter_legacy_mcp()` in `mcp_server/server.py` posts `/legacy-meter/usage`
+(kind `mcp_tool`, component `state-hub.mcp`) from all four legacy tools and the
+legacy resource; all five backlog phase-3 keys registered on the meter, so
+zero-window streaks accrue from 2026-07-10. Note: `mcp:list_workstreams` shows
+1 verification call in the 2026-07-10 window — streak counts from the next
+window. Removal remains gated on 7 consecutive zero windows.
+
 ## Task: Internal dual-key and param alias cleanup
 
 ```task
@@ -123,6 +132,13 @@ state_hub_task_id: "18af98bf-c74e-47c8-948a-e713cff88bb8"
 - Remove `workstream_id` query/body aliases on preferred routes.
 - Retire `flows/workstream.yaml` when no callers remain.
 
+Progress 2026-07-10: residual `POST /progress/ workstream_id` (3 calls/8h,
+`unknown`) traced to `.custodian-brief.md` files labelling workplans
+`workstream_id:` — agents copy the field name into session-close curl posts.
+Brief generator fixed (`consistency_check.py` → `workplan_id:`); briefs
+regenerate on each repo's next fix-consistency sweep. Expect this key to decay
+to zero once briefs refresh fleet-wide.
+
 ## Task: Closeout and fleet gate
 
 ```task