fix: exclude foreign-claimed work from allocation instead of blockading the queue (Closes #765)

Recovered preserved candidate d06198b onto current master 0c2f45a via clean
cherry-pick. Active foreign leases are excluded before allocator ranking;
controller_instance_id ownership is persisted; dashboard matches allocator
exclusion. Stable patch-id bacafc5f… preserved.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

gitea_mcp_server.py

@@ -19211,6 +19211,7 @@ def gitea_allocate_next_work(
         apply=bool(apply),
         profile_name=profile_name,
         username=username,
+        controller_instance_id=allocator_service.resolve_controller_instance_id(),
     )
     if inv_reasons:
         result.setdefault("inventory_warnings", inv_reasons)
@@ -19378,6 +19379,7 @@ def gitea_workflow_dashboard(
     leases: list[dict] = []
     terminal_pr: int | None = None
     terminal_lock: dict | None = None
+    claims: dict = {}
     db, db_errs = _control_plane_db_or_error()
     if db is None:
         inv_reasons.extend(db_errs or ["control-plane DB unavailable"])
@@ -19416,6 +19418,18 @@ def gitea_workflow_dashboard(
             inv_reasons.append(
                 f"terminal lock lookup failed: {_redact(str(exc))}"
             )
+        try:
+            # #765: live claims so the dashboard never advertises another
+            # controller's active task as safe next work.
+            claims = db.list_active_claims(
+                remote=remote if remote in REMOTES else remote,
+                org=o,
+                repo=r,
+            )
+        except Exception as exc:  # noqa: BLE001
+            inv_reasons.append(
+                f"active claim lookup failed: {_redact(str(exc))}"
+            )
 
     snap = workflow_dashboard.build_workflow_dashboard(
         candidates=candidates,
@@ -19427,6 +19441,8 @@ def gitea_workflow_dashboard(
         terminal_lock=terminal_lock,
         inventory_complete=inventory_complete,
         inventory_reasons=inv_reasons,
+        claims=claims,
+        controller_instance_id=allocator_service.resolve_controller_instance_id(),
     )
     payload = snap.as_dict()
     payload["inventory_source"] = (