fix(test/delegation): add CanCommunicate mock expectations

executeDelegation(sourceID, targetID) fires proxyA2ARequest which calls
registry.CanCommunicate(sourceID, targetID) when source != target. Both
IDs are different test fixtures (ws-source-159, ws-target-159), so the
lookup fires two separate getWorkspaceRef queries:

  SELECT id, parent_id FROM workspaces WHERE id = $1  -- sourceID
  SELECT id, parent_id FROM workspaces WHERE id = $1  -- targetID

expectExecuteDelegationBase only mocked the URL/status fallback query.
sqlmock would fail with "unexpected query" when the CanCommunicate
lookups fired — this was a silent failure because the tests never
verified ExpectationWereMet on the CanCommunicate path.

Fix: add two ExpectQuery rows for both parent_id lookups (both NULL,
root-level siblings, allowed).

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/handlers/delegation_test.go

@@ -983,7 +983,16 @@ func expectExecuteDelegationBase(mock sqlmock.Sqlmock) {
 		WithArgs("dispatched", "", testSourceID, testDelegationID).
 		WillReturnResult(sqlmock.NewResult(0, 1))
 
-	// CanCommunicate (source=target self-call is always allowed — no DB lookup needed)
+	// CanCommunicate: source != target → fires two getWorkspaceRef lookups.
+	// Both test fixtures have parent_id = NULL (root-level siblings) → allowed.
+	// Order matches call order: source first, then target.
+	mock.ExpectQuery("SELECT id, parent_id FROM workspaces WHERE id").
+		WithArgs(testSourceID).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id"}).AddRow(testSourceID, nil))
+	mock.ExpectQuery("SELECT id, parent_id FROM workspaces WHERE id").
+		WithArgs(testTargetID).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "parent_id"}).AddRow(testTargetID, nil))
+
 	// resolveAgentURL: reads ws:{id}:url from Redis, falls back to DB for target
 	mock.ExpectQuery("SELECT url, status FROM workspaces WHERE id = ").
 		WithArgs(testTargetID).