feat: add workflow dry-run observability

services/orchestrator/shadow-observer.test.mjs

@@ -72,6 +72,7 @@ test('shadow boundary returns an auditable dry-run plan without calling LangGrap
     runId: 'run-dry-1',
     requestId: 'request-dry-1',
     userId: 'user-1',
+    taskType: 'repo_refactor',
   });
   assert.equal(result.observed, false);
   assert.deepEqual(result.executionPlan, {
@@ -83,12 +84,49 @@ test('shadow boundary returns an auditable dry-run plan without calling LangGrap
     candidateReason: 'user_allowlist',
     configVersion: 8,
     bucket: 42,
+    taskType: 'repo_refactor',
     dryRun: true,
     handoffAllowed: false,
   });
   assert.equal(fetchCalls, 0);
 });
 
+test('shadow boundary records non-selected canary decisions for a complete rate denominator', async () => {
+  const observer = createWorkflowShadowObserver({
+    configService: {
+      async selectEngine() {
+        return {
+          engine: 'native',
+          candidateEngine: 'native',
+          shadowEngine: null,
+          fallbackEngine: 'native',
+          reason: 'canary_not_selected',
+          candidateReason: null,
+          mode: 'canary',
+          configVersion: 9,
+          bucket: 88,
+          dryRun: false,
+        };
+      },
+      async getRuntimeState() {
+        throw new Error('must not load runtime config');
+      },
+    },
+  });
+
+  const result = await observer({
+    runId: 'run-native-1',
+    requestId: 'request-native-1',
+    userId: 'user-1',
+    taskType: 'code_analysis',
+  });
+  assert.equal(result.observed, false);
+  assert.equal(result.executionPlan.dryRun, true);
+  assert.equal(result.executionPlan.candidateEngine, 'native');
+  assert.equal(result.executionPlan.reason, 'canary_not_selected');
+  assert.equal(result.executionPlan.taskType, 'code_analysis');
+});
+
 test('shadow observer sends a bounded observe-only RunSpec to LangGraph service', async () => {
   let capturedUrl = null;
   let capturedInit = null;