diff --git a/lib/services/pipeline-steps/notify.test.ts b/lib/services/pipeline-steps/notify.test.ts
new file mode 100644
index 0000000..115b850
--- /dev/null
+++ b/lib/services/pipeline-steps/notify.test.ts
@@ -0,0 +1,103 @@
+/**
+ * notify.ts — route_to_user unit tests
+ *
+ * Critical behavioral assertion (D-12 / ROUTE-05):
+ * When a user has the (event_key, channel_type) toggle DISABLED in
+ * user_event_subscriptions, the notify step must return success:true with
+ * notified:false and MUST NOT contact the global channel or any personal
+ * channel. Grep cannot prove this — only a behavioral test can.
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+// Mock postgresClient BEFORE importing the module under test.
+const queryMock = vi.fn();
+vi.mock('../postgres-client', () => ({
+  postgresClient: {
+    query: (...args: unknown[]) => queryMock(...args),
+  },
+}));
+
+// Mock the resolver registry to short-circuit user resolution.
+vi.mock('./notify-resolvers', () => ({
+  resolveRecipient: vi.fn(async () => ({
+    recipient: { user_id: 'test-user-id' },
+    resolverFound: true,
+  })),
+  RESOLVERS: new Map(),
+  registerResolver: vi.fn(),
+}));
+
+// Mock pipeline-engine to prevent the registerStepExecutor side effect.
+vi.mock('../pipeline-engine', () => ({
+  registerStepExecutor: vi.fn(),
+}));
+
+// Mock global fetch so any stray send call is observable and doesn't hit network.
+const fetchMock = vi.fn(async () => new Response('ok', { status: 200 }));
+vi.stubGlobal('fetch', fetchMock);
+
+// Import AFTER mocks are declared so vi.mock hoisting takes effect.
+import { _INTERNALS } from './notify';
+
+describe('notify.ts route_to_user', () => {
+  beforeEach(() => {
+    queryMock.mockReset();
+    fetchMock.mockReset();
+    fetchMock.mockResolvedValue(new Response('ok', { status: 200 }));
+  });
+
+  it('muted user must not fall back to global channel', async () => {
+    // Arrange: user has the (event_key, channel_type) toggle DISABLED.
+    // Any SQL beyond the user_event_subscriptions check is a failure —
+    // the mute branch must short-circuit before querying notification_channels
+    // or calling fallbackToGlobal.
+    queryMock.mockImplementation((sql: string) => {
+      if (sql.includes('user_event_subscriptions')) {
+        return Promise.resolve({ rows: [{ enabled: false }], rowCount: 1 });
+      }
+      // Any other SQL (notification_channels, "user" lookup, etc.) is unexpected.
+      throw new Error(`Unexpected SQL after mute: ${String(sql).slice(0, 80)}`);
+    });
+
+    const step = {
+      id: 1,
+      step_type: 'notify' as const,
+      name: 'test',
+      config: {
+        channel_id: 99,
+        message: 'hi',
+        route_to_user: {
+          source: 'ticket',
+          field: 'assignedResourceID',
+          resolve: 'pulse_user_id',
+          event_key: 'ticket_assigned_to_me',
+          channel_type: 'ntfy',
+        },
+      },
+    };
+    const context = { ticket: { assignedResourceID: 'test-user-id' } };
+
+    // Act — call dispatchUserRoute directly via the _INTERNALS test seam.
+    const result = await _INTERNALS.dispatchUserRoute({
+      step: step as any,
+      context,
+      message: 'hi',
+      channelId: 99,
+      route: step.config.route_to_user as any,
+    });
+
+    // Assert: success + notified=false + skipped_reason=user_muted, NO fallback key.
+    expect(result.success).toBe(true);
+    expect(result.output?.notified).toBe(false);
+    expect(result.output?.skipped_reason).toBe('user_muted');
+    expect(result.output?.user_route_fallback).toBeUndefined();
+
+    // The notification_channels SELECT must NEVER have been issued.
+    const calls = queryMock.mock.calls.map((c) => String(c[0]));
+    expect(calls.some((sql) => sql.includes('notification_channels'))).toBe(false);
+
+    // No outbound HTTP request must have occurred (no send to personal or global channel).
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+});