diff --git a/tests/test_engine.py b/tests/test_engine.py
index 70e9af3..541c40b 100644
--- a/tests/test_engine.py
+++ b/tests/test_engine.py
@@ -1,5 +1,6 @@
 """Tests for core.engine — Module lifecycle manager."""
 
+import os
 import time
 from unittest.mock import patch, MagicMock
 
@@ -173,3 +174,52 @@ class TestEngine:
         assert success is True
 
         engine.stop("mock_active")
+
+    def test_capture_bus_instantiated_in_start_all(self, mock_bus, mock_state, mock_config):
+        """Engine.start_all() creates and injects CaptureBus into passive modules."""
+        # Create a passive module that requires CaptureBus
+        class MockPassiveWithCaptureBus(BaseModule):
+            name = "mock_passive_capture"
+            module_type = "passive"
+            priority = 100
+            dependencies = []
+            requires_root = False
+            requires_capture_bus = True
+
+            def start(self):
+                # This module should receive capture_bus in config
+                self._capture_bus = self.config.get("capture_bus")
+                if not self._capture_bus:
+                    raise RuntimeError("capture_bus not provided in config")
+                self._running = True
+                self._pid = os.getpid()
+                self._start_time = time.time()
+
+            def stop(self):
+                self._running = False
+
+            def status(self):
+                return {"running": self._running, "pid": self._pid}
+
+            def configure(self, config):
+                pass
+
+        engine = Engine(bus=mock_bus, state=mock_state, config=mock_config)
+        engine.register(MockPassiveWithCaptureBus, config=mock_config)
+
+        # Mock CaptureBus.start() to avoid permission errors during test
+        with patch("core.capture_bus.CaptureBus.start"):
+            # start_all() should create CaptureBus and inject it
+            results = engine.start_all()
+
+        # Verify CaptureBus was created
+        assert engine.capture_bus is not None
+        assert results.get("mock_passive_capture") is True
+
+        # Verify the module config has capture_bus injected
+        entry = engine._modules["mock_passive_capture"]
+        assert "capture_bus" in entry.config
+        assert entry.config["capture_bus"] is not None
+
+        # Cleanup
+        engine.stop_all()