diff --git a/tests/test_app.py b/tests/test_app.py
new file mode 100644
index 0000000..eb4d9b9
--- /dev/null
+++ b/tests/test_app.py
@@ -0,0 +1,161 @@
+import pytest
+import asyncio
+from fastapi import FastAPI
+from asyncio import Queue, Event
+from agentic_security.core.app import create_app, get_tools_inbox, get_stop_event, get_current_run, set_current_run
+
+class TestApp:
+    """Test suite for agentic_security.core.app module."""
+
+    def test_create_app(self):
+        """Test that create_app returns a FastAPI instance."""
+        app = create_app()
+        assert isinstance(app, FastAPI)
+
+    @pytest.mark.asyncio
+    async def test_get_tools_inbox(self):
+        """Test that get_tools_inbox returns the global Queue instance."""
+        queue1 = get_tools_inbox()
+        await queue1.put("test item")
+        queue2 = get_tools_inbox()
+        result = queue2.get_nowait()
+        assert result == "test item"
+
+    def test_get_stop_event(self):
+        """Test that get_stop_event returns the global Event instance and is not set initially."""
+        event = get_stop_event()
+        assert isinstance(event, Event)
+        assert not event.is_set()
+
+    def test_current_run_initial(self):
+        """Test that get_current_run returns the global current_run with default values initially."""
+        run = get_current_run()
+        # Default values should be empty strings
+        assert run["spec"] == ""
+        assert run["id"] == ""
+
+    def test_set_current_run(self):
+        """Test that set_current_run correctly updates current_run."""
+        spec = "test run"
+        result = set_current_run(spec)
+        expected_id = hash(id(spec))
+        # Verify that spec is set correctly
+        assert result["spec"] == spec
+        assert result["id"] == expected_id
+
+    def test_current_run_after_set(self):
+        """Test that get_current_run returns the updated current_run after set_current_run is called."""
+        spec = "another test run"
+        set_current_run(spec)
+        current = get_current_run()
+        assert current["spec"] == spec
+        assert current["id"] == hash(id(spec))
+    def test_tools_inbox_same_instance(self):
+        """Test that get_tools_inbox returns the same Queue instance by default."""
+        queue1 = get_tools_inbox()
+        queue2 = get_tools_inbox()
+        assert queue1 is queue2
+
+    def test_stop_event_set(self):
+        """Test that setting the stop event is reflected in subsequent calls."""
+        event = get_stop_event()
+        event.set()  # set the global event
+        # Now, subsequent calls should return the same event which is set.
+        event2 = get_stop_event()
+        assert event2.is_set()
+
+    def test_set_current_run_with_none(self):
+        """Test that set_current_run handles None as a valid input and updates current_run accordingly."""
+        result = set_current_run(None)
+        expected_id = hash(id(None))
+        assert result["spec"] is None
+        assert result["id"] == expected_id
+
+    def test_multiple_current_run_assignments(self):
+        """Test multiple assignments to current_run to ensure it always updates correctly."""
+        first_spec = "first run"
+        result1 = set_current_run(first_spec)
+        expected_id1 = hash(id(first_spec))
+        assert result1["spec"] == first_spec
+        assert result1["id"] == expected_id1
+
+        second_spec = "second run"
+        result2 = set_current_run(second_spec)
+        expected_id2 = hash(id(second_spec))
+        assert result2["spec"] == second_spec
+        assert result2["id"] == expected_id2
+
+        current = get_current_run()
+        # The current_run should reflect the latest assignment.
+        assert current["spec"] == second_spec
+        assert current["id"] == expected_id2
+    @pytest.mark.asyncio
+    async def test_empty_tools_inbox_exception(self):
+        """Test that calling get_nowait on an empty tools_inbox raises QueueEmpty."""
+        from asyncio import QueueEmpty
+        queue = get_tools_inbox()
+        # Clear any existing items in the queue
+        while True:
+            try:
+                queue.get_nowait()
+            except QueueEmpty:
+                break
+        with pytest.raises(QueueEmpty):
+            queue.get_nowait()
+
+    def test_set_current_run_with_dict(self):
+        """Test that set_current_run correctly handles a dictionary input as spec."""
+        spec = {"key": "value"}
+        result = set_current_run(spec)
+        expected_id = hash(id(spec))
+        assert result["spec"] == spec
+        assert result["id"] == expected_id
+    @pytest.mark.asyncio
+    async def test_stop_event_wait(self):
+        """Test that waiting on the stop event returns once the event is set."""
+        event = get_stop_event()
+        event.clear()  # ensure event is not set
+        async def waiter():
+            await event.wait()
+            return True
+        waiter_task = asyncio.create_task(waiter())
+        # Wait a moment to ensure the waiter is pending
+        await asyncio.sleep(0.1)
+        assert not waiter_task.done()
+        event.set()
+        result = await waiter_task
+        assert result is True
+
+    def test_set_current_run_with_int(self):
+        """Test that set_current_run handles an integer input as spec."""
+        spec = 12345
+        result = set_current_run(spec)
+        expected_id = hash(id(spec))
+        assert result["spec"] == spec
+        assert result["id"] == expected_id
+
+    def test_create_app_routes(self):
+        """Test that create_app returns a FastAPI instance with default routes available."""
+        app = create_app()
+        paths = [route.path for route in app.routes]
+        # Check that the default OpenAPI route exists
+        assert "/openapi.json" in paths
+
+    @pytest.mark.asyncio
+    async def test_tools_inbox_async_put_get_order(self):
+        """Test that tools_inbox preserves order when items are added and retrieved asynchronously."""
+        queue = get_tools_inbox()
+        # Clear any existing items in the queue
+        from asyncio import QueueEmpty
+        while True:
+            try:
+                queue.get_nowait()
+            except QueueEmpty:
+                break
+        items = ["first", "second", "third"]
+        for item in items:
+            await queue.put(item)
+        result_items = []
+        for _ in items:
+            result_items.append(await queue.get())
+        assert result_items == items
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