fix: make _get_loop_agent singleton thread-safe with double-checked locking

Uses threading.Lock with double-checked locking pattern to prevent
race conditions when multiple agentic loops start concurrently.

Fixes #446

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/timmy/agentic_loop.py

@@ -18,6 +18,7 @@ from __future__ import annotations
 import asyncio
 import logging
 import re
+import threading
 import time
 import uuid
 from collections.abc import Callable
@@ -59,6 +60,7 @@ class AgenticResult:
 # ---------------------------------------------------------------------------
 
 _loop_agent = None
+_loop_agent_lock = threading.Lock()
 
 
 def _get_loop_agent():
@@ -66,12 +68,18 @@ def _get_loop_agent():
 
     Returns the same type of agent as `create_timmy()` but with a
     dedicated session so it doesn't pollute the main chat history.
+
+    Thread-safe: uses a lock to prevent duplicate agent creation
+    when multiple loops start concurrently.
     """
     global _loop_agent
-    if _loop_agent is None:
+    if _loop_agent is not None:
-        from timmy.agent import create_timmy
+        return _loop_agent
+    with _loop_agent_lock:
+        if _loop_agent is None:
+            from timmy.agent import create_timmy
 
-        _loop_agent = create_timmy()
+            _loop_agent = create_timmy()
     return _loop_agent
 
 

tests/timmy/test_agentic_loop.py

@@ -0,0 +1,386 @@
+"""Tests for timmy.agentic_loop — multi-step task execution engine."""
+
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from timmy.agentic_loop import (
+    AgenticResult,
+    AgenticStep,
+    _parse_steps,
+)
+
+# ---------------------------------------------------------------------------
+# Data structures
+# ---------------------------------------------------------------------------
+
+
+class TestAgenticStep:
+    """Unit tests for the AgenticStep dataclass."""
+
+    def test_creation(self):
+        step = AgenticStep(
+            step_num=1,
+            description="Do thing",
+            result="Done",
+            status="completed",
+            duration_ms=42,
+        )
+        assert step.step_num == 1
+        assert step.description == "Do thing"
+        assert step.result == "Done"
+        assert step.status == "completed"
+        assert step.duration_ms == 42
+
+    def test_failed_status(self):
+        step = AgenticStep(
+            step_num=2, description="Bad step", result="Error", status="failed", duration_ms=10
+        )
+        assert step.status == "failed"
+
+    def test_adapted_status(self):
+        step = AgenticStep(
+            step_num=3, description="Retried", result="OK", status="adapted", duration_ms=100
+        )
+        assert step.status == "adapted"
+
+
+class TestAgenticResult:
+    """Unit tests for the AgenticResult dataclass."""
+
+    def test_defaults(self):
+        result = AgenticResult(task_id="abc", task="Test", summary="Done")
+        assert result.steps == []
+        assert result.status == "completed"
+        assert result.total_duration_ms == 0
+
+    def test_with_steps(self):
+        s = AgenticStep(step_num=1, description="A", result="B", status="completed", duration_ms=5)
+        result = AgenticResult(task_id="x", task="T", summary="S", steps=[s])
+        assert len(result.steps) == 1
+
+
+# ---------------------------------------------------------------------------
+# _parse_steps — pure function, highly testable
+# ---------------------------------------------------------------------------
+
+
+class TestParseSteps:
+    """Unit tests for the plan parser."""
+
+    def test_numbered_with_dots(self):
+        text = "1. First step\n2. Second step\n3. Third step"
+        steps = _parse_steps(text)
+        assert steps == ["First step", "Second step", "Third step"]
+
+    def test_numbered_with_parens(self):
+        text = "1) Do this\n2) Do that"
+        steps = _parse_steps(text)
+        assert steps == ["Do this", "Do that"]
+
+    def test_mixed_numbering(self):
+        text = "1. Step one\n2) Step two\n3. Step three"
+        steps = _parse_steps(text)
+        assert len(steps) == 3
+
+    def test_indented_steps(self):
+        text = "  1. Indented step\n  2. Also indented"
+        steps = _parse_steps(text)
+        assert len(steps) == 2
+        assert steps[0] == "Indented step"
+
+    def test_no_numbered_steps_fallback(self):
+        text = "Do this first\nThen do that\nFinally wrap up"
+        steps = _parse_steps(text)
+        assert len(steps) == 3
+        assert steps[0] == "Do this first"
+
+    def test_empty_string(self):
+        steps = _parse_steps("")
+        assert steps == []
+
+    def test_blank_lines_ignored_in_fallback(self):
+        text = "Step A\n\n\nStep B\n"
+        steps = _parse_steps(text)
+        assert steps == ["Step A", "Step B"]
+
+    def test_strips_whitespace(self):
+        text = "1.  Lots of space  \n2.  Also spaced  "
+        steps = _parse_steps(text)
+        assert steps[0] == "Lots of space"
+        assert steps[1] == "Also spaced"
+
+    def test_preamble_ignored_when_numbered(self):
+        text = "Here is the plan:\n1. Step one\n2. Step two"
+        steps = _parse_steps(text)
+        assert steps == ["Step one", "Step two"]
+
+
+# ---------------------------------------------------------------------------
+# _get_loop_agent — singleton pattern
+# ---------------------------------------------------------------------------
+
+
+class TestGetLoopAgent:
+    """Tests for the agent singleton."""
+
+    def test_creates_agent_once(self):
+        import timmy.agentic_loop as mod
+
+        mod._loop_agent = None
+        mock_agent = MagicMock()
+        with patch("timmy.agent.create_timmy", return_value=mock_agent) as mock_create:
+            agent = mod._get_loop_agent()
+            assert agent is mock_agent
+            mock_create.assert_called_once()
+
+            # Second call should reuse singleton
+            agent2 = mod._get_loop_agent()
+            assert agent2 is mock_agent
+            mock_create.assert_called_once()
+
+        mod._loop_agent = None  # cleanup
+
+    def test_reuses_existing(self):
+        import timmy.agentic_loop as mod
+
+        sentinel = MagicMock()
+        mod._loop_agent = sentinel
+        assert mod._get_loop_agent() is sentinel
+        mod._loop_agent = None  # cleanup
+
+
+# ---------------------------------------------------------------------------
+# _broadcast_progress — best-effort WebSocket broadcast
+# ---------------------------------------------------------------------------
+
+
+class TestBroadcastProgress:
+    """Tests for the WebSocket broadcast helper."""
+
+    @pytest.mark.asyncio
+    async def test_successful_broadcast(self):
+        from timmy.agentic_loop import _broadcast_progress
+
+        mock_ws = MagicMock()
+        mock_ws.broadcast = AsyncMock()
+        mock_module = MagicMock()
+        mock_module.ws_manager = mock_ws
+        with patch.dict("sys.modules", {"infrastructure.ws_manager.handler": mock_module}):
+            await _broadcast_progress("test.event", {"key": "value"})
+            mock_ws.broadcast.assert_awaited_once_with("test.event", {"key": "value"})
+
+    @pytest.mark.asyncio
+    async def test_import_error_swallowed(self):
+        """When ws_manager import fails, broadcast silently succeeds."""
+        import sys
+
+        from timmy.agentic_loop import _broadcast_progress
+
+        # Remove the module so import fails
+        saved = sys.modules.pop("infrastructure.ws_manager.handler", None)
+        try:
+            with patch.dict("sys.modules", {"infrastructure": None}):
+                # Should not raise — errors are swallowed
+                await _broadcast_progress("fail.event", {})
+        finally:
+            if saved is not None:
+                sys.modules["infrastructure.ws_manager.handler"] = saved
+
+
+# ---------------------------------------------------------------------------
+# run_agentic_loop — integration-style tests with mocked agent
+# ---------------------------------------------------------------------------
+
+
+class TestRunAgenticLoop:
+    """Tests for the main agentic loop."""
+
+    @pytest.fixture(autouse=True)
+    def _reset_agent(self):
+        import timmy.agentic_loop as mod
+
+        mod._loop_agent = None
+        yield
+        mod._loop_agent = None
+
+    def _mock_agent(self, responses):
+        """Create a mock agent that returns responses in sequence."""
+        agent = MagicMock()
+        run_results = []
+        for r in responses:
+            mock_result = MagicMock()
+            mock_result.content = r
+            run_results.append(mock_result)
+        agent.run = MagicMock(side_effect=run_results)
+        return agent
+
+    @pytest.mark.asyncio
+    async def test_successful_two_step_task(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent(
+            [
+                "1. Step one\n2. Step two",  # planning
+                "Step one done",  # execution step 1
+                "Step two done",  # execution step 2
+            ]
+        )
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+        ):
+            result = await run_agentic_loop("Test task", max_steps=5)
+
+        assert result.status == "completed"
+        assert len(result.steps) == 2
+        assert result.steps[0].status == "completed"
+        assert result.steps[1].status == "completed"
+        assert result.total_duration_ms >= 0
+
+    @pytest.mark.asyncio
+    async def test_planning_failure(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = MagicMock()
+        agent.run = MagicMock(side_effect=RuntimeError("LLM down"))
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+        ):
+            result = await run_agentic_loop("Broken task", max_steps=3)
+
+        assert result.status == "failed"
+        assert "Planning failed" in result.summary
+
+    @pytest.mark.asyncio
+    async def test_empty_plan(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent([""])  # empty plan
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+        ):
+            result = await run_agentic_loop("Empty plan task", max_steps=3)
+
+        assert result.status == "failed"
+        assert "no steps" in result.summary.lower()
+
+    @pytest.mark.asyncio
+    async def test_step_failure_triggers_adaptation(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = MagicMock()
+        call_count = 0
+
+        def mock_run(prompt, **kwargs):
+            nonlocal call_count
+            call_count += 1
+            result = MagicMock()
+            if call_count == 1:
+                result.content = "1. Only step"
+            elif call_count == 2:
+                raise RuntimeError("Step failed")
+            else:
+                result.content = "Adapted successfully"
+            return result
+
+        agent.run = mock_run
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+        ):
+            result = await run_agentic_loop("Failing task", max_steps=5)
+
+        assert len(result.steps) == 1
+        assert result.steps[0].status == "adapted"
+        assert "[Adapted]" in result.steps[0].description
+
+    @pytest.mark.asyncio
+    async def test_max_steps_truncation(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent(
+            [
+                "1. A\n2. B\n3. C\n4. D\n5. E",  # 5 steps planned
+                "Done A",
+                "Done B",
+            ]
+        )
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+        ):
+            result = await run_agentic_loop("Big task", max_steps=2)
+
+        assert result.status == "partial"  # was truncated
+        assert len(result.steps) == 2
+
+    @pytest.mark.asyncio
+    async def test_on_progress_callback(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent(
+            [
+                "1. Only step",
+                "Step done",
+            ]
+        )
+        progress_calls = []
+
+        async def track_progress(desc, step_num, total):
+            progress_calls.append((desc, step_num, total))
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+        ):
+            await run_agentic_loop("Callback task", max_steps=5, on_progress=track_progress)
+
+        assert len(progress_calls) == 1
+        assert progress_calls[0][1] == 1  # step_num
+
+    @pytest.mark.asyncio
+    async def test_default_max_steps_from_settings(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent(["1. Step one", "Done"])
+
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 7
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+            patch("config.settings", mock_settings),
+        ):
+            result = await run_agentic_loop("Settings task")
+
+        assert result.status == "completed"
+
+    @pytest.mark.asyncio
+    async def test_task_id_generated(self):
+        from timmy.agentic_loop import run_agentic_loop
+
+        agent = self._mock_agent(["1. Step", "OK"])
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock),
+            patch("timmy.session._clean_response", side_effect=lambda x: x),
+        ):
+            result = await run_agentic_loop("ID task", max_steps=5)
+
+        assert result.task_id  # non-empty
+        assert len(result.task_id) == 8  # uuid[:8]

tests/unit/test_agentic_loop.py

@@ -0,0 +1,359 @@
+"""Unit tests for timmy.agentic_loop — agentic loop data structures, parsing, and execution."""
+
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from timmy.agentic_loop import (
+    AgenticResult,
+    AgenticStep,
+    _broadcast_progress,
+    _parse_steps,
+    run_agentic_loop,
+)
+
+# ── Data structures ──────────────────────────────────────────────────────────
+
+
+class TestAgenticStep:
+    def test_fields(self):
+        step = AgenticStep(
+            step_num=1,
+            description="Do something",
+            result="Done",
+            status="completed",
+            duration_ms=42,
+        )
+        assert step.step_num == 1
+        assert step.description == "Do something"
+        assert step.result == "Done"
+        assert step.status == "completed"
+        assert step.duration_ms == 42
+
+
+class TestAgenticResult:
+    def test_defaults(self):
+        r = AgenticResult(task_id="abc", task="test task", summary="ok")
+        assert r.steps == []
+        assert r.status == "completed"
+        assert r.total_duration_ms == 0
+
+    def test_with_steps(self):
+        step = AgenticStep(1, "s", "r", "completed", 10)
+        r = AgenticResult(task_id="x", task="t", summary="s", steps=[step])
+        assert len(r.steps) == 1
+
+
+# ── _parse_steps ─────────────────────────────────────────────────────────────
+
+
+class TestParseSteps:
+    def test_numbered_dot(self):
+        text = "1. First step\n2. Second step\n3. Third step"
+        assert _parse_steps(text) == ["First step", "Second step", "Third step"]
+
+    def test_numbered_paren(self):
+        text = "1) Alpha\n2) Beta"
+        assert _parse_steps(text) == ["Alpha", "Beta"]
+
+    def test_mixed_whitespace(self):
+        text = "  1. Indented step\n  2. Another  "
+        result = _parse_steps(text)
+        assert result == ["Indented step", "Another"]
+
+    def test_fallback_plain_lines(self):
+        text = "Do this\nDo that\nDo the other"
+        assert _parse_steps(text) == ["Do this", "Do that", "Do the other"]
+
+    def test_empty_string(self):
+        assert _parse_steps("") == []
+
+    def test_blank_lines_skipped_in_fallback(self):
+        text = "line one\n\nline two\n   \nline three"
+        assert _parse_steps(text) == ["line one", "line two", "line three"]
+
+
+# ── _get_loop_agent ──────────────────────────────────────────────────────────
+
+
+class TestGetLoopAgent:
+    def test_creates_agent_once(self):
+        import timmy.agentic_loop as al
+
+        saved = al._loop_agent
+        try:
+            al._loop_agent = None
+            mock_agent = MagicMock()
+            with patch("timmy.agent.create_timmy", return_value=mock_agent):
+                result = al._get_loop_agent()
+                assert result is mock_agent
+                # Second call returns cached
+                result2 = al._get_loop_agent()
+                assert result2 is mock_agent
+        finally:
+            al._loop_agent = saved
+
+    def test_returns_cached(self):
+        import timmy.agentic_loop as al
+
+        saved = al._loop_agent
+        try:
+            sentinel = object()
+            al._loop_agent = sentinel
+            assert al._get_loop_agent() is sentinel
+        finally:
+            al._loop_agent = saved
+
+    def test_thread_safe_creation(self):
+        """Concurrent calls must only create one agent (thread-safety)."""
+        import threading
+
+        import timmy.agentic_loop as al
+
+        saved = al._loop_agent
+        try:
+            al._loop_agent = None
+            mock_agent = MagicMock()
+            call_count = 0
+            barrier = threading.Barrier(4)
+
+            original_create = MagicMock(return_value=mock_agent)
+
+            def slow_create():
+                nonlocal call_count
+                call_count += 1
+                return original_create()
+
+            results = [None] * 4
+
+            def worker(idx):
+                barrier.wait()
+                results[idx] = al._get_loop_agent()
+
+            with patch("timmy.agent.create_timmy", side_effect=slow_create):
+                threads = [threading.Thread(target=worker, args=(i,)) for i in range(4)]
+                for t in threads:
+                    t.start()
+                for t in threads:
+                    t.join()
+
+            # All threads got the same agent
+            assert all(r is mock_agent for r in results)
+            # create_timmy called exactly once
+            assert call_count == 1
+        finally:
+            al._loop_agent = saved
+
+
+# ── _broadcast_progress ──────────────────────────────────────────────────────
+
+
+class TestBroadcastProgress:
+    @pytest.mark.asyncio
+    async def test_success(self):
+        mock_ws = AsyncMock()
+        with (
+            patch("timmy.agentic_loop.ws_manager", mock_ws, create=True),
+            patch.dict(
+                "sys.modules",
+                {"infrastructure.ws_manager.handler": MagicMock(ws_manager=mock_ws)},
+            ),
+        ):
+            await _broadcast_progress("test.event", {"key": "val"})
+            mock_ws.broadcast.assert_awaited_once_with("test.event", {"key": "val"})
+
+    @pytest.mark.asyncio
+    async def test_import_error_swallowed(self):
+        with patch.dict("sys.modules", {"infrastructure.ws_manager.handler": None}):
+            # Should not raise
+            await _broadcast_progress("test.event", {})
+
+
+# ── run_agentic_loop ─────────────────────────────────────────────────────────
+
+
+def _make_mock_agent(plan_text, step_responses=None):
+    """Create a mock agent whose .run returns predictable content."""
+    call_count = 0
+
+    def run_side_effect(prompt, *, stream=False, session_id=""):
+        nonlocal call_count
+        call_count += 1
+        resp = MagicMock()
+        if call_count == 1:
+            # Planning call
+            resp.content = plan_text
+        else:
+            idx = call_count - 2  # step index (0-based)
+            if step_responses and idx < len(step_responses):
+                val = step_responses[idx]
+                if isinstance(val, Exception):
+                    raise val
+                resp.content = val
+            else:
+                resp.content = f"Step result {call_count}"
+        return resp
+
+    agent = MagicMock()
+    agent.run = MagicMock(side_effect=run_side_effect)
+    return agent
+
+
+@pytest.fixture
+def _patch_broadcast():
+    with patch("timmy.agentic_loop._broadcast_progress", new_callable=AsyncMock):
+        yield
+
+
+@pytest.fixture
+def _patch_clean_response():
+    with patch("timmy.session._clean_response", side_effect=lambda x: x):
+        yield
+
+
+class TestRunAgenticLoop:
+    @pytest.mark.asyncio
+    async def test_successful_execution(self, _patch_broadcast, _patch_clean_response):
+        agent = _make_mock_agent("1. Step A\n2. Step B", ["Result A", "Result B"])
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 10
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch("timmy.agentic_loop.settings", mock_settings, create=True),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=5)
+
+        assert result.status == "completed"
+        assert len(result.steps) == 2
+        assert result.steps[0].status == "completed"
+        assert result.steps[0].description == "Step A"
+        assert result.total_duration_ms >= 0
+
+    @pytest.mark.asyncio
+    async def test_planning_failure(self, _patch_broadcast):
+        agent = MagicMock()
+        agent.run = MagicMock(side_effect=RuntimeError("LLM down"))
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 5
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=3)
+
+        assert result.status == "failed"
+        assert "Planning failed" in result.summary
+
+    @pytest.mark.asyncio
+    async def test_empty_plan(self, _patch_broadcast):
+        agent = _make_mock_agent("")
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 5
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=3)
+
+        assert result.status == "failed"
+        assert "no steps" in result.summary.lower()
+
+    @pytest.mark.asyncio
+    async def test_step_failure_triggers_adaptation(self, _patch_broadcast, _patch_clean_response):
+        agent = _make_mock_agent(
+            "1. Do X\n2. Do Y",
+            [RuntimeError("oops"), "Adapted result", "Y done"],
+        )
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 10
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=5)
+
+        # Step 1 should be adapted, step 2 completed
+        statuses = [s.status for s in result.steps]
+        assert "adapted" in statuses
+
+    @pytest.mark.asyncio
+    async def test_truncation_marks_partial(self, _patch_broadcast, _patch_clean_response):
+        agent = _make_mock_agent(
+            "1. A\n2. B\n3. C\n4. D\n5. E",
+            ["r1", "r2"],
+        )
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 10
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=2)
+
+        assert result.status == "partial"
+
+    @pytest.mark.asyncio
+    async def test_on_progress_callback(self, _patch_broadcast, _patch_clean_response):
+        agent = _make_mock_agent("1. Only step", ["done"])
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 10
+        callback = AsyncMock()
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=5, on_progress=callback)
+
+        callback.assert_awaited_once_with("Only step", 1, 1)
+        assert result.status == "completed"
+
+    @pytest.mark.asyncio
+    async def test_default_max_steps_from_settings(self, _patch_broadcast, _patch_clean_response):
+        agent = _make_mock_agent("1. S1", ["r1"])
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 3
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff")  # max_steps=0 → from settings
+
+        assert result.status == "completed"
+
+    @pytest.mark.asyncio
+    async def test_failed_step_and_failed_adaptation(self, _patch_broadcast, _patch_clean_response):
+        """When both step and adaptation fail, step is marked failed."""
+        call_count = 0
+
+        def run_side_effect(prompt, *, stream=False, session_id=""):
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                resp = MagicMock()
+                resp.content = "1. Only step"
+                return resp
+            # Both step execution and adaptation fail
+            raise RuntimeError("everything broken")
+
+        agent = MagicMock()
+        agent.run = MagicMock(side_effect=run_side_effect)
+        mock_settings = MagicMock()
+        mock_settings.max_agent_steps = 10
+
+        with (
+            patch("timmy.agentic_loop._get_loop_agent", return_value=agent),
+            patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}),
+        ):
+            result = await run_agentic_loop("do stuff", max_steps=5)
+
+        assert result.steps[0].status == "failed"
+        assert "Failed" in result.steps[0].result
+        assert result.status == "partial"

tests/unit/test_memory_embeddings.py

@@ -0,0 +1,162 @@
+"""Unit tests for timmy.memory.embeddings — embedding, similarity, and keyword overlap."""
+
+import math
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+import timmy.memory.embeddings as emb
+from timmy.memory.embeddings import (
+    _keyword_overlap,
+    _simple_hash_embedding,
+    cosine_similarity,
+    embed_text,
+)
+
+# ── _simple_hash_embedding ──────────────────────────────────────────────────
+
+
+class TestSimpleHashEmbedding:
+    def test_returns_128_dim_vector(self):
+        vec = _simple_hash_embedding("hello world")
+        assert len(vec) == 128
+
+    def test_normalized(self):
+        vec = _simple_hash_embedding("some text for embedding")
+        mag = math.sqrt(sum(x * x for x in vec))
+        assert mag == pytest.approx(1.0, abs=1e-6)
+
+    def test_deterministic(self):
+        a = _simple_hash_embedding("same input")
+        b = _simple_hash_embedding("same input")
+        assert a == b
+
+    def test_different_texts_differ(self):
+        a = _simple_hash_embedding("hello world")
+        b = _simple_hash_embedding("goodbye moon")
+        assert a != b
+
+    def test_empty_string(self):
+        vec = _simple_hash_embedding("")
+        assert len(vec) == 128
+        # All zeros normalised stays zero (mag fallback to 1.0)
+        assert all(x == 0.0 for x in vec)
+
+    def test_long_text_truncates_at_50_words(self):
+        """Words beyond 50 should not change the result."""
+        short = " ".join(f"word{i}" for i in range(50))
+        long = short + " extra1 extra2 extra3"
+        assert _simple_hash_embedding(short) == _simple_hash_embedding(long)
+
+
+# ── cosine_similarity ────────────────────────────────────────────────────────
+
+
+class TestCosineSimilarity:
+    def test_identical_vectors(self):
+        v = [1.0, 2.0, 3.0]
+        assert cosine_similarity(v, v) == pytest.approx(1.0)
+
+    def test_orthogonal_vectors(self):
+        a = [1.0, 0.0]
+        b = [0.0, 1.0]
+        assert cosine_similarity(a, b) == pytest.approx(0.0)
+
+    def test_opposite_vectors(self):
+        a = [1.0, 0.0]
+        b = [-1.0, 0.0]
+        assert cosine_similarity(a, b) == pytest.approx(-1.0)
+
+    def test_zero_vector_returns_zero(self):
+        assert cosine_similarity([0.0, 0.0], [1.0, 2.0]) == 0.0
+        assert cosine_similarity([1.0, 2.0], [0.0, 0.0]) == 0.0
+
+    def test_both_zero_vectors(self):
+        assert cosine_similarity([0.0], [0.0]) == 0.0
+
+
+# ── _keyword_overlap ─────────────────────────────────────────────────────────
+
+
+class TestKeywordOverlap:
+    def test_full_overlap(self):
+        assert _keyword_overlap("hello world", "hello world") == pytest.approx(1.0)
+
+    def test_partial_overlap(self):
+        assert _keyword_overlap("hello world", "hello moon") == pytest.approx(0.5)
+
+    def test_no_overlap(self):
+        assert _keyword_overlap("hello", "goodbye") == pytest.approx(0.0)
+
+    def test_empty_query(self):
+        assert _keyword_overlap("", "anything") == 0.0
+
+    def test_case_insensitive(self):
+        assert _keyword_overlap("Hello World", "hello world") == pytest.approx(1.0)
+
+
+# ── embed_text ───────────────────────────────────────────────────────────────
+
+
+class TestEmbedText:
+    def setup_method(self):
+        self._saved_model = emb.EMBEDDING_MODEL
+        emb.EMBEDDING_MODEL = None
+
+    def teardown_method(self):
+        emb.EMBEDDING_MODEL = self._saved_model
+
+    def test_uses_fallback_when_model_disabled(self):
+        emb.EMBEDDING_MODEL = False
+        vec = embed_text("test")
+        assert len(vec) == 128  # hash fallback dimension
+
+    def test_uses_model_when_available(self):
+        import numpy as np
+
+        mock_model = MagicMock()
+        mock_model.encode.return_value = np.array([0.1, 0.2, 0.3])
+        emb.EMBEDDING_MODEL = mock_model
+
+        result = embed_text("test")
+        assert result == pytest.approx([0.1, 0.2, 0.3])
+        mock_model.encode.assert_called_once_with("test")
+
+
+# ── _get_embedding_model ─────────────────────────────────────────────────────
+
+
+class TestGetEmbeddingModel:
+    def setup_method(self):
+        self._saved_model = emb.EMBEDDING_MODEL
+        emb.EMBEDDING_MODEL = None
+
+    def teardown_method(self):
+        emb.EMBEDDING_MODEL = self._saved_model
+
+    def test_skip_embeddings_setting(self):
+        mock_settings = MagicMock()
+        mock_settings.timmy_skip_embeddings = True
+        with patch.dict("sys.modules", {"config": MagicMock(settings=mock_settings)}):
+            emb.EMBEDDING_MODEL = None
+            result = emb._get_embedding_model()
+        assert result is False
+
+    def test_fallback_when_transformers_missing(self):
+        mock_settings = MagicMock()
+        mock_settings.timmy_skip_embeddings = False
+        with patch.dict(
+            "sys.modules",
+            {
+                "config": MagicMock(settings=mock_settings),
+                "sentence_transformers": None,
+            },
+        ):
+            emb.EMBEDDING_MODEL = None
+            result = emb._get_embedding_model()
+        assert result is False
+
+    def test_returns_cached_model(self):
+        sentinel = object()
+        emb.EMBEDDING_MODEL = sentinel
+        assert emb._get_embedding_model() is sentinel