refactor: break up create_timmy() into testable helpers (#520)

Co-authored-by: Kimi Agent <kimi@timmy.local>
Co-committed-by: Kimi Agent <kimi@timmy.local>

src/timmy/agent.py

@@ -197,6 +197,90 @@ def _resolve_backend(requested: str | None) -> str:
     return "ollama"
 
 
+def _build_tools_list(use_tools: bool, skip_mcp: bool, model_name: str) -> list:
+    """Assemble the tools list based on model capability and MCP flags.
+
+    Returns a list of Toolkit / MCPTools objects, or an empty list.
+    """
+    if not use_tools:
+        logger.info("Tools disabled for model %s (too small for reliable tool calling)", model_name)
+        return []
+
+    tools_list: list = [create_full_toolkit()]
+
+    # Add MCP tool servers (lazy-connected on first arun()).
+    # Skipped when skip_mcp=True — MCP's stdio transport uses anyio cancel
+    # scopes that conflict with asyncio background task cancellation (#72).
+    if not skip_mcp:
+        try:
+            from timmy.mcp_tools import create_filesystem_mcp_tools, create_gitea_mcp_tools
+
+            gitea_mcp = create_gitea_mcp_tools()
+            if gitea_mcp:
+                tools_list.append(gitea_mcp)
+
+            fs_mcp = create_filesystem_mcp_tools()
+            if fs_mcp:
+                tools_list.append(fs_mcp)
+        except Exception as exc:
+            logger.debug("MCP tools unavailable: %s", exc)
+
+    return tools_list
+
+
+def _build_prompt(use_tools: bool, session_id: str) -> str:
+    """Build the full system prompt with optional memory context."""
+    base_prompt = get_system_prompt(tools_enabled=use_tools, session_id=session_id)
+
+    try:
+        from timmy.memory_system import memory_system
+
+        memory_context = memory_system.get_system_context()
+        if memory_context:
+            # Smaller budget for small models — expanded prompt uses more tokens
+            max_context = 2000 if not use_tools else 8000
+            if len(memory_context) > max_context:
+                memory_context = memory_context[:max_context] + "\n... [truncated]"
+            return (
+                f"{base_prompt}\n\n"
+                f"## GROUNDED CONTEXT (verified sources — cite when using)\n\n"
+                f"{memory_context}"
+            )
+    except Exception as exc:
+        logger.warning("Failed to load memory context: %s", exc)
+
+    return base_prompt
+
+
+def _create_ollama_agent(
+    *,
+    db_file: str,
+    model_name: str,
+    tools_list: list,
+    full_prompt: str,
+    use_tools: bool,
+) -> Agent:
+    """Construct the Agno Agent with Ollama backend and warm up the model."""
+    model_kwargs = {}
+    if settings.ollama_num_ctx > 0:
+        model_kwargs["options"] = {"num_ctx": settings.ollama_num_ctx}
+
+    agent = Agent(
+        name="Agent",
+        model=Ollama(id=model_name, host=settings.ollama_url, timeout=300, **model_kwargs),
+        db=SqliteDb(db_file=db_file),
+        description=full_prompt,
+        add_history_to_context=True,
+        num_history_runs=20,
+        markdown=False,
+        tools=tools_list if tools_list else None,
+        tool_call_limit=settings.max_agent_steps if use_tools else None,
+        telemetry=settings.telemetry_enabled,
+    )
+    _warmup_model(model_name)
+    return agent
+
+
 def create_timmy(
     db_file: str = "timmy.db",
     backend: str | None = None,
@@ -238,16 +322,12 @@ def create_timmy(
         return TimmyAirLLMAgent(model_size=size)
 
     # Default: Ollama via Agno.
-    # Resolve model with automatic pulling and fallback
     model_name, is_fallback = _resolve_model_with_fallback(
         requested_model=None,
         require_vision=False,
         auto_pull=True,
     )
 
-    # If Ollama is completely unreachable, fail loudly.
-    # Sovereignty: never silently send data to a cloud API.
-    # Use --backend claude explicitly if you want cloud inference.
     if not _check_model_available(model_name):
         logger.error(
             "Ollama unreachable and no local models available. "
@@ -258,76 +338,16 @@ def create_timmy(
         logger.info("Using fallback model %s (requested was unavailable)", model_name)
 
     use_tools = _model_supports_tools(model_name)
+    tools_list = _build_tools_list(use_tools, skip_mcp, model_name)
+    full_prompt = _build_prompt(use_tools, session_id)
 
-    # Conditionally include tools — small models get none
-    toolkit = create_full_toolkit() if use_tools else None
-    if not use_tools:
-        logger.info("Tools disabled for model %s (too small for reliable tool calling)", model_name)
-
-    # Build the tools list — Agno accepts a list of Toolkit / MCPTools
-    tools_list: list = []
-    if toolkit:
-        tools_list.append(toolkit)
-
-    # Add MCP tool servers (lazy-connected on first arun()).
-    # Skipped when skip_mcp=True — MCP's stdio transport uses anyio cancel
-    # scopes that conflict with asyncio background task cancellation (#72).
-    if use_tools and not skip_mcp:
-        try:
-            from timmy.mcp_tools import create_filesystem_mcp_tools, create_gitea_mcp_tools
-
-            gitea_mcp = create_gitea_mcp_tools()
-            if gitea_mcp:
-                tools_list.append(gitea_mcp)
-
-            fs_mcp = create_filesystem_mcp_tools()
-            if fs_mcp:
-                tools_list.append(fs_mcp)
-        except Exception as exc:
-            logger.debug("MCP tools unavailable: %s", exc)
-
-    # Select prompt tier based on tool capability
-    base_prompt = get_system_prompt(tools_enabled=use_tools, session_id=session_id)
-
-    # Try to load memory context
-    try:
-        from timmy.memory_system import memory_system
-
-        memory_context = memory_system.get_system_context()
-        if memory_context:
-            # Truncate if too long — smaller budget for small models
-            # since the expanded prompt (roster, guardrails) uses more tokens
-            max_context = 2000 if not use_tools else 8000
-            if len(memory_context) > max_context:
-                memory_context = memory_context[:max_context] + "\n... [truncated]"
-            full_prompt = (
-                f"{base_prompt}\n\n"
-                f"## GROUNDED CONTEXT (verified sources — cite when using)\n\n"
-                f"{memory_context}"
-            )
-        else:
-            full_prompt = base_prompt
-    except Exception as exc:
-        logger.warning("Failed to load memory context: %s", exc)
-        full_prompt = base_prompt
-
-    model_kwargs = {}
-    if settings.ollama_num_ctx > 0:
-        model_kwargs["options"] = {"num_ctx": settings.ollama_num_ctx}
-    agent = Agent(
-        name="Agent",
-        model=Ollama(id=model_name, host=settings.ollama_url, timeout=300, **model_kwargs),
-        db=SqliteDb(db_file=db_file),
-        description=full_prompt,
-        add_history_to_context=True,
-        num_history_runs=20,
-        markdown=False,
-        tools=tools_list if tools_list else None,
-        tool_call_limit=settings.max_agent_steps if use_tools else None,
-        telemetry=settings.telemetry_enabled,
+    return _create_ollama_agent(
+        db_file=db_file,
+        model_name=model_name,
+        tools_list=tools_list,
+        full_prompt=full_prompt,
+        use_tools=use_tools,
     )
-    _warmup_model(model_name)
-    return agent
 
 
 class TimmyWithMemory:

tests/timmy/test_agent.py

@@ -444,6 +444,150 @@ def test_get_effective_ollama_model_walks_fallback_chain():
         assert result == "fb-2"
 
 
+# ── _build_tools_list ─────────────────────────────────────────────────────
+
+
+def test_build_tools_list_empty_when_tools_disabled():
+    """Small models get an empty tools list."""
+    from timmy.agent import _build_tools_list
+
+    result = _build_tools_list(use_tools=False, skip_mcp=False, model_name="llama3.2")
+    assert result == []
+
+
+def test_build_tools_list_includes_toolkit_when_enabled():
+    """Tool-capable models get the full toolkit."""
+    mock_toolkit = MagicMock()
+    with patch("timmy.agent.create_full_toolkit", return_value=mock_toolkit):
+        from timmy.agent import _build_tools_list
+
+        result = _build_tools_list(use_tools=True, skip_mcp=True, model_name="llama3.1")
+        assert mock_toolkit in result
+
+
+def test_build_tools_list_skips_mcp_when_flagged():
+    """skip_mcp=True must not call MCP factories."""
+    mock_toolkit = MagicMock()
+    with (
+        patch("timmy.agent.create_full_toolkit", return_value=mock_toolkit),
+        patch("timmy.mcp_tools.create_gitea_mcp_tools") as mock_gitea,
+        patch("timmy.mcp_tools.create_filesystem_mcp_tools") as mock_fs,
+    ):
+        from timmy.agent import _build_tools_list
+
+        _build_tools_list(use_tools=True, skip_mcp=True, model_name="llama3.1")
+        mock_gitea.assert_not_called()
+        mock_fs.assert_not_called()
+
+
+def test_build_tools_list_includes_mcp_when_not_skipped():
+    """skip_mcp=False should attempt MCP tool creation."""
+    mock_toolkit = MagicMock()
+    with (
+        patch("timmy.agent.create_full_toolkit", return_value=mock_toolkit),
+        patch("timmy.mcp_tools.create_gitea_mcp_tools", return_value=None) as mock_gitea,
+        patch("timmy.mcp_tools.create_filesystem_mcp_tools", return_value=None) as mock_fs,
+    ):
+        from timmy.agent import _build_tools_list
+
+        _build_tools_list(use_tools=True, skip_mcp=False, model_name="llama3.1")
+        mock_gitea.assert_called_once()
+        mock_fs.assert_called_once()
+
+
+# ── _build_prompt ─────────────────────────────────────────────────────────
+
+
+def test_build_prompt_includes_base_prompt():
+    """Prompt should always contain the base system prompt."""
+    from timmy.agent import _build_prompt
+
+    result = _build_prompt(use_tools=False, session_id="test")
+    assert "Timmy" in result
+
+
+def test_build_prompt_appends_memory_context():
+    """Memory context should be appended when available."""
+    mock_memory = MagicMock()
+    mock_memory.get_system_context.return_value = "User prefers dark mode."
+    with patch("timmy.memory_system.memory_system", mock_memory):
+        from timmy.agent import _build_prompt
+
+        result = _build_prompt(use_tools=True, session_id="test")
+        assert "GROUNDED CONTEXT" in result
+        assert "dark mode" in result
+
+
+def test_build_prompt_truncates_long_memory():
+    """Long memory context should be truncated."""
+    mock_memory = MagicMock()
+    mock_memory.get_system_context.return_value = "x" * 10000
+    with patch("timmy.memory_system.memory_system", mock_memory):
+        from timmy.agent import _build_prompt
+
+        result = _build_prompt(use_tools=False, session_id="test")
+        assert "[truncated]" in result
+
+
+def test_build_prompt_survives_memory_failure():
+    """Prompt should fall back to base when memory fails."""
+    mock_memory = MagicMock()
+    mock_memory.get_system_context.side_effect = RuntimeError("db locked")
+    with patch("timmy.memory_system.memory_system", mock_memory):
+        from timmy.agent import _build_prompt
+
+        result = _build_prompt(use_tools=True, session_id="test")
+        assert "Timmy" in result
+        # Memory context should NOT be appended (the db locked error was caught)
+        assert "db locked" not in result
+
+
+# ── _create_ollama_agent ──────────────────────────────────────────────────
+
+
+def test_create_ollama_agent_passes_correct_kwargs():
+    """_create_ollama_agent must pass the expected kwargs to Agent."""
+    with (
+        patch("timmy.agent.Agent") as MockAgent,
+        patch("timmy.agent.Ollama"),
+        patch("timmy.agent.SqliteDb"),
+        patch("timmy.agent._warmup_model", return_value=True),
+    ):
+        from timmy.agent import _create_ollama_agent
+
+        _create_ollama_agent(
+            db_file="test.db",
+            model_name="llama3.1",
+            tools_list=[MagicMock()],
+            full_prompt="test prompt",
+            use_tools=True,
+        )
+        kwargs = MockAgent.call_args.kwargs
+        assert kwargs["description"] == "test prompt"
+        assert kwargs["markdown"] is False
+
+
+def test_create_ollama_agent_none_tools_when_empty():
+    """Empty tools_list should pass tools=None to Agent."""
+    with (
+        patch("timmy.agent.Agent") as MockAgent,
+        patch("timmy.agent.Ollama"),
+        patch("timmy.agent.SqliteDb"),
+        patch("timmy.agent._warmup_model", return_value=True),
+    ):
+        from timmy.agent import _create_ollama_agent
+
+        _create_ollama_agent(
+            db_file="test.db",
+            model_name="llama3.2",
+            tools_list=[],
+            full_prompt="test prompt",
+            use_tools=False,
+        )
+        kwargs = MockAgent.call_args.kwargs
+        assert kwargs["tools"] is None
+
+
 def test_no_hardcoded_fallback_constants_in_agent():
     """agent.py must not define module-level DEFAULT_MODEL_FALLBACKS."""
     import timmy.agent as agent_mod