feat: add run_self_tests() tool for self-verification (#65)

Timmy can now run his own test suite via the run_self_tests() tool.
Supports 'fast' (unit only), 'full', or specific path scopes.
Returns structured results with pass/fail counts.

Sovereign self-verification — a fundamental capability.

tests/timmy/test_introspection.py

@@ -158,3 +158,101 @@ class TestGetOllamaModelExactMatch:
             result = _get_ollama_model()
 
         assert result == "qwen3:30b"
+
+
+class TestRunSelfTests:
+    """Tests for run_self_tests() — Timmy's self-verification tool."""
+
+    def test_returns_dict_with_expected_keys(self):
+        """run_self_tests should return structured test results."""
+        from timmy.tools_intro import run_self_tests
+
+        result = run_self_tests(scope="tests/timmy/test_introspection.py")
+        assert isinstance(result, dict)
+        assert "success" in result
+        # Should have count keys when tests ran
+        if result["success"] or "passed" in result:
+            assert "passed" in result
+            assert "failed" in result
+            assert "total" in result
+
+    def test_fast_scope_skips_integration(self, monkeypatch, tmp_path):
+        """Fast scope should exclude functional/e2e/integration dirs."""
+        import subprocess
+
+        calls = []
+
+        def capture_run(*args, **kwargs):
+            calls.append(args[0] if args else kwargs.get("cmd"))
+            # Return a fake result
+            return subprocess.CompletedProcess(
+                args=args[0] if args else [], returncode=0, stdout="1 passed in 0.5s", stderr=""
+            )
+
+        monkeypatch.setattr(subprocess, "run", capture_run)
+
+        # Create fake venv so check passes
+        venv_python = tmp_path / ".venv" / "bin" / "python"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("#!/bin/sh\necho mock")
+
+        from timmy.tools_intro import run_self_tests
+
+        run_self_tests(scope="fast", _repo_root=str(tmp_path))
+        assert len(calls) == 1
+        cmd = calls[0]
+        assert "--ignore=tests/functional" in cmd
+        assert "--ignore=tests/e2e" in cmd
+
+    def test_specific_path_scope(self, monkeypatch, tmp_path):
+        """Specific path scope passes path directly to pytest."""
+        import subprocess
+
+        calls = []
+
+        def capture_run(*args, **kwargs):
+            calls.append(args[0] if args else kwargs.get("cmd"))
+            return subprocess.CompletedProcess(
+                args=args[0] if args else [], returncode=0, stdout="5 passed in 1.0s", stderr=""
+            )
+
+        monkeypatch.setattr(subprocess, "run", capture_run)
+
+        # Create fake venv so check passes
+        venv_python = tmp_path / ".venv" / "bin" / "python"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("#!/bin/sh\necho mock")
+
+        from timmy.tools_intro import run_self_tests
+
+        run_self_tests(scope="tests/timmy/", _repo_root=str(tmp_path))
+        assert len(calls) == 1
+        assert "tests/timmy/" in calls[0]
+
+    def test_missing_venv_returns_error(self, monkeypatch, tmp_path):
+        """Should handle missing venv gracefully."""
+        from timmy.tools_intro import run_self_tests
+
+        result = run_self_tests(_repo_root=str(tmp_path))
+        assert result["success"] is False
+        assert "venv" in result.get("error", "").lower()
+
+    def test_timeout_returns_error(self, monkeypatch, tmp_path):
+        """Should handle subprocess timeout gracefully."""
+        import subprocess
+
+        def timeout_run(*args, **kwargs):
+            raise subprocess.TimeoutExpired(cmd="pytest", timeout=120)
+
+        monkeypatch.setattr(subprocess, "run", timeout_run)
+
+        # Create fake venv so check passes
+        venv_python = tmp_path / ".venv" / "bin" / "python"
+        venv_python.parent.mkdir(parents=True)
+        venv_python.write_text("#!/bin/sh\necho mock")
+
+        from timmy.tools_intro import run_self_tests
+
+        result = run_self_tests(_repo_root=str(tmp_path))
+        assert result["success"] is False
+        assert "timed out" in result.get("error", "").lower()