refactor(paths): v3 design - explicit initialize_paths + frozen PathsConfig singleton

tests/conftest.py

@@ -34,7 +34,7 @@ if _config_override_arg is None:
  _config_override_arg = _ISOLATION_WORKSPACE / "config_overrides.toml"
 
 from src import paths as _paths  # noqa: E402
-_paths.set_config_override(_config_override_arg)
+_paths.initialize_paths(_config_override_arg)
 
 thirdparty_dir = os.path.join(os.path.dirname(__file__), "..", "thirdparty")
 if thirdparty_dir not in sys.path:
@@ -381,11 +381,11 @@ def isolate_workspace(monkeypatch) -> Generator[None, None, None]:
  (tests/artifacts/_isolation_workspace_<RUN_ID>/). Also writes placeholder
  TOML files for the redirected paths. NO SLOP_* env vars are set;
  src/paths.py reads the overrides from config.toml [paths] (with env var
- as fallback if needed).
- [C: tests/conftest.py:_ISOLATION_WORKSPACE, src/paths.py:_resolve_path]
+ as fallback if needed). Also re-initializes the paths singleton so every
+ getter sees the test-workspace overrides.
+ [C: tests/conftest.py:_ISOLATION_WORKSPACE, src/paths.py:initialize_paths]
  """
  from src import paths as _paths
- _paths.reset_resolved()
 
  test_workspace = _ISOLATION_WORKSPACE
 
@@ -421,14 +421,15 @@ def isolate_workspace(monkeypatch) -> Generator[None, None, None]:
 @pytest.fixture(autouse=True)
 def reset_paths() -> Generator[None, None, None]:
  """
- 
-  
-   Autouse fixture that resets the paths global state before each test.
+ Autouse fixture that resets the paths singleton before each test.
+ The isolate_workspace fixture re-initializes paths before the test runs,
+ so reset_paths is a no-op here (PathsConfig is frozen at init time,
+ the per-getter cache is gone). Kept as a marker for backward compatibility
+ with test code that asserts the singleton is cleared at test boundaries.
  """
  from src import paths
- paths.reset_resolved()
  yield
- paths.reset_resolved()
+ paths.reset_paths()
 
 @pytest.fixture(autouse=True)
 def reset_ai_client() -> Generator[None, None, None]: