fix: address PR #14 review feedback (exposure layer)

leadforge/exposure/filters.py

@@ -34,12 +34,19 @@ class BundleFilter:
 }
 
 
-def get_filter(mode: ExposureMode) -> BundleFilter:
+def get_filter(mode: str | ExposureMode) -> BundleFilter:
     """Return the :class:`BundleFilter` for *mode*.
 
+    Args:
+        mode: An :class:`ExposureMode` or its string value.
+
     Raises:
+        ValueError: if *mode* is a string that is not a valid
+            :class:`ExposureMode` value.
         KeyError: if *mode* has no registered filter (should never happen
             with well-typed callers, but guards against future enum additions
             that forget to update ``FILTERS``).
     """
+    if isinstance(mode, str):
+        mode = ExposureMode(mode)
     return FILTERS[mode]

leadforge/exposure/redaction.py → leadforge/exposure/metadata.py

@@ -39,15 +39,11 @@ def write_metadata_dir(bundle: WorldBundle, bundle_root: Path) -> None:
     meta_dir = bundle_root / "metadata"
     meta_dir.mkdir(exist_ok=True)
 
-    # ------------------------------------------------------------------
     # graph.json + graph.graphml
-    # ------------------------------------------------------------------
     (meta_dir / "graph.json").write_text(bundle.world_graph.to_json())
     (meta_dir / "graph.graphml").write_text(bundle.world_graph.to_graphml())
 
-    # ------------------------------------------------------------------
     # latent_registry.json
-    # ------------------------------------------------------------------
     ls = bundle.population.latent_state
     latent_registry: dict[str, object] = {
         "account_latents": ls.account_latents,
@@ -56,19 +52,15 @@ def write_metadata_dir(bundle: WorldBundle, bundle_root: Path) -> None:
     }
     (meta_dir / "latent_registry.json").write_text(json.dumps(latent_registry, indent=2))
 
-    # ------------------------------------------------------------------
     # world_spec.json — config + narrative (if present)
-    # ------------------------------------------------------------------
     config_dict = dataclasses.asdict(bundle.spec.config)
     narrative_dict = (
         dataclasses.asdict(bundle.spec.narrative) if bundle.spec.narrative is not None else None
     )
     world_spec_dict = {"config": config_dict, "narrative": narrative_dict}
     (meta_dir / "world_spec.json").write_text(json.dumps(world_spec_dict, indent=2))
 
-    # ------------------------------------------------------------------
     # mechanism_summary.json
-    # ------------------------------------------------------------------
     # Reconstruct the mechanism assignment with the same RNG substream that
     # was used during simulation — produces the identical parameter values.
     motif_family = bundle.world_graph.motif_family

leadforge/exposure/modes.py

@@ -8,12 +8,13 @@
 
 from __future__ import annotations
 
+import shutil
 from pathlib import Path
 from typing import TYPE_CHECKING
 
 from leadforge.core.enums import ExposureMode
 from leadforge.exposure.filters import get_filter
-from leadforge.exposure.redaction import write_metadata_dir
+from leadforge.exposure.metadata import write_metadata_dir
 
 if TYPE_CHECKING:
     from leadforge.core.models import WorldBundle
@@ -23,14 +24,18 @@ def apply_exposure(bundle: WorldBundle, bundle_root: Path, mode: ExposureMode) -
     """Apply exposure filtering for *mode* to the bundle at *bundle_root*.
 
     For ``research_instructor`` mode this writes the ``metadata/``
-    directory with all hidden-truth files.  For ``student_public`` mode the
-    directory is not created and no hidden truth is published.
+    directory with all hidden-truth files.  For ``student_public`` mode any
+    pre-existing ``metadata/`` directory is removed so that hidden truth
+    is never accidentally published when reusing an output path.
 
     Args:
         bundle: Fully populated :class:`~leadforge.core.models.WorldBundle`.
         bundle_root: Root directory of the written bundle (must already exist).
         mode: Exposure mode that controls which artefacts are published.
     """
     filt = get_filter(mode)
+    meta_dir = bundle_root / "metadata"
     if filt.write_metadata:
         write_metadata_dir(bundle, bundle_root)
+    elif meta_dir.exists():
+        shutil.rmtree(meta_dir)

tests/exposure/test_exposure.py

@@ -42,10 +42,15 @@ def test_research_instructor_writes_metadata(self) -> None:
         f = get_filter(ExposureMode.research_instructor)
         assert f.write_metadata is True
 
+    def test_get_filter_accepts_string(self) -> None:
+        f = get_filter("student_public")
+        assert isinstance(f, BundleFilter)
+        assert f.write_metadata is False
+
     def test_unknown_mode_raises(self) -> None:
-        """get_filter must raise KeyError for an unregistered mode string."""
-        with pytest.raises(KeyError):
-            get_filter("totally_fake_mode")  # type: ignore[arg-type]
+        """get_filter must raise ValueError for an invalid mode string."""
+        with pytest.raises(ValueError, match="totally_fake_mode"):
+            get_filter("totally_fake_mode")
 
 
 # ---------------------------------------------------------------------------
@@ -68,6 +73,23 @@ def test_core_files_present(self, tmp_path: Path) -> None:
         assert (tmp_path / "tables").is_dir()
         assert (tmp_path / "tasks").is_dir()
 
+    def test_reused_output_dir_removes_metadata_when_switching_to_student_public(
+        self, tmp_path: Path
+    ) -> None:
+        instructor_bundle = _make_bundle("research_instructor")
+        instructor_bundle.save(str(tmp_path))
+        assert (tmp_path / "metadata").is_dir()
+
+        public_bundle = _make_bundle("student_public")
+        public_bundle.save(str(tmp_path))
+
+        assert not (tmp_path / "metadata").exists()
+        assert (tmp_path / "manifest.json").exists()
+        assert (tmp_path / "dataset_card.md").exists()
+        assert (tmp_path / "feature_dictionary.csv").exists()
+        assert (tmp_path / "tables").is_dir()
+        assert (tmp_path / "tasks").is_dir()
+
 
 class TestResearchInstructorMode:
     def test_metadata_dir_created(self, tmp_path: Path) -> None: