scope frontend contracts to the feature, not to one file

93 test files read a single frontend source and asserted identifiers in it. The
MapWorkspace split showed what that costs: 24 tests went red for a move that
changed no behaviour at all. A contract belongs to the feature — a container,
its hooks, its domain layer — not to whichever file currently holds it.

232 read sites now resolve through read_feature(). The distinction that makes
this safe is direction: a *positive* contract ("this is wired") may widen,
because the identifier must still exist somewhere in the feature; a *negative*
one ("this component performs no transport") is a statement about one file, and
widening it would quietly weaken the check. The 73 single-file reads that
remain are exactly those, and a guard now enforces the rule for new tests.

Verified rather than assumed: of the 732 migrated positive assertions, 644 still
match exactly one module — as specific as before — and the other 86 already
spanned a container and its hook by nature. Two apparent misses are an artefact
of the checking regex reading an escaped newline literally.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/tests/test_sprint236_bathymetry_expansion.py

@@ -31,7 +31,7 @@ if str(SCRIPTS) not in sys.path:
     sys.path.insert(0, str(SCRIPTS))
 
 import provision_flanders_geographic_scope as flanders_scope  # noqa: E402
-from tests.frontend_contract import read_map_workspace
+from tests.frontend_contract import read_map_workspace, read_feature
 
 
 class BinaryResponse:
@@ -433,9 +433,7 @@ def test_frontend_bounds_large_area_and_dataset_catalogs() -> None:
     area_panel = (
         ROOT / "frontend" / "src" / "components" / "project" / "AreaPanel.tsx"
     ).read_text(encoding="utf-8")
-    dataset_panel = (
-        ROOT / "frontend" / "src" / "components" / "datasets" / "DatasetPanel.tsx"
-    ).read_text(encoding="utf-8")
+    dataset_panel = read_feature("datasets")
 
     assert "const AREA_CATALOG_PAGE_SIZE = 12" in area_panel
     assert "{catalogOpen ? (" in area_panel
@@ -459,18 +457,14 @@ def test_frontend_labels_flanders_scope_without_kempen_mislabeling() -> None:
 
 
 def test_frontend_uses_partitioned_bathymetry_selection_for_regional_scope() -> None:
-    app = (ROOT / "frontend" / "src" / "App.tsx").read_text(encoding="utf-8")
+    app = read_feature("shell")
     index = (ROOT / "frontend" / "index.html").read_text(encoding="utf-8")
     focus = (
         ROOT / "frontend" / "src" / "config" / "primaryFocus.ts"
     ).read_text(encoding="utf-8")
     map_workspace = read_map_workspace()
-    theme_hook = (
-        ROOT / "frontend" / "src" / "hooks" / "useMapThemeSelectionInsights.ts"
-    ).read_text(encoding="utf-8")
-    dataset_api = (
-        ROOT / "frontend" / "src" / "services" / "api" / "datasets.ts"
-    ).read_text(encoding="utf-8")
+    theme_hook = read_feature("map_workspace")
+    dataset_api = read_feature("datasets")
 
     assert "isPartitionedBathymetry" in map_workspace
     assert "regionalPartitionedThemeActive" in map_workspace