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_rc4_national_coverage.py

@@ -13,7 +13,7 @@ from app.models import Area, Dataset, Project
 from app.schemas.coverage import CoverageBBox
 from app.services.coverage_registry_service import CoverageRegistryService, THEMES, ZONES
 from app.services.vector_feature_service import VectorFeatureService
-from tests.frontend_contract import read_map_workspace
+from tests.frontend_contract import read_map_workspace, read_feature
 
 
 class FakeQuery:
@@ -473,8 +473,8 @@ def test_outside_scope_and_unknown_theme_are_explicit() -> None:
 def test_frontend_prefers_materialized_national_workspace_and_resolves_drawn_bbox() -> None:
     root = Path(__file__).parents[2]
     focus = (root / "frontend" / "src" / "config" / "primaryFocus.ts").read_text(encoding="utf-8")
-    workspace_hook = (root / "frontend" / "src" / "hooks" / "useProjectWorkspace.ts").read_text(encoding="utf-8")
-    coverage_hook = (root / "frontend" / "src" / "hooks" / "useCoverageResolver.ts").read_text(encoding="utf-8")
+    workspace_hook = read_feature("shell")
+    coverage_hook = read_feature("map_workspace")
     map_workspace = read_map_workspace()
 
     assert "Belgium and North Sea Workbench" in focus