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_sprint27_frontend_workflow_hooks.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from pathlib import Path
+from tests.frontend_contract import read_feature
 
 
 ROOT = Path(__file__).resolve().parents[2]
@@ -18,7 +19,7 @@ def test_app_uses_export_and_quality_workflow_hooks() -> None:
 
 
 def test_export_workflow_hook_owns_export_api_calls() -> None:
-    hook = (ROOT / "frontend" / "src" / "hooks" / "useExportWorkflow.ts").read_text(encoding="utf-8")
+    hook = read_feature("exports")
 
     assert "exportsApi.listProjectExports" in hook
     assert "exportsApi.exportGeojson" in hook
@@ -30,7 +31,7 @@ def test_export_workflow_hook_owns_export_api_calls() -> None:
 
 
 def test_quality_workflow_hook_owns_quality_api_calls() -> None:
-    hook = (ROOT / "frontend" / "src" / "hooks" / "useQualityWorkflow.ts").read_text(encoding="utf-8")
+    hook = read_feature("quality")
 
     assert "qaApi.listQualityChecks" in hook
     assert "qaApi.runQa" in hook
@@ -41,9 +42,7 @@ def test_quality_workflow_hook_owns_quality_api_calls() -> None:
 
 def test_app_still_wires_quality_results_and_export_center() -> None:
     app = (ROOT / "frontend" / "src" / "App.tsx").read_text(encoding="utf-8")
-    quality_panel = (
-        ROOT / "frontend" / "src" / "components" / "quality" / "QualityResultsPanel.tsx"
-    ).read_text(encoding="utf-8")
+    quality_panel = read_feature("quality")
 
     assert "<QualityResultsPanel" in app
     assert "onRefresh={() => loadQualityChecks()}" in app