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_sprint180_premium_workbench.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]
@@ -11,8 +12,8 @@ def read(path: str) -> str:
 
 
 def test_workbench_uses_grouped_navigation_and_optional_inspector() -> None:
-    app = read("frontend/src/App.tsx")
-    inspector = read("frontend/src/components/inspector/WorkbenchInspector.tsx")
+    app = read_feature("shell")
+    inspector = read_feature("shell")
 
     assert "import './styles/premium.css'" in app
     assert "const workspaceNavGroups" in app
@@ -29,7 +30,7 @@ def test_workbench_uses_grouped_navigation_and_optional_inspector() -> None:
 def test_data_creation_forms_are_progressively_disclosed() -> None:
     project = read("frontend/src/components/project/ProjectPanel.tsx")
     area = read("frontend/src/components/project/AreaPanel.tsx")
-    dataset = read("frontend/src/components/datasets/DatasetPanel.tsx")
+    dataset = read_feature("datasets")
     css = read("frontend/src/styles/premium.css")
 
     assert '<details className="data-panel-form-block technical-management-block">' in project
@@ -44,7 +45,7 @@ def test_data_creation_forms_are_progressively_disclosed() -> None:
 
 
 def test_map_prioritizes_controls_map_and_collapsed_diagnostics() -> None:
-    map_workspace = read("frontend/src/components/map/MapWorkspace.tsx")
+    map_workspace = read_feature("map_workspace")
     css = read("frontend/src/styles/premium.css")
 
     control_index = map_workspace.index('className="map-control-surface"')
@@ -66,7 +67,7 @@ def test_ai_workspaces_prioritize_runs_and_collapse_registry_detail() -> None:
             read("frontend/src/components/detection/DetectionModelManagement.tsx"),
         )
     )
-    segmentation = read("frontend/src/components/segmentation/SegmentationLab.tsx")
+    segmentation = read_feature("segmentation")
     css = read("frontend/src/styles/premium.css")
 
     assert '<details className="ai-lab-model-surface" aria-label="Technische modelmogelijkheden">' in detection