feat(core): define datasource visibility policy contract

tests/test_datasource_contract.py

@@ -8,6 +8,7 @@ from govoplan_core.core.datasources import (
     CAPABILITY_DATASOURCE_LIFECYCLE,
     CAPABILITY_DATASOURCE_ORIGINS,
     CAPABILITY_DATASOURCE_PUBLICATION,
+    CAPABILITY_POLICY_DATASOURCE_VISIBILITY,
     DatasourceCatalogueProvider,
     DatasourceArtifactBackendProvider,
     DatasourceDescriptor,
@@ -21,11 +22,14 @@ from govoplan_core.core.datasources import (
     DatasourcePublicationResult,
     DatasourceReadResult,
     DatasourceStage,
+    DatasourceVisibilityPolicyDecision,
+    DatasourceVisibilityPolicyProvider,
     datasource_catalogue,
     datasource_artifact_backend_provider,
     datasource_lifecycle,
     datasource_origins,
     datasource_publication,
+    datasource_visibility_policy_provider,
 )
 from govoplan_core.core.modules import ModuleContext, ModuleManifest
 from govoplan_core.core.registry import PlatformRegistry
@@ -161,6 +165,10 @@ class _Provider:
     def artifact_backends(self):
         return ()
 
+    def decide_datasource_visibility(self, session, *, request):
+        del session, request
+        return DatasourceVisibilityPolicyDecision(allowed=True)
+
 
 class DatasourceContractTests(unittest.TestCase):
     def test_capabilities_are_runtime_checkable_and_resolved_without_modules(self) -> None:
@@ -170,6 +178,7 @@ class DatasourceContractTests(unittest.TestCase):
         self.assertIsInstance(provider, DatasourcePublicationProvider)
         self.assertIsInstance(provider, DatasourceOriginProvider)
         self.assertIsInstance(provider, DatasourceArtifactBackendProvider)
+        self.assertIsInstance(provider, DatasourceVisibilityPolicyProvider)
         registry = PlatformRegistry()
         registry.register(
             ModuleManifest(
@@ -182,6 +191,7 @@ class DatasourceContractTests(unittest.TestCase):
                     CAPABILITY_DATASOURCE_PUBLICATION: lambda context: provider,
                     CAPABILITY_DATASOURCE_ORIGINS: lambda context: provider,
                     CAPABILITY_DATASOURCE_ARTIFACT_BACKENDS: lambda context: provider,
+                    CAPABILITY_POLICY_DATASOURCE_VISIBILITY: lambda context: provider,
                 },
             )
         )
@@ -192,6 +202,7 @@ class DatasourceContractTests(unittest.TestCase):
         self.assertIs(provider, datasource_publication(registry))
         self.assertIs(provider, datasource_origins(registry))
         self.assertIs(provider, datasource_artifact_backend_provider(registry))
+        self.assertIs(provider, datasource_visibility_policy_provider(registry))
         self.assertIsNone(datasource_catalogue(PlatformRegistry()))
 
     def test_descriptor_distinguishes_mode_kind_shape_and_materialization(self) -> None: