Build presence-aware execution targets from effective configuration

internal/backend/registry.go

@@ -35,6 +35,23 @@ type Registry struct {
 	backends map[string]domain.Backend
 }
 
+// NewEffectiveRegistry stores already-validated effective backend definitions
+// under their exact configuration keys. Configuration validation and
+// normalization precede this ownership boundary.
+func NewEffectiveRegistry(definitions map[string]domain.Backend) (*Registry, error) {
+	registry := &Registry{backends: make(map[string]domain.Backend, len(definitions))}
+	for id, definition := range definitions {
+		params, err := jsonvalue.CopyMap(definition.ExtraParams)
+		if err != nil {
+			return nil, fmt.Errorf("backend %q extra parameters: %w", id, err)
+		}
+		definition.ID = id
+		definition.ExtraParams = params
+		registry.backends[id] = definition
+	}
+	return registry, nil
+}
+
 // NewRegistry constructs a registry containing maintained definitions followed
 // by consumer additions. Every ID must be unique across both groups.
 func NewRegistry(maintained, additions []domain.Backend) (*Registry, error) {

internal/backend/registry_test.go

@@ -48,6 +48,29 @@ func TestRegistryIncludesMaintainedDefinitions(t *testing.T) {
 	}
 }
 
+func TestEffectiveRegistryKeepsLiteralIDsAndOwnsValues(t *testing.T) {
+	params := map[string]any{"nested": map[string]any{"enabled": true}}
+	registry, err := backend.NewEffectiveRegistry(map[string]domain.Backend{
+		" local.v1 ": {Endpoint: validEndpoint, ExtraParams: params, ConcurrencyLimit: 2, QueueCapacitySet: true},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	params["nested"].(map[string]any)["enabled"] = false
+	selected, err := registry.GetBackend(" local.v1 ")
+	if err != nil || selected.ID != " local.v1 " || selected.ExtraParams["nested"].(map[string]any)["enabled"] != true {
+		t.Fatalf("effective registry changed identity or retained caller values: %+v, %v", selected, err)
+	}
+	if _, err := registry.GetBackend("local.v1"); !errors.Is(err, backend.ErrBackendNotFound) {
+		t.Fatalf("trimmed identity unexpectedly matched: %v", err)
+	}
+	selected.ExtraParams["nested"].(map[string]any)["enabled"] = false
+	again, _ := registry.GetBackend(" local.v1 ")
+	if again.ExtraParams["nested"].(map[string]any)["enabled"] != true {
+		t.Fatal("registry lookup exposed its stored values")
+	}
+}
+
 func TestRegistryNormalizesUniqueAdditionsAndIsolatesMutations(t *testing.T) {
 	nested := map[string]int{"limit": 2}
 	extraParams := map[string]any{