feat(dataflow): govern reusable definition updates

webui/src/api/dataflow.ts

@@ -95,6 +95,11 @@ export type PipelineGovernance = {
   derived_from_pipeline_id?: string | null;
   derived_from_revision?: number | null;
   derived_from_hash?: string | null;
+  source_available: boolean;
+  source_name?: string | null;
+  source_current_revision?: number | null;
+  source_current_hash?: string | null;
+  update_available: boolean;
   derivation_provenance: Record<string, unknown>;
   actions: Record<string, DefinitionActionDecision>;
 };
@@ -505,6 +510,23 @@ export function deriveDataflowPipeline(
   );
 }
 
+export function rebaseDataflowPipeline(
+  settings: ApiSettings,
+  pipelineId: string,
+  payload: {
+    expected_revision: number;
+    source_revision: number;
+    source_hash: string;
+    reason: string;
+  }
+): Promise<Pipeline> {
+  return apiFetch(
+    settings,
+    `/api/v1/dataflow/pipelines/${encodeURIComponent(pipelineId)}/rebase`,
+    { method: "POST", body: JSON.stringify(payload) }
+  );
+}
+
 export function dataflowScopeReferenceProvider(
   settings: ApiSettings,
   scopeType: "user" | "group"
@@ -564,7 +586,7 @@ export function deleteDataflowTrigger(
 
 export function validateDataflowPipeline(
   settings: ApiSettings,
-  payload: { graph?: PipelineGraph; sql_text?: string; source_nodes?: PipelineGraphNode[] }
+  payload: { pipeline_id?: string | null; graph?: PipelineGraph; sql_text?: string; source_nodes?: PipelineGraphNode[] }
 ): Promise<PipelineValidation> {
   return apiFetch<PipelineValidation>(settings, "/api/v1/dataflow/validate", {
     method: "POST",