fix: gate workspace diagnostic migration

backend/src/workspaces/runtime-renderer.ts

@@ -1,6 +1,6 @@
 import { stringify } from "yaml";
 import { buildInstallationContract } from "./contracts.js";
-import { validateCanonicalWorkspace, type CanonicalWorkspace } from "./schema.js";
+import { validateCanonicalWorkspace, type WorkspaceDescriptor } from "./schema.js";
 import type { ResolvedBinding } from "./bindings.js";
 
 export interface RuntimeBindings {
@@ -74,7 +74,7 @@ function placeholderConnection(identity: { database: string; schema: string }):
 
 /** Render the compatibility fields consumed by the current Python harness. */
 export function renderRuntimeConfig(
-  workspace: CanonicalWorkspace,
+  workspace: WorkspaceDescriptor,
   bindings: RuntimeBindings,
   paths: RuntimePaths,
 ): string {