feat: revision-qualified annotations root for pinned runtimes (P5)

backend/src/workspaces/runtime-config-lease.ts

@@ -240,7 +240,7 @@ function readSnapshotWorkspace(snapshotPath: string): {
   }
 }
 
-function runtimePaths(dataRoot: string, workspaceId: string): RuntimePaths {
+function runtimePaths(dataRoot: string, workspaceId: string, workspaceRevision?: string): RuntimePaths {
   if (!isAbsolute(dataRoot)) throw new Error("registry workspace runtime requires an absolute data root");
   const root = join(dataRoot, "sessions", workspaceId);
   return {
@@ -248,6 +248,9 @@ function runtimePaths(dataRoot: string, workspaceId: string): RuntimePaths {
     artifacts: join(root, "artifacts"),
     indexes: join(root, "indexes"),
     memory: join(root, "memory"),
+    ...(workspaceRevision === undefined
+      ? {}
+      : { annotations_root: join(dataRoot, "sessions", workspaceId, "revisions", workspaceRevision, "artifacts") }),
   };
 }
 
@@ -308,7 +311,7 @@ function renderWorkspaceRuntimeFromWorkspace(options: {
     workspaceId: options.workspaceId,
     workspaceRevision: options.workspaceRevision,
     revisionContentRoot: options.revisionContentRoot,
-    runtimePaths: runtimePaths(options.dataRoot, options.workspaceId),
+    runtimePaths: runtimePaths(options.dataRoot, options.workspaceId, options.workspaceRevision),
     installationOverlay: overlay,
     bindings,
     bindingDigest: stableBindingDigest(bindings),
@@ -316,7 +319,7 @@ function renderWorkspaceRuntimeFromWorkspace(options: {
     renderedConfig: renderRuntimeConfig(
       options.workspace,
       bindings,
-      runtimePaths(options.dataRoot, options.workspaceId),
+      runtimePaths(options.dataRoot, options.workspaceId, options.workspaceRevision),
       context,
       overlay,
       options.semanticRuntime,

backend/src/workspaces/runtime-renderer.ts

@@ -10,6 +10,8 @@ export interface RuntimePaths {
   artifacts: string;
   indexes: string;
   memory: string;
+  /** Revision-qualified root for curated FK annotations (P5); optional for legacy callers. */
+  annotations_root?: string;
 }
 
 export interface RuntimeIdentity {