feat(context): add recall fusion and zvec workspace adapters

Introduce RRF-based recall fusion for personal/episodic/temporal paths,
zvec-grep workspace shadow probing for code executors, and a local
headroom proxy starter aligned with the fusion plan defaults.

Co-authored-by: Cursor <cursoragent@cursor.com>

temporal-recall-service/runtime-context.mjs

@@ -1,6 +1,11 @@
 import { getActiveSnapshot } from '../user-model-service/snapshot.mjs';
 import { createUmsPool, isUmsDatabaseConfigured } from '../user-model-service/db.mjs';
 import { resolveCanonicalUserId } from '../user-model-service/canonical-user.mjs';
+import {
+  buildRecallFusionResolvedEvent,
+  fuseRecallCandidates,
+  resolveRecallFusionMode,
+} from '../recall-fusion.mjs';
 import { buildContextPlan } from './context-planner.mjs';
 import { queryTemporalRecall } from './recall.mjs';
 
@@ -164,12 +169,30 @@ export async function resolveRuntimeContext(input) {
     }
   }
 
+  let recallFusion = null;
+  if (resolveRecallFusionMode() !== 'off' && temporalRecall) {
+    const temporalItems = [
+      ...(Array.isArray(temporalRecall.items) ? temporalRecall.items : []),
+      ...(Array.isArray(temporalRecall.groups)
+        ? temporalRecall.groups.flatMap((group) => group.items ?? [])
+        : []),
+    ];
+    if (temporalItems.length > 0) {
+      recallFusion = buildRecallFusionResolvedEvent(fuseRecallCandidates({
+        query,
+        temporalItems,
+        limit: plan.output?.max_items ?? 20,
+      }));
+    }
+  }
+
   const injectionEnabled = Boolean(blocks.temporal || blocks.snapshot);
   return {
     enabled: true,
     plan,
     temporalRecall,
     userSnapshot,
+    recallFusion,
     injectionEnabled,
     blocks,
     injectionText: [blocks.snapshot, blocks.temporal].filter(Boolean).join('\n\n'),