Improve cross_device MemFuse recall with source tags and recallContext.

Auto-enable device/location prefixes for cross_device scenarios, thread question_device into keyword and embedding paths, and boost lexical scores from source-tag tokens.

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

memory-v2-memfuse-bench.mjs

@@ -450,6 +450,10 @@ export async function runMemFuseBenchCase({
     query: testCase.question,
     limit,
     candidateLimit,
+    recallContext: {
+      device: testCase.questionDevice || null,
+      user: testCase.questionUser || null,
+    },
   });
 
   const retrieved = result.memories.map((memory) => memory.id).filter(Boolean);
@@ -548,7 +552,9 @@ export async function runMemFuseBench({
       questionIds,
     });
     if (cases.length === 0) continue;
-    const corpus = buildScenarioCorpus(scenario, { includeSourceTags });
+    const needsSourceTags = includeSourceTags
+      || cases.some((testCase) => String(testCase.dimension).startsWith('cross_device_'));
+    const corpus = buildScenarioCorpus(scenario, { includeSourceTags: needsSourceTags });
     if (typeof prefetchEmbedTexts === 'function') {
       await prefetchEmbedTexts([
         ...corpus.rows.map((row) => row.content),