From 65ad9a4262e38d1407b75660cd65a68580579865 Mon Sep 17 00:00:00 2001
From: Rodrigo Uroz <rodrigouroz@gmail.com>
Date: Wed, 11 Feb 2026 20:56:56 +0000
Subject: [PATCH] Memory: fix MMR tie-break and temporal timestamp dedupe

---
 src/memory/mmr.ts            |  2 +-
 src/memory/temporal-decay.ts | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/memory/mmr.ts b/src/memory/mmr.ts
index ec87b9e3ff3..dc7144db10c 100644
--- a/src/memory/mmr.ts
+++ b/src/memory/mmr.ts
@@ -163,7 +163,7 @@ export function mmrRerank<T extends MMRItem>(items: T[], config: Partial<MMRConf
       // Use original score as tiebreaker (higher is better)
       if (
         mmrScore > bestMMRScore ||
-        (mmrScore === bestMMRScore && (bestItem === null || candidate.score > bestItem.score))
+        (mmrScore === bestMMRScore && candidate.score > (bestItem?.score ?? -Infinity))
       ) {
         bestMMRScore = mmrScore;
         bestItem = candidate;
diff --git a/src/memory/temporal-decay.ts b/src/memory/temporal-decay.ts
index adaf2ee4c37..d3643fc5c21 100644
--- a/src/memory/temporal-decay.ts
+++ b/src/memory/temporal-decay.ts
@@ -132,21 +132,22 @@ export async function applyTemporalDecayToHybridResults<
   }
 
   const nowMs = params.nowMs ?? Date.now();
-  const timestampCache = new Map<string, Date | null>();
+  const timestampPromiseCache = new Map<string, Promise<Date | null>>();
 
   return Promise.all(
     params.results.map(async (entry) => {
       const cacheKey = `${entry.source}:${entry.path}`;
-      if (!timestampCache.has(cacheKey)) {
-        const timestamp = await extractTimestamp({
+      let timestampPromise = timestampPromiseCache.get(cacheKey);
+      if (!timestampPromise) {
+        timestampPromise = extractTimestamp({
           filePath: entry.path,
           source: entry.source,
           workspaceDir: params.workspaceDir,
         });
-        timestampCache.set(cacheKey, timestamp);
+        timestampPromiseCache.set(cacheKey, timestampPromise);
       }
 
-      const timestamp = timestampCache.get(cacheKey) ?? null;
+      const timestamp = await timestampPromise;
       if (!timestamp) {
         return entry;
       }