diff --git a/src/auto-reply/reply/agent-runner-memory.ts b/src/auto-reply/reply/agent-runner-memory.ts
index 267326a7e20..ebef0f807ed 100644
--- a/src/auto-reply/reply/agent-runner-memory.ts
+++ b/src/auto-reply/reply/agent-runner-memory.ts
@@ -526,15 +526,16 @@ export async function runMemoryFlushIfNeeded(params: {
       (params.sessionKey ? activeSessionStore?.[params.sessionKey]?.compactionCount : 0) ??
       0;
     if (memoryCompactionCompleted) {
-      const nextCount = await incrementCompactionCount({
+      await incrementCompactionCount({
         sessionEntry: activeSessionEntry,
         sessionStore: activeSessionStore,
         sessionKey: params.sessionKey,
         storePath: params.storePath,
       });
-      if (typeof nextCount === "number") {
-        memoryFlushCompactionCount = nextCount;
-      }
+      // Do NOT reassign memoryFlushCompactionCount to the post-increment value.
+      // Keeping it at the pre-increment value ensures the next compaction cycle
+      // sees different counters, allowing memoryFlush to fire every cycle
+      // instead of every other. See #12590.
     }
     if (params.storePath && params.sessionKey) {
       try {