diff --git a/src/auto-reply/reply/agent-runner.ts b/src/auto-reply/reply/agent-runner.ts
index c80704f4cb9..36f0a173fa7 100644
--- a/src/auto-reply/reply/agent-runner.ts
+++ b/src/auto-reply/reply/agent-runner.ts
@@ -294,6 +294,11 @@ export async function runReplyAgent(params: {
       fallbackNoticeSelectedModel: undefined,
       fallbackNoticeActiveModel: undefined,
       fallbackNoticeReason: undefined,
+      lastMessagingToolSessionId: undefined,
+      lastMessagingToolSentAt: undefined,
+      lastMessagingToolSentTexts: undefined,
+      lastMessagingToolSentMediaUrls: undefined,
+      lastMessagingToolSentTargets: undefined,
     };
     const agentId = resolveAgentIdFromSessionKey(sessionKey);
     const nextSessionFile = resolveSessionTranscriptPath(
@@ -423,6 +428,7 @@ export async function runReplyAgent(params: {
     if (sessionDedupeEntry) {
       const now = Date.now();
       if (sentTexts.length || sentMediaUrls.length || sentTargets.length) {
+        sessionDedupeEntry.lastMessagingToolSessionId = followupRun.run.sessionId;
         sessionDedupeEntry.lastMessagingToolSentAt = now;
         sessionDedupeEntry.lastMessagingToolSentTexts = sentTexts;
         sessionDedupeEntry.lastMessagingToolSentMediaUrls = sentMediaUrls;
@@ -431,6 +437,7 @@ export async function runReplyAgent(params: {
         typeof sessionDedupeEntry.lastMessagingToolSentAt === "number" &&
         now - sessionDedupeEntry.lastMessagingToolSentAt > RECENT_MESSAGING_TOOL_DEDUPE_WINDOW_MS
       ) {
+        delete sessionDedupeEntry.lastMessagingToolSessionId;
         delete sessionDedupeEntry.lastMessagingToolSentAt;
         delete sessionDedupeEntry.lastMessagingToolSentTexts;
         delete sessionDedupeEntry.lastMessagingToolSentMediaUrls;
diff --git a/src/auto-reply/reply/followup-runner.test.ts b/src/auto-reply/reply/followup-runner.test.ts
index add48e3a129..db4a086923c 100644
--- a/src/auto-reply/reply/followup-runner.test.ts
+++ b/src/auto-reply/reply/followup-runner.test.ts
@@ -421,6 +421,7 @@ describe("createFollowupRunner messaging tool dedupe", () => {
     const sessionEntry: SessionEntry = {
       sessionId: "session",
       updatedAt: Date.now(),
+      lastMessagingToolSessionId: "session",
       lastMessagingToolSentAt: Date.now(),
       lastMessagingToolSentTexts: ["hello world!"],
       lastMessagingToolSentTargets: [{ tool: "message", provider: "telegram", to: "123" }],
@@ -446,6 +447,38 @@ describe("createFollowupRunner messaging tool dedupe", () => {
     expect(onBlockReply).not.toHaveBeenCalled();
   });
 
+  it("does not use session-level dedupe from a previous session id", async () => {
+    const onBlockReply = vi.fn(async () => {});
+    const sessionEntry: SessionEntry = {
+      sessionId: "current-session",
+      updatedAt: Date.now(),
+      lastMessagingToolSessionId: "old-session",
+      lastMessagingToolSentAt: Date.now(),
+      lastMessagingToolSentTexts: ["hello world!"],
+      lastMessagingToolSentTargets: [{ tool: "message", provider: "telegram", to: "123" }],
+    };
+    const sessionStore: Record<string, SessionEntry> = { main: sessionEntry };
+
+    runEmbeddedPiAgentMock.mockResolvedValueOnce({
+      payloads: [{ text: "hello world!" }],
+      meta: {},
+    });
+
+    const runner = createMessagingDedupeRunner(onBlockReply, {
+      sessionEntry,
+      sessionStore,
+      sessionKey: "main",
+    });
+
+    await runner({
+      ...baseQueuedRun("telegram"),
+      originatingTo: "123",
+      run: { ...baseQueuedRun("telegram").run, sessionId: "current-session" },
+    });
+
+    expect(onBlockReply).toHaveBeenCalled();
+  });
+
   it("does not use session-level text dedupe when recent target does not match", async () => {
     const onBlockReply = vi.fn(async () => {});
     const sessionEntry: SessionEntry = {
diff --git a/src/auto-reply/reply/followup-runner.ts b/src/auto-reply/reply/followup-runner.ts
index a8f0222d090..2793f588c94 100644
--- a/src/auto-reply/reply/followup-runner.ts
+++ b/src/auto-reply/reply/followup-runner.ts
@@ -333,6 +333,7 @@ export function createFollowupRunner(params: {
       const now = Date.now();
       const recentWindowActive =
         typeof sessionEntry?.lastMessagingToolSentAt === "number" &&
+        sessionEntry?.lastMessagingToolSessionId === queued.run.sessionId &&
         now - sessionEntry.lastMessagingToolSentAt <= RECENT_MESSAGING_TOOL_DEDUPE_WINDOW_MS;
       const recentTargetMatch =
         recentWindowActive &&
diff --git a/src/config/sessions/types.ts b/src/config/sessions/types.ts
index e133b4ae300..06ad3a53441 100644
--- a/src/config/sessions/types.ts
+++ b/src/config/sessions/types.ts
@@ -76,6 +76,8 @@ export type SessionEntry = {
   lastHeartbeatSentAt?: number;
   /** Timestamp (ms) for the most recent message-tool send fingerprint (cross-run dedupe). */
   lastMessagingToolSentAt?: number;
+  /** Session id that produced the most recent message-tool dedupe fingerprint. */
+  lastMessagingToolSessionId?: string;
   /** Recently sent message-tool text payloads for short-window cross-run dedupe. */
   lastMessagingToolSentTexts?: string[];
   /** Recently sent message-tool media urls for short-window cross-run dedupe. */