diff --git a/src/infra/outbound/agent-delivery.ts b/src/infra/outbound/agent-delivery.ts
index 7c856598d2d..b2e94a99247 100644
--- a/src/infra/outbound/agent-delivery.ts
+++ b/src/infra/outbound/agent-delivery.ts
@@ -7,6 +7,7 @@ import {
   isDeliverableMessageChannel,
   isGatewayMessageChannel,
   normalizeMessageChannel,
+  type DeliverableMessageChannel,
   type GatewayMessageChannel,
 } from "../../utils/message-channel.js";
 import type { OutboundTargetResolution } from "./targets.js";
@@ -32,6 +33,20 @@ export function resolveAgentDeliveryPlan(params: {
   explicitThreadId?: string | number;
   accountId?: string;
   wantsDelivery: boolean;
+  /**
+   * The channel that originated the current agent turn.  When provided,
+   * overrides session-level `lastChannel` to prevent cross-channel reply
+   * routing in shared sessions (dmScope="main").
+   *
+   * @see https://github.com/openclaw/openclaw/issues/24152
+   */
+  turnSourceChannel?: string;
+  /** Turn-source `to` — paired with `turnSourceChannel`. */
+  turnSourceTo?: string;
+  /** Turn-source `accountId` — paired with `turnSourceChannel`. */
+  turnSourceAccountId?: string;
+  /** Turn-source `threadId` — paired with `turnSourceChannel`. */
+  turnSourceThreadId?: string | number;
 }): AgentDeliveryPlan {
   const requestedRaw =
     typeof params.requestedChannel === "string" ? params.requestedChannel.trim() : "";
@@ -43,11 +58,24 @@ export function resolveAgentDeliveryPlan(params: {
       ? params.explicitTo.trim()
       : undefined;
 
+  // Resolve turn-source channel for cross-channel safety.
+  const normalizedTurnSource = params.turnSourceChannel
+    ? normalizeMessageChannel(params.turnSourceChannel)
+    : undefined;
+  const turnSourceChannel =
+    normalizedTurnSource && isDeliverableMessageChannel(normalizedTurnSource)
+      ? normalizedTurnSource
+      : undefined;
+
   const baseDelivery = resolveSessionDeliveryTarget({
     entry: params.sessionEntry,
     requestedChannel: requestedChannel === INTERNAL_MESSAGE_CHANNEL ? "last" : requestedChannel,
     explicitTo,
     explicitThreadId: params.explicitThreadId,
+    turnSourceChannel,
+    turnSourceTo: params.turnSourceTo,
+    turnSourceAccountId: params.turnSourceAccountId,
+    turnSourceThreadId: params.turnSourceThreadId,
   });
 
   const resolvedChannel = (() => {
diff --git a/src/infra/outbound/targets.test.ts b/src/infra/outbound/targets.test.ts
index 5cc004a4b3a..c9976414e21 100644
--- a/src/infra/outbound/targets.test.ts
+++ b/src/infra/outbound/targets.test.ts
@@ -357,3 +357,79 @@ describe("resolveSessionDeliveryTarget", () => {
     expect(resolved.threadId).toBe(1008013);
   });
 });
+
+describe("resolveSessionDeliveryTarget — cross-channel reply guard (#24152)", () => {
+  it("uses turnSourceChannel over session lastChannel when provided", () => {
+    // Simulate: WhatsApp message originated the turn, but a Slack message
+    // arrived concurrently and updated lastChannel to "slack"
+    const resolved = resolveSessionDeliveryTarget({
+      entry: {
+        sessionId: "sess-shared",
+        updatedAt: 1,
+        lastChannel: "slack",       // <- concurrently overwritten
+        lastTo: "U0AEMECNCBV",     // <- Slack user (wrong target)
+      },
+      requestedChannel: "last",
+      turnSourceChannel: "whatsapp",    // <- originated from WhatsApp
+      turnSourceTo: "+66972796305",     // <- WhatsApp user (correct target)
+    });
+
+    expect(resolved.channel).toBe("whatsapp");
+    expect(resolved.to).toBe("+66972796305");
+  });
+
+  it("falls back to session lastChannel when turnSourceChannel is not set", () => {
+    const resolved = resolveSessionDeliveryTarget({
+      entry: {
+        sessionId: "sess-normal",
+        updatedAt: 1,
+        lastChannel: "telegram",
+        lastTo: "8587265585",
+      },
+      requestedChannel: "last",
+    });
+
+    expect(resolved.channel).toBe("telegram");
+    expect(resolved.to).toBe("8587265585");
+  });
+
+  it("respects explicit requestedChannel over turnSourceChannel", () => {
+    const resolved = resolveSessionDeliveryTarget({
+      entry: {
+        sessionId: "sess-explicit",
+        updatedAt: 1,
+        lastChannel: "slack",
+        lastTo: "U12345",
+      },
+      requestedChannel: "telegram",
+      explicitTo: "8587265585",
+      turnSourceChannel: "whatsapp",
+      turnSourceTo: "+66972796305",
+    });
+
+    // Explicit requestedChannel "telegram" is not "last", so it takes priority
+    expect(resolved.channel).toBe("telegram");
+  });
+
+  it("preserves turnSourceAccountId and turnSourceThreadId", () => {
+    const resolved = resolveSessionDeliveryTarget({
+      entry: {
+        sessionId: "sess-meta",
+        updatedAt: 1,
+        lastChannel: "slack",
+        lastTo: "U_WRONG",
+        lastAccountId: "wrong-account",
+      },
+      requestedChannel: "last",
+      turnSourceChannel: "telegram",
+      turnSourceTo: "8587265585",
+      turnSourceAccountId: "bot-123",
+      turnSourceThreadId: 42,
+    });
+
+    expect(resolved.channel).toBe("telegram");
+    expect(resolved.to).toBe("8587265585");
+    expect(resolved.accountId).toBe("bot-123");
+    expect(resolved.threadId).toBe(42);
+  });
+});
diff --git a/src/infra/outbound/targets.ts b/src/infra/outbound/targets.ts
index f03918423e2..6df0ecee6d2 100644
--- a/src/infra/outbound/targets.ts
+++ b/src/infra/outbound/targets.ts
@@ -62,13 +62,41 @@ export function resolveSessionDeliveryTarget(params: {
   fallbackChannel?: DeliverableMessageChannel;
   allowMismatchedLastTo?: boolean;
   mode?: ChannelOutboundTargetMode;
+  /**
+   * When set, this overrides the session-level `lastChannel` for "last"
+   * resolution.  This prevents cross-channel reply routing when multiple
+   * channels share the same session (dmScope = "main") and an inbound
+   * message from a different channel updates `lastChannel` while an agent
+   * turn is still in flight.
+   *
+   * Callers should set this to the channel that originated the current
+   * agent turn so the reply always routes back to the correct channel.
+   *
+   * @see https://github.com/openclaw/openclaw/issues/24152
+   */
+  turnSourceChannel?: DeliverableMessageChannel;
+  /** Turn-source `to` — paired with `turnSourceChannel`. */
+  turnSourceTo?: string;
+  /** Turn-source `accountId` — paired with `turnSourceChannel`. */
+  turnSourceAccountId?: string;
+  /** Turn-source `threadId` — paired with `turnSourceChannel`. */
+  turnSourceThreadId?: string | number;
 }): SessionDeliveryTarget {
   const context = deliveryContextFromSession(params.entry);
-  const lastChannel =
+  const sessionLastChannel =
     context?.channel && isDeliverableMessageChannel(context.channel) ? context.channel : undefined;
-  const lastTo = context?.to;
-  const lastAccountId = context?.accountId;
-  const lastThreadId = context?.threadId;
+
+  // When a turn-source channel is provided, use it instead of the session's
+  // mutable lastChannel.  This prevents a concurrent inbound from a different
+  // channel from hijacking the reply target (cross-channel privacy leak).
+  const lastChannel = params.turnSourceChannel ?? sessionLastChannel;
+  const lastTo = params.turnSourceChannel ? (params.turnSourceTo ?? context?.to) : context?.to;
+  const lastAccountId = params.turnSourceChannel
+    ? (params.turnSourceAccountId ?? context?.accountId)
+    : context?.accountId;
+  const lastThreadId = params.turnSourceChannel
+    ? (params.turnSourceThreadId ?? context?.threadId)
+    : context?.threadId;
 
   const rawRequested = params.requestedChannel ?? "last";
   const requested = rawRequested === "last" ? "last" : normalizeMessageChannel(rawRequested);