diff --git a/src/config/sessions/delivery-info.test.ts b/src/config/sessions/delivery-info.test.ts
index e2c6897d87..23717338ea 100644
--- a/src/config/sessions/delivery-info.test.ts
+++ b/src/config/sessions/delivery-info.test.ts
@@ -17,7 +17,7 @@ vi.mock("./store.js", () => ({
   loadSessionStore: () => storeState.store,
 }));
 
-import { extractDeliveryInfo } from "./delivery-info.js";
+import { extractDeliveryInfo, parseSessionThreadInfo } from "./delivery-info.js";
 
 const buildEntry = (deliveryContext: SessionEntry["deliveryContext"]): SessionEntry => ({
   sessionId: "session-1",
@@ -30,6 +30,25 @@ beforeEach(() => {
 });
 
 describe("extractDeliveryInfo", () => {
+  it("parses base session and thread/topic ids", () => {
+    expect(parseSessionThreadInfo("agent:main:telegram:group:1:topic:55")).toEqual({
+      baseSessionKey: "agent:main:telegram:group:1",
+      threadId: "55",
+    });
+    expect(parseSessionThreadInfo("agent:main:slack:channel:C1:thread:123.456")).toEqual({
+      baseSessionKey: "agent:main:slack:channel:C1",
+      threadId: "123.456",
+    });
+    expect(parseSessionThreadInfo("agent:main:telegram:dm:user-1")).toEqual({
+      baseSessionKey: "agent:main:telegram:dm:user-1",
+      threadId: undefined,
+    });
+    expect(parseSessionThreadInfo(undefined)).toEqual({
+      baseSessionKey: undefined,
+      threadId: undefined,
+    });
+  });
+
   it("returns deliveryContext for direct session keys", () => {
     const sessionKey = "agent:main:webchat:dm:user-123";
     storeState.store[sessionKey] = buildEntry({
diff --git a/src/config/sessions/delivery-info.ts b/src/config/sessions/delivery-info.ts
index 006f1db449..b8c5a637c1 100644
--- a/src/config/sessions/delivery-info.ts
+++ b/src/config/sessions/delivery-info.ts
@@ -6,12 +6,12 @@ import { loadSessionStore } from "./store.js";
  * Extract deliveryContext and threadId from a sessionKey.
  * Supports both :thread: (most channels) and :topic: (Telegram).
  */
-export function extractDeliveryInfo(sessionKey: string | undefined): {
-  deliveryContext: { channel?: string; to?: string; accountId?: string } | undefined;
+export function parseSessionThreadInfo(sessionKey: string | undefined): {
+  baseSessionKey: string | undefined;
   threadId: string | undefined;
 } {
   if (!sessionKey) {
-    return { deliveryContext: undefined, threadId: undefined };
+    return { baseSessionKey: undefined, threadId: undefined };
   }
   const topicIndex = sessionKey.lastIndexOf(":topic:");
   const threadIndex = sessionKey.lastIndexOf(":thread:");
@@ -22,6 +22,17 @@ export function extractDeliveryInfo(sessionKey: string | undefined): {
   const threadIdRaw =
     markerIndex === -1 ? undefined : sessionKey.slice(markerIndex + marker.length);
   const threadId = threadIdRaw?.trim() || undefined;
+  return { baseSessionKey, threadId };
+}
+
+export function extractDeliveryInfo(sessionKey: string | undefined): {
+  deliveryContext: { channel?: string; to?: string; accountId?: string } | undefined;
+  threadId: string | undefined;
+} {
+  const { baseSessionKey, threadId } = parseSessionThreadInfo(sessionKey);
+  if (!sessionKey || !baseSessionKey) {
+    return { deliveryContext: undefined, threadId };
+  }
 
   let deliveryContext: { channel?: string; to?: string; accountId?: string } | undefined;
   try {
@@ -29,7 +40,7 @@ export function extractDeliveryInfo(sessionKey: string | undefined): {
     const storePath = resolveStorePath(cfg.session?.store);
     const store = loadSessionStore(storePath);
     let entry = store[sessionKey];
-    if (!entry?.deliveryContext && markerIndex !== -1 && baseSessionKey) {
+    if (!entry?.deliveryContext && baseSessionKey !== sessionKey) {
       entry = store[baseSessionKey];
     }
     if (entry?.deliveryContext) {
diff --git a/src/gateway/server-restart-sentinel.ts b/src/gateway/server-restart-sentinel.ts
index 32bff530b6..44e246282a 100644
--- a/src/gateway/server-restart-sentinel.ts
+++ b/src/gateway/server-restart-sentinel.ts
@@ -3,6 +3,7 @@ import { resolveAnnounceTargetFromKey } from "../agents/tools/sessions-send-help
 import { normalizeChannelId } from "../channels/plugins/index.js";
 import type { CliDeps } from "../cli/deps.js";
 import { resolveMainSessionKeyFromConfig } from "../config/sessions.js";
+import { parseSessionThreadInfo } from "../config/sessions/delivery-info.js";
 import { deliverOutboundPayloads } from "../infra/outbound/deliver.js";
 import { resolveOutboundTarget } from "../infra/outbound/targets.js";
 import {
@@ -30,17 +31,7 @@ export async function scheduleRestartSentinelWake(_params: { deps: CliDeps }) {
     return;
   }
 
-  // Extract topic/thread ID from sessionKey (supports both :topic: and :thread:)
-  // Telegram uses :topic:, other platforms use :thread:
-  const topicIndex = sessionKey.lastIndexOf(":topic:");
-  const threadIndex = sessionKey.lastIndexOf(":thread:");
-  const markerIndex = Math.max(topicIndex, threadIndex);
-  const marker = topicIndex > threadIndex ? ":topic:" : ":thread:";
-
-  const baseSessionKey = markerIndex === -1 ? sessionKey : sessionKey.slice(0, markerIndex);
-  const threadIdRaw =
-    markerIndex === -1 ? undefined : sessionKey.slice(markerIndex + marker.length);
-  const sessionThreadId = threadIdRaw?.trim() || undefined;
+  const { baseSessionKey, threadId: sessionThreadId } = parseSessionThreadInfo(sessionKey);
 
   const { cfg, entry } = loadSessionEntry(sessionKey);
   const parsedTarget = resolveAnnounceTargetFromKey(baseSessionKey);
@@ -49,7 +40,7 @@ export async function scheduleRestartSentinelWake(_params: { deps: CliDeps }) {
   // Handles race condition where store wasn't flushed before restart
   const sentinelContext = payload.deliveryContext;
   let sessionDeliveryContext = deliveryContextFromSession(entry);
-  if (!sessionDeliveryContext && markerIndex !== -1 && baseSessionKey) {
+  if (!sessionDeliveryContext && baseSessionKey && baseSessionKey !== sessionKey) {
     const { entry: baseEntry } = loadSessionEntry(baseSessionKey);
     sessionDeliveryContext = deliveryContextFromSession(baseEntry);
   }