diff --git a/src/gateway/chat-abort.test.ts b/src/gateway/chat-abort.test.ts
index 5d74382e624..5a1d464022e 100644
--- a/src/gateway/chat-abort.test.ts
+++ b/src/gateway/chat-abort.test.ts
@@ -505,6 +505,26 @@ describe("resolveInFlightRunSnapshot", () => {
     ).toEqual({ runId: "run-a", text: "main agent global text" });
   });
 
+  it("resolves bare global history snapshots to the default agent", () => {
+    const controllers = new Map<string, ChatAbortControllerEntry>([
+      ["run-main", inFlightEntry("global", { agentId: "main", startedAtMs: 1_000 })],
+      ["run-work", inFlightEntry("global", { agentId: "work", startedAtMs: 2_000 })],
+    ]);
+    const buffers = new Map([
+      ["run-main", "main default text"],
+      ["run-work", "work global text"],
+    ]);
+
+    expect(
+      snap({
+        chatAbortControllers: controllers,
+        chatRunBuffers: buffers,
+        sessionKey: "global",
+        defaultAgentId: "main",
+      }),
+    ).toEqual({ runId: "run-main", text: "main default text" });
+  });
+
   it("prefers the newest startedAtMs when several runs match the same session+agent", () => {
     // A fast restart/retry/stale-controller race can leave two active entries for
     // the same key; selection must not depend on Map insertion order. Insert the
diff --git a/src/gateway/chat-abort.ts b/src/gateway/chat-abort.ts
index cf8521117f8..7573480e0ca 100644
--- a/src/gateway/chat-abort.ts
+++ b/src/gateway/chat-abort.ts
@@ -191,12 +191,17 @@ export function resolveInFlightRunSnapshot(params: {
     if (entry.sessionKey !== key) {
       return false;
     }
-    if (key !== "global" || params.agentId === undefined) {
+    if (key !== "global") {
       return true;
     }
+    const requestedAgentId =
+      normalizeActiveAgentId(params.agentId) ?? normalizeActiveAgentId(params.defaultAgentId);
+    if (!requestedAgentId) {
+      return false;
+    }
     const runAgentId =
       normalizeActiveAgentId(entry.agentId) ?? normalizeActiveAgentId(params.defaultAgentId);
-    return runAgentId === normalizeActiveAgentId(params.agentId);
+    return runAgentId === requestedAgentId;
   };
   // Some callers/tests run without populated run state; guard like
   // collectTrackedActiveSessionRuns so a missing map is a no-op, not a throw.
diff --git a/src/gateway/server-methods/chat.ts b/src/gateway/server-methods/chat.ts
index 190011ec7b0..04457ef5397 100644
--- a/src/gateway/server-methods/chat.ts
+++ b/src/gateway/server-methods/chat.ts
@@ -2533,14 +2533,15 @@ export const chatHandlers: GatewayRequestHandlers = {
       agentId: selectedAgent.agentId,
       modelCatalog,
     });
+    const defaultAgentId = resolveDefaultAgentId(cfg);
+    const activeRunAgentId =
+      canonicalKey === "global" ? (selectedAgent.agentId ?? defaultAgentId) : selectedAgent.agentId;
     sessionInfo.hasActiveRun = hasTrackedActiveSessionRun({
       context,
       requestedKey: sessionKey,
       canonicalKey,
-      ...(canonicalKey === "global" && selectedAgent.agentId
-        ? { agentId: selectedAgent.agentId }
-        : {}),
-      defaultAgentId: resolveDefaultAgentId(cfg),
+      ...(activeRunAgentId ? { agentId: activeRunAgentId } : {}),
+      defaultAgentId,
     });
     const defaults = getSessionDefaults(cfg, modelCatalog, { allowPluginNormalization: false });
     const thinkingLevel = sessionInfo.thinkingLevel ?? sessionInfo.thinkingDefault;
@@ -2554,8 +2555,8 @@ export const chatHandlers: GatewayRequestHandlers = {
       chatRunBuffers: context.chatRunBuffers,
       requestedSessionKey: sessionKey,
       canonicalSessionKey: resolveSessionStoreKey({ cfg, sessionKey }),
-      agentId: requestedAgentId,
-      defaultAgentId: resolveDefaultAgentId(cfg),
+      agentId: activeRunAgentId,
+      defaultAgentId,
     });
     const boundedInFlightRun = boundInFlightRunSnapshotForChatHistory({
       snapshot: inFlightRun,