fix: scope global model results

ui/src/pages/chat/chat-commands.ts

@@ -20,6 +20,7 @@ import {
 } from "../../lib/sessions/index.ts";
 import {
   areUiSessionKeysEquivalent,
+  isUiGlobalSessionKey,
   resolveUiDefaultAgentId,
   type UiSessionDefaultsHost,
 } from "../../lib/sessions/session-key.ts";
@@ -137,6 +138,21 @@ function isChatCommandTargetCurrent(host: ChatCommandHost, target: ChatCommandTa
   );
 }
 
+function isChatCommandModelCacheOwnerCurrent(
+  host: ChatCommandHost,
+  target: ChatCommandTarget,
+): boolean {
+  if (!isChatCommandConnectionCurrent(host, target)) {
+    return false;
+  }
+  // The selected-agent global session shares one UI cache key across agents.
+  // Keep delayed results out when that selection changes on the same Gateway.
+  return (
+    !isUiGlobalSessionKey(target.sessionKey) ||
+    scopedAgentIdForSession(host, target.sessionKey) === target.agentId
+  );
+}
+
 export function readChatResetTargetAccess(
   host: ChatCommandHost,
   target: ChatCommandTarget,
@@ -461,7 +477,7 @@ export async function dispatchChatSlashCommand(
   if (result.sessionPatch && "modelOverride" in result.sessionPatch) {
     // A route switch on the same Gateway still owns the originating session's
     // cache. A replacement connection must not consume this late command result.
-    if (isChatCommandConnectionCurrent(host, target)) {
+    if (isChatCommandModelCacheOwnerCurrent(host, target)) {
       host.sessions.setModelOverride(
         target.sessionKey,
         result.sessionPatch.modelOverride?.value ?? null,

ui/src/pages/chat/chat-send.test.ts

@@ -4490,6 +4490,42 @@ describe("handleSendChat", () => {
     expect(host.sessions.state.modelOverrides[item.sessionKey]).toBeUndefined();
   });
 
+  it("does not apply a late global model result after the selected agent changes", async () => {
+    const command = createDeferred<Awaited<ReturnType<ExecuteSlashCommand>>>();
+    executeSlashCommandMock.mockImplementationOnce(() => command.promise);
+
+    const item = createQueuedLocalCommand("switched-global-model-command", "/model gpt-5-mini", {
+      sessionKey: "global",
+    });
+    const host = makeHost({
+      requestHandlers: {
+        "chat.history": () => idleChatHistory(item.sessionKey),
+      },
+      assistantAgentId: "work",
+      agentsList: { defaultId: "main" },
+      chatQueue: [item],
+      sessionKey: item.sessionKey,
+    });
+    const setModelOverride = vi.spyOn(host.sessions, "setModelOverride");
+    expect(admitQueuedMessageForSession(host, item.sessionKey, item)).toBe(true);
+
+    const draining = retryReconnectableQueuedChatSends(host);
+    await waitForFast(() => expect(executeSlashCommandMock).toHaveBeenCalledTimes(1));
+
+    host.assistantAgentId = "main";
+    command.resolve({
+      action: "refresh",
+      content: "Model set to `gpt-5-mini`.",
+      sessionPatch: {
+        modelOverride: { kind: "qualified", value: "openai/gpt-5-mini" },
+      },
+    });
+    await draining;
+
+    expect(setModelOverride).not.toHaveBeenCalled();
+    expect(host.sessions.state.modelOverrides[item.sessionKey]).toBeUndefined();
+  });
+
   it("does not borrow a replacement connection error for a stale queued command", async () => {
     const command = createDeferred<Awaited<ReturnType<ExecuteSlashCommand>>>();
     executeSlashCommandMock.mockImplementationOnce(() => command.promise);