fix(web): preserve queue on stop

packages/host/apiproxy/src/api-proxy.ts

@@ -1587,7 +1587,7 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
             details: { sessionId },
           }))
         }
-        agent.cancel({ kind: 'user' })
+        agent.cancel({ kind: 'user' }, { keepInbox: true })
         return Promise.resolve(ok(request, { accepted: true as const }))
       },
     },

packages/host/apiproxy/src/api/sessions.ts

@@ -279,7 +279,7 @@ export interface SessionsApi {
   updateQueue(request: RpcRequest<{ sessionId: SessionId; itemId: InboxItemId; action: QueueAction }>):
   Promise<RpcResponse<{ accepted: true }>>
 
-  /** Stops: clears both FIFOs + aborts the current step (1:1 with agent.cancel). */
+  /** Stops the active turn, preserving pending inbox work that resumes in FIFO order after cancellation settles. */
   cancel(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<{ accepted: true }>>
 
 }