fix(consult): 申报时段计算改为服务端预跑并走同请求缓存（BUG-957）

窗口计算挂在 agent context 缓存上，模型开口前预跑并注入 packet；工具再调用命中同请求缓存，成功次数仍为 1。

frontend/src/lib/stream-agent-response.ts

@@ -61,7 +61,9 @@ type EventOptions = {
   state?: ConsultationRuntimeState;
 };
 
-function activity(value: unknown): ConsultationAgentPublicEvent | null {
+export function consultationPublicActivityEvent(
+  value: unknown,
+): Extract<ConsultationAgentPublicEvent, { type: "activity" }> | null {
   if (!value || typeof value !== "object") return null;
   const data = value as { phase?: unknown; label?: unknown };
   const phase = publicActivityPhaseSchema.safeParse(data.phase);
@@ -224,7 +226,7 @@ function mapChunk(
 ): ConsultationAgentPublicEvent[] {
   const payload = chunk.payload ?? {};
   if (chunk.type === "data-jyotish-activity") {
-    const event = activity(chunk.data);
+    const event = consultationPublicActivityEvent(chunk.data);
     return event ? [event] : [];
   }
   if (chunk.type === "tool-call") {
@@ -311,9 +313,16 @@ export type ThinkFinding = Readonly<{
   text?: string;
 }>;
 
+type AgentStreamSource = ChunkStream | (() => ChunkStream | Promise<ChunkStream>);
+
+async function resolveAgentStream(stream: AgentStreamSource): Promise<ChunkStream> {
+  return typeof stream === "function" ? await stream() : stream;
+}
+
 type StreamAgentResponseOptions = EventOptions & {
   state: ConsultationRuntimeState;
-  stream: ChunkStream;
+  stream: AgentStreamSource;
+  warmup?: (send: (event: ConsultationAgentPublicEvent) => void) => Promise<void>;
   transformText?: (text: string) => string;
   requireTool: boolean;
   retry?: () => Promise<ChunkStream>;
@@ -744,7 +753,11 @@ export function streamAgentResponse(options: StreamAgentResponseOptions) {
         flushThinkingPlan(controller);
         try {
           let deliveredDegraded = false;
-          await consumeAttempt(controller, options.stream, {
+          if (options.warmup) {
+            await options.warmup((event) => send(controller, event));
+            flushThinkingPlan(controller);
+          }
+          await consumeAttempt(controller, await resolveAgentStream(options.stream), {
             drainSpoken: Boolean(options.composeAnswer),
           });
           if (!contractReady(options) && options.retry) {