fix: stream validated rectification replies

frontend/src/app/api/birth-time-conversation/route.ts

@@ -3,6 +3,7 @@ import path from "node:path";
 import {
   conversationalRectificationCommandSchema,
   type ConversationalRectificationCommand,
+  type ConversationalRectificationResponse,
   type ConversationalRectificationTurn,
 } from "../../../lib/conversational-rectification/contracts.ts";
 import {
@@ -42,6 +43,53 @@ import {
 export const runtime = "nodejs";
 export const maxDuration = 60;
 
+const RECTIFICATION_STREAM_CONTENT_TYPE = "application/x-ndjson; charset=utf-8";
+const RECTIFICATION_STREAM_CHUNK_SIZE = 10;
+const RECTIFICATION_STREAM_CHUNK_DELAY_MS = 18;
+
+function rectificationNarrativeChunks(narrative: string): string[] {
+  const characters = Array.from(narrative);
+  const chunks: string[] = [];
+  for (let index = 0; index < characters.length; index += RECTIFICATION_STREAM_CHUNK_SIZE) {
+    chunks.push(characters.slice(index, index + RECTIFICATION_STREAM_CHUNK_SIZE).join(""));
+  }
+  return chunks;
+}
+
+export function streamConversationalRectificationResponse(
+  turn: ConversationalRectificationResponse,
+  chunkDelayMs = RECTIFICATION_STREAM_CHUNK_DELAY_MS,
+): Response {
+  const encoder = new TextEncoder();
+  let cancelled = false;
+  const body = new ReadableStream<Uint8Array>({
+    async start(controller) {
+      try {
+        for (const text of rectificationNarrativeChunks(turn.narrative)) {
+          if (cancelled) return;
+          controller.enqueue(encoder.encode(`${JSON.stringify({ type: "delta", text })}\n`));
+          if (chunkDelayMs > 0) await new Promise((resolve) => setTimeout(resolve, chunkDelayMs));
+        }
+        if (cancelled) return;
+        controller.enqueue(encoder.encode(`${JSON.stringify({ type: "turn", turn })}\n`));
+        controller.close();
+      } catch (error) {
+        if (!cancelled) controller.error(error);
+      }
+    },
+    cancel() {
+      cancelled = true;
+    },
+  });
+  return new Response(body, {
+    headers: {
+      "Cache-Control": "no-cache, no-transform",
+      "Content-Type": RECTIFICATION_STREAM_CONTENT_TYPE,
+      "X-Accel-Buffering": "no",
+    },
+  });
+}
+
 const jyotishSkillPath = process.env.JYOTISH_SKILL_PATH?.trim()
   || path.resolve(process.cwd(), "..", "skills", "jyotish-vedic-astrology");
 
@@ -892,7 +940,9 @@ export function createBirthTimeConversationPostHandler(
         errorCategory: "none",
         deploymentSha,
       });
-      return Response.json(turn);
+      return request.headers.get("accept")?.includes("application/x-ndjson")
+        ? streamConversationalRectificationResponse(turn)
+        : Response.json(turn);
     } catch (error) {
       const publicError = toConversationalRectificationPublicError(error);
       const outcome = service ? conversationalRectificationTelemetryOutcome(service) : null;

frontend/src/app/page.tsx

@@ -822,6 +822,7 @@ export default function Home() {
   const [rectificationSessionId, setRectificationSessionId] = useState<string | null>(null);
   const [rectificationReturnSessionId, setRectificationReturnSessionId] = useState<string | null>(null);
   const [rectificationInitialTurn, setRectificationInitialTurn] = useState<ConversationalRectificationResponse | null>(null);
+  const [rectificationOpeningAssistantText, setRectificationOpeningAssistantText] = useState("");
   const [rectificationPendingQuestion, setRectificationPendingQuestion] = useState<string | null>(null);
   const [rectificationLoading, setRectificationLoading] = useState(false);
   const [rectificationMutationPending, setRectificationMutationPending] = useState(false);
@@ -1951,6 +1952,7 @@ export default function Home() {
     setDraftEntrypoint(null);
     setRectificationPendingQuestion(requestedQuestion);
     setRectificationInitialTurn(null);
+    setRectificationOpeningAssistantText("");
     setRectificationError("");
     setRectificationLoading(true);
     if (!reusingRectificationSession) {
@@ -1975,6 +1977,10 @@ export default function Home() {
               type: "start",
               actionId: globalThis.crypto.randomUUID(),
               pendingConsultationQuestion: requestedQuestion,
+            }, {
+              onNarrativeDelta(text) {
+                setRectificationOpeningAssistantText((current) => current + text);
+              },
             });
       } else {
         let current = resumeTarget;
@@ -2007,6 +2013,10 @@ export default function Home() {
             caseId: current.caseId,
             actionId: globalThis.crypto.randomUUID(),
             turnVersion: current.turnVersion,
+          }, {
+            onNarrativeDelta(text) {
+              setRectificationOpeningAssistantText((value) => value + text);
+            },
           });
         }
       }
@@ -2031,6 +2041,7 @@ export default function Home() {
         }
       }
       setRectificationInitialTurn(turn);
+      setRectificationOpeningAssistantText("");
       synchronizeRectificationQuestion(turn, sourceSession);
       setComposerNotice(sessionSyncFailed ? "校正已经开始，但会话关联暂时未同步到云端。" : "");
     } catch (caught) {
@@ -2038,6 +2049,7 @@ export default function Home() {
         ? caught.message
         : "生时校正暂时无法继续，请稍后重试。";
       setRectificationError(message);
+      setRectificationOpeningAssistantText("");
       setComposerNotice(message);
       if (!reusingRectificationSession) {
         setSessions((current) => current.filter((session) => session.id !== rectificationSession.id));
@@ -3084,6 +3096,7 @@ export default function Home() {
           ) : (
             <ConversationalBirthTimeRectification
               initialTurn={visibleRectificationTurn}
+              openingAssistantText={rectificationOpeningAssistantText}
               pendingConsultationQuestion={rectificationPendingQuestion}
               continuationPending={rectificationContinuationPending}
               onPendingChange={setRectificationMutationPending}