refactor: 收口前端 SSE 传输层

src/services/creation-agent/creationAgentSse.ts

@@ -1,5 +1,6 @@
 import type { VisualNovelAgentStreamEvent } from '../../../packages/shared/src/contracts/visualNovel';
 import type { TextStreamOptions } from '../aiTypes';
+import { readSseJsonStream } from '../sseStream';
 
 type CreationAgentSseOptions<TSession> = TextStreamOptions & {
   fallbackMessage: string;
@@ -24,65 +25,6 @@ type CreationAgentSseOptions<TSession> = TextStreamOptions & {
     | null;
 };
 
-function findSseEventBoundary(buffer: string) {
-  const lfBoundary = buffer.indexOf('\n\n');
-  const crlfBoundary = buffer.indexOf('\r\n\r\n');
-
-  if (lfBoundary === -1 && crlfBoundary === -1) {
-    return null;
-  }
-
-  if (lfBoundary === -1) {
-    return {
-      index: crlfBoundary,
-      length: 4,
-    };
-  }
-
-  if (crlfBoundary === -1 || lfBoundary < crlfBoundary) {
-    return {
-      index: lfBoundary,
-      length: 2,
-    };
-  }
-
-  return {
-    index: crlfBoundary,
-    length: 4,
-  };
-}
-
-function parseSseEventBlock(eventBlock: string) {
-  let eventName = 'message';
-  const dataLines: string[] = [];
-
-  for (const rawLine of eventBlock.split(/\r?\n/u)) {
-    const line = rawLine.trim();
-
-    if (line.startsWith('event:')) {
-      eventName = line.slice(6).trim() || 'message';
-      continue;
-    }
-
-    if (line.startsWith('data:')) {
-      dataLines.push(line.slice(5).trim());
-    }
-  }
-
-  return {
-    eventName,
-    data: dataLines.join('\n'),
-  };
-}
-
-function parseJsonObject(data: string) {
-  try {
-    return JSON.parse(data) as Record<string, unknown>;
-  } catch {
-    return null;
-  }
-}
-
 type NormalizedCreationAgentSseEvent = NonNullable<
   CreationAgentSseOptions<unknown>['normalizeEvent']
 > extends (eventName: string, parsed: Record<string, unknown>) => infer TResult
@@ -147,71 +89,30 @@ export async function readCreationAgentSessionFromSse<TSession>(
   response: Response,
   options: CreationAgentSseOptions<TSession>,
 ) {
-  const streamBody = response.body;
-  if (!streamBody) {
-    throw new Error('streaming response body is unavailable');
-  }
-
-  const reader = streamBody.getReader();
-  const decoder = new TextDecoder('utf-8');
   const resolveSession =
     options.resolveSession ??
     ((rawSession: unknown) => (rawSession as TSession | null) ?? null);
-  let buffer = '';
   let finalSession: TSession | null = null;
   const normalizeEvent =
     options.normalizeEvent ?? normalizeDefaultCreationAgentEvent;
 
-  const consumeBuffer = () => {
-    for (;;) {
-      const boundary = findSseEventBoundary(buffer);
-      if (!boundary) {
-        break;
-      }
-
-      const eventBlock = buffer.slice(0, boundary.index);
-      buffer = buffer.slice(boundary.index + boundary.length);
-      const { eventName, data } = parseSseEventBlock(eventBlock);
-
-      if (!data) {
-        continue;
-      }
-
-      const parsed = parseJsonObject(data);
-      if (!parsed) {
-        continue;
-      }
+  await readSseJsonStream(response, ({ eventName, parsed }) => {
       const normalized = normalizeEvent(eventName, parsed);
 
       if (normalized?.kind === 'reply_delta') {
         options.onUpdate?.(normalized.text);
-        continue;
+        return;
       }
 
       if (normalized?.kind === 'session') {
         finalSession = resolveSession(normalized.session);
-        continue;
+        return;
       }
 
       if (normalized?.kind === 'error') {
         throw new Error(normalized.message || options.fallbackMessage);
       }
-    }
-  };
-
-  for (;;) {
-    const { done, value } = await reader.read();
-    if (done) {
-      break;
-    }
-
-    buffer += decoder.decode(value, { stream: true });
-    consumeBuffer();
-  }
-
-  // 流结束后再 flush 一次解码器，避免 UTF-8 多字节字符残留在内部缓冲里。
-  buffer += decoder.decode();
-  consumeBuffer();
+  });
 
   if (!finalSession) {
     throw new Error(options.incompleteMessage);