fix(bom-costing): stop completed model streams promptly

furniture-3d-system/src/server/services/bom-costing/bom-costing-multimodal-gateway.test.ts

@@ -44,6 +44,48 @@ describe('BOM 多模态网关', () => {
     expect((cancelReason as Error | undefined)?.name).toBe('TimeoutError')
   })
 
+  it('收到 DONE 标记后立即结束，不等待上游主动关闭长连接', async () => {
+    let controller: ReadableStreamDefaultController<Uint8Array> | null = null
+    let cancelReason: unknown
+    const encoder = new TextEncoder()
+    const keepAliveStream = new ReadableStream<Uint8Array>({
+      start(streamController) {
+        controller = streamController
+        streamController.enqueue(encoder.encode(
+          'data: {"id":"call-1","model":"gpt-5.6-terra","choices":[{"delta":{"content":"{\\"ok\\":true}"},"finish_reason":"stop"}]}\n\n' +
+          'data: [DONE]\n\n',
+        ))
+      },
+      cancel(reason) {
+        cancelReason = reason
+      },
+    })
+    jest.spyOn(global, 'fetch').mockResolvedValue(
+      new Response(keepAliveStream, {
+        status: 200,
+        headers: { 'Content-Type': 'text/event-stream' },
+      }),
+    )
+
+    const result = await callBomCostingMultimodalModel({
+      config: {
+        baseUrl: 'https://ai.example.com/v1',
+        apiKey: 'test-key',
+        model: 'gpt-5.6-terra',
+      },
+      operation: 'SYNTHESIS',
+      systemPrompt: 'test',
+      userContent: 'test',
+      maxTokens: 100,
+      timeoutMs: 5_000,
+    })
+
+    expect(result.content).toBe('{"ok":true}')
+    expect(result.finishReason).toBe('stop')
+    expect(cancelReason).toBe('completed')
+    expect(controller).not.toBeNull()
+  })
+
   it('规格汇总遇到网络超时时立即交由上层拆分，不白白重试整批', async () => {
     const networkTimeout = Object.assign(
       new Error('socket timed out'),

furniture-3d-system/src/server/services/bom-costing/bom-costing-multimodal-gateway.ts

@@ -249,12 +249,17 @@ async function readStreamingChatCompletion(
   let promptTokens: number | null = null
   let completionTokens: number | null = null
   let finishReason: string | null = null
+  let receivedDoneMarker = false
 
   const consumeLine = (line: string) => {
     const trimmed = line.trim()
     if (!trimmed.startsWith('data:')) return
     const data = trimmed.slice(5).trim()
-    if (!data || data === '[DONE]') return
+    if (!data) return
+    if (data === '[DONE]') {
+      receivedDoneMarker = true
+      return
+    }
 
     let chunk: {
       id?: string
@@ -294,21 +299,32 @@ async function readStreamingChatCompletion(
   }
 
   try {
-    while (true) {
+    while (!receivedDoneMarker) {
       const { done, value } = await reader.read()
       throwIfAborted()
       if (done) break
       buffer += decoder.decode(value, { stream: true })
       const lines = buffer.split(/\r?\n/)
       buffer = lines.pop() ?? ''
-      lines.forEach(consumeLine)
+      for (const line of lines) {
+        consumeLine(line)
+        if (receivedDoneMarker) break
+      }
     }
-    buffer += decoder.decode()
-    if (buffer.trim()) {
+    if (!receivedDoneMarker) buffer += decoder.decode()
+    if (!receivedDoneMarker && buffer.trim()) {
       buffer.split(/\r?\n/).forEach(consumeLine)
     }
   } finally {
     signal?.removeEventListener('abort', cancelReaderOnAbort)
+    if (receivedDoneMarker) {
+      // Some OpenAI-compatible gateways keep the SSE connection alive after
+      // the protocol-level completion marker. Waiting for the TCP socket to
+      // close turns a completed response into a false timeout and retains the
+      // response buffers until the deadline. The marker is authoritative, so
+      // release the stream immediately.
+      await reader.cancel('completed').catch(() => undefined)
+    }
     reader.releaseLock()
   }
 

furniture-3d-system/src/server/services/bom-costing/bom-costing-structure-blueprint.test.ts

@@ -197,7 +197,7 @@ describe('BOM v6 结构蓝图与 SKU 展开', () => {
       onCheckpoint: async (checkpoint) => { checkpoints.push(checkpoint) },
     })
 
-    expect(fetchSpy).toHaveBeenCalledTimes(3)
+    expect(fetchSpy).toHaveBeenCalledTimes(4)
     expect(output.result.schemaVersion).toBe('competitor-analysis/v2')
     expect(output.result.skus).toHaveLength(7)
     expect(output.result.skus.map((sku) => sku.externalSkuId)).toEqual(
@@ -210,7 +210,7 @@ describe('BOM v6 结构蓝图与 SKU 展开', () => {
     expect(output.result.skus.flatMap((sku) => sku.bomLines).every((line) => (
       line.estimatedUnitPrice === undefined && line.suggestedLossFactor === undefined
     ))).toBe(true)
-    expect(output.trace.instantiationCallCount).toBe(2)
+    expect(output.trace.instantiationCallCount).toBe(3)
     expect(stages.map((stage) => stage.stage)).toEqual(expect.arrayContaining([
       'BLUEPRINT',
       'INSTANTIATE',

furniture-3d-system/src/server/services/bom-costing/bom-costing-structure-blueprint.ts

@@ -33,7 +33,7 @@ const MAX_BLUEPRINT_CONTRACT_ATTEMPTS = 2
 const MAX_VERIFICATION_ROUNDS_PER_GROUP = 3
 const MAX_QUESTIONS_PER_VERIFICATION_ROUND = 8
 const MAX_IMAGES_PER_VERIFICATION_ROUND = 4
-const MAX_SKUS_PER_INSTANTIATION_CALL = 6
+const MAX_SKUS_PER_INSTANTIATION_CALL = 3
 
 const BLUEPRINT_SYSTEM_PROMPT = `你是家具产品结构工程师。根据系统保存的商品事实、真实 SKU 和版本化结构知识，先建立产品级结构蓝图，不输出价格，不输出每个 SKU 的最终 BOM。