refactor(desktop): streamStore sendMessage 拆分 Phase 3 — 提取 DeltaBuffer+4 Handler

- DeltaBuffer 类: ~60fps 文本/思考增量缓冲，替换内联 textBuffer/thinkBuffer
- createToolHandler: 工具步骤管理 (toolStart/toolEnd + artifact 自动创建)
- createHandHandler: Hand 能力消息生成
- createSubtaskHandler: 子任务状态映射
- createCompleteHandler: 完成回调 (token 统计+记忆提取+反思+建议)
- sendMessage 内联回调从 ~350 行缩减到 ~130 行 (-63%)
- TypeScript 类型检查通过, 8 个 seam 测试通过

desktop/src/store/chat/streamStore.ts

@@ -144,6 +144,265 @@ interface ChatStoreAccess {
   setChatStoreState: (partial: Record<string, unknown>) => void;
 }
 
+// ---------------------------------------------------------------------------
+// Delta buffer — batches text/thinking deltas at ~60fps
+// ---------------------------------------------------------------------------
+
+class DeltaBuffer {
+  private text = '';
+  private think = '';
+  private timer: ReturnType<typeof setTimeout> | null = null;
+
+  constructor(
+    private readonly assistantId: string,
+    private readonly chat: ChatStoreAccess,
+  ) {}
+
+  appendText(delta: string) {
+    this.text += delta;
+    this.scheduleFlush();
+  }
+
+  appendThinking(delta: string) {
+    this.think += delta;
+    this.scheduleFlush();
+  }
+
+  flush() {
+    this.timer = null;
+    const text = this.text;
+    const think = this.think;
+    this.text = '';
+    this.think = '';
+    if (text || think) {
+      this.chat.updateMessages(msgs =>
+        msgs.map(m => {
+          if (m.id !== this.assistantId) return m;
+          return {
+            ...m,
+            ...(text ? { content: m.content + text } : {}),
+            ...(think ? { thinkingContent: (m.thinkingContent || '') + think } : {}),
+          };
+        })
+      );
+    }
+  }
+
+  clear() {
+    if (this.timer !== null) {
+      clearTimeout(this.timer);
+      this.timer = null;
+    }
+    this.text = '';
+    this.think = '';
+  }
+
+  flushRemaining() {
+    if (this.timer !== null) {
+      clearTimeout(this.timer);
+      this.timer = null;
+    }
+    this.flush();
+  }
+
+  private scheduleFlush() {
+    if (this.timer === null) {
+      this.timer = setTimeout(() => this.flush(), 0);
+    }
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Stream event handlers (extracted from sendMessage)
+// ---------------------------------------------------------------------------
+
+function createToolHandler(assistantId: string, chat: ChatStoreAccess) {
+  return (tool: string, input: string, output: string) => {
+    if (output) {
+      // toolEnd: complete the last running step for this tool
+      chat.updateMessages(msgs =>
+        msgs.map(m => {
+          if (m.id !== assistantId) return m;
+          const steps = [...(m.toolSteps || [])];
+          for (let i = steps.length - 1; i >= 0; i--) {
+            if (steps[i].toolName === tool && steps[i].status === 'running') {
+              steps[i] = { ...steps[i], output, status: 'completed' as const };
+              break;
+            }
+          }
+          return { ...m, toolSteps: steps };
+        })
+      );
+
+      // Auto-create artifact when file_write tool produces output
+      if (tool === 'file_write') {
+        try {
+          const parsed = JSON.parse(output);
+          const filePath = parsed?.path || parsed?.file_path || '';
+          const content = parsed?.content || '';
+          if (filePath && content) {
+            const fileName = filePath.split('/').pop() || filePath;
+            const ext = fileName.split('.').pop()?.toLowerCase() || '';
+            const typeMap: Record<string, 'code' | 'markdown' | 'text'> = {
+              ts: 'code', tsx: 'code', js: 'code', jsx: 'code',
+              py: 'code', rs: 'code', go: 'code', java: 'code',
+              md: 'markdown', txt: 'text', json: 'code',
+              html: 'code', css: 'code', sql: 'code', sh: 'code',
+            };
+            const langMap: Record<string, string> = {
+              ts: 'typescript', tsx: 'typescript', js: 'javascript', jsx: 'javascript',
+              py: 'python', rs: 'rust', go: 'go', java: 'java',
+              html: 'html', css: 'css', sql: 'sql', sh: 'bash', json: 'json',
+            };
+            useArtifactStore.getState().addArtifact({
+              id: `artifact_${Date.now()}`,
+              name: fileName,
+              content: typeof content === 'string' ? content : JSON.stringify(content, null, 2),
+              type: typeMap[ext] || 'text',
+              language: langMap[ext],
+              createdAt: new Date(),
+              sourceStepId: assistantId,
+            });
+          }
+        } catch { /* non-critical: artifact creation from tool output */ }
+      }
+    } else {
+      // toolStart: create new running step
+      const step: ToolCallStep = {
+        id: `step_${Date.now()}_${generateRandomString(4)}`,
+        toolName: tool,
+        input,
+        output: '',
+        status: 'running',
+        timestamp: new Date(),
+      };
+      chat.updateMessages(msgs =>
+        msgs.map(m =>
+          m.id === assistantId
+            ? { ...m, toolSteps: [...(m.toolSteps || []), step] }
+            : m
+        )
+      );
+    }
+  };
+}
+
+function createHandHandler(chat: ChatStoreAccess, runId: string) {
+  return (name: string, status: string, result?: unknown) => {
+    const handMsg: StreamMsg = {
+      id: `hand_${Date.now()}_${generateRandomString(4)}`,
+      role: 'hand',
+      content: result
+        ? (typeof result === 'string' ? result : JSON.stringify(result, null, 2))
+        : `Hand: ${name} - ${status}`,
+      timestamp: new Date(),
+      runId,
+      handName: name,
+      handStatus: status,
+      handResult: result,
+    };
+    chat.updateMessages(msgs => [...msgs, handMsg]);
+  };
+}
+
+function createSubtaskHandler(assistantId: string, chat: ChatStoreAccess) {
+  return (taskId: string, description: string, status: string, detail?: string) => {
+    const statusMap: Record<string, Subtask['status']> = {
+      started: 'pending',
+      running: 'in_progress',
+      completed: 'completed',
+      failed: 'failed',
+    };
+    const mappedStatus = statusMap[status] || 'in_progress';
+
+    chat.updateMessages(msgs =>
+      msgs.map(m => {
+        if (m.id !== assistantId) return m;
+        const subtasks = [...(m.subtasks || [])];
+        const existingIdx = subtasks.findIndex(st => st.id === taskId);
+        if (existingIdx >= 0) {
+          subtasks[existingIdx] = { ...subtasks[existingIdx], status: mappedStatus, result: detail };
+        } else {
+          subtasks.push({ id: taskId, description, status: mappedStatus, result: detail });
+        }
+        return { ...m, subtasks };
+      })
+    );
+  };
+}
+
+function createCompleteHandler(
+  assistantId: string,
+  _streamStartTime: number,
+  chat: ChatStoreAccess,
+  buffer: DeltaBuffer,
+  agentId: string,
+  set: (partial: Partial<StreamState>) => void,
+) {
+  return (inputTokens?: number, outputTokens?: number) => {
+    buffer.flushRemaining();
+
+    const currentMsgs = chat.getMessages();
+    if (currentMsgs) {
+      useConversationStore.getState().upsertActiveConversation(currentMsgs);
+    }
+
+    chat.updateMessages(msgs =>
+      msgs.map(m => {
+        if (m.id === assistantId) return { ...m, streaming: false };
+        if (m.optimistic) return { ...m, optimistic: false };
+        return m;
+      })
+    );
+    set({ isStreaming: false, activeRunId: null });
+
+    if (inputTokens !== undefined && outputTokens !== undefined) {
+      useMessageStore.getState().addTokenUsage(inputTokens, outputTokens);
+      chat.setChatStoreState({
+        totalInputTokens: useMessageStore.getState().totalInputTokens,
+        totalOutputTokens: useMessageStore.getState().totalOutputTokens,
+      });
+    }
+
+    // Async memory extraction
+    const msgs = chat.getMessages() || [];
+    const filtered = msgs
+      .filter(m => m.role === 'user' || m.role === 'assistant')
+      .map(m => ({ role: m.role, content: m.content }));
+    const convId = useConversationStore.getState().currentConversationId;
+    getMemoryExtractor().extractFromConversation(filtered, agentId, convId ?? undefined)
+      .then(() => {
+        if (typeof window !== 'undefined') {
+          window.dispatchEvent(new CustomEvent('zclaw:agent-profile-updated', {
+            detail: { agentId }
+          }));
+        }
+      })
+      .catch(err => log.warn('Memory extraction failed:', err));
+
+    intelligenceClient.reflection.recordConversation().catch(err => {
+      log.warn('Recording conversation failed:', err);
+    });
+    intelligenceClient.reflection.shouldReflect().then(shouldReflect => {
+      if (shouldReflect) {
+        intelligenceClient.reflection.reflect(agentId, []).catch(err => {
+          log.warn('Reflection failed:', err);
+        });
+      }
+    });
+
+    // Follow-up suggestions
+    const latestMsgs = chat.getMessages() || [];
+    const completedMsg = latestMsgs.find(m => m.id === assistantId);
+    if (completedMsg?.content) {
+      const suggestions = generateFollowUpSuggestions(completedMsg.content);
+      if (suggestions.length > 0) {
+        set({ suggestions });
+      }
+    }
+  };
+}
+
 export interface StreamState {
   isStreaming: boolean;
   /** Brief cooldown after cancelStream — prevents race with backend active-stream check */
@@ -322,40 +581,8 @@ export const useStreamStore = create<StreamState>()(
     });
     set({ isStreaming: true, activeRunId: null });
 
-    // ── Delta buffering ──
-    // Accumulate text/thinking deltas in local buffers and flush to store
-    // at ~60fps intervals. This prevents React "Maximum update depth exceeded"
-    // when the LLM emits many small deltas per frame (e.g. Kimi thinking).
-    let textBuffer = '';
-    let thinkBuffer = '';
-    let flushTimer: ReturnType<typeof setTimeout> | null = null;
-
-    const flushBuffers = () => {
-      flushTimer = null;
-      const text = textBuffer;
-      const think = thinkBuffer;
-      textBuffer = '';
-      thinkBuffer = '';
-
-      if (text || think) {
-        _chat?.updateMessages(msgs =>
-          msgs.map(m => {
-            if (m.id !== assistantId) return m;
-            return {
-              ...m,
-              ...(text ? { content: m.content + text } : {}),
-              ...(think ? { thinkingContent: (m.thinkingContent || '') + think } : {}),
-            };
-          })
-        );
-      }
-    };
-
-    const scheduleFlush = () => {
-      if (flushTimer === null) {
-        flushTimer = setTimeout(flushBuffers, 0);
-      }
-    };
+    // Delta buffer — batches updates at ~60fps
+    const buffer = new DeltaBuffer(assistantId, _chat);
 
     try {
       const client = getClient();
@@ -384,213 +611,16 @@ export const useStreamStore = create<StreamState>()(
       const result = await client.chatStream(
         content,
         {
-          onDelta: (delta: string) => {
-            textBuffer += delta;
-            scheduleFlush();
-          },
-          onThinkingDelta: (delta: string) => {
-            thinkBuffer += delta;
-            scheduleFlush();
-          },
-          onTool: (tool: string, input: string, output: string) => {
-            if (output) {
-              // toolEnd: find the last running step for this tool and complete it
-              _chat?.updateMessages(msgs =>
-                msgs.map(m => {
-                  if (m.id !== assistantId) return m;
-                  const steps = [...(m.toolSteps || [])];
-                  for (let i = steps.length - 1; i >= 0; i--) {
-                    if (steps[i].toolName === tool && steps[i].status === 'running') {
-                      steps[i] = { ...steps[i], output, status: 'completed' as const };
-                      break;
-                    }
-                  }
-                  return { ...m, toolSteps: steps };
-                })
-              );
-
-              // Auto-create artifact when file_write tool produces output
-              if (tool === 'file_write' && output) {
-                try {
-                  const parsed = JSON.parse(output);
-                  const filePath = parsed?.path || parsed?.file_path || '';
-                  const content = parsed?.content || '';
-                  if (filePath && content) {
-                    const fileName = filePath.split('/').pop() || filePath;
-                    const ext = fileName.split('.').pop()?.toLowerCase() || '';
-                    const typeMap: Record<string, 'code' | 'markdown' | 'text'> = {
-                      ts: 'code', tsx: 'code', js: 'code', jsx: 'code',
-                      py: 'code', rs: 'code', go: 'code', java: 'code',
-                      md: 'markdown', txt: 'text', json: 'code',
-                      html: 'code', css: 'code', sql: 'code', sh: 'code',
-                    };
-                    const langMap: Record<string, string> = {
-                      ts: 'typescript', tsx: 'typescript', js: 'javascript', jsx: 'javascript',
-                      py: 'python', rs: 'rust', go: 'go', java: 'java',
-                      html: 'html', css: 'css', sql: 'sql', sh: 'bash', json: 'json',
-                    };
-                    useArtifactStore.getState().addArtifact({
-                      id: `artifact_${Date.now()}`,
-                      name: fileName,
-                      content: typeof content === 'string' ? content : JSON.stringify(content, null, 2),
-                      type: typeMap[ext] || 'text',
-                      language: langMap[ext],
-                      createdAt: new Date(),
-                      sourceStepId: assistantId,
-                    });
-                  }
-                } catch { /* non-critical: artifact creation from tool output */ }
-              }
-            } else {
-              // toolStart: create new running step
-              const step: ToolCallStep = {
-                id: `step_${Date.now()}_${generateRandomString(4)}`,
-                toolName: tool,
-                input,
-                output: '',
-                status: 'running',
-                timestamp: new Date(),
-              };
-              _chat?.updateMessages(msgs =>
-                msgs.map(m =>
-                  m.id === assistantId
-                    ? { ...m, toolSteps: [...(m.toolSteps || []), step] }
-                    : m
-                )
-              );
-            }
-          },
-          onHand: (name: string, status: string, result?: unknown) => {
-            const handMsg: StreamMsg = {
-              id: `hand_${Date.now()}_${generateRandomString(4)}`,
-              role: 'hand',
-              content: result
-                ? (typeof result === 'string' ? result : JSON.stringify(result, null, 2))
-                : `Hand: ${name} - ${status}`,
-              timestamp: new Date(),
-              runId,
-              handName: name,
-              handStatus: status,
-              handResult: result,
-            };
-            _chat?.updateMessages(msgs => [...msgs, handMsg]);
-
-          },
-          onSubtaskStatus: (taskId: string, description: string, status: string, detail?: string) => {
-            // Map backend status to frontend Subtask status
-            const statusMap: Record<string, Subtask['status']> = {
-              started: 'pending',
-              running: 'in_progress',
-              completed: 'completed',
-              failed: 'failed',
-            };
-            const mappedStatus = statusMap[status] || 'in_progress';
-
-            _chat?.updateMessages(msgs =>
-              msgs.map(m => {
-                if (m.id !== assistantId) return m;
-                const subtasks = [...(m.subtasks || [])];
-                const existingIdx = subtasks.findIndex(st => st.id === taskId);
-                if (existingIdx >= 0) {
-                  subtasks[existingIdx] = { ...subtasks[existingIdx], status: mappedStatus, result: detail };
-                } else {
-                  subtasks.push({
-                    id: taskId,
-                    description,
-                    status: mappedStatus,
-                    result: detail,
-                  });
-                }
-                return { ...m, subtasks };
-              })
-            );
-          },
-          onComplete: (inputTokens?: number, outputTokens?: number) => {
-            // Flush any remaining buffered deltas before finalizing
-            if (flushTimer !== null) {
-              clearTimeout(flushTimer);
-              flushTimer = null;
-            }
-            flushBuffers();
-
-            const currentMsgs = _chat?.getMessages();
-
-            if (currentMsgs) {
-              useConversationStore.getState().upsertActiveConversation(currentMsgs);
-            }
-
-            _chat?.updateMessages(msgs =>
-              msgs.map(m => {
-                if (m.id === assistantId) {
-                  return { ...m, streaming: false, runId };
-                }
-                if (m.optimistic) {
-                  return { ...m, optimistic: false };
-                }
-                return m;
-              })
-            );
-            set({ isStreaming: false, activeRunId: null });
-
-            if (inputTokens !== undefined && outputTokens !== undefined) {
-              useMessageStore.getState().addTokenUsage(inputTokens, outputTokens);
-              _chat?.setChatStoreState({
-                totalInputTokens: useMessageStore.getState().totalInputTokens,
-                totalOutputTokens: useMessageStore.getState().totalOutputTokens,
-              });
-            }
-
-            // Async memory extraction — dispatch update event AFTER extraction completes
-            const msgs = _chat?.getMessages() || [];
-            const filtered = msgs
-              .filter(m => m.role === 'user' || m.role === 'assistant')
-              .map(m => ({ role: m.role, content: m.content }));
-            const convId = useConversationStore.getState().currentConversationId;
-            getMemoryExtractor().extractFromConversation(filtered, agentId, convId ?? undefined)
-              .then(() => {
-                // Notify RightPanel to refresh UserProfile after memory extraction completes
-                if (typeof window !== 'undefined') {
-                  window.dispatchEvent(new CustomEvent('zclaw:agent-profile-updated', {
-                    detail: { agentId }
-                  }));
-                }
-              })
-              .catch(err => {
-                log.warn('Memory extraction failed:', err);
-              });
-            intelligenceClient.reflection.recordConversation().catch(err => {
-              log.warn('Recording conversation failed:', err);
-            });
-            intelligenceClient.reflection.shouldReflect().then(shouldReflect => {
-              if (shouldReflect) {
-                intelligenceClient.reflection.reflect(agentId, []).catch(err => {
-                  log.warn('Reflection failed:', err);
-                });
-              }
-            });
-
-            // Follow-up suggestions
-            const latestMsgs = _chat?.getMessages() || [];
-            const completedMsg = latestMsgs.find(m => m.id === assistantId);
-            if (completedMsg?.content) {
-              const suggestions = generateFollowUpSuggestions(completedMsg.content);
-              if (suggestions.length > 0) {
-                get().setSuggestions(suggestions);
-              }
-            }
-          },
+          onDelta: (delta: string) => buffer.appendText(delta),
+          onThinkingDelta: (delta: string) => buffer.appendThinking(delta),
+          onTool: createToolHandler(assistantId, _chat),
+          onHand: createHandHandler(_chat, runId),
+          onSubtaskStatus: createSubtaskHandler(assistantId, _chat),
+          onComplete: createCompleteHandler(assistantId, streamStartTime, _chat, buffer, agentId, set),
           onError: async (error: string) => {
-            // Flush any remaining buffered deltas before erroring
-            if (flushTimer !== null) {
-              clearTimeout(flushTimer);
-              flushTimer = null;
-            }
-            flushBuffers();
-
-            // Attempt 401 auth recovery (token refresh + kernel reconnect)
+            buffer.flushRemaining();
             const recoveryMsg = await tryRecoverFromAuthError(error);
-            const rawError = recoveryMsg || error;
-            const displayError = formatUserError(rawError);
+            const displayError = formatUserError(recoveryMsg || error);
 
             _chat?.updateMessages(msgs =>
               msgs.map(m =>
@@ -604,7 +634,6 @@ export const useStreamStore = create<StreamState>()(
             set({ isStreaming: false, activeRunId: null });
           },
         },
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
         {
           sessionKey: effectiveSessionKey,
           agentId: effectiveAgentId,
@@ -632,21 +661,13 @@ export const useStreamStore = create<StreamState>()(
         )
       );
     } catch (err: unknown) {
-      // Flush remaining buffers on error
-      if (flushTimer !== null) {
-        clearTimeout(flushTimer);
-        flushTimer = null;
-      }
-      textBuffer = '';
-      thinkBuffer = '';
+      buffer.clear();
 
       let errorMessage = err instanceof Error ? err.message : '无法连接 Gateway';
-
-      // Attempt 401 auth recovery
       const recoveryMsg = await tryRecoverFromAuthError(errorMessage);
       if (recoveryMsg) errorMessage = recoveryMsg;
 
-      _chat?.updateMessages(msgs =>
+      _chat.updateMessages(msgs =>
         msgs.map(m =>
           m.id === assistantId
             ? {