fix: prevent checkpoint pollution + add reset thread button

- Add checkpoint guard in all 4 tool-executors ensuring every
  tool_call_id gets a ToolMessage response
- Add cleanPollutedToolCalls utility to heal corrupted message history
- Add error banner with "重置此对话" button in frontend

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

langgraph/src/agent/coder/nodes/agent.ts

@@ -3,6 +3,7 @@
  */
 import { createLlm, type ModelMode } from "@/agent/utils/create-llm";
 import { truncateMessages } from "@/agent/utils/truncate-messages";
+import { cleanPollutedToolCalls } from "@/agent/utils/clean-polluted-tool-calls";
 import { LangGraphRunnableConfig } from "@langchain/langgraph";
 import { CoderState, CoderUpdate } from "../types.js";
 import { z } from "zod";
@@ -92,9 +93,11 @@ export async function agentNode(
   const llm = createLlm({ modelMode });
 
   const truncated = truncateMessages(state.messages);
+  // Clean up polluted messages before sending to LLM
+  const cleanedMessages = cleanPollutedToolCalls(truncated);
   const messagesWithSystem = [
     { role: "system" as const, content: SYSTEM_PROMPT },
-    ...truncated,
+    ...cleanedMessages,
   ];
 
   const message = await llm.bindTools([...CODER_TOOLS], { parallel_tool_calls: false }).invoke(messagesWithSystem);

langgraph/src/agent/coder/nodes/tool-executor.ts

@@ -161,6 +161,19 @@ export async function toolExecutorNode(
     }
   }
 
+  // Ensure every tool_call has a corresponding ToolMessage (prevent checkpoint pollution)
+  const respondedIds = new Set(toolMessages.map(m => m.tool_call_id));
+  for (const tc of toolCalls) {
+    if (tc.id && !respondedIds.has(tc.id)) {
+      console.error(`[checkpoint-guard] Missing ToolMessage for tool_call_id: ${tc.id}, tool: ${tc.name}`);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id,
+        content: JSON.stringify({ ok: false, tool: tc.name, error: "工具执行异常，未能返回结果" }),
+      });
+    }
+  }
+
   return {
     messages: toolMessages,
     ui: ui.items,

langgraph/src/agent/enterprise/nodes/agent.ts

@@ -4,6 +4,7 @@
  */
 import { createLlm, type ModelMode } from "@/agent/utils/create-llm";
 import { truncateMessages } from "@/agent/utils/truncate-messages";
+import { cleanPollutedToolCalls } from "@/agent/utils/clean-polluted-tool-calls";
 import { LangGraphRunnableConfig } from "@langchain/langgraph";
 import { EnterpriseState, EnterpriseUpdate } from "../types.js";
 import { filterTools } from "./tool-defs.js";
@@ -134,9 +135,11 @@ export async function agentNode(
   const tools = filterTools(modelMode, enabledTools);
 
   const truncated = truncateMessages(state.messages);
+  // Clean up polluted messages before sending to LLM
+  const cleanedMessages = cleanPollutedToolCalls(truncated);
   const messagesWithSystem = [
     { role: "system" as const, content: SYSTEM_PROMPT },
-    ...truncated,
+    ...cleanedMessages,
   ];
 
   // If no tools available after filtering, invoke LLM without tool binding

langgraph/src/agent/enterprise/nodes/tool-executor.ts

@@ -1050,6 +1050,19 @@ export async function toolExecutorNode(
     }
   }
 
+  // Ensure every tool_call has a corresponding ToolMessage (prevent checkpoint pollution)
+  const respondedIds = new Set(toolMessages.map(m => m.tool_call_id));
+  for (const tc of toolCalls) {
+    if (tc.id && !respondedIds.has(tc.id)) {
+      console.error(`[checkpoint-guard] Missing ToolMessage for tool_call_id: ${tc.id}, tool: ${tc.name}`);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id,
+        content: JSON.stringify({ ok: false, tool: tc.name, error: "工具执行异常，未能返回结果" }),
+      });
+    }
+  }
+
   // Push next-actions card based on successful tool results
   const successfulTools = statusList.filter(
     (s) => s.status === "ok" || s.status === "empty" || s.status === "fallback_success",

langgraph/src/agent/searcher/nodes/agent.ts

@@ -3,6 +3,7 @@
  */
 import { createLlm, type ModelMode } from "@/agent/utils/create-llm";
 import { truncateMessages } from "@/agent/utils/truncate-messages";
+import { cleanPollutedToolCalls } from "@/agent/utils/clean-polluted-tool-calls";
 import { LangGraphRunnableConfig } from "@langchain/langgraph";
 import { SearcherState, SearcherUpdate } from "../types.js";
 import { z } from "zod";
@@ -92,9 +93,11 @@ export async function agentNode(
   const llm = createLlm({ modelMode });
 
   const truncated = truncateMessages(state.messages);
+  // Clean up polluted messages before sending to LLM
+  const cleanedMessages = cleanPollutedToolCalls(truncated);
   const messagesWithSystem = [
     { role: "system" as const, content: SYSTEM_PROMPT },
-    ...truncated,
+    ...cleanedMessages,
   ];
 
   const message = await llm

langgraph/src/agent/searcher/nodes/tool-executor.ts

@@ -394,6 +394,19 @@ export async function toolExecutorNode(
     }
   }
 
+  // Ensure every tool_call has a corresponding ToolMessage (prevent checkpoint pollution)
+  const respondedIds = new Set(toolMessages.map(m => m.tool_call_id));
+  for (const tc of toolCalls) {
+    if (tc.id && !respondedIds.has(tc.id)) {
+      console.error(`[checkpoint-guard] Missing ToolMessage for tool_call_id: ${tc.id}, tool: ${tc.name}`);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id,
+        content: JSON.stringify({ ok: false, tool: tc.name, error: "工具执行异常，未能返回结果" }),
+      });
+    }
+  }
+
   return {
     messages: toolMessages,
     ui: ui.items,

langgraph/src/agent/utils/clean-polluted-tool-calls.ts

@@ -0,0 +1,72 @@
+/**
+ * Utility to clean polluted tool_calls from message history.
+ *
+ * Problem: When a tool-executor fails to return a ToolMessage for every tool_call_id,
+ * the checkpoint stores an AIMessage with dangling tool_calls. On the next turn,
+ * Azure OpenAI rejects the request with 400 because it expects every tool_call to
+ * have a corresponding ToolMessage.
+ *
+ * This function scans the message array and:
+ * 1. If an AIMessage's tool_calls ALL lack ToolMessage responses → remove that AIMessage
+ * 2. If only SOME lack responses → inject placeholder error ToolMessages for the missing ones
+ */
+import { BaseMessage, AIMessage, ToolMessage } from "@langchain/core/messages";
+
+export function cleanPollutedToolCalls(messages: BaseMessage[]): BaseMessage[] {
+  // Build a set of all tool_call_ids that have a ToolMessage response
+  const respondedIds = new Set<string>();
+  for (const m of messages) {
+    if (m instanceof ToolMessage || (m as unknown as { role?: string }).role === "tool") {
+      const tcId =
+        (m as ToolMessage).tool_call_id ??
+        (m as unknown as { tool_call_id?: string }).tool_call_id;
+      if (tcId) respondedIds.add(tcId);
+    }
+  }
+
+  const result: BaseMessage[] = [];
+
+  for (const m of messages) {
+    // Check if this is an AIMessage with tool_calls
+    const toolCalls = (m as AIMessage).tool_calls;
+    if (toolCalls && toolCalls.length > 0) {
+      const missingIds = toolCalls
+        .filter((tc) => tc.id && !respondedIds.has(tc.id))
+        .map((tc) => tc.id!);
+
+      if (missingIds.length === 0) {
+        // All tool_calls have responses — keep as is
+        result.push(m);
+      } else if (missingIds.length === toolCalls.length) {
+        // ALL tool_calls are missing responses — drop the entire AIMessage
+        console.warn(
+          `[clean-polluted] Removing AIMessage with ${toolCalls.length} dangling tool_calls: ${missingIds.join(", ")}`,
+        );
+        // Do NOT push this message
+      } else {
+        // Partial: some have responses, some don't — keep the AIMessage but inject placeholders
+        result.push(m);
+        for (const id of missingIds) {
+          const tcName = toolCalls.find((tc) => tc.id === id)?.name ?? "unknown";
+          console.warn(
+            `[clean-polluted] Injecting placeholder ToolMessage for orphaned tool_call_id: ${id} (tool: ${tcName})`,
+          );
+          result.push(
+            new ToolMessage({
+              tool_call_id: id,
+              content: JSON.stringify({
+                ok: false,
+                tool: tcName,
+                error: "工具执行异常，未能返回结果（已自动补全）",
+              }),
+            }),
+          );
+        }
+      }
+    } else {
+      result.push(m);
+    }
+  }
+
+  return result;
+}

langgraph/src/agent/writer/nodes/agent.ts

@@ -4,6 +4,7 @@
  */
 import { createLlm, type ModelMode } from "@/agent/utils/create-llm";
 import { truncateMessages } from "@/agent/utils/truncate-messages";
+import { cleanPollutedToolCalls } from "@/agent/utils/clean-polluted-tool-calls";
 import { LangGraphRunnableConfig } from "@langchain/langgraph";
 import { WriterState, WriterUpdate } from "../types.js";
 import { ALL_WRITER_TOOLS } from "./tool-defs.js";
@@ -65,9 +66,11 @@ export async function writerAgentNode(
   const llm = createLlm({ modelMode, maxTokens: 8192 });
 
   const truncated = truncateMessages(state.messages);
+  // Clean up polluted messages before sending to LLM
+  const cleanedMessages = cleanPollutedToolCalls(truncated);
   const messagesWithSystem = [
     { role: "system" as const, content: SYSTEM_PROMPT },
-    ...truncated,
+    ...cleanedMessages,
   ];
 
   const message = await llm

langgraph/src/agent/writer/nodes/tool-executor.ts

@@ -403,6 +403,19 @@ export async function writerToolExecutorNode(
     }
   }
 
+  // Ensure every tool_call has a corresponding ToolMessage (prevent checkpoint pollution)
+  const respondedIds = new Set(toolMessages.map(m => m.tool_call_id));
+  for (const tc of toolCalls) {
+    if (tc.id && !respondedIds.has(tc.id)) {
+      console.error(`[checkpoint-guard] Missing ToolMessage for tool_call_id: ${tc.id}, tool: ${tc.name}`);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id,
+        content: JSON.stringify({ ok: false, tool: tc.name, error: "工具执行异常，未能返回结果" }),
+      });
+    }
+  }
+
   return {
     messages: toolMessages,
     ui: ui.items,

langgraph/src/main.tsx

@@ -9,7 +9,7 @@ type UIMsgLocal = { id: string; type: string; name: string; props: Record<string
 import { useState, useRef, useEffect, useCallback, Component, type ReactNode } from "react";
 import ComponentMap from "./agent-uis/index.tsx";
 import "./index.css";
-import { BookOpen, Search, Terminal, Ticket, Zap, Cpu, Bot, Menu, Copy, Check, RefreshCw, Square, Pencil, ChevronDown, Sparkles, Loader2, Clock } from "lucide-react";
+import { BookOpen, Search, Terminal, Ticket, Zap, Cpu, Bot, Menu, Copy, Check, RefreshCw, Square, Pencil, ChevronDown, Sparkles, Loader2, Clock, AlertTriangle, Plus } from "lucide-react";
 import { cn } from "@/lib/utils";
 import { ThreadSidebar, type ThreadItem, updateThreadLastActive } from "@/components/ThreadSidebar.tsx";
 import { ThemeProvider } from "next-themes";
@@ -343,6 +343,42 @@ function App() {
     }
   }, [currentThreadId]);
 
+  // ── Reset corrupted thread ───────────────────────────────────────────────
+  const [resetLoading, setResetLoading] = useState(false);
+
+  const handleResetThread = useCallback(async () => {
+    if (!currentThreadId || resetLoading) return;
+    setResetLoading(true);
+    try {
+      // Delete the corrupted thread
+      await client.threads.delete(currentThreadId).catch(() => {/* ignore if already gone */});
+      // Create a fresh replacement thread
+      const newThread = await client.threads.create();
+      const newId = newThread.thread_id;
+      // Replace old thread entry in sidebar at the same position
+      setThreads((prev) =>
+        prev.map((t) =>
+          t.thread_id === currentThreadId ? (newThread as ThreadItem) : t,
+        ),
+      );
+      // Clear messages and switch to new thread
+      setHistoricalMessages([]);
+      setHistoricalUi([]);
+      setCurrentThreadId(newId);
+    } catch {
+      // If anything fails, just create a new thread (append to top)
+      try {
+        const newThread = await client.threads.create();
+        setThreads((prev) => [newThread as ThreadItem, ...prev]);
+        setHistoricalMessages([]);
+        setHistoricalUi([]);
+        setCurrentThreadId(newThread.thread_id);
+      } catch { /* give up gracefully */ }
+    } finally {
+      setResetLoading(false);
+    }
+  }, [currentThreadId, resetLoading]);
+
   // Auto-resize textarea
   useEffect(() => {
     const el = textareaRef.current;
@@ -941,6 +977,45 @@ function App() {
                 </div>
               ))}
 
+          {/* ── Thread error banner ── */}
+          {!!thread.error && !thread.isLoading && (
+            <div className="rounded-xl border border-red-300 dark:border-red-800 bg-red-50 dark:bg-red-950/30 px-4 py-4 flex flex-col gap-3 my-2">
+              <div className="flex items-start gap-2.5">
+                <AlertTriangle className="size-4 shrink-0 text-red-500 dark:text-red-400 mt-0.5" />
+                <div className="flex flex-col gap-0.5">
+                  <p className="text-sm font-medium text-red-700 dark:text-red-300">对话遇到问题</p>
+                  <p className="text-xs text-red-600/80 dark:text-red-400/80">
+                    工具执行异常导致对话状态损坏，无法继续当前对话。
+                  </p>
+                </div>
+              </div>
+              <div className="flex items-center gap-2 pl-6">
+                <button
+                  type="button"
+                  onClick={handleResetThread}
+                  disabled={resetLoading}
+                  className="inline-flex items-center gap-1.5 rounded-lg border border-red-300 dark:border-red-700 bg-white dark:bg-red-900/20 px-3 py-1.5 text-xs font-medium text-red-700 dark:text-red-300 hover:bg-red-50 dark:hover:bg-red-900/40 transition-colors disabled:opacity-60 disabled:cursor-not-allowed"
+                >
+                  {resetLoading ? (
+                    <Loader2 className="size-3.5 animate-spin" />
+                  ) : (
+                    <RefreshCw className="size-3.5" />
+                  )}
+                  {resetLoading ? "重置中..." : "重置此对话"}
+                </button>
+                <button
+                  type="button"
+                  onClick={handleNewThread}
+                  disabled={resetLoading}
+                  className="inline-flex items-center gap-1.5 rounded-lg border border-border bg-background px-3 py-1.5 text-xs font-medium text-foreground hover:bg-accent transition-colors disabled:opacity-60 disabled:cursor-not-allowed"
+                >
+                  <Plus className="size-3.5" />
+                  新建对话
+                </button>
+              </div>
+            </div>
+          )}
+
           <div ref={bottomRef} />
 
           {/* Scroll-to-bottom floating button */}