fix: use Promise.allSettled to prevent missing ToolMessage responses

When LLM sends multiple parallel tool_calls but one throws unexpectedly,
Promise.all loses all results causing 400 error from OpenAI.
Promise.allSettled ensures every tool_call_id gets a response.

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

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

@@ -144,8 +144,22 @@ export async function toolExecutorNode(
     }
   });
 
-  const results = await Promise.all(executions);
-  toolMessages.push(...results);
+  const settled = await Promise.allSettled(executions);
+  for (let i = 0; i < settled.length; i++) {
+    const result = settled[i];
+    if (result.status === "fulfilled") {
+      toolMessages.push(result.value);
+    } else {
+      const tc = toolCalls[i];
+      const errMsg = result.reason instanceof Error ? result.reason.message : String(result.reason);
+      console.error(`[tool-executor] Unhandled rejection for ${tc.name}:`, result.reason);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id ?? "",
+        content: JSON.stringify({ ok: false, tool: tc.name, error: errMsg }),
+      });
+    }
+  }
 
   return {
     messages: toolMessages,

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

@@ -1033,8 +1033,22 @@ export async function toolExecutorNode(
     }
   });
 
-  const results = await Promise.all(executions);
-  toolMessages.push(...results);
+  const settled = await Promise.allSettled(executions);
+  for (let i = 0; i < settled.length; i++) {
+    const result = settled[i];
+    if (result.status === "fulfilled") {
+      toolMessages.push(result.value);
+    } else {
+      const tc = toolCalls[i];
+      const errMsg = result.reason instanceof Error ? result.reason.message : String(result.reason);
+      console.error(`[tool-executor] Unhandled rejection for ${tc.name}:`, result.reason);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id ?? "",
+        content: JSON.stringify({ ok: false, tool: tc.name, error: errMsg }),
+      });
+    }
+  }
 
   // Push next-actions card based on successful tool results
   const successfulTools = statusList.filter(

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

@@ -375,8 +375,24 @@ export async function toolExecutorNode(
     }
   });
 
-  const results = await Promise.all(executions);
-  toolMessages.push(...results);
+  const settled = await Promise.allSettled(executions);
+  for (let i = 0; i < settled.length; i++) {
+    const result = settled[i];
+    if (result.status === "fulfilled") {
+      toolMessages.push(result.value);
+    } else {
+      // Ensure every tool_call_id gets a response even if execution threw unexpectedly
+      const tc = toolCalls[i];
+      const errMsg = result.reason instanceof Error ? result.reason.message : String(result.reason);
+      console.error(`[tool-executor] Unhandled rejection for ${tc.name}:`, result.reason);
+      toolMessages.push({
+        role: "tool" as const,
+        tool_call_id: tc.id ?? "",
+        content: JSON.stringify({ ok: false, tool: tc.name, error: errMsg }),
+      });
+      statusList.push({ tool: tc.name ?? "unknown", status: "error", message: errMsg });
+    }
+  }
 
   return {
     messages: toolMessages,