fix: buildModelMessages approval-responded without result should not emit tool-call

When a tool-call is in 'approval-responded' state with approved=true but
hasResult=false (approval executed but result not yet available in
approvalToolResults), the code was pushing a tool-call part to the
assistant message without a corresponding tool-result in the tool message.

This caused providers (e.g. deepseek) to reject the prompt with
'Tool result is missing for tool call' or
'Invalid prompt: The messages do not match the ModelMessage[] schema'.

Fix: only push tool-approval-request (not tool-call) when hasResult=false.
Also clean up approval-requested branch to only include required fields
(type, approvalId, toolCallId) per AI SDK schema.

Co-authored-by: CodeFree <codefree@chinatelcom.cn>

server/service/agent/chat-engine.ts

@@ -90,8 +90,6 @@ function buildModelMessages(
               type: "tool-approval-request",
               approvalId: p.approvalId,
               toolCallId: p.toolCallId,
-              toolName: p.toolName,
-              input: p.args ?? {},
             });
           } else if (p.state === "approval-responded" && p.approvalId) {
             const hasResult = opts.approvalToolResults?.[p.toolCallId] !== undefined;
@@ -104,17 +102,9 @@ function buildModelMessages(
               });
             } else {
               assistantContent.push({
-                type: "tool-call",
-                toolCallId: p.toolCallId,
-                toolName: p.toolName,
-                input: p.args ?? {},
-              });
-              assistantContent.push({
                 type: "tool-approval-request",
                 approvalId: p.approvalId,
                 toolCallId: p.toolCallId,
-                toolName: p.toolName,
-                input: p.args ?? {},
               });
             }
           } else {
@@ -440,10 +430,10 @@ export async function executeChat(params: ChatEngineParams): Promise<ChatEngineR
         }
       : {}),
     onError: (errorData) => {
-      const errMsg = errorData?.error instanceof Error
-        ? errorData.error.message
-        : String(errorData?.error ?? "未知错误");
-      logger.error("[%s] [CHAT-ENGINE] streamText error: %s", requestId, errMsg);
+      const err = errorData?.error;
+      const errMsg = err instanceof Error ? err.message : String(err ?? "未知错误");
+      const errCause = err instanceof Error ? JSON.stringify(err.cause ?? null, null, 2) : "";
+      logger.error("[%s] [CHAT-ENGINE] streamText error: %s\ncause: %s", requestId, errMsg, errCause);
     },
     onChunk: ({ chunk }) => {
       if (chunk.type === "text-delta") {