增强各厂商思考与采样参数映射，并统一流式推理字段解析。

避免不同接口字段差异导致思考链丢失或采样参数被忽略。

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/stream-complete.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+import { consumeOpenAiToolStream } from "../src/llm/stream-complete.js";
+
+function sseStream(chunks: string[]): ReadableStream<Uint8Array> {
+  const encoder = new TextEncoder();
+  return new ReadableStream({
+    start(controller) {
+      for (const chunk of chunks) controller.enqueue(encoder.encode(chunk));
+      controller.close();
+    },
+  });
+}
+
+describe("consumeOpenAiToolStream", () => {
+  it("reads reasoning from reasoning_content and content from delta", async () => {
+    const parts = await consumeOpenAiToolStream(
+      sseStream([
+        'data: {"choices":[{"delta":{"reasoning_content":"想一下"}}]}\n',
+        'data: {"choices":[{"delta":{"content":"门开了"}}]}\n',
+        "data: [DONE]\n",
+      ]),
+      {},
+    );
+    expect(parts.reasoning).toBe("想一下");
+    expect(parts.content).toBe("门开了");
+  });
+
+  it("accepts reasoning / thinking aliases and last-frame message content", async () => {
+    const parts = await consumeOpenAiToolStream(
+      sseStream([
+        'data: {"choices":[{"delta":{"reasoning":"先想"}}]}\n',
+        'data: {"choices":[{"message":{"content":"她摘下耳机。"}}]}\n',
+        "data: [DONE]\n",
+      ]),
+      {},
+    );
+    expect(parts.reasoning).toBe("先想");
+    expect(parts.content).toBe("她摘下耳机。");
+  });
+});