fix(teacher): 区分词元预算与传输字节避免短问题被拦截

tests/unit/coding-teacher-cloud.test.ts

@@ -85,7 +85,7 @@ async function submitCompiledContext(
   );
   const compiled = compileTeacherContext(
     f.topic.definition, f.access.source, [], intent === 'check-in' ? '' : '下一步怎么想？', [],
-    model.inputLimit, intent, presentationInstructions, true
+    model.inputLimit, intent, presentationInstructions, true, model.measureInput
   );
   await model.run(compiled.messages, new AbortController().signal, vi.fn());
   const body = vi.mocked(transport.json).mock.calls.find(([url]) => url === '/questions')?.[1] as {
@@ -130,6 +130,32 @@ it('submits the active discussion protocol, current tool content and selected fo
   expect(protocol).toContain('比较两种重力');
 });
 
+it('submits a short first question with the normal discussion protocol and published budget', async () => {
+  const f = await fixture();
+  const { body } = await submitCompiledContext(f, 'question', discussionInstructions(f.topic));
+  expect(body.query).toContain('下一步怎么想？');
+});
+
+it('excerpts long code context to fit the serialized cloud query', async () => {
+  const f = await fixture();
+  f.access.source.messages[0].text = 'const title = "game";\n'.repeat(500);
+  const { body, compiled } = await submitCompiledContext(f);
+  expect(compiled.truncatedMessages).toBeGreaterThan(0);
+  expect(body.query).toContain('下一步怎么想？');
+});
+
+it('fits code excerpts beside the unchanged discussion protocol in the original cloud budget', async () => {
+  const f = await fixture();
+  const original = 'const config = { "title": "小游戏" };\n'.repeat(500);
+  f.access.source.messages[0].text = original;
+  const protocol = discussionInstructions(f.topic);
+  const { body, compiled } = await submitCompiledContext(f, 'question', protocol);
+  expect(compiled.messages.at(-2)?.content).toBe(protocol);
+  expect(compiled.truncatedMessages).toBeGreaterThan(0);
+  expect(f.access.source.messages[0].text).toBe(original);
+  expect(JSON.parse(body.query).messages.at(-1).content).toContain('下一步怎么想？');
+});
+
 it('submits a nonempty proactive check-in without inventing a user message', async () => {
   const f = await fixture();
   f.access.source.messages = [];