fix(teacher): 改善只读工具分页与读取预算

electron/coding-teacher/cloud-runner.ts

@@ -10,7 +10,8 @@ import {
   type TeacherAccount,
 } from './config-client';
 import type { TeacherModelMessage } from './context';
-import { createTeacherReadTools, type TeacherReadAccess } from './read-tools';
+import { createTeacherReadTools, type TeacherReadAccess, TEACHER_READ_PROTOCOL, TEACHER_READ_ROUNDS,
+  TEACHER_READ_BYTES, TEACHER_READ_PAGE_BYTES, TEACHER_READ_MIN_BYTES } from './read-tools';
 
 interface TeacherSession {
   access_token: string;
@@ -209,6 +210,7 @@ export function prepareCloudTeacher(
         || currentRequest?.presentation === 'discussion-v1';
       const localContext = {
         id: requestId,
+        read_protocol: TEACHER_READ_PROTOCOL,
         scope: {
           project_id: topic.projectId,
           source_session_id: currentRequest?.sourceConversationId ?? topic.sourceConversationId,
@@ -274,7 +276,8 @@ export function prepareCloudTeacher(
         }
         let runId = identifier(queued.run_id),
           cursor = '0-0',
-          rounds = 0;
+          rounds = 0,
+          readBytes = 0;
         let runText = '',
           messageId = '';
         while (Date.now() < deadline) {
@@ -308,7 +311,7 @@ export function prepareCloudTeacher(
               );
             if (!Array.isArray(pending.calls) || !pending.calls.length || pending.calls.length > 32)
               throw new TeacherError(502, 'teacher_protocol_invalid', '智能体读取请求格式无效，请重试。');
-            if (++rounds > 6)
+            if (++rounds > TEACHER_READ_ROUNDS)
               throw new TeacherError(
                 409,
                 'teacher_read_limit',
@@ -321,7 +324,11 @@ export function prepareCloudTeacher(
               if (typeof call.tool_call_id !== 'string' || typeof call.name !== 'string')
                 throw new TeacherError(502, 'teacher_protocol_invalid', '智能体读取请求无效。');
               reportActivity({ id: requestId + ':' + call.tool_call_id, name: call.name, status: 'running' });
-              const result = await tools.executeResult(call.name, JSON.stringify(call.arguments), bounded);
+              const remaining = TEACHER_READ_BYTES - readBytes;
+              const result = remaining < TEACHER_READ_MIN_BYTES
+                ? { status: 'error' as const, content: 'Read budget exhausted. Answer from the evidence already returned and state any gaps.', truncated: false }
+                : await tools.executeResult(call.name, JSON.stringify(call.arguments), bounded, Math.min(TEACHER_READ_PAGE_BYTES, remaining));
+              if (result.status === 'success') readBytes += Buffer.byteLength(result.content);
               results.push({
                 tool_call_id: call.tool_call_id,
                 ...result,