feat: align teacher guidance with persistent discussion tools

tests/unit/coding-teacher.test.ts

@@ -6,6 +6,7 @@ import { afterEach, describe, expect, it, vi } from 'vitest';
 import { CodingTeacherService, type TeacherScope } from '../../electron/coding-teacher/service';
 import { TeacherTopicStore } from '../../electron/coding-teacher/store';
 import { compileTeacherContext, estimateTeacherTokens, sourceContext } from '../../electron/coding-teacher/context';
+import { TEACHER_BEHAVIOR_PROMPT } from '../../electron/coding-teacher/behavior-prompt';
 import { streamTeacherReply } from '../../electron/coding-teacher/model-runner';
 import { TeacherError } from '../../electron/coding-teacher/config-client';
 import { consultationDefinition } from '../../electron/coding-teacher/consultation-role';
@@ -985,6 +986,10 @@ describe('teacher context and wire contract', () => {
     expect(selected.cursor).toEqual(snapshot.cursor);
   });
   it('trims old source messages but retains instructions, Skill, explicit quote and question', () => {
+    const references = [{ kind: 'code' as const, text: 'count += 1' }];
+    const budget = estimateTeacherTokens(compileTeacherContext(
+      definition, context, [], '为什么这样？', references
+    ).messages);
     const compiled = compileTeacherContext(
       definition,
       {
@@ -993,13 +998,15 @@ describe('teacher context and wire contract', () => {
       },
       [],
       '为什么这样？',
-      [{ kind: 'code', text: 'count += 1' }],
-      1200
+      references,
+      budget
     );
     const text = JSON.stringify(compiled.messages);
     expect(text).toContain('通过问题引导思考');
     expect(text).toContain('使用具体的小例子');
     expect(text).toContain('count += 1');
+    expect(compiled.messages[0].content).toContain(TEACHER_BEHAVIOR_PROMPT);
+    expect(compiled.includedSourceMessageIds).toEqual(['source-user']);
     expect(compiled.omittedMessages).toBe(1);
     expect(() => compileTeacherContext(definition, context, [], 'x'.repeat(9000), [])).toThrow(
       '超过上下文预算'
@@ -1169,6 +1176,9 @@ describe('structured teacher service integration', () => {
       requestId: crypto.randomUUID(), text, presentation: 'discussion-v1', sourceConversationId: f.scope.sourceId, discussion,
     });
     const pending = await send('想养只小狗');
+    const modelMessages = f.run.mock.calls[0][0] as Array<{ role: string; content: string }>;
+    expect(modelMessages[0].content).toContain(TEACHER_BEHAVIOR_PROMPT);
+    expect(modelMessages.some(message => message.role === 'system' && message.content.includes('本轮界面协议'))).toBe(true);
     expect(pending.requests[0].response).toBe('');
     expect(pending.discussion).toBeUndefined();
     f.finish();