代码编辑器：代码补全、悬停提示、参数提示、边写边检查

- 运行器新增 language-server 模式：常驻语言服务，和编译服务分开；用 Roslyn 的
  CompletionService、QuickInfoService（和 VS 的 IntelliSense 同一套引擎），参数提示用语义模型实现；
  每个浏览器标签页一份工程，只更新有变化的文件；去掉仿真类库的可空注解（string? → string）
- 编译和语言服务共用同一套编译选项和引用；检查结果带上禁止 API 的报错和中文提示
- 服务端 POST /api/language 转发请求（按用户区分会话，10 秒超时）
- 编辑器：补全（"." 触发，选中时取说明）、悬停、参数提示（"(" "," 触发）；停止输入 1 秒后检查整个工程，
  和"运行"时的编译结果以较新的为准
- 实测（2 核）：50 个标签页同时检查 1.2 秒内完成，同时补全 0.7 秒；内存约 260 MB

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/app.ts

@@ -16,6 +16,7 @@ import {
   updateAssignment,
 } from './assignments'
 import { parseChecks } from './grading/checks'
+import { languageService } from './language-service'
 import { getReview, gradebook, manualScore, saveReview, studentDetail, submissionFiles } from './reviews'
 import type { GradingQueue } from './grading/queue'
 import { listSamples, loadChecks, loadSample } from './samples'
@@ -83,6 +84,17 @@ export function createApp(db: Database, gradingQueue: GradingQueue) {
     return files ? c.json(files) : c.notFound()
   })
 
+  // 代码编辑器的语言服务：补全、悬停提示、参数提示、边写边检查
+  const LANGUAGE_REQUESTS = new Set(['complete', 'completionDetail', 'hover', 'signature', 'diagnostics'])
+  app.post('/api/language', async (c) => {
+    const r = await body<{ type: string; session: string; files: unknown; file: string; line: number; column: number; index: number }>(c)
+    if (!LANGUAGE_REQUESTS.has(String(r.type)) || typeof r.session !== 'string') return c.json({ message: '请求格式不对' }, 400)
+    if (r.files !== undefined && !validFiles(r.files)) return c.json({ message: '作品格式不对或太大' }, 400)
+    // 会话按用户区分，不同学生的工程不会混在一起
+    const reply = await languageService.request({ ...r, session: `${c.get('user').id}:${r.session.slice(0, 64)}` })
+    return c.json(reply ?? { type: 'empty' })
+  })
+
   // 自己的作品：key 如 "sample:p2-t1-LED显示屏"
   app.get('/api/works/:key', (c) => c.json(getWork(db, c.get('user').id, c.req.param('key'))))
 

server/src/index.ts

@@ -2,6 +2,7 @@ import type { ClientMessage, ServerMessage } from '@iot/shared'
 import { createApp } from './app'
 import { ensureTeacher, tokenUser } from './auth'
 import { compileService } from './compile-service'
+import { languageService } from './language-service'
 import { config } from './config'
 import { openDatabase } from './db'
 import { createGradingQueue } from './grading/queue'
@@ -69,5 +70,5 @@ const server = Bun.serve({
 })
 
 console.log(`服务器已启动：http://localhost:${server.port}`)
-await compileService.start()
+await Promise.all([compileService.start(), languageService.start()])
 console.log('C# 编译服务已就绪')

server/src/language-service.ts

@@ -0,0 +1,75 @@
+import type { Subprocess } from 'bun'
+import { config } from './config'
+import { readLines } from './runner-process'
+
+/** 一个请求最多等多久；语言服务忙或卡住时，编辑器不弹补全也不影响写代码 */
+const TIMEOUT_MS = 10_000
+
+/**
+ * 常驻语言服务：代码补全、悬停提示、参数提示、边写边检查。全服务器共用一个进程（和编译服务分开），
+ * 请求按编号对应回复。进程意外退出时，挂起的请求失败，下一次请求自动重启。
+ */
+class LanguageService {
+  private proc?: Subprocess<'pipe', 'pipe', 'inherit'>
+  private ready?: Promise<void>
+  private nextId = 1
+  private readonly pending = new Map<number, (reply: Record<string, unknown> | null) => void>()
+
+  /** 发一个请求（type、session、files、file、line、column 等原样转给语言服务）；超时或出错返回 null */
+  async request(body: Record<string, unknown>): Promise<Record<string, unknown> | null> {
+    await this.start()
+    const id = this.nextId++
+    const reply = new Promise<Record<string, unknown> | null>((resolve) => {
+      const timer = setTimeout(() => {
+        this.pending.delete(id)
+        resolve(null)
+      }, TIMEOUT_MS)
+      this.pending.set(id, (r) => {
+        clearTimeout(timer)
+        resolve(r)
+      })
+    })
+    this.proc!.stdin.write(`${JSON.stringify({ ...body, id })}\n`)
+    this.proc!.stdin.flush()
+    return reply
+  }
+
+  stop() {
+    this.proc?.kill()
+  }
+
+  /** 服务器启动时调用，提前完成加载和预热 */
+  start() {
+    if (this.ready) return this.ready
+    const proc = Bun.spawn(['dotnet', config.runnerDll, 'language-server'], {
+      stdin: 'pipe',
+      stdout: 'pipe',
+      stderr: 'inherit',
+      env: { PATH: process.env.PATH ?? '/usr/bin:/bin', HOME: process.env.HOME ?? '/tmp', DOTNET_CLI_TELEMETRY_OPTOUT: '1', DOTNET_NOLOGO: '1' },
+    })
+    this.proc = proc
+    this.ready = new Promise<void>((resolveReady) => {
+      void readLines(proc.stdout, (line) => {
+        const message = JSON.parse(line) as { type: string; id?: number }
+        if (message.type === 'ready') {
+          resolveReady()
+          return
+        }
+        const resolve = this.pending.get(message.id!)
+        if (!resolve) return
+        this.pending.delete(message.id!)
+        resolve(message.type === 'error' ? null : message)
+      })
+    })
+    proc.exited.then(() => {
+      if (this.proc !== proc) return
+      this.proc = undefined
+      this.ready = undefined
+      for (const resolve of this.pending.values()) resolve(null)
+      this.pending.clear()
+    })
+    return this.ready
+  }
+}
+
+export const languageService = new LanguageService()

server/test/api.test.ts

@@ -1,10 +1,11 @@
 // HTTP 接口测试：内存数据库，直接调用 app.fetch。
-import { beforeEach, describe, expect, test } from 'bun:test'
+import { afterAll, beforeEach, describe, expect, test } from 'bun:test'
 import { createApp } from '../src/app'
 import { ensureTeacher } from '../src/auth'
 import { config } from '../src/config'
 import { openDatabase } from '../src/db'
 import { createGradingQueue, type GradingQueue } from '../src/grading/queue'
+import { languageService } from '../src/language-service'
 import { loadSample } from '../src/samples'
 
 let app: ReturnType<typeof createApp>
@@ -405,3 +406,20 @@ describe('评阅与成绩', () => {
     expect((await student.get(`/api/teacher/submissions/${submission.id}`)).status).toBe(403)
   }, 60000)
 })
+
+describe('语言服务', () => {
+  afterAll(() => languageService.stop())
+
+  test('代码补全、边写边检查（中文提示）；请求格式不对拒绝；没登录不能用', async () => {
+    const t = await teacher()
+    const files = [{ path: 'Program.cs', content: 'using System.Windows.Forms;\nstatic class P\n{\n    static void Main()\n    {\n        var b = new Button();\n        b.\n    }\n}\n' }]
+    const completions = await t.post('/api/language', { type: 'complete', session: 'tab1', files, file: 'Program.cs', line: 7, column: 11 })
+    expect(completions.body.items.map((i: any) => i.label)).toEqual(expect.arrayContaining(['Text', 'Click', 'Enabled']))
+
+    const check = await t.post('/api/language', { type: 'diagnostics', session: 'tab1', files })
+    expect(check.body.diagnostics).toEqual(expect.arrayContaining([expect.objectContaining({ code: 'CS1002', hint: 'C# 每条语句末尾要有英文分号 ;' })]))
+
+    expect((await t.post('/api/language', { type: 'run', session: 'tab1' })).status).toBe(400)
+    expect((await new Browser().post('/api/language', { type: 'complete', session: 'tab1', files })).status).toBe(401)
+  }, 60000)
+})