deepseek-harness/apps/desktop/src/host-process.ts

/** Electron Node-mode child lifecycle for the shared Web application. */

import { spawn, type ChildProcess } from 'node:child_process'
import { join } from 'node:path'
import { desktopNodeEnvironment } from './node-environment.ts'

interface ReadyEvent {
  readonly type: 'ready'
  readonly url: string
}

interface FatalEvent {
  readonly type: 'fatal'
  readonly message: string
}

type DesktopHostEvent = ReadyEvent | FatalEvent

const MAX_HOST_DIAGNOSTIC_CHARS = 64 * 1024

function isDesktopHostEvent(message: unknown): message is DesktopHostEvent {
  if (typeof message !== 'object' || message === null || !('type' in message)) return false
  const candidate = message as Record<string, unknown>
  switch (candidate.type) {
    case 'ready':
      return typeof candidate.url === 'string'
    case 'fatal':
      return typeof candidate.message === 'string'
    default:
      return false
  }
}

async function exitsWithin(exit: Promise<void>, milliseconds: number): Promise<boolean> {
  let timer: ReturnType<typeof setTimeout> | undefined
  const timeout = new Promise<false>((resolve) => {
    timer = setTimeout(() => { resolve(false) }, milliseconds)
    timer.unref()
  })
  try {
    return await Promise.race([exit.then(() => true), timeout])
  } finally {
    if (timer !== undefined) clearTimeout(timer)
  }
}

/** Browser authentication URL reported by the running Web application. */
export interface DesktopHostReady {
  readonly url: string
}

/** One Web backend running under the Electron executable in Node mode. */
export class DesktopHostProcess {
  private child: ChildProcess | undefined
  private readyResolve!: (ready: DesktopHostReady) => void
  private readyReject!: (error: Error) => void
  private readonly readyPromise = new Promise<DesktopHostReady>((resolve, reject) => {
    this.readyResolve = resolve
    this.readyReject = reject
  })
  private exitPromise: Promise<void> | undefined
  private stderr = ''
  private failureReported = false
  private stopping = false

  /**
   * @param node - Absolute Electron executable in Node mode.
   * @param runtimeDir - Immutable packages carried by the current application.
   * @param projectDir - Desktop plugin profile and child working directory.
   * @param inspectPort - Optional loopback inspector port for workspace development.
   * @param environment - Environment inherited by the Host and its plugin subprocesses.
   * @param onFailure - Receives the first unexpected child failure, including after readiness.
   */
  constructor(
    private readonly node: string,
    private readonly runtimeDir: string,
    private readonly projectDir: string,
    private readonly inspectPort?: number,
    private readonly environment: NodeJS.ProcessEnv = process.env,
    private readonly onFailure?: (error: Error) => void,
  ) {}

  /**
   * Start this child once and await its Web application URL.
   * @returns Ready facts supplied by the child after application startup.
   */
  async start(): Promise<DesktopHostReady> {
    if (this.child !== undefined) return this.readyPromise
    const entry = join(this.runtimeDir, 'node_modules', '@deepseek-ai', 'dsh-desktop-host', 'lib', 'index.js')
    const child = spawn(this.node, [
      '--expose-internals',
      ...(this.inspectPort === undefined ? [] : [`--inspect=127.0.0.1:${String(this.inspectPort)}`]),
      entry,
      this.runtimeDir,
      this.projectDir,
    ], {
      cwd: this.projectDir,
      env: desktopNodeEnvironment(this.node, undefined, this.environment),
      stdio: ['ignore', 'pipe', 'pipe', 'ipc'],
    })
    this.child = child
    child.stderr?.setEncoding('utf8')
    child.stderr?.on('data', (chunk: string) => { this.stderr = (this.stderr + chunk).slice(-MAX_HOST_DIAGNOSTIC_CHARS) })
    child.stdout?.pipe(process.stdout)
    child.on('message', (message: unknown) => {
      if (!isDesktopHostEvent(message)) {
        this.fail(new Error('dsh desktop host sent an invalid IPC event'))
        child.kill('SIGTERM')
        return
      }
      if (message.type === 'ready') this.readyResolve({ url: message.url })
      else this.fail(new Error(message.message))
    })
    child.once('error', (error) => { this.fail(error) })
    this.exitPromise = new Promise<void>((resolve) => {
      child.once('close', (code) => {
        const suffix = this.stderr.trim() === '' ? '' : `: ${this.stderr.trim()}`
        if (code !== 0 && code !== null) this.fail(new Error(`dsh desktop host exited with ${String(code)}${suffix}`))
        else this.fail(new Error(`dsh desktop host stopped${suffix}`))
        resolve()
      })
    })
    return this.readyPromise
  }

  /** Request graceful teardown and await exit, escalating termination when needed. */
  async stop(): Promise<void> {
    const child = this.child
    if (child === undefined) return
    this.stopping = true
    if (child.connected) child.send({ type: 'shutdown' }, (error) => { if (error !== null) this.fail(error) })
    const exited = this.exitPromise ?? Promise.resolve()
    if (!await exitsWithin(exited, 10_000)) child.kill('SIGTERM')
    if (!await exitsWithin(exited, 5_000)) {
      child.kill('SIGKILL')
      if (!await exitsWithin(exited, 5_000)) {
        throw new Error('dsh desktop host did not exit after SIGKILL')
      }
    }
    this.child = undefined
  }

  private fail(error: Error): void {
    this.readyReject(error)
    if (!this.failureReported && !this.stopping) {
      this.failureReported = true
      try { this.onFailure?.(error) } catch (listenerError) {
        console.error('desktop host failure listener failed', listenerError)
      }
    }
  }
}