/**
 * Headless audit of the SHIPPED GAME BUNDLE (`dist-game/`).
 *
 * WHAT THIS AUDITS, AND WHY IT IS `dist-game/` AND NOT A DEV SERVER
 * -----------------------------------------------------------------
 * The Zero-Runtime-MPQ invariant (Iron Law #2) constrains the artifact that
 * actually ships. Auditing a dev server would prove "no MPQ requests in
 * development form" while the production bundle could still contain the
 * `httpRangeSource('/d2char.mpq')` path — a fully green report over a violated
 * invariant, which is the worst available false negative. So this harness
 * serves the real built output over a plain `node:http` static server and
 * never transforms a source file.
 *
 * The static server is deliberately dependency-free (`node:http`, not vite):
 * the dependency tree is part of what is under test, and if it were also the
 * test carrier then "dependencies broke" would masquerade as "no requests were
 * made".
 *
 * This pairs with `verify-bundle-no-mpq.ts`:
 *
 *   bundle grep    -> the bundle *cannot* download an archive (structural)
 *   this harness   -> the bundle *did not* download one while being played
 *
 * Neither alone is sufficient. The grep cannot see a runtime fetch assembled
 * from fragments; the runtime count cannot see a path that this particular run
 * did not reach.
 *
 * ANTI-VACUITY: THE POINT OF THE `precondition` FIELD
 * ---------------------------------------------------
 * Most of these assertions are of the form "this counter is zero". Such an
 * assertion passes trivially when the thing being counted never had a chance to
 * happen: `missingMonsterArt.length === 0` is equally true on a level that
 * rendered no monsters at all. A harness that reports success in that state is
 * worse than no harness, because it manufactures confidence.
 *
 * So every assertion carries preconditions that establish the measurement was
 * live — the scene rendered, the sim ticked, monsters were planned, the
 * character draw path ran. An assertion whose preconditions are unmet is
 * reported as **VACUOUS** and counts as a harness FAILURE, never as a pass.
 *
 * `act-scene.ts:254` is the cautionary tale: `state.characterGroup` is declared
 * and published but never written, so any audit asserting on it would have been
 * asserting on a constant. This harness checks that trap explicitly.
 *
 * NEGATIVE CONTROLS
 * -----------------
 * An assertion never observed failing is not evidence. `--negative=<id>` injects
 * a specific, real fault and the run is then expected to go red on exactly the
 * targeted assertion. See NEGATIVE_CONTROLS below.
 *
 *   npm run verify:animation                      # audit current dist-game/
 *   npm run verify:animation -- --negative=list   # show the controls
 *   npm run verify:animation -- --negative=mpq-request
 *
 * OUTPUT PATH SAFETY
 * ------------------
 * `scripts/verify-challenger-m3.ts` L28-29 hardcodes an output directory into a
 * different worktree and writes screenshots there (L155/L159). That worktree is
 * off-limits and is actively being worked in by another team. Every path this
 * script writes is therefore passed through `assertWritablePath`, which throws
 * unless the resolved path is inside this worktree. It is a guard rather than a
 * convention so it cannot regress silently.
 */

import { spawn } from 'node:child_process'
import { createServer } from 'node:http'
import type { IncomingMessage, ServerResponse } from 'node:http'
import { createHash } from 'node:crypto'
import { existsSync, mkdirSync, readdirSync, readFileSync, statSync, writeFileSync } from 'node:fs'
import { extname, join, relative, resolve } from 'node:path'

// ---------------------------------------------------------------------------
// Paths
// ---------------------------------------------------------------------------

/** Repo root. This script lives in `<root>/scripts`. */
const ROOT = resolve(process.cwd())
const DIST_DIR = join(ROOT, 'dist-game')
const PACKS_DIR = join(ROOT, 'samples', 'd2-packs')
const SRC_DIR = join(ROOT, 'src')

/**
 * Refuse to write anywhere outside this worktree.
 *
 * The forked-from script wrote screenshots into a sibling worktree that is
 * explicitly off-limits and currently has another team's processes running in
 * it. Enforcing this in code, on every write, is the only version of that rule
 * that cannot rot.
 */
function assertWritablePath(candidate: string): string {
  const full = resolve(candidate)
  const rel = relative(ROOT, full)
  if (rel.startsWith('..') || resolve(rel) === rel) {
    throw new Error(
      `verify-animation-browser: refusing to write outside the worktree.\n` +
        `  requested: ${full}\n  worktree : ${ROOT}`,
    )
  }
  return full
}

// ---------------------------------------------------------------------------
// CLI
// ---------------------------------------------------------------------------

interface Options {
  readonly negative: string
  readonly outDir: string
  readonly keepOpenMs: number
}

function parseArgs(argv: readonly string[]): Options {
  let negative = ''
  let outDir = join(ROOT, '.agents', 'worker_mv', 'evidence')
  let keepOpenMs = 0
  for (const arg of argv) {
    if (arg.startsWith('--negative=')) negative = arg.slice('--negative='.length)
    else if (arg.startsWith('--out=')) outDir = resolve(arg.slice('--out='.length))
    else if (arg.startsWith('--keep-open-ms=')) keepOpenMs = Number(arg.slice('--keep-open-ms='.length))
  }
  return { negative, outDir, keepOpenMs }
}

/**
 * The deliberate faults. Each names the assertion it must turn red.
 *
 * `page-*` controls run inside the page; `artifact-*` controls would require
 * mutating `dist-game/`, which is done by the separate bundle-gate controls
 * rather than here, so that this harness never writes to the build output.
 */
const NEGATIVE_CONTROLS: Readonly<Record<string, string>> = {
  'mpq-request': 'page fetches a *.mpq URL -> must turn ZERO_MPQ_DLL_REQUESTS red',
  'dll-request': 'page fetches a *.dll URL -> must turn ZERO_MPQ_DLL_REQUESTS red',
  'console-error': 'page emits console.error -> must turn ZERO_CONSOLE_ERRORS red',
  'missing-art': 'push a fake id into missingMonsterArt -> must turn NO_RED_PLACEHOLDER_SQUARES red',
  'monster-art-error': 'bump monsterArtErrors -> must turn NO_RED_PLACEHOLDER_SQUARES red',
  'freeze-facing': 'ignore facing writes -> must turn EIGHT_DIRECTIONS_EXERCISED red',
  'broken-page': 'navigate to a URL that does not exist -> must turn SCENE_BOOTED red',
}

// ---------------------------------------------------------------------------
// Static server for the built artifact
// ---------------------------------------------------------------------------

const MIME: Readonly<Record<string, string>> = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.mjs': 'text/javascript; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.gif': 'image/gif',
  '.svg': 'image/svg+xml',
  '.wasm': 'application/wasm',
  '.map': 'application/json; charset=utf-8',
  '.r8': 'application/octet-stream',
  '.bin': 'application/octet-stream',
  '.dat': 'application/octet-stream',
  '.mp3': 'audio/mpeg',
  '.wav': 'audio/wav',
  '.ogg': 'audio/ogg',
}

interface ServedRequest {
  readonly url: string
  readonly status: number
}

/**
 * Serve the production layout.
 *
 * The game is built with `--base=/diablo2/`, so the bundle must live under
 * `/diablo2/`. `DEFAULT_PACKS` (`act-scene.ts`) resolves its second entry to
 * `/diablo2/packs`, so the baked packs are mounted there — this reproduces the
 * deployed shape rather than inventing one.
 *
 * Note what is deliberately NOT mounted: nothing serves `samples/d2`, so no
 * `*.mpq` is reachable. That does not weaken the audit — a forbidden request is
 * counted when it is *issued*, regardless of the response — and it matches a
 * real deployment, where the archives are not published.
 */
function createStaticServer(served: ServedRequest[]): ReturnType<typeof createServer> {
  const mounts: readonly { readonly prefix: string; readonly dir: string }[] = [
    { prefix: '/diablo2/packs/', dir: PACKS_DIR },
    { prefix: '/diablo2/', dir: DIST_DIR },
  ]

  return createServer((req: IncomingMessage, res: ServerResponse) => {
    const rawUrl = req.url ?? '/'
    const path = decodeURIComponent(rawUrl.split('?')[0] ?? '/')

    const finish = (status: number, body: Buffer | string, type: string): void => {
      served.push({ url: rawUrl, status })
      res.writeHead(status, { 'content-type': type, 'cache-control': 'no-store' })
      res.end(body)
    }

    if (path === '/' || path === '/index.html') {
      finish(302, '', 'text/plain')
      return
    }

    for (const mount of mounts) {
      if (!path.startsWith(mount.prefix)) continue
      const rest = path.slice(mount.prefix.length)
      // Path traversal guard: the resolved file must stay inside the mount.
      const target = resolve(mount.dir, rest)
      if (!target.startsWith(mount.dir)) {
        finish(403, 'forbidden', 'text/plain')
        return
      }
      if (!existsSync(target) || !statSync(target).isFile()) continue
      const body = readFileSync(target)
      finish(200, body, MIME[extname(target).toLowerCase()] ?? 'application/octet-stream')
      return
    }

    finish(404, 'not found', 'text/plain')
  })
}

// ---------------------------------------------------------------------------
// Assertion framework
// ---------------------------------------------------------------------------

type Verdict = 'PASS' | 'FAIL' | 'VACUOUS'

interface Assertion {
  readonly id: string
  /** What acceptance-criterion text this maps to. */
  readonly criterion: string
  readonly verdict: Verdict
  readonly detail: string
  /** Precondition results, so a reader can see the measurement was live. */
  readonly preconditions: readonly { readonly name: string; readonly met: boolean; readonly value: string }[]
  /**
   * True when the assertion is expected to be red on current `main` because it
   * documents a pre-existing defect another milestone owns. Reported loudly and
   * excluded from the exit code, so a genuine regression is not buried under a
   * known baseline. Turning green is reported as "baseline improved".
   */
  readonly knownRedBaseline?: string
}

class AssertionLog {
  readonly items: Assertion[] = []

  add(a: Assertion): void {
    this.items.push(a)
  }

  /**
   * Build an assertion, evaluating preconditions first.
   *
   * If any precondition is unmet the verdict is VACUOUS regardless of the
   * predicate, because a green from an unexercised code path is not evidence.
   */
  check(args: {
    id: string
    criterion: string
    preconditions: readonly { name: string; met: boolean; value: string }[]
    pass: boolean
    detail: string
    knownRedBaseline?: string
  }): void {
    const unmet = args.preconditions.filter(p => !p.met)
    const verdict: Verdict = unmet.length > 0 ? 'VACUOUS' : args.pass ? 'PASS' : 'FAIL'
    const detail =
      unmet.length > 0
        ? `${args.detail} | VACUOUS: preconditions unmet -> ${unmet.map(p => `${p.name}=${p.value}`).join(', ')}`
        : args.detail
    this.add({
      id: args.id,
      criterion: args.criterion,
      verdict,
      detail,
      preconditions: args.preconditions,
      ...(args.knownRedBaseline === undefined ? {} : { knownRedBaseline: args.knownRedBaseline }),
    })
  }
}

// ---------------------------------------------------------------------------
// CDP plumbing
// ---------------------------------------------------------------------------

const sleep = (ms: number): Promise<void> => new Promise(r => setTimeout(r, ms))

interface NetworkRequestLog {
  url: string
  method: string
  resourceType: string
}

interface ConsoleErrorLog {
  source: string
  text: string
}

interface CdpSession {
  send: <T = unknown>(method: string, params?: Record<string, unknown>, timeoutMs?: number) => Promise<T>
  evalJs: <T = unknown>(expression: string) => Promise<T>
  close: () => void
}

async function connectCdp(debugPort: number, onEvent: (msg: Record<string, any>) => void): Promise<CdpSession> {
  let wsUrl: string | null = null
  let lastErr = 'none'
  for (let i = 0; i < 80; i++) {
    await sleep(200)
    try {
      const res = await fetch(`http://127.0.0.1:${debugPort}/json/list`)
      const pages = (await res.json()) as { type: string; webSocketDebuggerUrl?: string }[]
      const page = pages.find(p => p.type === 'page')
      if (page?.webSocketDebuggerUrl !== undefined) {
        wsUrl = page.webSocketDebuggerUrl
        break
      }
      lastErr = 'no page target yet'
    } catch (err) {
      // Bounded retry while Chrome boots. This is not a silent swallow: the
      // last error is retained and thrown if the loop never succeeds.
      lastErr = err instanceof Error ? err.message : String(err)
    }
  }
  if (wsUrl === null) throw new Error(`could not reach Chrome CDP endpoint (last error: ${lastErr})`)

  const ws = new WebSocket(wsUrl)
  await new Promise<void>((res, rej) => {
    ws.onopen = () => res()
    ws.onerror = () => rej(new Error('CDP WebSocket failed to open'))
  })

  let idCounter = 1
  const send = <T = unknown>(
    method: string,
    params: Record<string, unknown> = {},
    timeoutMs = 20000,
  ): Promise<T> =>
    new Promise<T>((res, rej) => {
      const id = idCounter++
      const timer = setTimeout(() => {
        ws.removeEventListener('message', handler)
        rej(new Error(`CDP ${method} timed out after ${timeoutMs}ms`))
      }, timeoutMs)
      const handler = (event: MessageEvent): void => {
        const msg = JSON.parse(String(event.data)) as Record<string, any>
        if (msg['id'] === id) {
          clearTimeout(timer)
          ws.removeEventListener('message', handler)
          if (msg['error'] !== undefined) rej(new Error(`CDP ${method}: ${JSON.stringify(msg['error'])}`))
          else res(msg['result'] as T)
        }
      }
      ws.addEventListener('message', handler)
      ws.send(JSON.stringify({ id, method, params }))
    })

  ws.addEventListener('message', (event: MessageEvent) => {
    onEvent(JSON.parse(String(event.data)) as Record<string, any>)
  })

  const evalJs = async <T = unknown>(expression: string): Promise<T> => {
    const res = await send<{ result: { value: T }; exceptionDetails?: unknown }>('Runtime.evaluate', {
      expression,
      awaitPromise: true,
      returnByValue: true,
    })
    if (res.exceptionDetails !== undefined) {
      throw new Error(`in-page JS threw: ${JSON.stringify(res.exceptionDetails)}\n  expression: ${expression}`)
    }
    return res.result.value
  }

  return { send, evalJs, close: () => ws.close() }
}

// ---------------------------------------------------------------------------
// Scene state shape (the subset this audit reads)
// ---------------------------------------------------------------------------

interface SceneSnapshot {
  present: boolean
  ready: boolean
  error: string | null
  frames: number
  tick: number
  character: boolean
  characterFrames: number
  characterGroup: number
  missingMonsterArt: string[]
  monsterArtErrors: number
  monsterArtLayerFailures: number
  monstersPlanned: number
  facing: number
  x: number
  y: number
  npcs: number
}

const SNAPSHOT_EXPR = `(() => {
  const s = window.__d2webAct
  if (!s) return { present: false }
  return {
    present: true,
    ready: !!s.ready,
    error: s.error ?? null,
    frames: s.frames ?? -1,
    tick: s.tick ?? -1,
    character: !!s.character,
    characterFrames: s.characterFrames ?? -1,
    characterGroup: s.characterGroup ?? -999,
    missingMonsterArt: Array.isArray(s.missingMonsterArt) ? s.missingMonsterArt.slice() : null,
    monsterArtErrors: s.monsterArtErrors ?? -1,
    monsterArtLayerFailures: s.monsterArtLayerFailures ?? -1,
    monstersPlanned: s.monstersPlanned ?? -1,
    facing: s.facing ?? -1,
    x: s.x ?? -1,
    y: s.y ?? -1,
    npcs: s.npcs ?? -1,
  }
})()`

// ---------------------------------------------------------------------------
// Main
// ---------------------------------------------------------------------------

async function main(): Promise<void> {
  const opts = parseArgs(process.argv.slice(2))

  if (opts.negative === 'list') {
    console.log('Negative controls:')
    for (const [id, what] of Object.entries(NEGATIVE_CONTROLS)) console.log(`  --negative=${id.padEnd(20)} ${what}`)
    process.exit(0)
  }
  if (opts.negative !== '' && NEGATIVE_CONTROLS[opts.negative] === undefined) {
    console.error(`Unknown negative control: ${opts.negative}`)
    console.error(`Known: ${Object.keys(NEGATIVE_CONTROLS).join(', ')}`)
    process.exit(2)
  }

  console.log('======================================================================')
  console.log('HEADLESS AUDIT of the SHIPPED BUNDLE (dist-game/)')
  if (opts.negative !== '') console.log(`NEGATIVE CONTROL ACTIVE: ${opts.negative} — ${NEGATIVE_CONTROLS[opts.negative]}`)
  console.log('======================================================================')

  // --- Precondition: a real, fresh build exists -----------------------------
  // Auditing a missing or stale artifact is the silent-nothing failure mode.
  assertBuildPresentAndFresh()

  const outDir = assertWritablePath(opts.negative === '' ? opts.outDir : join(opts.outDir, `negative-${opts.negative}`))
  mkdirSync(outDir, { recursive: true })
  console.log(`Evidence directory: ${outDir}`)

  const log = new AssertionLog()
  const served: ServedRequest[] = []
  const networkRequests: NetworkRequestLog[] = []
  const consoleErrors: ConsoleErrorLog[] = []

  const server = createStaticServer(served)
  await new Promise<void>(r => server.listen(0, '127.0.0.1', r))
  const addr = server.address()
  const port = typeof addr === 'object' && addr !== null ? addr.port : 0
  const baseUrl = `http://127.0.0.1:${port}`
  console.log(`Static server (node:http, serving dist-game/): ${baseUrl}/diablo2/`)

  const debugPort = 9246
  const chrome = spawn('/usr/bin/google-chrome', [
    '--headless=new',
    `--remote-debugging-port=${debugPort}`,
    '--no-sandbox',
    '--disable-dev-shm-usage',
    '--enable-webgl',
    '--ignore-gpu-blocklist',
    '--use-gl=angle',
    '--use-angle=swiftshader',
    '--window-size=1280,840',
    'about:blank',
  ])

  let exitCode = 0
  try {
    const cdp = await connectCdp(debugPort, msg => {
      const method = msg['method'] as string | undefined
      if (method === 'Network.requestWillBeSent') {
        const req = msg['params'].request as { url: string; method: string }
        networkRequests.push({ url: req.url, method: req.method, resourceType: String(msg['params'].type) })
      } else if (method === 'Runtime.consoleAPICalled') {
        // This capture does not exist anywhere else in the repo; it is the
        // whole mechanism behind the "console.error count is 0" criterion.
        if (msg['params'].type === 'error') {
          const args = (msg['params'].args ?? []) as { value?: unknown; description?: string }[]
          const text = args.map(a => String(a.value ?? a.description ?? '')).join(' ')
          consoleErrors.push({ source: 'console.error', text })
        }
      } else if (method === 'Runtime.exceptionThrown') {
        const d = msg['params'].exceptionDetails as { text?: string; exception?: { description?: string } }
        consoleErrors.push({ source: 'uncaught', text: d.exception?.description ?? d.text ?? 'unknown exception' })
      } else if (method === 'Log.entryAdded') {
        // Browser-level errors (failed subresource loads, CORS, WebGL) never
        // reach `consoleAPICalled`. Without this the count would miss exactly
        // the failures that matter most for an asset-loading invariant.
        const e = msg['params'].entry as { level: string; text: string; source: string }
        if (e.level === 'error') consoleErrors.push({ source: `log:${e.source}`, text: e.text })
      }
    })

    await cdp.send('Page.enable')
    await cdp.send('Runtime.enable')
    await cdp.send('Network.enable')
    await cdp.send('Log.enable')

    const saveScreenshot = async (filename: string): Promise<string> => {
      const shot = await cdp.send<{ data: string }>('Page.captureScreenshot', { format: 'png' })
      const filePath = assertWritablePath(join(outDir, filename))
      const buf = Buffer.from(shot.data, 'base64')
      writeFileSync(filePath, buf)
      console.log(`   screenshot: ${filename} (${buf.length} bytes)`)
      return filePath
    }

    // --- Navigate -----------------------------------------------------------
    const targetUrl =
      opts.negative === 'broken-page'
        ? `${baseUrl}/diablo2/this-page-does-not-exist.html`
        : `${baseUrl}/diablo2/acts.html?act=1`
    console.log(`\n--- Navigating to ${targetUrl}`)
    await cdp.send('Page.navigate', { url: targetUrl })

    // The freeze-facing control must be installed before the scene can be
    // driven, so it goes in as soon as the document exists.
    if (opts.negative === 'freeze-facing') {
      await sleep(1500)
      await cdp.evalJs(`(() => { window.__mvFreezeFacing = true; return 1 })()`)
    }

    let snap: SceneSnapshot = { present: false } as SceneSnapshot
    for (let i = 0; i < 150; i++) {
      snap = await cdp.evalJs<SceneSnapshot>(SNAPSHOT_EXPR)
      if (snap.present && (snap.ready || snap.error !== null)) break
      await sleep(400)
    }

    console.log(`   scene present=${snap.present} ready=${snap.ready} error=${String(snap.error)}`)

    log.check({
      id: 'SCENE_BOOTED',
      criterion: 'audit precondition: the scene under test actually loaded and rendered',
      preconditions: [{ name: '__d2webAct published', met: snap.present === true, value: String(snap.present) }],
      pass: snap.ready === true && snap.error === null,
      detail: `ready=${snap.ready} error=${String(snap.error)} frames=${snap.frames} tick=${snap.tick}`,
    })

    if (snap.present && snap.ready) {
      // --- Drive gameplay ---------------------------------------------------
      // Walking and swinging is what makes the audit cover "during play" rather
      // than "at load": it exercises the walk clip, the attack path, and the
      // monster draw path that produces the red placeholder square.
      console.log('\n--- Driving gameplay (walk + attack)')
      await cdp.evalJs(`(() => {
        const sleep = ms => new Promise(r => setTimeout(r, ms))
        const press = (code, down) =>
          window.dispatchEvent(new KeyboardEvent(down ? 'keydown' : 'keyup', { code, bubbles: true }))
        window.__mvDrive = (async () => {
          const dirs = ['ArrowRight', 'ArrowDown', 'ArrowLeft', 'ArrowUp']
          for (let round = 0; round < 4; round += 1) {
            const dir = dirs[round % dirs.length]
            press(dir, true)
            await sleep(700)
            press(dir, false)
            for (let i = 0; i < 3; i += 1) {
              press('Space', true); await sleep(160); press('Space', false); await sleep(80)
            }
          }
          return true
        })()
        return true
      })()`)
      await cdp.evalJs(`window.__mvDrive`)
      await sleep(500)

      const played = await cdp.evalJs<SceneSnapshot>(SNAPSHOT_EXPR)
      console.log(
        `   after play: frames=${played.frames} tick=${played.tick} characterFrames=${played.characterFrames} ` +
          `monstersPlanned=${played.monstersPlanned} missingMonsterArt=${JSON.stringify(played.missingMonsterArt)}`,
      )

      // --- Inject the requested fault --------------------------------------
      await injectNegativeControl(cdp, opts.negative)
      await sleep(600)

      // --- Assertions -------------------------------------------------------
      const live = await cdp.evalJs<SceneSnapshot>(SNAPSHOT_EXPR)
      const rendered = { name: 'frames rendered', met: live.frames > 0, value: String(live.frames) }
      const ticked = { name: 'sim ticked', met: live.tick > 0, value: String(live.tick) }

      // 1. Zero runtime MPQ / DLL requests.
      const forbidden = networkRequests.filter(r => {
        const u = r.url.toLowerCase().split('?')[0] ?? ''
        return u.endsWith('.mpq') || u.endsWith('.dll') || u.includes('/mpq/') || u.includes('/dll/')
      })
      log.check({
        id: 'ZERO_MPQ_DLL_REQUESTS',
        criterion: 'AC: 加载并游玩场景期间，对 *.mpq / *.dll 的网络请求数为 0',
        preconditions: [
          rendered,
          ticked,
          // Without this, "0 forbidden requests" could simply mean the network
          // layer was never observed at all.
          { name: 'network capture live', met: networkRequests.length > 0, value: String(networkRequests.length) },
        ],
        pass: forbidden.length === 0,
        detail:
          `${forbidden.length} forbidden of ${networkRequests.length} total requests` +
          (forbidden.length > 0 ? ` -> ${forbidden.map(f => f.url).join(', ')}` : ''),
      })

      // 2. Zero console.error.
      log.check({
        id: 'ZERO_CONSOLE_ERRORS',
        criterion: 'AC: 审计期间 console.error 计数为 0',
        preconditions: [rendered, ticked],
        pass: consoleErrors.length === 0,
        detail:
          `${consoleErrors.length} error-level messages` +
          (consoleErrors.length > 0
            ? ` -> ${consoleErrors.slice(0, 8).map(e => `[${e.source}] ${e.text.slice(0, 200)}`).join(' || ')}`
            : ''),
      })

      // 3. No red placeholder squares.
      //
      // Read from published state, not pixels: `act-scene.ts:3352` already
      // records every monster id drawn as a red box. The precondition that
      // monsters were actually planned is what stops this being vacuous on a
      // town level, where zero red squares is true but meaningless.
      const missing = live.missingMonsterArt ?? []
      log.check({
        id: 'NO_RED_PLACEHOLDER_SQUARES',
        criterion: 'AC: 无红色占位方块',
        preconditions: [
          rendered,
          ticked,
          { name: 'monsters planned on this level', met: live.monstersPlanned > 0, value: String(live.monstersPlanned) },
          { name: 'missingMonsterArt field exists', met: live.missingMonsterArt !== null, value: String(live.missingMonsterArt !== null) },
        ],
        pass: missing.length === 0 && live.monsterArtErrors === 0 && live.monsterArtLayerFailures === 0,
        detail:
          `missingMonsterArt=${JSON.stringify(missing)} monsterArtErrors=${live.monsterArtErrors} ` +
          `monsterArtLayerFailures=${live.monsterArtLayerFailures}`,
      })

      // 3b. The published-state trap.
      //
      // `state.characterGroup` is declared (L254) and initialised to -1 (L328)
      // and never written. It is proof that a published field can be a
      // constant, so any audit reading state must verify the fields it trusts
      // are actually written. This assertion documents the trap rather than
      // depending on it.
      log.add({
        id: 'PUBLISHED_STATE_TRAP_CHARACTERGROUP',
        criterion: 'harness self-check: a published field can lie (act-scene.ts:254 characterGroup)',
        verdict: live.characterGroup === -1 ? 'PASS' : 'PASS',
        detail:
          `characterGroup=${live.characterGroup} (init -1 at act-scene.ts:328, never written). ` +
          `${live.characterGroup === -1 ? 'Confirmed still dead — no assertion may depend on it.' : 'It is now written; it became usable.'}`,
        preconditions: [rendered],
      })

      // 4. Eight-direction foot-anchor evidence.
      await captureEightDirections(cdp, log, saveScreenshot, live, opts)

      // 5. Weapon-swap evidence.
      await captureWeaponSwap(cdp, log, saveScreenshot, outDir)
    }

    // --- Report -------------------------------------------------------------
    exitCode = report(log, opts, outDir, { networkRequests, consoleErrors, served })

    if (opts.keepOpenMs > 0) await sleep(opts.keepOpenMs)
    cdp.close()
  } finally {
    chrome.kill('SIGKILL')
    await new Promise<void>(r => server.close(() => r()))
  }

  process.exit(exitCode)
}

/**
 * Fail loudly when there is nothing real to audit.
 *
 * A missing `dist-game/` must not degrade into "audited nothing, all green",
 * and a stale one silently audits code that no longer exists.
 */
function assertBuildPresentAndFresh(): void {
  if (!existsSync(DIST_DIR) || !existsSync(join(DIST_DIR, 'acts.html'))) {
    console.error(`\nFAIL: no built artifact at ${DIST_DIR} (acts.html missing).`)
    console.error('      This harness audits the SHIPPED bundle. Build it first:')
    console.error('        npm run build:game')
    process.exit(1)
  }
  const newest = (dir: string): number => {
    let best = 0
    const walk = (d: string): void => {
      for (const e of readdirSync(d)) {
        const f = join(d, e)
        const st = statSync(f)
        if (st.isDirectory()) walk(f)
        else best = Math.max(best, st.mtimeMs)
      }
    }
    walk(dir)
    return best
  }
  const distTime = newest(DIST_DIR)
  const srcTime = newest(SRC_DIR)
  if (srcTime > distTime) {
    console.error('\nFAIL: dist-game/ is STALE — a file under src/ is newer than the build.')
    console.error(`      newest src/       : ${new Date(srcTime).toISOString()}`)
    console.error(`      newest dist-game/ : ${new Date(distTime).toISOString()}`)
    console.error('      Auditing a stale bundle proves nothing about the current code.')
    console.error('      Rebuild:  npm run build:game')
    process.exit(1)
  }
  console.log(`Artifact OK: dist-game/ built ${new Date(distTime).toISOString()} (newer than src/)`)
}

async function injectNegativeControl(cdp: CdpSession, negative: string): Promise<void> {
  if (negative === '') return
  console.log(`\n--- Injecting negative control: ${negative}`)
  switch (negative) {
    case 'mpq-request':
      // A genuine network request for an archive, issued by the page. It is
      // expected to 404 — the invariant is about the request being made.
      await cdp.evalJs(`fetch('/diablo2/data/d2char.mpq').then(()=>1).catch(()=>1)`)
      break
    case 'dll-request':
      await cdp.evalJs(`fetch('/diablo2/data/D2Common.dll').then(()=>1).catch(()=>1)`)
      break
    case 'console-error':
      await cdp.evalJs(`(() => { console.error('MV negative control: synthetic console.error'); return 1 })()`)
      break
    case 'missing-art':
      await cdp.evalJs(
        `(() => { window.__d2webAct.missingMonsterArt.push('mv-synthetic-missing-monster'); return 1 })()`,
      )
      break
    case 'monster-art-error':
      await cdp.evalJs(`(() => { window.__d2webAct.monsterArtErrors += 1; return 1 })()`)
      break
    case 'freeze-facing':
    case 'broken-page':
      // Handled at their own point in the flow.
      break
    default:
      throw new Error(`unhandled negative control ${negative}`)
  }
}

/**
 * Drive the player through all eight facings and capture one screenshot each.
 *
 * WHY THE MACHINE ASSERTION IS NOT "the screenshots differ".
 * The background has animated tiles and independently moving monsters, so any
 * two full-frame captures differ even if the player never turned. An assertion
 * on image difference would therefore pass unconditionally — vacuous in the
 * most dangerous way, since it *looks* like pixel evidence.
 *
 * What is actually checkable is the mechanism: that all eight distinct facings
 * were really reached, and that the character draw path was live at each one
 * (`characterFrames` strictly increasing). The screenshots are then human
 * review material for anchor drift, which is a judgement a script cannot make
 * without a per-frame draw rect the runtime does not yet publish.
 */
async function captureEightDirections(
  cdp: CdpSession,
  log: AssertionLog,
  saveScreenshot: (name: string) => Promise<string>,
  before: SceneSnapshot,
  opts: Options,
): Promise<void> {
  console.log('\n--- Capturing 8 facings')
  const observed: number[] = []
  const charFrames: number[] = []

  for (let dir = 0; dir < 8; dir++) {
    await cdp.evalJs(`(() => {
      if (window.__mvFreezeFacing) return 1
      const e = window.__d2webEngine
      if (!e) throw new Error('__d2webEngine is not published; cannot set facing')
      e.world.player.facing = ${dir}
      return 1
    })()`)
    // Two sim ticks at 25 Hz plus a render.
    await sleep(160)
    const s = await cdp.evalJs<SceneSnapshot>(SNAPSHOT_EXPR)
    observed.push(s.facing)
    charFrames.push(s.characterFrames)
    await saveScreenshot(`anchor_facing_${dir}.png`)
  }

  const uniqueFacings = new Set(observed)
  const charPathLive = charFrames.every((v, i) => i === 0 || v > (charFrames[i - 1] ?? -1))

  console.log(`   facings observed: ${JSON.stringify(observed)} (unique=${uniqueFacings.size})`)
  console.log(`   characterFrames : ${JSON.stringify(charFrames)} (strictly increasing=${charPathLive})`)

  log.check({
    id: 'EIGHT_DIRECTIONS_EXERCISED',
    criterion: 'AC: 8 个方向下角色脚底位置稳定（锚点正确），有截图证据 — mechanism half',
    preconditions: [
      { name: '__d2webEngine published', met: true, value: 'act-scene.ts:2677' },
      { name: 'character art loaded (not the marker box)', met: before.character === true, value: String(before.character) },
    ],
    pass: uniqueFacings.size === 8 && charPathLive,
    detail:
      `observed facings=${JSON.stringify(observed)} unique=${uniqueFacings.size}/8; ` +
      `characterFrames=${JSON.stringify(charFrames)} strictlyIncreasing=${charPathLive}; ` +
      `8 screenshots written (anchor_facing_0..7.png)`,
  })

  // The numeric half of the criterion is not yet evidenceable — say so rather
  // than quietly shipping screenshots as if they were a regression test.
  log.add({
    id: 'FOOT_ANCHOR_NUMERIC_INVARIANT',
    criterion: 'AC: 脚底位置稳定（无漂移）— numeric half',
    verdict: 'VACUOUS',
    detail:
      'NOT EVIDENCEABLE on current main. The draw rect is computed inline at act-scene.ts:3321 ' +
      '(`player.x - frame.width/2, player.y - frame.height + FEET_HEIGHT/2`) from closure-local ' +
      '`character`/`frame`, neither of which is published, so no in-page read can recover it. ' +
      'REQUIRED OF M4: publish `state.playerDrawRect = {x,y,w,h}` each frame; this harness will ' +
      'then assert |(y+h) - player.y| <= 1 across all 8 facings, which is the actual anti-drift test. ' +
      'Screenshots alone are human-review evidence, not a regression gate.',
    preconditions: [{ name: 'state.playerDrawRect published', met: false, value: 'absent' }],
  })

  if (opts.negative === 'freeze-facing') {
    console.log('   (freeze-facing control active: facing writes were suppressed in-page)')
  }
}

/**
 * Capture evidence for "swapping weapon class changes the attack animation".
 *
 * On current `main` the player COF is hardcoded to `hth` (tier-3 char load
 * passes the literal `'hth'`, `act-scene.ts:2388-2389`), and no weapon class
 * reaches the clip choice at all, so this is a known-red baseline that M3 owns.
 * The harness still captures the before/after so the change is reviewable, and
 * records the equipped codes structurally rather than claiming a screenshot
 * proves something it does not.
 */
async function captureWeaponSwap(
  cdp: CdpSession,
  log: AssertionLog,
  saveScreenshot: (name: string) => Promise<string>,
  outDir: string,
): Promise<void> {
  console.log('\n--- Weapon-swap evidence')

  const readWeapon = `(() => {
    const hud = window.__d2webHudInstance
    const inv = hud && hud.inventory
    const eq = inv && inv.equipped
    const w1 = eq && eq.weapon1
    return {
      hudPresent: !!hud,
      inventoryPresent: !!inv,
      weapon1: w1 ? { code: w1.code, name: w1.name } : null,
      // The runtime does not publish a resolved weapon class or the COF clip in
      // use. Recorded as null so the gap is visible in the artifact rather than
      // implied by omission.
      resolvedWeaponClass: (window.__d2webAct && window.__d2webAct.weaponClass) ?? null,
      activeClip: (window.__d2webAct && window.__d2webAct.playerClip) ?? null,
    }
  })()`

  interface WeaponEvidence {
    hudPresent: boolean
    inventoryPresent: boolean
    weapon1: { code: string; name: string } | null
    resolvedWeaponClass: string | null
    activeClip: string | null
  }

  const before = await cdp.evalJs<WeaponEvidence>(readWeapon)
  await saveScreenshot('weapon_before.png')

  // Swap to a two-handed weapon so the weapon class genuinely differs. `2hs`
  // vs `hth` is the coarsest possible distinction, which is the right one for a
  // first regression signal.
  const swapped = await cdp.evalJs<boolean>(`(() => {
    const inv = window.__d2webHudInstance && window.__d2webHudInstance.inventory
    if (!inv) return false
    inv.equipped.weapon1 = {
      id: 'mv-swap-2hs', code: '7wa', invFile: 'invgpa', name: 'Colossus Blade',
      quality: 'normal', invWidth: 2, invHeight: 4, allowedSlots: ['weapon1'],
    }
    return true
  })()`)
  await sleep(600)
  const after = await cdp.evalJs<WeaponEvidence>(readWeapon)
  await saveScreenshot('weapon_after.png')

  const evidencePath = assertWritablePath(join(outDir, 'weapon-swap-evidence.json'))
  writeFileSync(evidencePath, JSON.stringify({ swapped, before, after }, null, 2))
  console.log(`   weapon evidence: ${relative(ROOT, evidencePath)}`)
  console.log(`   before=${JSON.stringify(before)}`)
  console.log(`   after =${JSON.stringify(after)}`)

  log.check({
    id: 'WEAPON_SWAP_EVIDENCE_CAPTURED',
    criterion: 'AC: 换装不同武器类后…有截图或日志证据 — capture half',
    preconditions: [{ name: 'HUD inventory reachable', met: before.inventoryPresent, value: String(before.inventoryPresent) }],
    pass: swapped && before.weapon1 !== null && after.weapon1 !== null && before.weapon1.code !== after.weapon1.code,
    detail: `equipped weapon1 ${before.weapon1?.code ?? 'none'} -> ${after.weapon1?.code ?? 'none'}; screenshots + JSON written`,
  })

  log.check({
    id: 'WEAPON_SWAP_CHANGES_ANIMATION',
    criterion: 'AC: 换装不同武器类后，攻击动作随之变化',
    preconditions: [
      {
        name: 'runtime publishes the resolved weapon class / active clip',
        met: after.resolvedWeaponClass !== null || after.activeClip !== null,
        value: `weaponClass=${String(after.resolvedWeaponClass)} activeClip=${String(after.activeClip)}`,
      },
    ],
    pass: before.activeClip !== after.activeClip,
    detail:
      'Player COF weapon class is hardcoded to `hth` on current main ' +
      '(act-scene.ts:2388-2389 passes the literal), and neither the resolved weapon class nor the ' +
      'active clip is published, so there is nothing to compare. REQUIRED OF M3: publish ' +
      '`state.weaponClass` and `state.playerClip`; this assertion then becomes real.',
    knownRedBaseline: 'M3 owns weapon-class-aware COF selection (R3). Expected red until M3 lands.',
  })
}

function report(
  log: AssertionLog,
  opts: Options,
  outDir: string,
  raw: { networkRequests: NetworkRequestLog[]; consoleErrors: ConsoleErrorLog[]; served: ServedRequest[] },
): number {
  console.log('\n======================================================================')
  console.log('RESULTS')
  console.log('======================================================================')

  let hardFail = 0
  let vacuous = 0
  let knownRed = 0
  let baselineImproved = 0

  for (const a of log.items) {
    const isKnownRed = a.knownRedBaseline !== undefined
    let tag: string
    if (a.verdict === 'PASS') {
      if (isKnownRed) {
        tag = 'BASELINE-IMPROVED'
        baselineImproved++
      } else tag = 'PASS'
    } else if (a.verdict === 'VACUOUS') {
      if (isKnownRed) {
        tag = 'KNOWN-RED'
        knownRed++
      } else {
        tag = 'VACUOUS(=FAIL)'
        vacuous++
      }
    } else {
      if (isKnownRed) {
        tag = 'KNOWN-RED'
        knownRed++
      } else {
        tag = 'FAIL'
        hardFail++
      }
    }
    console.log(`\n[${tag}] ${a.id}`)
    console.log(`   criterion: ${a.criterion}`)
    console.log(`   detail   : ${a.detail}`)
    for (const p of a.preconditions) {
      console.log(`   precond  : ${p.met ? 'met' : 'UNMET'} — ${p.name} = ${p.value}`)
    }
    if (a.knownRedBaseline !== undefined) console.log(`   baseline : ${a.knownRedBaseline}`)
  }

  const summaryPath = assertWritablePath(join(outDir, 'audit-report.json'))
  writeFileSync(
    summaryPath,
    JSON.stringify(
      {
        negativeControl: opts.negative === '' ? null : opts.negative,
        generated: new Date().toISOString(),
        assertions: log.items,
        totals: { hardFail, vacuous, knownRed, baselineImproved },
        networkRequestCount: raw.networkRequests.length,
        forbiddenRequests: raw.networkRequests
          .filter(r => {
            const u = r.url.toLowerCase().split('?')[0] ?? ''
            return u.endsWith('.mpq') || u.endsWith('.dll')
          })
          .map(r => r.url),
        consoleErrors: raw.consoleErrors,
        serverRequestCount: raw.served.length,
        server404s: raw.served.filter(s => s.status === 404).map(s => s.url),
      },
      null,
      2,
    ),
  )

  console.log('\n----------------------------------------------------------------------')
  console.log(
    `SUMMARY: ${log.items.length} assertions | FAIL=${hardFail} VACUOUS=${vacuous} ` +
      `KNOWN-RED=${knownRed} BASELINE-IMPROVED=${baselineImproved}`,
  )
  console.log(`Report: ${relative(ROOT, summaryPath)}`)

  if (baselineImproved > 0) {
    console.log('\nNOTE: a known-red baseline turned green. Update the baseline annotation in this script.')
  }

  if (opts.negative !== '') {
    // Under a negative control the run is SUPPOSED to be red. Report the
    // inversion explicitly so a control that failed to bite is not mistaken
    // for a clean run.
    const red = hardFail + vacuous
    console.log('\n----------------------------------------------------------------------')
    if (red > 0) {
      console.log(`NEGATIVE CONTROL '${opts.negative}': harness went RED as required (${red} failing assertion(s)).`)
      return 0
    }
    console.log(`NEGATIVE CONTROL '${opts.negative}': ***HARNESS STAYED GREEN — THE CONTROL DID NOT BITE***`)
    console.log('This means the assertion it targets cannot detect its own failure mode.')
    return 1
  }

  return hardFail + vacuous > 0 ? 1 : 0
}

main().catch((err: unknown) => {
  console.error('\nHARNESS ERROR:', err)
  process.exit(1)
})