mcpServer.ts

Full source

import {
  type ClaudeForChromeContext,
  createClaudeForChromeMcpServer,
  type Logger,
  type PermissionMode,
} from '@ant/claude-for-chrome-mcp'
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
import { format } from 'util'
import { shutdownDatadog } from '../../services/analytics/datadog.js'
import { shutdown1PEventLogging } from '../../services/analytics/firstPartyEventLogger.js'
import { getFeatureValue_CACHED_MAY_BE_STALE } from '../../services/analytics/growthbook.js'
import {
  type AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
  logEvent,
} from '../../services/analytics/index.js'
import { initializeAnalyticsSink } from '../../services/analytics/sink.js'
import { getClaudeAIOAuthTokens } from '../auth.js'
import { enableConfigs, getGlobalConfig, saveGlobalConfig } from '../config.js'
import { logForDebugging } from '../debug.js'
import { isEnvTruthy } from '../envUtils.js'
import { sideQuery } from '../sideQuery.js'
import { getAllSocketPaths, getSecureSocketPath } from './common.js'

const EXTENSION_DOWNLOAD_URL = 'https://claude.ai/chrome'
const BUG_REPORT_URL =
  'https://github.com/anthropics/claude-code/issues/new?labels=bug,claude-in-chrome'

// String metadata keys safe to forward to analytics. Keys like error_message
// are excluded because they could contain page content or user data.
const SAFE_BRIDGE_STRING_KEYS = new Set([
  'bridge_status',
  'error_type',
  'tool_name',
])

const PERMISSION_MODES: readonly PermissionMode[] = [
  'ask',
  'skip_all_permission_checks',
  'follow_a_plan',
]

function isPermissionMode(raw: string): raw is PermissionMode {
  return PERMISSION_MODES.some(m => m === raw)
}

/**
 * Resolves the Chrome bridge URL based on environment and feature flag.
 * Bridge is used when the feature flag is enabled; ant users always get
 * bridge. API key / 3P users fall back to native messaging.
 */
function getChromeBridgeUrl(): string | undefined {
  const bridgeEnabled =
    process.env.USER_TYPE === 'ant' ||
    getFeatureValue_CACHED_MAY_BE_STALE('tengu_copper_bridge', false)

  if (!bridgeEnabled) {
    return undefined
  }

  if (
    isEnvTruthy(process.env.USE_LOCAL_OAUTH) ||
    isEnvTruthy(process.env.LOCAL_BRIDGE)
  ) {
    return 'ws://localhost:8765'
  }

  if (isEnvTruthy(process.env.USE_STAGING_OAUTH)) {
    return 'wss://bridge-staging.claudeusercontent.com'
  }

  return 'wss://bridge.claudeusercontent.com'
}

function isLocalBridge(): boolean {
  return (
    isEnvTruthy(process.env.USE_LOCAL_OAUTH) ||
    isEnvTruthy(process.env.LOCAL_BRIDGE)
  )
}

/**
 * Build the ClaudeForChromeContext used by both the subprocess MCP server
 * and the in-process path in the MCP client.
 */
export function createChromeContext(
  env?: Record<string, string>,
): ClaudeForChromeContext {
  const logger = new DebugLogger()
  const chromeBridgeUrl = getChromeBridgeUrl()
  logger.info(`Bridge URL: ${chromeBridgeUrl ?? 'none (using native socket)'}`)
  const rawPermissionMode =
    env?.CLAUDE_CHROME_PERMISSION_MODE ??
    process.env.CLAUDE_CHROME_PERMISSION_MODE
  let initialPermissionMode: PermissionMode | undefined
  if (rawPermissionMode) {
    if (isPermissionMode(rawPermissionMode)) {
      initialPermissionMode = rawPermissionMode
    } else {
      logger.warn(
        `Invalid CLAUDE_CHROME_PERMISSION_MODE "${rawPermissionMode}". Valid values: ${PERMISSION_MODES.join(', ')}`,
      )
    }
  }
  return {
    serverName: 'Claude in Chrome',
    logger,
    socketPath: getSecureSocketPath(),
    getSocketPaths: getAllSocketPaths,
    clientTypeId: 'claude-code',
    onAuthenticationError: () => {
      logger.warn(
        'Authentication error occurred. Please ensure you are logged into the Claude browser extension with the same claude.ai account as Claude Code.',
      )
    },
    onToolCallDisconnected: () => {
      return `Browser extension is not connected. Please ensure the Claude browser extension is installed and running (${EXTENSION_DOWNLOAD_URL}), and that you are logged into claude.ai with the same account as Claude Code. If this is your first time connecting to Chrome, you may need to restart Chrome for the installation to take effect. If you continue to experience issues, please report a bug: ${BUG_REPORT_URL}`
    },
    onExtensionPaired: (deviceId: string, name: string) => {
      saveGlobalConfig(config => {
        if (
          config.chromeExtension?.pairedDeviceId === deviceId &&
          config.chromeExtension?.pairedDeviceName === name
        ) {
          return config
        }
        return {
          ...config,
          chromeExtension: {
            pairedDeviceId: deviceId,
            pairedDeviceName: name,
          },
        }
      })
      logger.info(`Paired with "${name}" (${deviceId.slice(0, 8)})`)
    },
    getPersistedDeviceId: () => {
      return getGlobalConfig().chromeExtension?.pairedDeviceId
    },
    ...(chromeBridgeUrl && {
      bridgeConfig: {
        url: chromeBridgeUrl,
        getUserId: async () => {
          return getGlobalConfig().oauthAccount?.accountUuid
        },
        getOAuthToken: async () => {
          return getClaudeAIOAuthTokens()?.accessToken ?? ''
        },
        ...(isLocalBridge() && { devUserId: 'dev_user_local' }),
      },
    }),
    ...(initialPermissionMode && { initialPermissionMode }),
    // Wire inference for the browser_task tool — the chrome-mcp server runs
    // a lightning-mode agent loop in Node and calls the extension's
    // lightning_turn tool once per iteration for execution.
    //
    // Ant-only: the extension's lightning_turn is build-time-gated via
    // import.meta.env.ANT_ONLY_BUILD — the whole lightning/ module graph is
    // tree-shaken from the public extension build (build:prod greps for a
    // marker to verify). Without this injection, the Node MCP server's
    // ListTools also filters browser_task + lightning_turn out, so external
    // users never see the tools advertised. Three independent gates.
    //
    // Types inlined: AnthropicMessagesRequest/Response live in
    // @ant/claude-for-chrome-mcp@0.4.0 which isn't published yet. CI installs
    // 0.3.0. The callAnthropicMessages field is also 0.4.0-only, but spreading
    // an extra property into ClaudeForChromeContext is fine against either
    // version — 0.3.0 sees an unknown field (allowed in spread), 0.4.0 sees a
    // structurally-matching one. Once 0.4.0 is published, this can switch to
    // the package's exported types and the dep can be bumped.
    ...(process.env.USER_TYPE === 'ant' && {
      callAnthropicMessages: async (req: {
        model: string
        max_tokens: number
        system: string
        messages: Parameters<typeof sideQuery>[0]['messages']
        stop_sequences?: string[]
        signal?: AbortSignal
      }): Promise<{
        content: Array<{ type: 'text'; text: string }>
        stop_reason: string | null
        usage?: { input_tokens: number; output_tokens: number }
      }> => {
        // sideQuery handles OAuth attribution fingerprint, proxy, model betas.
        // skipSystemPromptPrefix: the lightning prompt is complete on its own;
        // the CLI prefix would dilute the batching instructions.
        // tools: [] is load-bearing — without it Sonnet emits
        // <function_calls> XML before the text commands. Original
        // lightning-harness.js (apps repo) does the same.
        const response = await sideQuery({
          model: req.model,
          system: req.system,
          messages: req.messages,
          max_tokens: req.max_tokens,
          stop_sequences: req.stop_sequences,
          signal: req.signal,
          skipSystemPromptPrefix: true,
          tools: [],
          querySource: 'chrome_mcp',
        })
        // BetaContentBlock is TextBlock | ThinkingBlock | ToolUseBlock | ...
        // Only text blocks carry the model's command output.
        const textBlocks: Array<{ type: 'text'; text: string }> = []
        for (const b of response.content) {
          if (b.type === 'text') {
            textBlocks.push({ type: 'text', text: b.text })
          }
        }
        return {
          content: textBlocks,
          stop_reason: response.stop_reason,
          usage: {
            input_tokens: response.usage.input_tokens,
            output_tokens: response.usage.output_tokens,
          },
        }
      },
    }),
    trackEvent: (eventName, metadata) => {
      const safeMetadata: {
        [key: string]:
          | boolean
          | number
          | AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS
          | undefined
      } = {}
      if (metadata) {
        for (const [key, value] of Object.entries(metadata)) {
          // Rename 'status' to 'bridge_status' to avoid Datadog's reserved field
          const safeKey = key === 'status' ? 'bridge_status' : key
          if (typeof value === 'boolean' || typeof value === 'number') {
            safeMetadata[safeKey] = value
          } else if (
            typeof value === 'string' &&
            SAFE_BRIDGE_STRING_KEYS.has(safeKey)
          ) {
            // Only forward allowlisted string keys — fields like error_message
            // could contain page content or user data
            safeMetadata[safeKey] =
              value as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS
          }
        }
      }
      logEvent(eventName, safeMetadata)
    },
  }
}

export async function runClaudeInChromeMcpServer(): Promise<void> {
  enableConfigs()
  initializeAnalyticsSink()
  const context = createChromeContext()

  const server = createClaudeForChromeMcpServer(context)
  const transport = new StdioServerTransport()

  // Exit when parent process dies (stdin pipe closes).
  // Flush analytics before exiting so final-batch events (e.g. disconnect) aren't lost.
  let exiting = false
  const shutdownAndExit = async (): Promise<void> => {
    if (exiting) {
      return
    }
    exiting = true
    await shutdown1PEventLogging()
    await shutdownDatadog()
    // eslint-disable-next-line custom-rules/no-process-exit
    process.exit(0)
  }
  process.stdin.on('end', () => void shutdownAndExit())
  process.stdin.on('error', () => void shutdownAndExit())

  logForDebugging('[Claude in Chrome] Starting MCP server')
  await server.connect(transport)
  logForDebugging('[Claude in Chrome] MCP server started')
}

class DebugLogger implements Logger {
  silly(message: string, ...args: unknown[]): void {
    logForDebugging(format(message, ...args), { level: 'debug' })
  }
  debug(message: string, ...args: unknown[]): void {
    logForDebugging(format(message, ...args), { level: 'debug' })
  }
  info(message: string, ...args: unknown[]): void {
    logForDebugging(format(message, ...args), { level: 'info' })
  }
  warn(message: string, ...args: unknown[]): void {
    logForDebugging(format(message, ...args), { level: 'warn' })
  }
  error(message: string, ...args: unknown[]): void {
    logForDebugging(format(message, ...args), { level: 'error' })
  }
}