chore: experimental agent mode (#516)

README.md

@@ -124,6 +124,7 @@ Playwright MCP server supports following arguments. They can be provided in the
   --block-service-workers      block service workers
   --browser <browser>          browser or chrome channel to use, possible
                                values: chrome, firefox, webkit, msedge.
+  --browser-agent <endpoint>   Use browser agent (experimental).
   --caps <caps>                comma-separated list of capabilities to enable,
                                possible values: tabs, pdf, history, wait, files,
                                install. Default is all.

config.d.ts

@@ -23,6 +23,11 @@ export type Config = {
    * The browser to use.
    */
   browser?: {
+    /**
+     * Use browser agent (experimental).
+     */
+    browserAgent?: string;
+
     /**
      * The type of browser to use.
      */

package-lock.json

@@ -12,6 +12,7 @@
         "@modelcontextprotocol/sdk": "^1.11.0",
         "commander": "^13.1.0",
         "debug": "^4.4.1",
+        "mime": "^4.0.7",
         "playwright": "1.53.0-alpha-2025-05-27",
         "zod-to-json-schema": "^3.24.4"
       },
@@ -853,16 +854,16 @@
       "license": "MIT"
     },
     "node_modules/body-parser": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-2.1.0.tgz",
-      "integrity": "sha512-/hPxh61E+ll0Ujp24Ilm64cykicul1ypfwjVttduAiEdtnJFvLePSrIPk+HMImtNv5270wOGCb1Tns2rybMkoQ==",
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-2.2.0.tgz",
+      "integrity": "sha512-02qvAaxv8tp7fBa/mw1ga98OGm+eCbqzJOKoRt70sLmfEEi+jyBYVTDGfCL/k06/4EMk/z01gCe7HoCH/f2LTg==",
       "license": "MIT",
       "dependencies": {
         "bytes": "^3.1.2",
         "content-type": "^1.0.5",
         "debug": "^4.4.0",
         "http-errors": "^2.0.0",
-        "iconv-lite": "^0.5.2",
+        "iconv-lite": "^0.6.3",
         "on-finished": "^2.4.1",
         "qs": "^6.14.0",
         "raw-body": "^3.0.0",
@@ -872,21 +873,6 @@
         "node": ">=18"
       }
     },
-    "node_modules/body-parser/node_modules/qs": {
-      "version": "6.14.0",
-      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.0.tgz",
-      "integrity": "sha512-YWWTjgABSKcvs/nWBi9PycY/JiPJqOD4JA6o9Sej2AtvSGarXxKC3OQSk4pAarbdQlKAh5D4FCQkJNkW+GAn3w==",
-      "license": "BSD-3-Clause",
-      "dependencies": {
-        "side-channel": "^1.1.0"
-      },
-      "engines": {
-        "node": ">=0.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/ljharb"
-      }
-    },
     "node_modules/brace-expansion": {
       "version": "1.1.11",
       "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
@@ -1220,16 +1206,6 @@
         "node": ">= 0.8"
       }
     },
-    "node_modules/destroy": {
-      "version": "1.2.0",
-      "resolved": "https://registry.npmjs.org/destroy/-/destroy-1.2.0.tgz",
-      "integrity": "sha512-2sJGJTaXIIaR1w4iJSNoN0hnMY7Gpc/n8D4qSCJw8QqFWXf7cuAgnEHxBpweaVcPevC2l3KpjYCx3NypQQgaJg==",
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.8",
-        "npm": "1.2.8000 || >= 1.4.16"
-      }
-    },
     "node_modules/doctrine": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/doctrine/-/doctrine-2.1.0.tgz",
@@ -1765,46 +1741,45 @@
       }
     },
     "node_modules/express": {
-      "version": "5.0.1",
-      "resolved": "https://registry.npmjs.org/express/-/express-5.0.1.tgz",
-      "integrity": "sha512-ORF7g6qGnD+YtUG9yx4DFoqCShNMmUKiXuT5oWMHiOvt/4WFbHC6yCwQMTSBMno7AqntNCAzzcnnjowRkTL9eQ==",
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/express/-/express-5.1.0.tgz",
+      "integrity": "sha512-DT9ck5YIRU+8GYzzU5kT3eHGA5iL+1Zd0EutOmTE9Dtk+Tvuzd23VBU+ec7HPNSTxXYO55gPV/hq4pSBJDjFpA==",
       "license": "MIT",
       "dependencies": {
         "accepts": "^2.0.0",
-        "body-parser": "^2.0.1",
+        "body-parser": "^2.2.0",
         "content-disposition": "^1.0.0",
-        "content-type": "~1.0.4",
-        "cookie": "0.7.1",
+        "content-type": "^1.0.5",
+        "cookie": "^0.7.1",
         "cookie-signature": "^1.2.1",
-        "debug": "4.3.6",
-        "depd": "2.0.0",
-        "encodeurl": "~2.0.0",
-        "escape-html": "~1.0.3",
-        "etag": "~1.8.1",
-        "finalhandler": "^2.0.0",
-        "fresh": "2.0.0",
-        "http-errors": "2.0.0",
+        "debug": "^4.4.0",
+        "encodeurl": "^2.0.0",
+        "escape-html": "^1.0.3",
+        "etag": "^1.8.1",
+        "finalhandler": "^2.1.0",
+        "fresh": "^2.0.0",
+        "http-errors": "^2.0.0",
         "merge-descriptors": "^2.0.0",
-        "methods": "~1.1.2",
         "mime-types": "^3.0.0",
-        "on-finished": "2.4.1",
-        "once": "1.4.0",
-        "parseurl": "~1.3.3",
-        "proxy-addr": "~2.0.7",
-        "qs": "6.13.0",
-        "range-parser": "~1.2.1",
-        "router": "^2.0.0",
-        "safe-buffer": "5.2.1",
+        "on-finished": "^2.4.1",
+        "once": "^1.4.0",
+        "parseurl": "^1.3.3",
+        "proxy-addr": "^2.0.7",
+        "qs": "^6.14.0",
+        "range-parser": "^1.2.1",
+        "router": "^2.2.0",
         "send": "^1.1.0",
-        "serve-static": "^2.1.0",
-        "setprototypeof": "1.2.0",
-        "statuses": "2.0.1",
-        "type-is": "^2.0.0",
-        "utils-merge": "1.0.1",
-        "vary": "~1.1.2"
+        "serve-static": "^2.2.0",
+        "statuses": "^2.0.1",
+        "type-is": "^2.0.1",
+        "vary": "^1.1.2"
       },
       "engines": {
         "node": ">= 18"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/express"
       }
     },
     "node_modules/express-rate-limit": {
@@ -1822,29 +1797,6 @@
         "express": "^4.11 || 5 || ^5.0.0-beta.1"
       }
     },
-    "node_modules/express/node_modules/debug": {
-      "version": "4.3.6",
-      "resolved": "https://registry.npmjs.org/debug/-/debug-4.3.6.tgz",
-      "integrity": "sha512-O/09Bd4Z1fBrU4VzkhFqVgpPzaGbw6Sm9FEkBT1A/YBXQFGuuSxa1dN2nxgxS34JmKXqYx8CZAwEVoJFImUXIg==",
-      "license": "MIT",
-      "dependencies": {
-        "ms": "2.1.2"
-      },
-      "engines": {
-        "node": ">=6.0"
-      },
-      "peerDependenciesMeta": {
-        "supports-color": {
-          "optional": true
-        }
-      }
-    },
-    "node_modules/express/node_modules/ms": {
-      "version": "2.1.2",
-      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.2.tgz",
-      "integrity": "sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w==",
-      "license": "MIT"
-    },
     "node_modules/fast-deep-equal": {
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
@@ -2308,12 +2260,12 @@
       }
     },
     "node_modules/iconv-lite": {
-      "version": "0.5.2",
-      "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.5.2.tgz",
-      "integrity": "sha512-kERHXvpSaB4aU3eANwidg79K8FlrN77m8G9V+0vOR3HYaRifrlwMEpT7ZBJqLSEIHnEgJTHcWK82wwLwwKwtag==",
+      "version": "0.6.3",
+      "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.6.3.tgz",
+      "integrity": "sha512-4fCk79wshMdzMp2rH06qWrJE4iolqLhCUH+OiuIgU++RB0+94NlDL81atO7GX55uUKueo0txHNtvEyI6D7WdMw==",
       "license": "MIT",
       "dependencies": {
-        "safer-buffer": ">= 2.1.2 < 3"
+        "safer-buffer": ">= 2.1.2 < 3.0.0"
       },
       "engines": {
         "node": ">=0.10.0"
@@ -2924,15 +2876,6 @@
         "node": ">= 8"
       }
     },
-    "node_modules/methods": {
-      "version": "1.1.2",
-      "resolved": "https://registry.npmjs.org/methods/-/methods-1.1.2.tgz",
-      "integrity": "sha512-iclAHeNqNm68zFtnZ0e+1L2yUIdvzNoauKU4WBA3VvH/vPFieF7qfRlwUZU+DA9P9bPXIS90ulxoUoCH23sV2w==",
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.6"
-      }
-    },
     "node_modules/metric-lcs": {
       "version": "0.1.2",
       "resolved": "https://registry.npmjs.org/metric-lcs/-/metric-lcs-0.1.2.tgz",
@@ -2954,6 +2897,21 @@
         "node": ">=8.6"
       }
     },
+    "node_modules/mime": {
+      "version": "4.0.7",
+      "resolved": "https://registry.npmjs.org/mime/-/mime-4.0.7.tgz",
+      "integrity": "sha512-2OfDPL+e03E0LrXaGYOtTFIYhiuzep94NSsuhrNULq+stylcJedcHdzHtz0atMUuGwJfFYs0YL5xeC/Ca2x0eQ==",
+      "funding": [
+        "https://github.com/sponsors/broofa"
+      ],
+      "license": "MIT",
+      "bin": {
+        "mime": "bin/cli.js"
+      },
+      "engines": {
+        "node": ">=16"
+      }
+    },
     "node_modules/mime-db": {
       "version": "1.54.0",
       "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.54.0.tgz",
@@ -2964,12 +2922,12 @@
       }
     },
     "node_modules/mime-types": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-3.0.0.tgz",
-      "integrity": "sha512-XqoSHeCGjVClAmoGFG3lVFqQFRIrTVw2OH3axRqAcfaw+gHWIfnASS92AV+Rl/mk0MupgZTRHQOjxY6YVnzK5w==",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-3.0.1.tgz",
+      "integrity": "sha512-xRc4oEhT6eaBpU1XF7AjpOFD+xQmXNB5OVKwp4tqCuBpHLS/ZbBDrc07mYTDqVMg6PfxUjjNp85O6Cd2Z/5HWA==",
       "license": "MIT",
       "dependencies": {
-        "mime-db": "^1.53.0"
+        "mime-db": "^1.54.0"
       },
       "engines": {
         "node": ">= 0.6"
@@ -3367,12 +3325,12 @@
       }
     },
     "node_modules/qs": {
-      "version": "6.13.0",
-      "resolved": "https://registry.npmjs.org/qs/-/qs-6.13.0.tgz",
-      "integrity": "sha512-+38qI9SOr8tfZ4QmJNplMUxqjbe7LKvvZgWdExBOmd+egZTtjLB67Gu0HRX3u/XOq7UU2Nx6nsjvS16Z9uwfpg==",
+      "version": "6.14.0",
+      "resolved": "https://registry.npmjs.org/qs/-/qs-6.14.0.tgz",
+      "integrity": "sha512-YWWTjgABSKcvs/nWBi9PycY/JiPJqOD4JA6o9Sej2AtvSGarXxKC3OQSk4pAarbdQlKAh5D4FCQkJNkW+GAn3w==",
       "license": "BSD-3-Clause",
       "dependencies": {
-        "side-channel": "^1.0.6"
+        "side-channel": "^1.1.0"
       },
       "engines": {
         "node": ">=0.6"
@@ -3426,18 +3384,6 @@
         "node": ">= 0.8"
       }
     },
-    "node_modules/raw-body/node_modules/iconv-lite": {
-      "version": "0.6.3",
-      "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.6.3.tgz",
-      "integrity": "sha512-4fCk79wshMdzMp2rH06qWrJE4iolqLhCUH+OiuIgU++RB0+94NlDL81atO7GX55uUKueo0txHNtvEyI6D7WdMw==",
-      "license": "MIT",
-      "dependencies": {
-        "safer-buffer": ">= 2.1.2 < 3.0.0"
-      },
-      "engines": {
-        "node": ">=0.10.0"
-      }
-    },
     "node_modules/reflect.getprototypeof": {
       "version": "1.0.10",
       "resolved": "https://registry.npmjs.org/reflect.getprototypeof/-/reflect.getprototypeof-1.0.10.tgz",
@@ -3525,11 +3471,13 @@
       }
     },
     "node_modules/router": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/router/-/router-2.1.0.tgz",
-      "integrity": "sha512-/m/NSLxeYEgWNtyC+WtNHCF7jbGxOibVWKnn+1Psff4dJGOfoXP+MuC/f2CwSmyiHdOIzYnYFp4W6GxWfekaLA==",
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/router/-/router-2.2.0.tgz",
+      "integrity": "sha512-nLTrUKm2UyiL7rlhapu/Zl45FwNgkZGaCpZbIHajDYgwlJCOzLSk+cIPAnsEqV955GjILJnKbdQC1nVPz+gAYQ==",
       "license": "MIT",
       "dependencies": {
+        "debug": "^4.4.0",
+        "depd": "^2.0.0",
         "is-promise": "^4.0.0",
         "parseurl": "^1.3.3",
         "path-to-regexp": "^8.0.0"
@@ -3657,19 +3605,18 @@
       }
     },
     "node_modules/send": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/send/-/send-1.1.0.tgz",
-      "integrity": "sha512-v67WcEouB5GxbTWL/4NeToqcZiAWEq90N888fczVArY8A79J0L4FD7vj5hm3eUMua5EpoQ59wa/oovY6TLvRUA==",
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/send/-/send-1.2.0.tgz",
+      "integrity": "sha512-uaW0WwXKpL9blXE2o0bRhoL2EGXIrZxQ2ZQ4mgcfoBxdFmQold+qWsD2jLrfZ0trjKL6vOw0j//eAwcALFjKSw==",
       "license": "MIT",
       "dependencies": {
         "debug": "^4.3.5",
-        "destroy": "^1.2.0",
         "encodeurl": "^2.0.0",
         "escape-html": "^1.0.3",
         "etag": "^1.8.1",
-        "fresh": "^0.5.2",
+        "fresh": "^2.0.0",
         "http-errors": "^2.0.0",
-        "mime-types": "^2.1.35",
+        "mime-types": "^3.0.1",
         "ms": "^2.1.3",
         "on-finished": "^2.4.1",
         "range-parser": "^1.2.1",
@@ -3679,46 +3626,16 @@
         "node": ">= 18"
       }
     },
-    "node_modules/send/node_modules/fresh": {
-      "version": "0.5.2",
-      "resolved": "https://registry.npmjs.org/fresh/-/fresh-0.5.2.tgz",
-      "integrity": "sha512-zJ2mQYM18rEFOudeV4GShTGIQ7RbzA7ozbU9I/XBpm7kqgMywgmylMwXHxZJmkVoYkna9d2pVXVXPdYTP9ej8Q==",
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.6"
-      }
-    },
-    "node_modules/send/node_modules/mime-db": {
-      "version": "1.52.0",
-      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.52.0.tgz",
-      "integrity": "sha512-sPU4uV7dYlvtWJxwwxHD0PuihVNiE7TyAbQ5SWxDCB9mUYvOgroQOwYQQOKPJ8CIbE+1ETVlOoK1UC2nU3gYvg==",
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.6"
-      }
-    },
-    "node_modules/send/node_modules/mime-types": {
-      "version": "2.1.35",
-      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.35.tgz",
-      "integrity": "sha512-ZDY+bPm5zTTF+YpCrAU9nK0UgICYPT0QtT1NZWFv4s++TNkcgVaT0g6+4R2uI4MjQjzysHB1zxuWL50hzaeXiw==",
-      "license": "MIT",
-      "dependencies": {
-        "mime-db": "1.52.0"
-      },
-      "engines": {
-        "node": ">= 0.6"
-      }
-    },
     "node_modules/serve-static": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/serve-static/-/serve-static-2.1.0.tgz",
-      "integrity": "sha512-A3We5UfEjG8Z7VkDv6uItWw6HY2bBSBJT1KtVESn6EOoOr2jAxNhxWCLY3jDE2WcuHXByWju74ck3ZgLwL8xmA==",
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/serve-static/-/serve-static-2.2.0.tgz",
+      "integrity": "sha512-61g9pCh0Vnh7IutZjtLGGpTA355+OPn2TyDv/6ivP2h/AdAVX9azsoxmg2/M6nZeQZNYBEwIcsne1mJd9oQItQ==",
       "license": "MIT",
       "dependencies": {
         "encodeurl": "^2.0.0",
         "escape-html": "^1.0.3",
         "parseurl": "^1.3.3",
-        "send": "^1.0.0"
+        "send": "^1.2.0"
       },
       "engines": {
         "node": ">= 18"
@@ -4051,9 +3968,9 @@
       }
     },
     "node_modules/type-is": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/type-is/-/type-is-2.0.0.tgz",
-      "integrity": "sha512-gd0sGezQYCbWSbkZr75mln4YBidWUN60+devscpLF5mtRDUpiaTvKpBNrdaCvel1NdR2k6vclXybU5fBd2i+nw==",
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/type-is/-/type-is-2.0.1.tgz",
+      "integrity": "sha512-OZs6gsjF4vMp32qrCbiVSkrFmXtG/AZhY3t0iAMrMBiAZyV9oALtXO8hsrHbMXF9x6L3grlFuwW2oAz7cav+Gw==",
       "license": "MIT",
       "dependencies": {
         "content-type": "^1.0.5",
@@ -4201,15 +4118,6 @@
         "punycode": "^2.1.0"
       }
     },
-    "node_modules/utils-merge": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/utils-merge/-/utils-merge-1.0.1.tgz",
-      "integrity": "sha512-pMZTvIkT1d+TFGvDOqodOclx0QWkkgi6Tdoa8gC8ffGAAqz9pzPTZWAybbsHHoED/ztMtkv/VoYTYyShUn81hA==",
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.4.0"
-      }
-    },
     "node_modules/vary": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/vary/-/vary-1.1.2.tgz",

package.json

@@ -38,6 +38,7 @@
     "@modelcontextprotocol/sdk": "^1.11.0",
     "commander": "^13.1.0",
     "debug": "^4.4.1",
+    "mime": "^4.0.7",
     "playwright": "1.53.0-alpha-2025-05-27",
     "zod-to-json-schema": "^3.24.4"
   },

src/browserAgent.ts

@@ -0,0 +1,197 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* eslint-disable no-console */
+
+import net from 'net';
+
+import { program } from 'commander';
+import playwright from 'playwright';
+
+import { HttpServer } from './httpServer.js';
+import { packageJSON } from './package.js';
+
+import type http from 'http';
+
+export type LaunchBrowserRequest = {
+  browserType: string;
+  userDataDir: string;
+  launchOptions: playwright.LaunchOptions;
+  contextOptions: playwright.BrowserContextOptions;
+};
+
+export type BrowserInfo = {
+  browserType: string;
+  userDataDir: string;
+  cdpPort: number;
+  launchOptions: playwright.LaunchOptions;
+  contextOptions: playwright.BrowserContextOptions;
+  error?: string;
+};
+
+type BrowserEntry = {
+  browser?: playwright.Browser;
+  info: BrowserInfo;
+};
+
+class Agent {
+  private _server = new HttpServer();
+  private _entries: BrowserEntry[] = [];
+
+  constructor() {
+    this._setupExitHandler();
+  }
+
+  async start(port: number) {
+    await this._server.start({ port });
+    this._server.routePath('/json/list', (req, res) => {
+      this._handleJsonList(res);
+    });
+    this._server.routePath('/json/launch', async (req, res) => {
+      void this._handleLaunchBrowser(req, res).catch(e => console.error(e));
+    });
+    this._setEntries([]);
+  }
+
+  private _handleJsonList(res: http.ServerResponse) {
+    const list = this._entries.map(browser => browser.info);
+    res.end(JSON.stringify(list));
+  }
+
+  private async _handleLaunchBrowser(req: http.IncomingMessage, res: http.ServerResponse) {
+    const request = await readBody<LaunchBrowserRequest>(req);
+    let info = this._entries.map(entry => entry.info).find(info => info.userDataDir === request.userDataDir);
+    if (!info || info.error)
+      info = await this._newBrowser(request);
+    res.end(JSON.stringify(info));
+  }
+
+  private async _newBrowser(request: LaunchBrowserRequest): Promise<BrowserInfo> {
+    const cdpPort = await findFreePort();
+    (request.launchOptions as any).cdpPort = cdpPort;
+    const info: BrowserInfo = {
+      browserType: request.browserType,
+      userDataDir: request.userDataDir,
+      cdpPort,
+      launchOptions: request.launchOptions,
+      contextOptions: request.contextOptions,
+    };
+
+    const browserType = playwright[request.browserType as 'chromium' | 'firefox' | 'webkit'];
+    const { browser, error } = await browserType.launchPersistentContext(request.userDataDir, {
+      ...request.launchOptions,
+      ...request.contextOptions,
+      handleSIGINT: false,
+      handleSIGTERM: false,
+    }).then(context => {
+      return { browser: context.browser()!, error: undefined };
+    }).catch(error => {
+      return { browser: undefined, error: error.message };
+    });
+    this._setEntries([...this._entries, {
+      browser,
+      info: {
+        browserType: request.browserType,
+        userDataDir: request.userDataDir,
+        cdpPort,
+        launchOptions: request.launchOptions,
+        contextOptions: request.contextOptions,
+        error,
+      },
+    }]);
+    browser?.on('disconnected', () => {
+      this._setEntries(this._entries.filter(entry => entry.browser !== browser));
+    });
+    return info;
+  }
+
+  private _updateReport() {
+    // Clear the current line and move cursor to top of screen
+    process.stdout.write('\x1b[2J\x1b[H');
+    process.stdout.write(`Playwright Browser agent v${packageJSON.version}\n`);
+    process.stdout.write(`Listening on ${this._server.urlPrefix('human-readable')}\n\n`);
+
+    if (this._entries.length === 0) {
+      process.stdout.write('No browsers currently running\n');
+      return;
+    }
+
+    process.stdout.write('Running browsers:\n');
+    for (const entry of this._entries) {
+      const status = entry.browser ? 'running' : 'error';
+      const statusColor = entry.browser ? '\x1b[32m' : '\x1b[31m'; // green for running, red for error
+      process.stdout.write(`${statusColor}${entry.info.browserType}\x1b[0m (${entry.info.userDataDir}) - ${statusColor}${status}\x1b[0m\n`);
+      if (entry.info.error)
+        process.stdout.write(`  Error: ${entry.info.error}\n`);
+    }
+
+  }
+
+  private _setEntries(entries: BrowserEntry[]) {
+    this._entries = entries;
+    this._updateReport();
+  }
+
+  private _setupExitHandler() {
+    let isExiting = false;
+    const handleExit = async () => {
+      if (isExiting)
+        return;
+      isExiting = true;
+      setTimeout(() => process.exit(0), 15000);
+      for (const entry of this._entries)
+        await entry.browser?.close().catch(() => {});
+      process.exit(0);
+    };
+
+    process.stdin.on('close', handleExit);
+    process.on('SIGINT', handleExit);
+    process.on('SIGTERM', handleExit);
+  }
+}
+
+program
+    .name('browser-agent')
+    .option('-p, --port <port>', 'Port to listen on', '9224')
+    .action(async options => {
+      await main(options);
+    });
+
+void program.parseAsync(process.argv);
+
+async function main(options: { port: string }) {
+  const agent = new Agent();
+  await agent.start(+options.port);
+}
+
+function readBody<T>(req: http.IncomingMessage): Promise<T> {
+  return new Promise((resolve, reject) => {
+    const chunks: Buffer[] = [];
+    req.on('data', (chunk: Buffer) => chunks.push(chunk));
+    req.on('end', () => resolve(JSON.parse(Buffer.concat(chunks).toString())));
+  });
+}
+
+async function findFreePort(): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const server = net.createServer();
+    server.listen(0, () => {
+      const { port } = server.address() as net.AddressInfo;
+      server.close(() => resolve(port));
+    });
+    server.on('error', reject);
+  });
+}

src/browserContextFactory.ts

@@ -15,13 +15,16 @@
  */
 
 import fs from 'node:fs';
-import os from 'node:os';
+import net from 'node:net';
 import path from 'node:path';
+import os from 'node:os';
 
 import debug from 'debug';
 import * as playwright from 'playwright';
+import { userDataDir } from './fileUtils.js';
 
 import type { FullConfig } from './config.js';
+import type { BrowserInfo, LaunchBrowserRequest } from './browserAgent.js';
 
 const testDebug = debug('pw:mcp:test');
 
@@ -32,6 +35,8 @@ export function contextFactory(browserConfig: FullConfig['browser']): BrowserCon
     return new CdpContextFactory(browserConfig);
   if (browserConfig.isolated)
     return new IsolatedContextFactory(browserConfig);
+  if (browserConfig.browserAgent)
+    return new AgentContextFactory(browserConfig);
   return new PersistentContextFactory(browserConfig);
 }
 
@@ -97,6 +102,7 @@ class IsolatedContextFactory extends BaseContextFactory {
   }
 
   protected override async _doObtainBrowser(): Promise<playwright.Browser> {
+    await injectCdpPort(this.browserConfig);
     const browserType = playwright[this.browserConfig.browserName];
     return browserType.launch({
       ...this.browserConfig.launchOptions,
@@ -155,6 +161,7 @@ class PersistentContextFactory implements BrowserContextFactory {
   }
 
   async createContext(): Promise<{ browserContext: playwright.BrowserContext, close: () => Promise<void> }> {
+    await injectCdpPort(this.browserConfig);
     testDebug('create browser context (persistent)');
     const userDataDir = this.browserConfig.userDataDir ?? await this._createUserDataDir();
 
@@ -209,3 +216,51 @@ class PersistentContextFactory implements BrowserContextFactory {
     return result;
   }
 }
+
+export class AgentContextFactory extends BaseContextFactory {
+  constructor(browserConfig: FullConfig['browser']) {
+    super('persistent', browserConfig);
+  }
+
+  protected override async _doObtainBrowser(): Promise<playwright.Browser> {
+    const response = await fetch(new URL(`/json/launch`, this.browserConfig.browserAgent), {
+      method: 'POST',
+      body: JSON.stringify({
+        browserType: this.browserConfig.browserName,
+        userDataDir: this.browserConfig.userDataDir ?? await this._createUserDataDir(),
+        launchOptions: this.browserConfig.launchOptions,
+        contextOptions: this.browserConfig.contextOptions,
+      } as LaunchBrowserRequest),
+    });
+    const info = await response.json() as BrowserInfo;
+    if (info.error)
+      throw new Error(info.error);
+    return await playwright.chromium.connectOverCDP(`http://localhost:${info.cdpPort}/`);
+  }
+
+  protected override async _doCreateContext(browser: playwright.Browser): Promise<playwright.BrowserContext> {
+    return this.browserConfig.isolated ? await browser.newContext() : browser.contexts()[0];
+  }
+
+  private async _createUserDataDir() {
+    const dir = await userDataDir(this.browserConfig);
+    await fs.promises.mkdir(dir, { recursive: true });
+    return dir;
+  }
+}
+
+async function injectCdpPort(browserConfig: FullConfig['browser']) {
+  if (browserConfig.browserName === 'chromium')
+    (browserConfig.launchOptions as any).cdpPort = await findFreePort();
+}
+
+async function findFreePort() {
+  return new Promise((resolve, reject) => {
+    const server = net.createServer();
+    server.listen(0, () => {
+      const { port } = server.address() as net.AddressInfo;
+      server.close(() => resolve(port));
+    });
+    server.on('error', reject);
+  });
+}

src/config.ts

@@ -15,7 +15,6 @@
  */
 
 import fs from 'fs';
-import net from 'net';
 import os from 'os';
 import path from 'path';
 import { devices } from 'playwright';
@@ -29,6 +28,7 @@ export type CLIOptions = {
   blockedOrigins?: string[];
   blockServiceWorkers?: boolean;
   browser?: string;
+  browserAgent?: string;
   caps?: string;
   cdpEndpoint?: string;
   config?: string;
@@ -96,8 +96,6 @@ export async function resolveCLIConfig(cliOptions: CLIOptions): Promise<FullConf
   // Derive artifact output directory from config.outputDir
   if (result.saveTrace)
     result.browser.launchOptions.tracesDir = path.join(result.outputDir, 'traces');
-  if (result.browser.browserName === 'chromium')
-    (result.browser.launchOptions as any).cdpPort = await findFreePort();
   return result;
 }
 
@@ -171,6 +169,7 @@ export async function configFromCLIOptions(cliOptions: CLIOptions): Promise<Conf
 
   const result: Config = {
     browser: {
+      browserAgent: cliOptions.browserAgent ?? process.env.PW_BROWSER_AGENT,
       browserName,
       isolated: cliOptions.isolated,
       userDataDir: cliOptions.userDataDir,
@@ -196,17 +195,6 @@ export async function configFromCLIOptions(cliOptions: CLIOptions): Promise<Conf
   return result;
 }
 
-async function findFreePort() {
-  return new Promise((resolve, reject) => {
-    const server = net.createServer();
-    server.listen(0, () => {
-      const { port } = server.address() as net.AddressInfo;
-      server.close(() => resolve(port));
-    });
-    server.on('error', reject);
-  });
-}
-
 async function loadConfig(configFile: string | undefined): Promise<Config> {
   if (!configFile)
     return {};
@@ -232,6 +220,8 @@ function pickDefined<T extends object>(obj: T | undefined): Partial<T> {
 
 function mergeConfig(base: FullConfig, overrides: Config): FullConfig {
   const browser: FullConfig['browser'] = {
+    ...pickDefined(base.browser),
+    ...pickDefined(overrides.browser),
     browserName: overrides.browser?.browserName ?? base.browser?.browserName ?? 'chromium',
     isolated: overrides.browser?.isolated ?? base.browser?.isolated ?? false,
     launchOptions: {
@@ -243,9 +233,6 @@ function mergeConfig(base: FullConfig, overrides: Config): FullConfig {
       ...pickDefined(base.browser?.contextOptions),
       ...pickDefined(overrides.browser?.contextOptions),
     },
-    userDataDir: overrides.browser?.userDataDir ?? base.browser?.userDataDir,
-    cdpEndpoint: overrides.browser?.cdpEndpoint ?? base.browser?.cdpEndpoint,
-    remoteEndpoint: overrides.browser?.remoteEndpoint ?? base.browser?.remoteEndpoint,
   };
 
   if (browser.browserName !== 'chromium' && browser.launchOptions)

src/fileUtils.ts

@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import os from 'node:os';
+import path from 'node:path';
+
+import type { FullConfig } from './config.js';
+
+export function cacheDir() {
+  let cacheDirectory: string;
+  if (process.platform === 'linux')
+    cacheDirectory = process.env.XDG_CACHE_HOME || path.join(os.homedir(), '.cache');
+  else if (process.platform === 'darwin')
+    cacheDirectory = path.join(os.homedir(), 'Library', 'Caches');
+  else if (process.platform === 'win32')
+    cacheDirectory = process.env.LOCALAPPDATA || path.join(os.homedir(), 'AppData', 'Local');
+  else
+    throw new Error('Unsupported platform: ' + process.platform);
+  return path.join(cacheDirectory, 'ms-playwright');
+}
+
+export async function userDataDir(browserConfig: FullConfig['browser']) {
+  return path.join(cacheDir(), 'ms-playwright', `mcp-${browserConfig.launchOptions?.channel ?? browserConfig?.browserName}-profile`);
+}

src/httpServer.ts

@@ -0,0 +1,232 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import fs from 'fs';
+import path from 'path';
+import http from 'http';
+import net from 'net';
+
+import mime from 'mime';
+
+import { ManualPromise } from './manualPromise.js';
+
+
+export type ServerRouteHandler = (request: http.IncomingMessage, response: http.ServerResponse) => void;
+
+export type Transport = {
+  sendEvent?: (method: string, params: any) => void;
+  close?: () => void;
+  onconnect: () => void;
+  dispatch: (method: string, params: any) => Promise<any>;
+  onclose: () => void;
+};
+
+export class HttpServer {
+  private _server: http.Server;
+  private _urlPrefixPrecise: string = '';
+  private _urlPrefixHumanReadable: string = '';
+  private _port: number = 0;
+  private _routes: { prefix?: string, exact?: string, handler: ServerRouteHandler }[] = [];
+
+  constructor() {
+    this._server = http.createServer(this._onRequest.bind(this));
+    decorateServer(this._server);
+  }
+
+  server() {
+    return this._server;
+  }
+
+  routePrefix(prefix: string, handler: ServerRouteHandler) {
+    this._routes.push({ prefix, handler });
+  }
+
+  routePath(path: string, handler: ServerRouteHandler) {
+    this._routes.push({ exact: path, handler });
+  }
+
+  port(): number {
+    return this._port;
+  }
+
+  private async _tryStart(port: number | undefined, host: string) {
+    const errorPromise = new ManualPromise();
+    const errorListener = (error: Error) => errorPromise.reject(error);
+    this._server.on('error', errorListener);
+
+    try {
+      this._server.listen(port, host);
+      await Promise.race([
+        new Promise(cb => this._server!.once('listening', cb)),
+        errorPromise,
+      ]);
+    } finally {
+      this._server.removeListener('error', errorListener);
+    }
+  }
+
+  async start(options: { port?: number, preferredPort?: number, host?: string } = {}): Promise<void> {
+    const host = options.host || 'localhost';
+    if (options.preferredPort) {
+      try {
+        await this._tryStart(options.preferredPort, host);
+      } catch (e: any) {
+        if (!e || !e.message || !e.message.includes('EADDRINUSE'))
+          throw e;
+        await this._tryStart(undefined, host);
+      }
+    } else {
+      await this._tryStart(options.port, host);
+    }
+
+    const address = this._server.address();
+    if (typeof address === 'string') {
+      this._urlPrefixPrecise = address;
+      this._urlPrefixHumanReadable = address;
+    } else {
+      this._port = address!.port;
+      const resolvedHost = address!.family === 'IPv4' ? address!.address : `[${address!.address}]`;
+      this._urlPrefixPrecise = `http://${resolvedHost}:${address!.port}`;
+      this._urlPrefixHumanReadable = `http://${host}:${address!.port}`;
+    }
+  }
+
+  async stop() {
+    await new Promise(cb => this._server!.close(cb));
+  }
+
+  urlPrefix(purpose: 'human-readable' | 'precise'): string {
+    return purpose === 'human-readable' ? this._urlPrefixHumanReadable : this._urlPrefixPrecise;
+  }
+
+  serveFile(request: http.IncomingMessage, response: http.ServerResponse, absoluteFilePath: string, headers?: { [name: string]: string }): boolean {
+    try {
+      for (const [name, value] of Object.entries(headers || {}))
+        response.setHeader(name, value);
+      if (request.headers.range)
+        this._serveRangeFile(request, response, absoluteFilePath);
+      else
+        this._serveFile(response, absoluteFilePath);
+      return true;
+    } catch (e) {
+      return false;
+    }
+  }
+
+  _serveFile(response: http.ServerResponse, absoluteFilePath: string) {
+    const content = fs.readFileSync(absoluteFilePath);
+    response.statusCode = 200;
+    const contentType = mime.getType(path.extname(absoluteFilePath)) || 'application/octet-stream';
+    response.setHeader('Content-Type', contentType);
+    response.setHeader('Content-Length', content.byteLength);
+    response.end(content);
+  }
+
+  _serveRangeFile(request: http.IncomingMessage, response: http.ServerResponse, absoluteFilePath: string) {
+    const range = request.headers.range;
+    if (!range || !range.startsWith('bytes=') || range.includes(', ') || [...range].filter(char => char === '-').length !== 1) {
+      response.statusCode = 400;
+      return response.end('Bad request');
+    }
+
+    // Parse the range header: https://datatracker.ietf.org/doc/html/rfc7233#section-2.1
+    const [startStr, endStr] = range.replace(/bytes=/, '').split('-');
+
+    // Both start and end (when passing to fs.createReadStream) and the range header are inclusive and start counting at 0.
+    let start: number;
+    let end: number;
+    const size = fs.statSync(absoluteFilePath).size;
+    if (startStr !== '' && endStr === '') {
+      // No end specified: use the whole file
+      start = +startStr;
+      end = size - 1;
+    } else if (startStr === '' && endStr !== '') {
+      // No start specified: calculate start manually
+      start = size - +endStr;
+      end = size - 1;
+    } else {
+      start = +startStr;
+      end = +endStr;
+    }
+
+    // Handle unavailable range request
+    if (Number.isNaN(start) || Number.isNaN(end) || start >= size || end >= size || start > end) {
+      // Return the 416 Range Not Satisfiable: https://datatracker.ietf.org/doc/html/rfc7233#section-4.4
+      response.writeHead(416, {
+        'Content-Range': `bytes */${size}`
+      });
+      return response.end();
+    }
+
+    // Sending Partial Content: https://datatracker.ietf.org/doc/html/rfc7233#section-4.1
+    response.writeHead(206, {
+      'Content-Range': `bytes ${start}-${end}/${size}`,
+      'Accept-Ranges': 'bytes',
+      'Content-Length': end - start + 1,
+      'Content-Type': mime.getType(path.extname(absoluteFilePath))!,
+    });
+
+    const readable = fs.createReadStream(absoluteFilePath, { start, end });
+    readable.pipe(response);
+  }
+
+  private _onRequest(request: http.IncomingMessage, response: http.ServerResponse) {
+    if (request.method === 'OPTIONS') {
+      response.writeHead(200);
+      response.end();
+      return;
+    }
+
+    request.on('error', () => response.end());
+    try {
+      if (!request.url) {
+        response.end();
+        return;
+      }
+      const url = new URL('http://localhost' + request.url);
+      for (const route of this._routes) {
+        if (route.exact && url.pathname === route.exact) {
+          route.handler(request, response);
+          return;
+        }
+        if (route.prefix && url.pathname.startsWith(route.prefix)) {
+          route.handler(request, response);
+          return;
+        }
+      }
+      response.statusCode = 404;
+      response.end();
+    } catch (e) {
+      response.end();
+    }
+  }
+}
+
+function decorateServer(server: net.Server) {
+  const sockets = new Set<net.Socket>();
+  server.on('connection', socket => {
+    sockets.add(socket);
+    socket.once('close', () => sockets.delete(socket));
+  });
+
+  const close = server.close;
+  server.close = (callback?: (err?: Error) => void) => {
+    for (const socket of sockets)
+      socket.destroy();
+    sockets.clear();
+    return close.call(server, callback);
+  };
+}

src/program.ts

@@ -30,6 +30,7 @@ program
     .option('--blocked-origins <origins>', 'semicolon-separated list of origins to block the browser from requesting. Blocklist is evaluated before allowlist. If used without the allowlist, requests not matching the blocklist are still allowed.', semicolonSeparatedList)
     .option('--block-service-workers', 'block service workers')
     .option('--browser <browser>', 'browser or chrome channel to use, possible values: chrome, firefox, webkit, msedge.')
+    .option('--browser-agent <endpoint>', 'Use browser agent (experimental).')
     .option('--caps <caps>', 'comma-separated list of capabilities to enable, possible values: tabs, pdf, history, wait, files, install. Default is all.')
     .option('--cdp-endpoint <endpoint>', 'CDP endpoint to connect to.')
     .option('--config <path>', 'path to the configuration file.')

tests/agent.spec.ts

@@ -0,0 +1,77 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import path from 'path';
+import url from 'node:url';
+
+import { spawn } from 'child_process';
+import { test as baseTest, expect } from './fixtures.js';
+
+import type { ChildProcess } from 'child_process';
+
+const __filename = url.fileURLToPath(import.meta.url);
+
+const test = baseTest.extend<{ agentEndpoint: (options?: { args?: string[] }) => Promise<{ url: URL, stdout: () => string }> }>({
+  agentEndpoint: async ({}, use) => {
+    let cp: ChildProcess | undefined;
+    await use(async (options?: { args?: string[] }) => {
+      if (cp)
+        throw new Error('Process already running');
+
+      cp = spawn('node', [
+        path.join(path.dirname(__filename), '../lib/browserAgent.js'),
+        ...(options?.args || []),
+      ], {
+        stdio: 'pipe',
+        env: {
+          ...process.env,
+          DEBUG: 'pw:mcp:test',
+          DEBUG_COLORS: '0',
+          DEBUG_HIDE_DATE: '1',
+        },
+      });
+      let stdout = '';
+      const url = await new Promise<string>(resolve => cp!.stdout?.on('data', data => {
+        stdout += data.toString();
+        const match = stdout.match(/Listening on (http:\/\/.*)/);
+        if (match)
+          resolve(match[1]);
+      }));
+
+      return { url: new URL(url), stdout: () => stdout };
+    });
+    cp?.kill('SIGTERM');
+  },
+});
+
+test.skip(({ mcpBrowser }) => mcpBrowser !== 'chrome', 'Agent is CDP-only for now');
+
+test('browser lifecycle', async ({ agentEndpoint, startClient, server }) => {
+  const { url: agentUrl } = await agentEndpoint();
+  const { client: client1 } = await startClient({ args: ['--browser-agent', agentUrl.toString()] });
+  expect(await client1.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  })).toContainTextContent('Hello, world!');
+
+  const { client: client2 } = await startClient({ args: ['--browser-agent', agentUrl.toString()] });
+  expect(await client2.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  })).toContainTextContent('Hello, world!');
+
+  await client1.close();
+  await client2.close();
+});

tests/fixtures.ts

@@ -65,12 +65,14 @@ export const test = baseTest.extend<TestFixtures & TestOptions, WorkerFixtures>(
   },
 
   startClient: async ({ mcpHeadless, mcpBrowser, mcpMode }, use, testInfo) => {
-    const userDataDir = testInfo.outputPath('user-data-dir');
+    const userDataDir = mcpMode !== 'docker' ? testInfo.outputPath('user-data-dir') : undefined;
     const configDir = path.dirname(test.info().config.configFile!);
     let client: Client | undefined;
 
     await use(async options => {
-      const args = ['--user-data-dir', path.relative(configDir, userDataDir)];
+      const args: string[] = [];
+      if (userDataDir)
+        args.push('--user-data-dir', userDataDir);
       if (process.env.CI && process.platform === 'linux')
         args.push('--no-sandbox');
       if (mcpHeadless)
@@ -239,5 +241,5 @@ export const expect = baseExpect.extend({
 });
 
 export function formatOutput(output: string): string[] {
-  return output.split('\n').map(line => line.replace(/^pw:mcp:test /, '').replace(/test-results.*/, '').trim()).filter(Boolean);
+  return output.split('\n').map(line => line.replace(/^pw:mcp:test /, '').replace(/user data dir.*/, 'user data dir').trim()).filter(Boolean);
 }