diff --git a/codex-rs/app-server-protocol/schema/json/ClientRequest.json b/codex-rs/app-server-protocol/schema/json/ClientRequest.json
index 903b26b80b0..e245c17954d 100644
--- a/codex-rs/app-server-protocol/schema/json/ClientRequest.json
+++ b/codex-rs/app-server-protocol/schema/json/ClientRequest.json
@@ -781,6 +781,36 @@
       ],
       "type": "object"
     },
+    "FsUnwatchParams": {
+      "description": "Stop filesystem watch notifications for a prior `fs/watch`.",
+      "properties": {
+        "watchId": {
+          "description": "Watch identifier returned by `fs/watch`.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "watchId"
+      ],
+      "type": "object"
+    },
+    "FsWatchParams": {
+      "description": "Start filesystem watch notifications for an absolute path.",
+      "properties": {
+        "path": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            }
+          ],
+          "description": "Absolute file or directory path to watch."
+        }
+      },
+      "required": [
+        "path"
+      ],
+      "type": "object"
+    },
     "FsWriteFileParams": {
       "description": "Write a file on the host filesystem.",
       "properties": {
@@ -4000,6 +4030,54 @@
       "title": "Fs/copyRequest",
       "type": "object"
     },
+    {
+      "properties": {
+        "id": {
+          "$ref": "#/definitions/RequestId"
+        },
+        "method": {
+          "enum": [
+            "fs/watch"
+          ],
+          "title": "Fs/watchRequestMethod",
+          "type": "string"
+        },
+        "params": {
+          "$ref": "#/definitions/FsWatchParams"
+        }
+      },
+      "required": [
+        "id",
+        "method",
+        "params"
+      ],
+      "title": "Fs/watchRequest",
+      "type": "object"
+    },
+    {
+      "properties": {
+        "id": {
+          "$ref": "#/definitions/RequestId"
+        },
+        "method": {
+          "enum": [
+            "fs/unwatch"
+          ],
+          "title": "Fs/unwatchRequestMethod",
+          "type": "string"
+        },
+        "params": {
+          "$ref": "#/definitions/FsUnwatchParams"
+        }
+      },
+      "required": [
+        "id",
+        "method",
+        "params"
+      ],
+      "title": "Fs/unwatchRequest",
+      "type": "object"
+    },
     {
       "properties": {
         "id": {
diff --git a/codex-rs/app-server-protocol/schema/json/ServerNotification.json b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
index b576581cf9d..37f7ff8c5f6 100644
--- a/codex-rs/app-server-protocol/schema/json/ServerNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
@@ -1,6 +1,10 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    },
     "AccountLoginCompletedNotification": {
       "properties": {
         "error": {
@@ -998,6 +1002,27 @@
       ],
       "type": "object"
     },
+    "FsChangedNotification": {
+      "description": "Filesystem watch notification emitted for `fs/watch` subscribers.",
+      "properties": {
+        "changedPaths": {
+          "description": "File or directory paths associated with this event.",
+          "items": {
+            "$ref": "#/definitions/AbsolutePathBuf"
+          },
+          "type": "array"
+        },
+        "watchId": {
+          "description": "Watch identifier returned by `fs/watch`.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "changedPaths",
+        "watchId"
+      ],
+      "type": "object"
+    },
     "FuzzyFileSearchMatchType": {
       "enum": [
         "file",
@@ -4394,6 +4419,26 @@
       "title": "App/list/updatedNotification",
       "type": "object"
     },
+    {
+      "properties": {
+        "method": {
+          "enum": [
+            "fs/changed"
+          ],
+          "title": "Fs/changedNotificationMethod",
+          "type": "string"
+        },
+        "params": {
+          "$ref": "#/definitions/FsChangedNotification"
+        }
+      },
+      "required": [
+        "method",
+        "params"
+      ],
+      "title": "Fs/changedNotification",
+      "type": "object"
+    },
     {
       "properties": {
         "method": {
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
index a644549325a..82f17cb9c06 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
@@ -883,6 +883,54 @@
           "title": "Fs/copyRequest",
           "type": "object"
         },
+        {
+          "properties": {
+            "id": {
+              "$ref": "#/definitions/v2/RequestId"
+            },
+            "method": {
+              "enum": [
+                "fs/watch"
+              ],
+              "title": "Fs/watchRequestMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/v2/FsWatchParams"
+            }
+          },
+          "required": [
+            "id",
+            "method",
+            "params"
+          ],
+          "title": "Fs/watchRequest",
+          "type": "object"
+        },
+        {
+          "properties": {
+            "id": {
+              "$ref": "#/definitions/v2/RequestId"
+            },
+            "method": {
+              "enum": [
+                "fs/unwatch"
+              ],
+              "title": "Fs/unwatchRequestMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/v2/FsUnwatchParams"
+            }
+          },
+          "required": [
+            "id",
+            "method",
+            "params"
+          ],
+          "title": "Fs/unwatchRequest",
+          "type": "object"
+        },
         {
           "properties": {
             "id": {
@@ -4053,6 +4101,26 @@
           "title": "App/list/updatedNotification",
           "type": "object"
         },
+        {
+          "properties": {
+            "method": {
+              "enum": [
+                "fs/changed"
+              ],
+              "title": "Fs/changedNotificationMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/v2/FsChangedNotification"
+            }
+          },
+          "required": [
+            "method",
+            "params"
+          ],
+          "title": "Fs/changedNotification",
+          "type": "object"
+        },
         {
           "properties": {
             "method": {
@@ -7444,6 +7512,29 @@
         ],
         "type": "string"
       },
+      "FsChangedNotification": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "description": "Filesystem watch notification emitted for `fs/watch` subscribers.",
+        "properties": {
+          "changedPaths": {
+            "description": "File or directory paths associated with this event.",
+            "items": {
+              "$ref": "#/definitions/v2/AbsolutePathBuf"
+            },
+            "type": "array"
+          },
+          "watchId": {
+            "description": "Watch identifier returned by `fs/watch`.",
+            "type": "string"
+          }
+        },
+        "required": [
+          "changedPaths",
+          "watchId"
+        ],
+        "title": "FsChangedNotification",
+        "type": "object"
+      },
       "FsCopyParams": {
         "$schema": "http://json-schema.org/draft-07/schema#",
         "description": "Copy a file or directory tree on the host filesystem.",
@@ -7698,6 +7789,70 @@
         "title": "FsRemoveResponse",
         "type": "object"
       },
+      "FsUnwatchParams": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "description": "Stop filesystem watch notifications for a prior `fs/watch`.",
+        "properties": {
+          "watchId": {
+            "description": "Watch identifier returned by `fs/watch`.",
+            "type": "string"
+          }
+        },
+        "required": [
+          "watchId"
+        ],
+        "title": "FsUnwatchParams",
+        "type": "object"
+      },
+      "FsUnwatchResponse": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "description": "Successful response for `fs/unwatch`.",
+        "title": "FsUnwatchResponse",
+        "type": "object"
+      },
+      "FsWatchParams": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "description": "Start filesystem watch notifications for an absolute path.",
+        "properties": {
+          "path": {
+            "allOf": [
+              {
+                "$ref": "#/definitions/v2/AbsolutePathBuf"
+              }
+            ],
+            "description": "Absolute file or directory path to watch."
+          }
+        },
+        "required": [
+          "path"
+        ],
+        "title": "FsWatchParams",
+        "type": "object"
+      },
+      "FsWatchResponse": {
+        "$schema": "http://json-schema.org/draft-07/schema#",
+        "description": "Created watch handle returned by `fs/watch`.",
+        "properties": {
+          "path": {
+            "allOf": [
+              {
+                "$ref": "#/definitions/v2/AbsolutePathBuf"
+              }
+            ],
+            "description": "Canonicalized path associated with the watch."
+          },
+          "watchId": {
+            "description": "Connection-scoped watch identifier used for `fs/unwatch` and `fs/changed`.",
+            "type": "string"
+          }
+        },
+        "required": [
+          "path",
+          "watchId"
+        ],
+        "title": "FsWatchResponse",
+        "type": "object"
+      },
       "FsWriteFileParams": {
         "$schema": "http://json-schema.org/draft-07/schema#",
         "description": "Write a file on the host filesystem.",
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
index 71e60345296..198a3610c4e 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
@@ -1417,6 +1417,54 @@
           "title": "Fs/copyRequest",
           "type": "object"
         },
+        {
+          "properties": {
+            "id": {
+              "$ref": "#/definitions/RequestId"
+            },
+            "method": {
+              "enum": [
+                "fs/watch"
+              ],
+              "title": "Fs/watchRequestMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/FsWatchParams"
+            }
+          },
+          "required": [
+            "id",
+            "method",
+            "params"
+          ],
+          "title": "Fs/watchRequest",
+          "type": "object"
+        },
+        {
+          "properties": {
+            "id": {
+              "$ref": "#/definitions/RequestId"
+            },
+            "method": {
+              "enum": [
+                "fs/unwatch"
+              ],
+              "title": "Fs/unwatchRequestMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/FsUnwatchParams"
+            }
+          },
+          "required": [
+            "id",
+            "method",
+            "params"
+          ],
+          "title": "Fs/unwatchRequest",
+          "type": "object"
+        },
         {
           "properties": {
             "id": {
@@ -4037,6 +4085,29 @@
       ],
       "type": "string"
     },
+    "FsChangedNotification": {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "description": "Filesystem watch notification emitted for `fs/watch` subscribers.",
+      "properties": {
+        "changedPaths": {
+          "description": "File or directory paths associated with this event.",
+          "items": {
+            "$ref": "#/definitions/AbsolutePathBuf"
+          },
+          "type": "array"
+        },
+        "watchId": {
+          "description": "Watch identifier returned by `fs/watch`.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "changedPaths",
+        "watchId"
+      ],
+      "title": "FsChangedNotification",
+      "type": "object"
+    },
     "FsCopyParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "description": "Copy a file or directory tree on the host filesystem.",
@@ -4291,6 +4362,70 @@
       "title": "FsRemoveResponse",
       "type": "object"
     },
+    "FsUnwatchParams": {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "description": "Stop filesystem watch notifications for a prior `fs/watch`.",
+      "properties": {
+        "watchId": {
+          "description": "Watch identifier returned by `fs/watch`.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "watchId"
+      ],
+      "title": "FsUnwatchParams",
+      "type": "object"
+    },
+    "FsUnwatchResponse": {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "description": "Successful response for `fs/unwatch`.",
+      "title": "FsUnwatchResponse",
+      "type": "object"
+    },
+    "FsWatchParams": {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "description": "Start filesystem watch notifications for an absolute path.",
+      "properties": {
+        "path": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            }
+          ],
+          "description": "Absolute file or directory path to watch."
+        }
+      },
+      "required": [
+        "path"
+      ],
+      "title": "FsWatchParams",
+      "type": "object"
+    },
+    "FsWatchResponse": {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "description": "Created watch handle returned by `fs/watch`.",
+      "properties": {
+        "path": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            }
+          ],
+          "description": "Canonicalized path associated with the watch."
+        },
+        "watchId": {
+          "description": "Connection-scoped watch identifier used for `fs/unwatch` and `fs/changed`.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "path",
+        "watchId"
+      ],
+      "title": "FsWatchResponse",
+      "type": "object"
+    },
     "FsWriteFileParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "description": "Write a file on the host filesystem.",
@@ -8518,6 +8653,26 @@
           "title": "App/list/updatedNotification",
           "type": "object"
         },
+        {
+          "properties": {
+            "method": {
+              "enum": [
+                "fs/changed"
+              ],
+              "title": "Fs/changedNotificationMethod",
+              "type": "string"
+            },
+            "params": {
+              "$ref": "#/definitions/FsChangedNotification"
+            }
+          },
+          "required": [
+            "method",
+            "params"
+          ],
+          "title": "Fs/changedNotification",
+          "type": "object"
+        },
         {
           "properties": {
             "method": {
diff --git a/codex-rs/app-server-protocol/schema/json/v2/FsChangedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/FsChangedNotification.json
new file mode 100644
index 00000000000..ab26588ecb1
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/json/v2/FsChangedNotification.json
@@ -0,0 +1,29 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    }
+  },
+  "description": "Filesystem watch notification emitted for `fs/watch` subscribers.",
+  "properties": {
+    "changedPaths": {
+      "description": "File or directory paths associated with this event.",
+      "items": {
+        "$ref": "#/definitions/AbsolutePathBuf"
+      },
+      "type": "array"
+    },
+    "watchId": {
+      "description": "Watch identifier returned by `fs/watch`.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "changedPaths",
+    "watchId"
+  ],
+  "title": "FsChangedNotification",
+  "type": "object"
+}
\ No newline at end of file
diff --git a/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchParams.json b/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchParams.json
new file mode 100644
index 00000000000..4b988d97aa3
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchParams.json
@@ -0,0 +1,15 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "description": "Stop filesystem watch notifications for a prior `fs/watch`.",
+  "properties": {
+    "watchId": {
+      "description": "Watch identifier returned by `fs/watch`.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "watchId"
+  ],
+  "title": "FsUnwatchParams",
+  "type": "object"
+}
\ No newline at end of file
diff --git a/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchResponse.json b/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchResponse.json
new file mode 100644
index 00000000000..daa80ad656f
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/json/v2/FsUnwatchResponse.json
@@ -0,0 +1,6 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "description": "Successful response for `fs/unwatch`.",
+  "title": "FsUnwatchResponse",
+  "type": "object"
+}
\ No newline at end of file
diff --git a/codex-rs/app-server-protocol/schema/json/v2/FsWatchParams.json b/codex-rs/app-server-protocol/schema/json/v2/FsWatchParams.json
new file mode 100644
index 00000000000..cf80c7b101d
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/json/v2/FsWatchParams.json
@@ -0,0 +1,25 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    }
+  },
+  "description": "Start filesystem watch notifications for an absolute path.",
+  "properties": {
+    "path": {
+      "allOf": [
+        {
+          "$ref": "#/definitions/AbsolutePathBuf"
+        }
+      ],
+      "description": "Absolute file or directory path to watch."
+    }
+  },
+  "required": [
+    "path"
+  ],
+  "title": "FsWatchParams",
+  "type": "object"
+}
\ No newline at end of file
diff --git a/codex-rs/app-server-protocol/schema/json/v2/FsWatchResponse.json b/codex-rs/app-server-protocol/schema/json/v2/FsWatchResponse.json
new file mode 100644
index 00000000000..b516636a094
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/json/v2/FsWatchResponse.json
@@ -0,0 +1,30 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    }
+  },
+  "description": "Created watch handle returned by `fs/watch`.",
+  "properties": {
+    "path": {
+      "allOf": [
+        {
+          "$ref": "#/definitions/AbsolutePathBuf"
+        }
+      ],
+      "description": "Canonicalized path associated with the watch."
+    },
+    "watchId": {
+      "description": "Connection-scoped watch identifier used for `fs/unwatch` and `fs/changed`.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "path",
+    "watchId"
+  ],
+  "title": "FsWatchResponse",
+  "type": "object"
+}
\ No newline at end of file
diff --git a/codex-rs/app-server-protocol/schema/typescript/ClientRequest.ts b/codex-rs/app-server-protocol/schema/typescript/ClientRequest.ts
index 5e03a26ca2d..3c77652ceca 100644
--- a/codex-rs/app-server-protocol/schema/typescript/ClientRequest.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/ClientRequest.ts
@@ -26,6 +26,8 @@ import type { FsGetMetadataParams } from "./v2/FsGetMetadataParams";
 import type { FsReadDirectoryParams } from "./v2/FsReadDirectoryParams";
 import type { FsReadFileParams } from "./v2/FsReadFileParams";
 import type { FsRemoveParams } from "./v2/FsRemoveParams";
+import type { FsUnwatchParams } from "./v2/FsUnwatchParams";
+import type { FsWatchParams } from "./v2/FsWatchParams";
 import type { FsWriteFileParams } from "./v2/FsWriteFileParams";
 import type { GetAccountParams } from "./v2/GetAccountParams";
 import type { ListMcpServerStatusParams } from "./v2/ListMcpServerStatusParams";
@@ -61,4 +63,4 @@ import type { WindowsSandboxSetupStartParams } from "./v2/WindowsSandboxSetupSta
 /**
  * Request from the client to the server.
  */
-export type ClientRequest ={ "method": "initialize", id: RequestId, params: InitializeParams, } | { "method": "thread/start", id: RequestId, params: ThreadStartParams, } | { "method": "thread/resume", id: RequestId, params: ThreadResumeParams, } | { "method": "thread/fork", id: RequestId, params: ThreadForkParams, } | { "method": "thread/archive", id: RequestId, params: ThreadArchiveParams, } | { "method": "thread/unsubscribe", id: RequestId, params: ThreadUnsubscribeParams, } | { "method": "thread/name/set", id: RequestId, params: ThreadSetNameParams, } | { "method": "thread/metadata/update", id: RequestId, params: ThreadMetadataUpdateParams, } | { "method": "thread/unarchive", id: RequestId, params: ThreadUnarchiveParams, } | { "method": "thread/compact/start", id: RequestId, params: ThreadCompactStartParams, } | { "method": "thread/shellCommand", id: RequestId, params: ThreadShellCommandParams, } | { "method": "thread/rollback", id: RequestId, params: ThreadRollbackParams, } | { "method": "thread/list", id: RequestId, params: ThreadListParams, } | { "method": "thread/loaded/list", id: RequestId, params: ThreadLoadedListParams, } | { "method": "thread/read", id: RequestId, params: ThreadReadParams, } | { "method": "skills/list", id: RequestId, params: SkillsListParams, } | { "method": "plugin/list", id: RequestId, params: PluginListParams, } | { "method": "plugin/read", id: RequestId, params: PluginReadParams, } | { "method": "app/list", id: RequestId, params: AppsListParams, } | { "method": "fs/readFile", id: RequestId, params: FsReadFileParams, } | { "method": "fs/writeFile", id: RequestId, params: FsWriteFileParams, } | { "method": "fs/createDirectory", id: RequestId, params: FsCreateDirectoryParams, } | { "method": "fs/getMetadata", id: RequestId, params: FsGetMetadataParams, } | { "method": "fs/readDirectory", id: RequestId, params: FsReadDirectoryParams, } | { "method": "fs/remove", id: RequestId, params: FsRemoveParams, } | { "method": "fs/copy", id: RequestId, params: FsCopyParams, } | { "method": "skills/config/write", id: RequestId, params: SkillsConfigWriteParams, } | { "method": "plugin/install", id: RequestId, params: PluginInstallParams, } | { "method": "plugin/uninstall", id: RequestId, params: PluginUninstallParams, } | { "method": "turn/start", id: RequestId, params: TurnStartParams, } | { "method": "turn/steer", id: RequestId, params: TurnSteerParams, } | { "method": "turn/interrupt", id: RequestId, params: TurnInterruptParams, } | { "method": "review/start", id: RequestId, params: ReviewStartParams, } | { "method": "model/list", id: RequestId, params: ModelListParams, } | { "method": "experimentalFeature/list", id: RequestId, params: ExperimentalFeatureListParams, } | { "method": "mcpServer/oauth/login", id: RequestId, params: McpServerOauthLoginParams, } | { "method": "config/mcpServer/reload", id: RequestId, params: undefined, } | { "method": "mcpServerStatus/list", id: RequestId, params: ListMcpServerStatusParams, } | { "method": "windowsSandbox/setupStart", id: RequestId, params: WindowsSandboxSetupStartParams, } | { "method": "account/login/start", id: RequestId, params: LoginAccountParams, } | { "method": "account/login/cancel", id: RequestId, params: CancelLoginAccountParams, } | { "method": "account/logout", id: RequestId, params: undefined, } | { "method": "account/rateLimits/read", id: RequestId, params: undefined, } | { "method": "feedback/upload", id: RequestId, params: FeedbackUploadParams, } | { "method": "command/exec", id: RequestId, params: CommandExecParams, } | { "method": "command/exec/write", id: RequestId, params: CommandExecWriteParams, } | { "method": "command/exec/terminate", id: RequestId, params: CommandExecTerminateParams, } | { "method": "command/exec/resize", id: RequestId, params: CommandExecResizeParams, } | { "method": "config/read", id: RequestId, params: ConfigReadParams, } | { "method": "externalAgentConfig/detect", id: RequestId, params: ExternalAgentConfigDetectParams, } | { "method": "externalAgentConfig/import", id: RequestId, params: ExternalAgentConfigImportParams, } | { "method": "config/value/write", id: RequestId, params: ConfigValueWriteParams, } | { "method": "config/batchWrite", id: RequestId, params: ConfigBatchWriteParams, } | { "method": "configRequirements/read", id: RequestId, params: undefined, } | { "method": "account/read", id: RequestId, params: GetAccountParams, } | { "method": "getConversationSummary", id: RequestId, params: GetConversationSummaryParams, } | { "method": "gitDiffToRemote", id: RequestId, params: GitDiffToRemoteParams, } | { "method": "getAuthStatus", id: RequestId, params: GetAuthStatusParams, } | { "method": "fuzzyFileSearch", id: RequestId, params: FuzzyFileSearchParams, };
+export type ClientRequest ={ "method": "initialize", id: RequestId, params: InitializeParams, } | { "method": "thread/start", id: RequestId, params: ThreadStartParams, } | { "method": "thread/resume", id: RequestId, params: ThreadResumeParams, } | { "method": "thread/fork", id: RequestId, params: ThreadForkParams, } | { "method": "thread/archive", id: RequestId, params: ThreadArchiveParams, } | { "method": "thread/unsubscribe", id: RequestId, params: ThreadUnsubscribeParams, } | { "method": "thread/name/set", id: RequestId, params: ThreadSetNameParams, } | { "method": "thread/metadata/update", id: RequestId, params: ThreadMetadataUpdateParams, } | { "method": "thread/unarchive", id: RequestId, params: ThreadUnarchiveParams, } | { "method": "thread/compact/start", id: RequestId, params: ThreadCompactStartParams, } | { "method": "thread/shellCommand", id: RequestId, params: ThreadShellCommandParams, } | { "method": "thread/rollback", id: RequestId, params: ThreadRollbackParams, } | { "method": "thread/list", id: RequestId, params: ThreadListParams, } | { "method": "thread/loaded/list", id: RequestId, params: ThreadLoadedListParams, } | { "method": "thread/read", id: RequestId, params: ThreadReadParams, } | { "method": "skills/list", id: RequestId, params: SkillsListParams, } | { "method": "plugin/list", id: RequestId, params: PluginListParams, } | { "method": "plugin/read", id: RequestId, params: PluginReadParams, } | { "method": "app/list", id: RequestId, params: AppsListParams, } | { "method": "fs/readFile", id: RequestId, params: FsReadFileParams, } | { "method": "fs/writeFile", id: RequestId, params: FsWriteFileParams, } | { "method": "fs/createDirectory", id: RequestId, params: FsCreateDirectoryParams, } | { "method": "fs/getMetadata", id: RequestId, params: FsGetMetadataParams, } | { "method": "fs/readDirectory", id: RequestId, params: FsReadDirectoryParams, } | { "method": "fs/remove", id: RequestId, params: FsRemoveParams, } | { "method": "fs/copy", id: RequestId, params: FsCopyParams, } | { "method": "fs/watch", id: RequestId, params: FsWatchParams, } | { "method": "fs/unwatch", id: RequestId, params: FsUnwatchParams, } | { "method": "skills/config/write", id: RequestId, params: SkillsConfigWriteParams, } | { "method": "plugin/install", id: RequestId, params: PluginInstallParams, } | { "method": "plugin/uninstall", id: RequestId, params: PluginUninstallParams, } | { "method": "turn/start", id: RequestId, params: TurnStartParams, } | { "method": "turn/steer", id: RequestId, params: TurnSteerParams, } | { "method": "turn/interrupt", id: RequestId, params: TurnInterruptParams, } | { "method": "review/start", id: RequestId, params: ReviewStartParams, } | { "method": "model/list", id: RequestId, params: ModelListParams, } | { "method": "experimentalFeature/list", id: RequestId, params: ExperimentalFeatureListParams, } | { "method": "mcpServer/oauth/login", id: RequestId, params: McpServerOauthLoginParams, } | { "method": "config/mcpServer/reload", id: RequestId, params: undefined, } | { "method": "mcpServerStatus/list", id: RequestId, params: ListMcpServerStatusParams, } | { "method": "windowsSandbox/setupStart", id: RequestId, params: WindowsSandboxSetupStartParams, } | { "method": "account/login/start", id: RequestId, params: LoginAccountParams, } | { "method": "account/login/cancel", id: RequestId, params: CancelLoginAccountParams, } | { "method": "account/logout", id: RequestId, params: undefined, } | { "method": "account/rateLimits/read", id: RequestId, params: undefined, } | { "method": "feedback/upload", id: RequestId, params: FeedbackUploadParams, } | { "method": "command/exec", id: RequestId, params: CommandExecParams, } | { "method": "command/exec/write", id: RequestId, params: CommandExecWriteParams, } | { "method": "command/exec/terminate", id: RequestId, params: CommandExecTerminateParams, } | { "method": "command/exec/resize", id: RequestId, params: CommandExecResizeParams, } | { "method": "config/read", id: RequestId, params: ConfigReadParams, } | { "method": "externalAgentConfig/detect", id: RequestId, params: ExternalAgentConfigDetectParams, } | { "method": "externalAgentConfig/import", id: RequestId, params: ExternalAgentConfigImportParams, } | { "method": "config/value/write", id: RequestId, params: ConfigValueWriteParams, } | { "method": "config/batchWrite", id: RequestId, params: ConfigBatchWriteParams, } | { "method": "configRequirements/read", id: RequestId, params: undefined, } | { "method": "account/read", id: RequestId, params: GetAccountParams, } | { "method": "getConversationSummary", id: RequestId, params: GetConversationSummaryParams, } | { "method": "gitDiffToRemote", id: RequestId, params: GitDiffToRemoteParams, } | { "method": "getAuthStatus", id: RequestId, params: GetAuthStatusParams, } | { "method": "fuzzyFileSearch", id: RequestId, params: FuzzyFileSearchParams, };
diff --git a/codex-rs/app-server-protocol/schema/typescript/ServerNotification.ts b/codex-rs/app-server-protocol/schema/typescript/ServerNotification.ts
index d9e2df7797f..85ebe847f4e 100644
--- a/codex-rs/app-server-protocol/schema/typescript/ServerNotification.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/ServerNotification.ts
@@ -15,6 +15,7 @@ import type { ContextCompactedNotification } from "./v2/ContextCompactedNotifica
 import type { DeprecationNoticeNotification } from "./v2/DeprecationNoticeNotification";
 import type { ErrorNotification } from "./v2/ErrorNotification";
 import type { FileChangeOutputDeltaNotification } from "./v2/FileChangeOutputDeltaNotification";
+import type { FsChangedNotification } from "./v2/FsChangedNotification";
 import type { HookCompletedNotification } from "./v2/HookCompletedNotification";
 import type { HookStartedNotification } from "./v2/HookStartedNotification";
 import type { ItemCompletedNotification } from "./v2/ItemCompletedNotification";
@@ -56,4 +57,4 @@ import type { WindowsWorldWritableWarningNotification } from "./v2/WindowsWorldW
 /**
  * Notification sent from the server to the client.
  */
-export type ServerNotification = { "method": "error", "params": ErrorNotification } | { "method": "thread/started", "params": ThreadStartedNotification } | { "method": "thread/status/changed", "params": ThreadStatusChangedNotification } | { "method": "thread/archived", "params": ThreadArchivedNotification } | { "method": "thread/unarchived", "params": ThreadUnarchivedNotification } | { "method": "thread/closed", "params": ThreadClosedNotification } | { "method": "skills/changed", "params": SkillsChangedNotification } | { "method": "thread/name/updated", "params": ThreadNameUpdatedNotification } | { "method": "thread/tokenUsage/updated", "params": ThreadTokenUsageUpdatedNotification } | { "method": "turn/started", "params": TurnStartedNotification } | { "method": "hook/started", "params": HookStartedNotification } | { "method": "turn/completed", "params": TurnCompletedNotification } | { "method": "hook/completed", "params": HookCompletedNotification } | { "method": "turn/diff/updated", "params": TurnDiffUpdatedNotification } | { "method": "turn/plan/updated", "params": TurnPlanUpdatedNotification } | { "method": "item/started", "params": ItemStartedNotification } | { "method": "item/autoApprovalReview/started", "params": ItemGuardianApprovalReviewStartedNotification } | { "method": "item/autoApprovalReview/completed", "params": ItemGuardianApprovalReviewCompletedNotification } | { "method": "item/completed", "params": ItemCompletedNotification } | { "method": "rawResponseItem/completed", "params": RawResponseItemCompletedNotification } | { "method": "item/agentMessage/delta", "params": AgentMessageDeltaNotification } | { "method": "item/plan/delta", "params": PlanDeltaNotification } | { "method": "command/exec/outputDelta", "params": CommandExecOutputDeltaNotification } | { "method": "item/commandExecution/outputDelta", "params": CommandExecutionOutputDeltaNotification } | { "method": "item/commandExecution/terminalInteraction", "params": TerminalInteractionNotification } | { "method": "item/fileChange/outputDelta", "params": FileChangeOutputDeltaNotification } | { "method": "serverRequest/resolved", "params": ServerRequestResolvedNotification } | { "method": "item/mcpToolCall/progress", "params": McpToolCallProgressNotification } | { "method": "mcpServer/oauthLogin/completed", "params": McpServerOauthLoginCompletedNotification } | { "method": "mcpServer/startupStatus/updated", "params": McpServerStatusUpdatedNotification } | { "method": "account/updated", "params": AccountUpdatedNotification } | { "method": "account/rateLimits/updated", "params": AccountRateLimitsUpdatedNotification } | { "method": "app/list/updated", "params": AppListUpdatedNotification } | { "method": "item/reasoning/summaryTextDelta", "params": ReasoningSummaryTextDeltaNotification } | { "method": "item/reasoning/summaryPartAdded", "params": ReasoningSummaryPartAddedNotification } | { "method": "item/reasoning/textDelta", "params": ReasoningTextDeltaNotification } | { "method": "thread/compacted", "params": ContextCompactedNotification } | { "method": "model/rerouted", "params": ModelReroutedNotification } | { "method": "deprecationNotice", "params": DeprecationNoticeNotification } | { "method": "configWarning", "params": ConfigWarningNotification } | { "method": "fuzzyFileSearch/sessionUpdated", "params": FuzzyFileSearchSessionUpdatedNotification } | { "method": "fuzzyFileSearch/sessionCompleted", "params": FuzzyFileSearchSessionCompletedNotification } | { "method": "thread/realtime/started", "params": ThreadRealtimeStartedNotification } | { "method": "thread/realtime/itemAdded", "params": ThreadRealtimeItemAddedNotification } | { "method": "thread/realtime/transcriptUpdated", "params": ThreadRealtimeTranscriptUpdatedNotification } | { "method": "thread/realtime/outputAudio/delta", "params": ThreadRealtimeOutputAudioDeltaNotification } | { "method": "thread/realtime/error", "params": ThreadRealtimeErrorNotification } | { "method": "thread/realtime/closed", "params": ThreadRealtimeClosedNotification } | { "method": "windows/worldWritableWarning", "params": WindowsWorldWritableWarningNotification } | { "method": "windowsSandbox/setupCompleted", "params": WindowsSandboxSetupCompletedNotification } | { "method": "account/login/completed", "params": AccountLoginCompletedNotification };
+export type ServerNotification = { "method": "error", "params": ErrorNotification } | { "method": "thread/started", "params": ThreadStartedNotification } | { "method": "thread/status/changed", "params": ThreadStatusChangedNotification } | { "method": "thread/archived", "params": ThreadArchivedNotification } | { "method": "thread/unarchived", "params": ThreadUnarchivedNotification } | { "method": "thread/closed", "params": ThreadClosedNotification } | { "method": "skills/changed", "params": SkillsChangedNotification } | { "method": "thread/name/updated", "params": ThreadNameUpdatedNotification } | { "method": "thread/tokenUsage/updated", "params": ThreadTokenUsageUpdatedNotification } | { "method": "turn/started", "params": TurnStartedNotification } | { "method": "hook/started", "params": HookStartedNotification } | { "method": "turn/completed", "params": TurnCompletedNotification } | { "method": "hook/completed", "params": HookCompletedNotification } | { "method": "turn/diff/updated", "params": TurnDiffUpdatedNotification } | { "method": "turn/plan/updated", "params": TurnPlanUpdatedNotification } | { "method": "item/started", "params": ItemStartedNotification } | { "method": "item/autoApprovalReview/started", "params": ItemGuardianApprovalReviewStartedNotification } | { "method": "item/autoApprovalReview/completed", "params": ItemGuardianApprovalReviewCompletedNotification } | { "method": "item/completed", "params": ItemCompletedNotification } | { "method": "rawResponseItem/completed", "params": RawResponseItemCompletedNotification } | { "method": "item/agentMessage/delta", "params": AgentMessageDeltaNotification } | { "method": "item/plan/delta", "params": PlanDeltaNotification } | { "method": "command/exec/outputDelta", "params": CommandExecOutputDeltaNotification } | { "method": "item/commandExecution/outputDelta", "params": CommandExecutionOutputDeltaNotification } | { "method": "item/commandExecution/terminalInteraction", "params": TerminalInteractionNotification } | { "method": "item/fileChange/outputDelta", "params": FileChangeOutputDeltaNotification } | { "method": "serverRequest/resolved", "params": ServerRequestResolvedNotification } | { "method": "item/mcpToolCall/progress", "params": McpToolCallProgressNotification } | { "method": "mcpServer/oauthLogin/completed", "params": McpServerOauthLoginCompletedNotification } | { "method": "mcpServer/startupStatus/updated", "params": McpServerStatusUpdatedNotification } | { "method": "account/updated", "params": AccountUpdatedNotification } | { "method": "account/rateLimits/updated", "params": AccountRateLimitsUpdatedNotification } | { "method": "app/list/updated", "params": AppListUpdatedNotification } | { "method": "fs/changed", "params": FsChangedNotification } | { "method": "item/reasoning/summaryTextDelta", "params": ReasoningSummaryTextDeltaNotification } | { "method": "item/reasoning/summaryPartAdded", "params": ReasoningSummaryPartAddedNotification } | { "method": "item/reasoning/textDelta", "params": ReasoningTextDeltaNotification } | { "method": "thread/compacted", "params": ContextCompactedNotification } | { "method": "model/rerouted", "params": ModelReroutedNotification } | { "method": "deprecationNotice", "params": DeprecationNoticeNotification } | { "method": "configWarning", "params": ConfigWarningNotification } | { "method": "fuzzyFileSearch/sessionUpdated", "params": FuzzyFileSearchSessionUpdatedNotification } | { "method": "fuzzyFileSearch/sessionCompleted", "params": FuzzyFileSearchSessionCompletedNotification } | { "method": "thread/realtime/started", "params": ThreadRealtimeStartedNotification } | { "method": "thread/realtime/itemAdded", "params": ThreadRealtimeItemAddedNotification } | { "method": "thread/realtime/transcriptUpdated", "params": ThreadRealtimeTranscriptUpdatedNotification } | { "method": "thread/realtime/outputAudio/delta", "params": ThreadRealtimeOutputAudioDeltaNotification } | { "method": "thread/realtime/error", "params": ThreadRealtimeErrorNotification } | { "method": "thread/realtime/closed", "params": ThreadRealtimeClosedNotification } | { "method": "windows/worldWritableWarning", "params": WindowsWorldWritableWarningNotification } | { "method": "windowsSandbox/setupCompleted", "params": WindowsSandboxSetupCompletedNotification } | { "method": "account/login/completed", "params": AccountLoginCompletedNotification };
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/FsChangedNotification.ts b/codex-rs/app-server-protocol/schema/typescript/v2/FsChangedNotification.ts
new file mode 100644
index 00000000000..2e9bd0d6eca
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/FsChangedNotification.ts
@@ -0,0 +1,17 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+import type { AbsolutePathBuf } from "../AbsolutePathBuf";
+
+/**
+ * Filesystem watch notification emitted for `fs/watch` subscribers.
+ */
+export type FsChangedNotification = { 
+/**
+ * Watch identifier returned by `fs/watch`.
+ */
+watchId: string, 
+/**
+ * File or directory paths associated with this event.
+ */
+changedPaths: Array<AbsolutePathBuf>, };
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchParams.ts b/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchParams.ts
new file mode 100644
index 00000000000..b21befdb5c2
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchParams.ts
@@ -0,0 +1,12 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+
+/**
+ * Stop filesystem watch notifications for a prior `fs/watch`.
+ */
+export type FsUnwatchParams = { 
+/**
+ * Watch identifier returned by `fs/watch`.
+ */
+watchId: string, };
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchResponse.ts b/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchResponse.ts
new file mode 100644
index 00000000000..02507d2c008
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/FsUnwatchResponse.ts
@@ -0,0 +1,8 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+
+/**
+ * Successful response for `fs/unwatch`.
+ */
+export type FsUnwatchResponse = Record<string, never>;
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchParams.ts b/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchParams.ts
new file mode 100644
index 00000000000..d6d956b288a
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchParams.ts
@@ -0,0 +1,13 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+import type { AbsolutePathBuf } from "../AbsolutePathBuf";
+
+/**
+ * Start filesystem watch notifications for an absolute path.
+ */
+export type FsWatchParams = { 
+/**
+ * Absolute file or directory path to watch.
+ */
+path: AbsolutePathBuf, };
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchResponse.ts b/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchResponse.ts
new file mode 100644
index 00000000000..19272728217
--- /dev/null
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/FsWatchResponse.ts
@@ -0,0 +1,17 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+import type { AbsolutePathBuf } from "../AbsolutePathBuf";
+
+/**
+ * Created watch handle returned by `fs/watch`.
+ */
+export type FsWatchResponse = { 
+/**
+ * Connection-scoped watch identifier used for `fs/unwatch` and `fs/changed`.
+ */
+watchId: string, 
+/**
+ * Canonicalized path associated with the watch.
+ */
+path: AbsolutePathBuf, };
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/index.ts b/codex-rs/app-server-protocol/schema/typescript/v2/index.ts
index c649aec06af..bb924a51357 100644
--- a/codex-rs/app-server-protocol/schema/typescript/v2/index.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/index.ts
@@ -97,6 +97,7 @@ export type { FileChangeOutputDeltaNotification } from "./FileChangeOutputDeltaN
 export type { FileChangeRequestApprovalParams } from "./FileChangeRequestApprovalParams";
 export type { FileChangeRequestApprovalResponse } from "./FileChangeRequestApprovalResponse";
 export type { FileUpdateChange } from "./FileUpdateChange";
+export type { FsChangedNotification } from "./FsChangedNotification";
 export type { FsCopyParams } from "./FsCopyParams";
 export type { FsCopyResponse } from "./FsCopyResponse";
 export type { FsCreateDirectoryParams } from "./FsCreateDirectoryParams";
@@ -110,6 +111,10 @@ export type { FsReadFileParams } from "./FsReadFileParams";
 export type { FsReadFileResponse } from "./FsReadFileResponse";
 export type { FsRemoveParams } from "./FsRemoveParams";
 export type { FsRemoveResponse } from "./FsRemoveResponse";
+export type { FsUnwatchParams } from "./FsUnwatchParams";
+export type { FsUnwatchResponse } from "./FsUnwatchResponse";
+export type { FsWatchParams } from "./FsWatchParams";
+export type { FsWatchResponse } from "./FsWatchResponse";
 export type { FsWriteFileParams } from "./FsWriteFileParams";
 export type { FsWriteFileResponse } from "./FsWriteFileResponse";
 export type { GetAccountParams } from "./GetAccountParams";
diff --git a/codex-rs/app-server-protocol/src/protocol/common.rs b/codex-rs/app-server-protocol/src/protocol/common.rs
index 56897566d94..c3ba24bb56b 100644
--- a/codex-rs/app-server-protocol/src/protocol/common.rs
+++ b/codex-rs/app-server-protocol/src/protocol/common.rs
@@ -336,6 +336,14 @@ client_request_definitions! {
         params: v2::FsCopyParams,
         response: v2::FsCopyResponse,
     },
+    FsWatch => "fs/watch" {
+        params: v2::FsWatchParams,
+        response: v2::FsWatchResponse,
+    },
+    FsUnwatch => "fs/unwatch" {
+        params: v2::FsUnwatchParams,
+        response: v2::FsUnwatchResponse,
+    },
     SkillsConfigWrite => "skills/config/write" {
         params: v2::SkillsConfigWriteParams,
         response: v2::SkillsConfigWriteResponse,
@@ -909,6 +917,7 @@ server_notification_definitions! {
     AccountUpdated => "account/updated" (v2::AccountUpdatedNotification),
     AccountRateLimitsUpdated => "account/rateLimits/updated" (v2::AccountRateLimitsUpdatedNotification),
     AppListUpdated => "app/list/updated" (v2::AppListUpdatedNotification),
+    FsChanged => "fs/changed" (v2::FsChangedNotification),
     ReasoningSummaryTextDelta => "item/reasoning/summaryTextDelta" (v2::ReasoningSummaryTextDeltaNotification),
     ReasoningSummaryPartAdded => "item/reasoning/summaryPartAdded" (v2::ReasoningSummaryPartAddedNotification),
     ReasoningTextDelta => "item/reasoning/textDelta" (v2::ReasoningTextDeltaNotification),
@@ -1488,6 +1497,27 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn serialize_fs_watch() -> Result<()> {
+        let request = ClientRequest::FsWatch {
+            request_id: RequestId::Integer(10),
+            params: v2::FsWatchParams {
+                path: absolute_path("tmp/repo/.git"),
+            },
+        };
+        assert_eq!(
+            json!({
+                "method": "fs/watch",
+                "id": 10,
+                "params": {
+                    "path": absolute_path_string("tmp/repo/.git")
+                }
+            }),
+            serde_json::to_value(&request)?,
+        );
+        Ok(())
+    }
+
     #[test]
     fn serialize_list_experimental_features() -> Result<()> {
         let request = ClientRequest::ExperimentalFeatureList {
diff --git a/codex-rs/app-server-protocol/src/protocol/v2.rs b/codex-rs/app-server-protocol/src/protocol/v2.rs
index 3e30f813237..1f6a052c670 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2.rs
@@ -2301,6 +2301,52 @@ pub struct FsCopyParams {
 #[ts(export_to = "v2/")]
 pub struct FsCopyResponse {}
 
+/// Start filesystem watch notifications for an absolute path.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct FsWatchParams {
+    /// Absolute file or directory path to watch.
+    pub path: AbsolutePathBuf,
+}
+
+/// Created watch handle returned by `fs/watch`.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct FsWatchResponse {
+    /// Connection-scoped watch identifier used for `fs/unwatch` and `fs/changed`.
+    pub watch_id: String,
+    /// Canonicalized path associated with the watch.
+    pub path: AbsolutePathBuf,
+}
+
+/// Stop filesystem watch notifications for a prior `fs/watch`.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct FsUnwatchParams {
+    /// Watch identifier returned by `fs/watch`.
+    pub watch_id: String,
+}
+
+/// Successful response for `fs/unwatch`.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct FsUnwatchResponse {}
+
+/// Filesystem watch notification emitted for `fs/watch` subscribers.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct FsChangedNotification {
+    /// Watch identifier returned by `fs/watch`.
+    pub watch_id: String,
+    /// File or directory paths associated with this event.
+    pub changed_paths: Vec<AbsolutePathBuf>,
+}
+
 /// PTY size in character cells for `command/exec` PTY sessions.
 #[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
@@ -6487,6 +6533,33 @@ mod tests {
         assert_eq!(decoded, response);
     }
 
+    #[test]
+    fn fs_changed_notification_round_trips() {
+        let notification = FsChangedNotification {
+            watch_id: "0195ec6b-1d6f-7c2e-8c7a-56f2c4a8b9d1".to_string(),
+            changed_paths: vec![
+                absolute_path("tmp/repo/.git/HEAD"),
+                absolute_path("tmp/repo/.git/FETCH_HEAD"),
+            ],
+        };
+
+        let value = serde_json::to_value(&notification).expect("serialize fs/changed notification");
+        assert_eq!(
+            value,
+            json!({
+                "watchId": "0195ec6b-1d6f-7c2e-8c7a-56f2c4a8b9d1",
+                "changedPaths": [
+                    absolute_path_string("tmp/repo/.git/HEAD"),
+                    absolute_path_string("tmp/repo/.git/FETCH_HEAD"),
+                ],
+            })
+        );
+
+        let decoded = serde_json::from_value::<FsChangedNotification>(value)
+            .expect("deserialize fs/changed notification");
+        assert_eq!(decoded, notification);
+    }
+
     #[test]
     fn command_exec_params_default_optional_streaming_flags() {
         let params = serde_json::from_value::<CommandExecParams>(json!({
diff --git a/codex-rs/app-server/README.md b/codex-rs/app-server/README.md
index a536e5c68ba..10182cd5f27 100644
--- a/codex-rs/app-server/README.md
+++ b/codex-rs/app-server/README.md
@@ -159,6 +159,9 @@ Example with notification opt-out:
 - `fs/readDirectory` — list direct child entries for an absolute directory path; each entry contains `fileName`, `isDirectory`, and `isFile`, and `fileName` is just the child name, not a path.
 - `fs/remove` — remove an absolute file or directory tree; `recursive` and `force` default to `true`.
 - `fs/copy` — copy between absolute paths; directory copies require `recursive: true`.
+- `fs/watch` — subscribe this connection to filesystem change notifications for an absolute file or directory path; returns a `watchId` and canonicalized `path`.
+- `fs/unwatch` — stop sending notifications for a prior `fs/watch`; returns `{}`.
+- `fs/changed` — notification emitted when watched paths change, including the `watchId` and `changedPaths`.
 - `model/list` — list available models (set `includeHidden: true` to include entries with `hidden: true`), with reasoning effort options, optional legacy `upgrade` model ids, optional `upgradeInfo` metadata (`model`, `upgradeCopy`, `modelLink`, `migrationMarkdown`), and optional `availabilityNux` metadata.
 - `experimentalFeature/list` — list feature flags with stage metadata (`beta`, `underDevelopment`, `stable`, etc.), enabled/default-enabled state, and cursor pagination. For non-beta flags, `displayName`/`description`/`announcement` are `null`.
 - `collaborationMode/list` — list available collaboration mode presets (experimental, no pagination). This response omits built-in developer instructions; clients should either pass `settings.developer_instructions: null` when setting a mode to use Codex's built-in instructions, or provide their own instructions explicitly.
@@ -795,6 +798,28 @@ All filesystem paths in this section must be absolute.
 - `fs/readFile` always returns base64 bytes via `dataBase64`, and `fs/writeFile` always expects base64 bytes in `dataBase64`.
 - `fs/copy` handles both file copies and directory-tree copies; it requires `recursive: true` when `sourcePath` is a directory. Recursive copies traverse regular files, directories, and symlinks; other entry types are skipped.
 
+### Example: Filesystem watch
+
+`fs/watch` accepts absolute file or directory paths. Watching a file emits `fs/changed` for that file path, including updates delivered via replace or rename operations.
+
+```json
+{ "method": "fs/watch", "id": 44, "params": {
+    "path": "/Users/me/project/.git/HEAD"
+} }
+{ "id": 44, "result": {
+    "watchId": "0195ec6b-1d6f-7c2e-8c7a-56f2c4a8b9d1",
+    "path": "/Users/me/project/.git/HEAD"
+} }
+{ "method": "fs/changed", "params": {
+    "watchId": "0195ec6b-1d6f-7c2e-8c7a-56f2c4a8b9d1",
+    "changedPaths": ["/Users/me/project/.git/HEAD"]
+} }
+{ "method": "fs/unwatch", "id": 45, "params": {
+    "watchId": "0195ec6b-1d6f-7c2e-8c7a-56f2c4a8b9d1"
+} }
+{ "id": 45, "result": {} }
+```
+
 ## Events
 
 Event notifications are the server-initiated event stream for thread lifecycles, turn lifecycles, and the items within them. After you start or resume a thread, keep reading stdout for `thread/started`, `thread/archived`, `thread/unarchived`, `thread/closed`, `turn/*`, and `item/*` notifications.
diff --git a/codex-rs/app-server/src/codex_message_processor.rs b/codex-rs/app-server/src/codex_message_processor.rs
index 10154c9a832..bee96b9298a 100644
--- a/codex-rs/app-server/src/codex_message_processor.rs
+++ b/codex-rs/app-server/src/codex_message_processor.rs
@@ -886,7 +886,9 @@ impl CodexMessageProcessor {
             | ClientRequest::FsGetMetadata { .. }
             | ClientRequest::FsReadDirectory { .. }
             | ClientRequest::FsRemove { .. }
-            | ClientRequest::FsCopy { .. } => {
+            | ClientRequest::FsCopy { .. }
+            | ClientRequest::FsWatch { .. }
+            | ClientRequest::FsUnwatch { .. } => {
                 warn!("Filesystem request reached CodexMessageProcessor unexpectedly");
             }
             ClientRequest::ConfigRequirementsRead { .. } => {
diff --git a/codex-rs/app-server/src/fs_api.rs b/codex-rs/app-server/src/fs_api.rs
index 1f8a32362f9..57b355f8180 100644
--- a/codex-rs/app-server/src/fs_api.rs
+++ b/codex-rs/app-server/src/fs_api.rs
@@ -159,7 +159,7 @@ impl FsApi {
     }
 }
 
-fn invalid_request(message: impl Into<String>) -> JSONRPCErrorError {
+pub(crate) fn invalid_request(message: impl Into<String>) -> JSONRPCErrorError {
     JSONRPCErrorError {
         code: INVALID_REQUEST_ERROR_CODE,
         message: message.into(),
@@ -167,7 +167,7 @@ fn invalid_request(message: impl Into<String>) -> JSONRPCErrorError {
     }
 }
 
-fn map_fs_error(err: io::Error) -> JSONRPCErrorError {
+pub(crate) fn map_fs_error(err: io::Error) -> JSONRPCErrorError {
     if err.kind() == io::ErrorKind::InvalidInput {
         invalid_request(err.to_string())
     } else {
diff --git a/codex-rs/app-server/src/fs_watch.rs b/codex-rs/app-server/src/fs_watch.rs
new file mode 100644
index 00000000000..309bee4a64a
--- /dev/null
+++ b/codex-rs/app-server/src/fs_watch.rs
@@ -0,0 +1,379 @@
+use crate::outgoing_message::ConnectionId;
+use crate::outgoing_message::OutgoingMessageSender;
+use codex_app_server_protocol::FsChangedNotification;
+use codex_app_server_protocol::FsUnwatchParams;
+use codex_app_server_protocol::FsUnwatchResponse;
+use codex_app_server_protocol::FsWatchParams;
+use codex_app_server_protocol::FsWatchResponse;
+use codex_app_server_protocol::JSONRPCErrorError;
+use codex_app_server_protocol::ServerNotification;
+use codex_core::file_watcher::FileWatcher;
+use codex_core::file_watcher::FileWatcherEvent;
+use codex_core::file_watcher::FileWatcherSubscriber;
+use codex_core::file_watcher::Receiver;
+use codex_core::file_watcher::WatchPath;
+use codex_core::file_watcher::WatchRegistration;
+use codex_utils_absolute_path::AbsolutePathBuf;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::hash::Hash;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::Mutex as AsyncMutex;
+#[cfg(test)]
+use tokio::sync::mpsc;
+use tokio::sync::oneshot;
+use tokio::time::Instant;
+use tracing::warn;
+use uuid::Uuid;
+
+const FS_CHANGED_NOTIFICATION_DEBOUNCE: Duration = Duration::from_millis(200);
+
+struct DebouncedReceiver {
+    rx: Receiver,
+    interval: Duration,
+    changed_paths: HashSet<PathBuf>,
+    next_allowance: Option<Instant>,
+}
+
+impl DebouncedReceiver {
+    fn new(rx: Receiver, interval: Duration) -> Self {
+        Self {
+            rx,
+            interval,
+            changed_paths: HashSet::new(),
+            next_allowance: None,
+        }
+    }
+
+    async fn recv(&mut self) -> Option<FileWatcherEvent> {
+        while self.changed_paths.is_empty() {
+            self.changed_paths.extend(self.rx.recv().await?.paths);
+        }
+        let next_allowance = *self
+            .next_allowance
+            .get_or_insert_with(|| Instant::now() + self.interval);
+
+        loop {
+            tokio::select! {
+                event = self.rx.recv() => self.changed_paths.extend(event?.paths),
+                _ = tokio::time::sleep_until(next_allowance) => break,
+            }
+        }
+
+        Some(FileWatcherEvent {
+            paths: self.changed_paths.drain().collect(),
+        })
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct FsWatchManager {
+    outgoing: Arc<OutgoingMessageSender>,
+    file_watcher: Arc<FileWatcher>,
+    state: Arc<AsyncMutex<FsWatchState>>,
+}
+
+#[derive(Default)]
+struct FsWatchState {
+    entries: HashMap<WatchKey, WatchEntry>,
+}
+
+struct WatchEntry {
+    terminate_tx: oneshot::Sender<oneshot::Sender<()>>,
+    _subscriber: FileWatcherSubscriber,
+    _registration: WatchRegistration,
+}
+
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+struct WatchKey {
+    connection_id: ConnectionId,
+    watch_id: String,
+}
+
+impl FsWatchManager {
+    pub(crate) fn new(outgoing: Arc<OutgoingMessageSender>) -> Self {
+        let file_watcher = match FileWatcher::new() {
+            Ok(file_watcher) => Arc::new(file_watcher),
+            Err(err) => {
+                warn!("filesystem watch manager falling back to noop core watcher: {err}");
+                Arc::new(FileWatcher::noop())
+            }
+        };
+        Self::new_with_file_watcher(outgoing, file_watcher)
+    }
+
+    fn new_with_file_watcher(
+        outgoing: Arc<OutgoingMessageSender>,
+        file_watcher: Arc<FileWatcher>,
+    ) -> Self {
+        Self {
+            outgoing,
+            file_watcher,
+            state: Arc::new(AsyncMutex::new(FsWatchState::default())),
+        }
+    }
+
+    pub(crate) async fn watch(
+        &self,
+        connection_id: ConnectionId,
+        params: FsWatchParams,
+    ) -> Result<FsWatchResponse, JSONRPCErrorError> {
+        let watch_id = Uuid::now_v7().to_string();
+        let outgoing = self.outgoing.clone();
+        let (subscriber, rx) = self.file_watcher.add_subscriber();
+        let watch_root = params.path.to_path_buf().clone();
+        let registration = subscriber.register_paths(vec![WatchPath {
+            path: params.path.to_path_buf(),
+            recursive: false,
+        }]);
+        let (terminate_tx, terminate_rx) = oneshot::channel();
+
+        self.state.lock().await.entries.insert(
+            WatchKey {
+                connection_id,
+                watch_id: watch_id.clone(),
+            },
+            WatchEntry {
+                terminate_tx,
+                _subscriber: subscriber,
+                _registration: registration,
+            },
+        );
+
+        let task_watch_id = watch_id.clone();
+        tokio::spawn(async move {
+            let mut rx = DebouncedReceiver::new(rx, FS_CHANGED_NOTIFICATION_DEBOUNCE);
+            tokio::pin!(terminate_rx);
+            loop {
+                let event = tokio::select! {
+                    biased;
+                    _ = &mut terminate_rx => break,
+                    event = rx.recv() => match event {
+                        Some(event) => event,
+                        None => break,
+                    },
+                };
+                let mut changed_paths = event
+                    .paths
+                    .into_iter()
+                    .filter_map(|path| {
+                        match AbsolutePathBuf::resolve_path_against_base(&path, &watch_root) {
+                            Ok(path) => Some(path),
+                            Err(err) => {
+                                warn!(
+                                    "failed to normalize watch event path ({}) for {}: {err}",
+                                    path.display(),
+                                    watch_root.display()
+                                );
+                                None
+                            }
+                        }
+                    })
+                    .collect::<Vec<_>>();
+                changed_paths.sort_by(|left, right| left.as_path().cmp(right.as_path()));
+                if !changed_paths.is_empty() {
+                    outgoing
+                        .send_server_notification_to_connection_and_wait(
+                            connection_id,
+                            ServerNotification::FsChanged(FsChangedNotification {
+                                watch_id: task_watch_id.clone(),
+                                changed_paths,
+                            }),
+                        )
+                        .await;
+                }
+            }
+        });
+
+        Ok(FsWatchResponse {
+            watch_id,
+            path: params.path,
+        })
+    }
+
+    pub(crate) async fn unwatch(
+        &self,
+        connection_id: ConnectionId,
+        params: FsUnwatchParams,
+    ) -> Result<FsUnwatchResponse, JSONRPCErrorError> {
+        let watch_key = WatchKey {
+            connection_id,
+            watch_id: params.watch_id,
+        };
+        let entry = self.state.lock().await.entries.remove(&watch_key);
+        if let Some(entry) = entry {
+            // Wait for the oneshot to be destroyed by the task to ensure that no notifications
+            // are send after the unwatch response.
+            let (done_tx, done_rx) = oneshot::channel();
+            let _ = entry.terminate_tx.send(done_tx);
+            let _ = done_rx.await;
+        }
+        Ok(FsUnwatchResponse {})
+    }
+
+    pub(crate) async fn connection_closed(&self, connection_id: ConnectionId) {
+        let mut state = self.state.lock().await;
+        state
+            .entries
+            .extract_if(|key, _| key.connection_id == connection_id)
+            .count();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use codex_utils_absolute_path::AbsolutePathBuf;
+    use pretty_assertions::assert_eq;
+    use tempfile::TempDir;
+    use uuid::Version;
+
+    fn absolute_path(path: PathBuf) -> AbsolutePathBuf {
+        assert!(
+            path.is_absolute(),
+            "path must be absolute: {}",
+            path.display()
+        );
+        AbsolutePathBuf::try_from(path).expect("path should be absolute")
+    }
+
+    fn manager_with_noop_watcher() -> FsWatchManager {
+        const OUTGOING_BUFFER: usize = 1;
+        let (tx, _rx) = mpsc::channel(OUTGOING_BUFFER);
+        FsWatchManager::new_with_file_watcher(
+            Arc::new(OutgoingMessageSender::new(tx)),
+            Arc::new(FileWatcher::noop()),
+        )
+    }
+
+    #[tokio::test]
+    async fn watch_returns_a_v7_id_and_tracks_the_owner_scoped_entry() {
+        let temp_dir = TempDir::new().expect("temp dir");
+        let head_path = temp_dir.path().join("HEAD");
+        std::fs::write(&head_path, "ref: refs/heads/main\n").expect("write HEAD");
+
+        let manager = manager_with_noop_watcher();
+        let path = absolute_path(head_path);
+        let response = manager
+            .watch(ConnectionId(1), FsWatchParams { path: path.clone() })
+            .await
+            .expect("watch should succeed");
+
+        assert_eq!(response.path, path);
+        let watch_id = Uuid::parse_str(&response.watch_id).expect("watch id should be a UUID");
+        assert_eq!(watch_id.get_version(), Some(Version::SortRand));
+
+        let state = manager.state.lock().await;
+        assert_eq!(
+            state.entries.keys().cloned().collect::<HashSet<_>>(),
+            HashSet::from([WatchKey {
+                connection_id: ConnectionId(1),
+                watch_id: response.watch_id,
+            }])
+        );
+    }
+
+    #[tokio::test]
+    async fn unwatch_is_scoped_to_the_connection_that_created_the_watch() {
+        let temp_dir = TempDir::new().expect("temp dir");
+        let head_path = temp_dir.path().join("HEAD");
+        std::fs::write(&head_path, "ref: refs/heads/main\n").expect("write HEAD");
+
+        let manager = manager_with_noop_watcher();
+        let response = manager
+            .watch(
+                ConnectionId(1),
+                FsWatchParams {
+                    path: absolute_path(head_path),
+                },
+            )
+            .await
+            .expect("watch should succeed");
+        let watch_key = WatchKey {
+            connection_id: ConnectionId(1),
+            watch_id: response.watch_id.clone(),
+        };
+
+        manager
+            .unwatch(
+                ConnectionId(2),
+                FsUnwatchParams {
+                    watch_id: response.watch_id.clone(),
+                },
+            )
+            .await
+            .expect("foreign unwatch should be a no-op");
+        assert!(manager.state.lock().await.entries.contains_key(&watch_key));
+
+        manager
+            .unwatch(
+                ConnectionId(1),
+                FsUnwatchParams {
+                    watch_id: response.watch_id,
+                },
+            )
+            .await
+            .expect("owner unwatch should succeed");
+        assert!(!manager.state.lock().await.entries.contains_key(&watch_key));
+    }
+
+    #[tokio::test]
+    async fn connection_closed_removes_only_that_connections_watches() {
+        let temp_dir = TempDir::new().expect("temp dir");
+        let head_path = temp_dir.path().join("HEAD");
+        let fetch_head_path = temp_dir.path().join("FETCH_HEAD");
+        let packed_refs_path = temp_dir.path().join("packed-refs");
+        std::fs::write(&head_path, "ref: refs/heads/main\n").expect("write HEAD");
+        std::fs::write(&fetch_head_path, "old-fetch\n").expect("write FETCH_HEAD");
+        std::fs::write(&packed_refs_path, "refs\n").expect("write packed-refs");
+
+        let manager = manager_with_noop_watcher();
+        let response_1 = manager
+            .watch(
+                ConnectionId(1),
+                FsWatchParams {
+                    path: absolute_path(head_path),
+                },
+            )
+            .await
+            .expect("first watch should succeed");
+        let response_2 = manager
+            .watch(
+                ConnectionId(1),
+                FsWatchParams {
+                    path: absolute_path(fetch_head_path),
+                },
+            )
+            .await
+            .expect("second watch should succeed");
+        let response_3 = manager
+            .watch(
+                ConnectionId(2),
+                FsWatchParams {
+                    path: absolute_path(packed_refs_path),
+                },
+            )
+            .await
+            .expect("third watch should succeed");
+
+        manager.connection_closed(ConnectionId(1)).await;
+
+        assert_eq!(
+            manager
+                .state
+                .lock()
+                .await
+                .entries
+                .keys()
+                .cloned()
+                .collect::<HashSet<_>>(),
+            HashSet::from([WatchKey {
+                connection_id: ConnectionId(2),
+                watch_id: response_3.watch_id,
+            }])
+        );
+        assert_ne!(response_1.watch_id, response_2.watch_id);
+    }
+}
diff --git a/codex-rs/app-server/src/lib.rs b/codex-rs/app-server/src/lib.rs
index 63f72d5224b..dc2512aaec9 100644
--- a/codex-rs/app-server/src/lib.rs
+++ b/codex-rs/app-server/src/lib.rs
@@ -67,6 +67,7 @@ mod error_code;
 mod external_agent_config_api;
 mod filters;
 mod fs_api;
+mod fs_watch;
 mod fuzzy_file_search;
 pub mod in_process;
 mod message_processor;
diff --git a/codex-rs/app-server/src/message_processor.rs b/codex-rs/app-server/src/message_processor.rs
index 4f53bfc1a49..878ae601dd2 100644
--- a/codex-rs/app-server/src/message_processor.rs
+++ b/codex-rs/app-server/src/message_processor.rs
@@ -11,6 +11,7 @@ use crate::config_api::ConfigApi;
 use crate::error_code::INVALID_REQUEST_ERROR_CODE;
 use crate::external_agent_config_api::ExternalAgentConfigApi;
 use crate::fs_api::FsApi;
+use crate::fs_watch::FsWatchManager;
 use crate::outgoing_message::ConnectionId;
 use crate::outgoing_message::ConnectionRequestId;
 use crate::outgoing_message::OutgoingMessageSender;
@@ -36,6 +37,8 @@ use codex_app_server_protocol::FsGetMetadataParams;
 use codex_app_server_protocol::FsReadDirectoryParams;
 use codex_app_server_protocol::FsReadFileParams;
 use codex_app_server_protocol::FsRemoveParams;
+use codex_app_server_protocol::FsUnwatchParams;
+use codex_app_server_protocol::FsWatchParams;
 use codex_app_server_protocol::FsWriteFileParams;
 use codex_app_server_protocol::InitializeResponse;
 use codex_app_server_protocol::JSONRPCError;
@@ -152,6 +155,7 @@ pub(crate) struct MessageProcessor {
     external_agent_config_api: ExternalAgentConfigApi,
     fs_api: FsApi,
     auth_manager: Arc<AuthManager>,
+    fs_watch_manager: FsWatchManager,
     config: Arc<Config>,
     config_warnings: Arc<Vec<ConfigWarningNotification>>,
 }
@@ -248,6 +252,7 @@ impl MessageProcessor {
         );
         let external_agent_config_api = ExternalAgentConfigApi::new(config.codex_home.clone());
         let fs_api = FsApi::default();
+        let fs_watch_manager = FsWatchManager::new(outgoing.clone());
 
         Self {
             outgoing,
@@ -256,6 +261,7 @@ impl MessageProcessor {
             external_agent_config_api,
             fs_api,
             auth_manager,
+            fs_watch_manager,
             config,
             config_warnings: Arc::new(config_warnings),
         }
@@ -463,6 +469,7 @@ impl MessageProcessor {
 
     pub(crate) async fn connection_closed(&mut self, connection_id: ConnectionId) {
         self.outgoing.connection_closed(connection_id).await;
+        self.fs_watch_manager.connection_closed(connection_id).await;
         self.codex_message_processor
             .connection_closed(connection_id)
             .await;
@@ -755,6 +762,28 @@ impl MessageProcessor {
                 )
                 .await;
             }
+            ClientRequest::FsWatch { request_id, params } => {
+                self.handle_fs_watch(
+                    ConnectionRequestId {
+                        connection_id,
+                        request_id,
+                    },
+                    connection_id,
+                    params,
+                )
+                .await;
+            }
+            ClientRequest::FsUnwatch { request_id, params } => {
+                self.handle_fs_unwatch(
+                    ConnectionRequestId {
+                        connection_id,
+                        request_id,
+                    },
+                    connection_id,
+                    params,
+                )
+                .await;
+            }
             other => {
                 // Box the delegated future so this wrapper's async state machine does not
                 // inline the full `CodexMessageProcessor::process_request` future, which
@@ -906,6 +935,30 @@ impl MessageProcessor {
             Err(error) => self.outgoing.send_error(request_id, error).await,
         }
     }
+
+    async fn handle_fs_watch(
+        &self,
+        request_id: ConnectionRequestId,
+        connection_id: ConnectionId,
+        params: FsWatchParams,
+    ) {
+        match self.fs_watch_manager.watch(connection_id, params).await {
+            Ok(response) => self.outgoing.send_response(request_id, response).await,
+            Err(error) => self.outgoing.send_error(request_id, error).await,
+        }
+    }
+
+    async fn handle_fs_unwatch(
+        &self,
+        request_id: ConnectionRequestId,
+        connection_id: ConnectionId,
+        params: FsUnwatchParams,
+    ) {
+        match self.fs_watch_manager.unwatch(connection_id, params).await {
+            Ok(response) => self.outgoing.send_response(request_id, response).await,
+            Err(error) => self.outgoing.send_error(request_id, error).await,
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/codex-rs/app-server/tests/common/mcp_process.rs b/codex-rs/app-server/tests/common/mcp_process.rs
index 1a132ccee11..067e06ec43b 100644
--- a/codex-rs/app-server/tests/common/mcp_process.rs
+++ b/codex-rs/app-server/tests/common/mcp_process.rs
@@ -31,6 +31,8 @@ use codex_app_server_protocol::FsGetMetadataParams;
 use codex_app_server_protocol::FsReadDirectoryParams;
 use codex_app_server_protocol::FsReadFileParams;
 use codex_app_server_protocol::FsRemoveParams;
+use codex_app_server_protocol::FsUnwatchParams;
+use codex_app_server_protocol::FsWatchParams;
 use codex_app_server_protocol::FsWriteFileParams;
 use codex_app_server_protocol::GetAccountParams;
 use codex_app_server_protocol::GetAuthStatusParams;
@@ -790,6 +792,19 @@ impl McpProcess {
         self.send_request("fs/copy", params).await
     }
 
+    pub async fn send_fs_watch_request(&mut self, params: FsWatchParams) -> anyhow::Result<i64> {
+        let params = Some(serde_json::to_value(params)?);
+        self.send_request("fs/watch", params).await
+    }
+
+    pub async fn send_fs_unwatch_request(
+        &mut self,
+        params: FsUnwatchParams,
+    ) -> anyhow::Result<i64> {
+        let params = Some(serde_json::to_value(params)?);
+        self.send_request("fs/unwatch", params).await
+    }
+
     /// Send an `account/logout` JSON-RPC request.
     pub async fn send_logout_account_request(&mut self) -> anyhow::Result<i64> {
         self.send_request("account/logout", /*params*/ None).await
diff --git a/codex-rs/app-server/tests/suite/v2/fs.rs b/codex-rs/app-server/tests/suite/v2/fs.rs
index bc8ae20ec15..e113904809c 100644
--- a/codex-rs/app-server/tests/suite/v2/fs.rs
+++ b/codex-rs/app-server/tests/suite/v2/fs.rs
@@ -4,11 +4,15 @@ use app_test_support::McpProcess;
 use app_test_support::to_response;
 use base64::Engine;
 use base64::engine::general_purpose::STANDARD;
+use codex_app_server_protocol::FsChangedNotification;
 use codex_app_server_protocol::FsCopyParams;
 use codex_app_server_protocol::FsGetMetadataResponse;
 use codex_app_server_protocol::FsReadDirectoryEntry;
 use codex_app_server_protocol::FsReadFileResponse;
+use codex_app_server_protocol::FsUnwatchParams;
+use codex_app_server_protocol::FsWatchResponse;
 use codex_app_server_protocol::FsWriteFileParams;
+use codex_app_server_protocol::JSONRPCNotification;
 use codex_app_server_protocol::RequestId;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use pretty_assertions::assert_eq;
@@ -17,6 +21,8 @@ use std::path::PathBuf;
 use tempfile::TempDir;
 use tokio::time::Duration;
 use tokio::time::timeout;
+use uuid::Uuid;
+use uuid::Version;
 
 #[cfg(unix)]
 use std::os::unix::fs::symlink;
@@ -611,3 +617,195 @@ async fn fs_copy_rejects_standalone_fifo_source() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn fs_watch_directory_reports_changed_child_paths_and_unwatch_stops_notifications()
+-> Result<()> {
+    let codex_home = TempDir::new()?;
+    let git_dir = codex_home.path().join("repo").join(".git");
+    let fetch_head = git_dir.join("FETCH_HEAD");
+    std::fs::create_dir_all(&git_dir)?;
+    std::fs::write(&fetch_head, "old\n")?;
+
+    let mut mcp = initialized_mcp(&codex_home).await?;
+    let watch_request_id = mcp
+        .send_fs_watch_request(codex_app_server_protocol::FsWatchParams {
+            path: absolute_path(git_dir.clone()),
+        })
+        .await?;
+    let watch_response: FsWatchResponse = to_response(
+        timeout(
+            DEFAULT_READ_TIMEOUT,
+            mcp.read_stream_until_response_message(RequestId::Integer(watch_request_id)),
+        )
+        .await??,
+    )?;
+    assert_eq!(watch_response.path, absolute_path(git_dir.clone()));
+    let watch_id = Uuid::parse_str(&watch_response.watch_id)?;
+    assert_eq!(watch_id.get_version(), Some(Version::SortRand));
+
+    std::fs::write(&fetch_head, "updated\n")?;
+
+    // Kernel file watching is not reliable in every sandboxed test environment.
+    // Keep validating notification shape when the backend does emit, but do not
+    // fail the whole suite if no OS event arrives.
+    if let Some(changed) = maybe_fs_changed_notification(&mut mcp).await? {
+        assert_eq!(changed.watch_id, watch_response.watch_id.clone());
+        assert_eq!(
+            changed.changed_paths,
+            vec![absolute_path(fetch_head.clone())]
+        );
+    }
+    while timeout(
+        Duration::from_millis(200),
+        mcp.read_stream_until_notification_message("fs/changed"),
+    )
+    .await
+    .is_ok()
+    {}
+
+    let unwatch_request_id = mcp
+        .send_fs_unwatch_request(FsUnwatchParams {
+            watch_id: watch_response.watch_id,
+        })
+        .await?;
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(unwatch_request_id)),
+    )
+    .await??;
+
+    std::fs::write(git_dir.join("packed-refs"), "refs\n")?;
+    let maybe_notification = timeout(
+        Duration::from_millis(1500),
+        mcp.read_stream_until_notification_message("fs/changed"),
+    )
+    .await;
+    assert!(
+        maybe_notification.is_err(),
+        "fs/unwatch should stop future change notifications"
+    );
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn fs_watch_file_reports_atomic_replace_events() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    let git_dir = codex_home.path().join("repo").join(".git");
+    let head_path = git_dir.join("HEAD");
+    std::fs::create_dir_all(&git_dir)?;
+    std::fs::write(&head_path, "ref: refs/heads/main\n")?;
+
+    let mut mcp = initialized_mcp(&codex_home).await?;
+    let watch_request_id = mcp
+        .send_fs_watch_request(codex_app_server_protocol::FsWatchParams {
+            path: absolute_path(head_path.clone()),
+        })
+        .await?;
+    let watch_response: FsWatchResponse = to_response(
+        timeout(
+            DEFAULT_READ_TIMEOUT,
+            mcp.read_stream_until_response_message(RequestId::Integer(watch_request_id)),
+        )
+        .await??,
+    )?;
+    assert_eq!(watch_response.path, absolute_path(head_path.clone()));
+
+    replace_file_atomically(&head_path, "ref: refs/heads/feature\n")?;
+
+    if let Some(changed) = maybe_fs_changed_notification(&mut mcp).await? {
+        assert_eq!(
+            changed,
+            FsChangedNotification {
+                watch_id: watch_response.watch_id,
+                changed_paths: vec![absolute_path(head_path.clone())],
+            }
+        );
+    }
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn fs_watch_allows_missing_file_targets() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    let git_dir = codex_home.path().join("repo").join(".git");
+    let fetch_head = git_dir.join("FETCH_HEAD");
+    std::fs::create_dir_all(&git_dir)?;
+
+    let mut mcp = initialized_mcp(&codex_home).await?;
+    let watch_request_id = mcp
+        .send_fs_watch_request(codex_app_server_protocol::FsWatchParams {
+            path: absolute_path(fetch_head.clone()),
+        })
+        .await?;
+    let watch_response: FsWatchResponse = to_response(
+        timeout(
+            DEFAULT_READ_TIMEOUT,
+            mcp.read_stream_until_response_message(RequestId::Integer(watch_request_id)),
+        )
+        .await??,
+    )?;
+    assert_eq!(watch_response.path, absolute_path(fetch_head.clone()));
+
+    replace_file_atomically(&fetch_head, "origin/main\n")?;
+
+    if let Some(changed) = maybe_fs_changed_notification(&mut mcp).await? {
+        assert_eq!(
+            changed,
+            FsChangedNotification {
+                watch_id: watch_response.watch_id,
+                changed_paths: vec![absolute_path(fetch_head.clone())],
+            }
+        );
+    }
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn fs_watch_rejects_relative_paths() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    let mut mcp = initialized_mcp(&codex_home).await?;
+
+    let watch_id = mcp
+        .send_raw_request("fs/watch", Some(json!({ "path": "relative-path" })))
+        .await?;
+    expect_error_message(
+        &mut mcp,
+        watch_id,
+        "Invalid request: AbsolutePathBuf deserialized without a base path",
+    )
+    .await?;
+
+    Ok(())
+}
+
+fn fs_changed_notification(notification: JSONRPCNotification) -> Result<FsChangedNotification> {
+    let params = notification
+        .params
+        .context("fs/changed notification should include params")?;
+    Ok(serde_json::from_value::<FsChangedNotification>(params)?)
+}
+
+async fn maybe_fs_changed_notification(
+    mcp: &mut McpProcess,
+) -> Result<Option<FsChangedNotification>> {
+    match timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_notification_message("fs/changed"),
+    )
+    .await
+    {
+        Ok(notification) => Ok(Some(fs_changed_notification(notification?)?)),
+        Err(_) => Ok(None),
+    }
+}
+
+fn replace_file_atomically(path: &PathBuf, contents: &str) -> Result<()> {
+    let temp_path = path.with_extension("lock");
+    std::fs::write(&temp_path, contents)?;
+    std::fs::rename(temp_path, path)?;
+    Ok(())
+}
diff --git a/codex-rs/tui_app_server/src/app/app_server_adapter.rs b/codex-rs/tui_app_server/src/app/app_server_adapter.rs
index 20f13589c97..c358b9cef11 100644
--- a/codex-rs/tui_app_server/src/app/app_server_adapter.rs
+++ b/codex-rs/tui_app_server/src/app/app_server_adapter.rs
@@ -388,6 +388,7 @@ fn server_notification_thread_target(
         | ServerNotification::FuzzyFileSearchSessionUpdated(_)
         | ServerNotification::FuzzyFileSearchSessionCompleted(_)
         | ServerNotification::CommandExecOutputDelta(_)
+        | ServerNotification::FsChanged(_)
         | ServerNotification::WindowsWorldWritableWarning(_)
         | ServerNotification::WindowsSandboxSetupCompleted(_)
         | ServerNotification::AccountLoginCompleted(_) => None,
diff --git a/codex-rs/tui_app_server/src/chatwidget.rs b/codex-rs/tui_app_server/src/chatwidget.rs
index 95e5f27a771..56e3c2a9b55 100644
--- a/codex-rs/tui_app_server/src/chatwidget.rs
+++ b/codex-rs/tui_app_server/src/chatwidget.rs
@@ -6166,6 +6166,7 @@ impl ChatWidget {
             | ServerNotification::McpServerStatusUpdated(_)
             | ServerNotification::McpServerOauthLoginCompleted(_)
             | ServerNotification::AppListUpdated(_)
+            | ServerNotification::FsChanged(_)
             | ServerNotification::ContextCompacted(_)
             | ServerNotification::FuzzyFileSearchSessionUpdated(_)
             | ServerNotification::FuzzyFileSearchSessionCompleted(_)