diff --git a/package.json b/package.json
index e14550bf16..dd49c3a007 100644
--- a/package.json
+++ b/package.json
@@ -120,6 +120,7 @@
     "@types/throttle-debounce": "^5.0.2",
     "@types/tinycolor2": "^1.4.5",
     "@types/turndown": "^5.0.1",
+    "@types/winchan": "^0.2.0",
     "@typescript-eslint/eslint-plugin": "^8.2.0",
     "@typescript-eslint/parser": "^8.2.0",
     "babel-plugin-istanbul": "^7.0.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 576e9c0ec6..b198535ab1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -377,6 +377,9 @@ importers:
       '@types/turndown':
         specifier: ^5.0.1
         version: 5.0.5
+      '@types/winchan':
+        specifier: ^0.2.0
+        version: 0.2.0
       '@typescript-eslint/eslint-plugin':
         specifier: ^8.2.0
         version: 8.32.0(@typescript-eslint/parser@8.32.0(eslint@9.26.0(jiti@1.21.7))(typescript@5.8.3))(eslint@9.26.0(jiti@1.21.7))(typescript@5.8.3)
@@ -2810,6 +2813,9 @@ packages:
   '@types/unist@3.0.3':
     resolution: {integrity: sha512-ko/gIFJRv177XgZsZcBwnqJN5x/Gien8qNOn0D5bQU/zAzVf9Zt3BlcUiLqhV9y4ARk0GbT3tnUiPNgnTXzc/Q==}
 
+  '@types/winchan@0.2.0':
+    resolution: {integrity: sha512-1NyyjFkmpFf9T5hpyB1KgS4kljPwy45nxaq/I6CndEU2kw6BpxzFIAa0SXs620EtnEsvkFljquX+yRdlLxqDkA==}
+
   '@types/ws@8.18.1':
     resolution: {integrity: sha512-ThVF6DCVhA8kUGy+aazFQ4kXQ7E1Ty7A3ypFOe0IcJV8O/M511G99AW24irKrW56Wt44yG9+ij8FaqoBGkuBXg==}
 
@@ -12190,6 +12196,8 @@ snapshots:
 
   '@types/unist@3.0.3': {}
 
+  '@types/winchan@0.2.0': {}
+
   '@types/ws@8.18.1':
     dependencies:
       '@types/node': 22.15.6
diff --git a/version.py b/version.py
index 1230d435c7..1fe8743b08 100644
--- a/version.py
+++ b/version.py
@@ -49,4 +49,4 @@ API_FEATURE_LEVEL = 390
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = (326, 6)  # bumped 2025-05-20 to add pydantic-partials
+PROVISION_VERSION = (326, 7)  # bumped 2025-05-23 to add @types/winchan
diff --git a/web/src/types/winchan.d.ts b/web/src/types/winchan.d.ts
deleted file mode 100644
index c6cda08d7b..0000000000
--- a/web/src/types/winchan.d.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-// Types for https://www.npmjs.com/package/winchan
-
-/**
- * Opens a window and initiates a cross-domain request. Call this from the
- * "untrusted" or "client" site.
- *
- * @param options - Options for `open`
- * @param responseCallback - Called when the request completes with a response
- * or an error
- */
-export function open(
-    options: {
-        /**
-         * URL of the "trusted" window
-         */
-        url: string;
-        /**
-         * URL of the `relay.html` iframe (used for Internet Explorer support)
-         */
-        relay_url: string;
-        /**
-         * Target name passed to `window.open`
-         */
-        window_name?: string | undefined;
-        /**
-         * Comma-separated features passed to `window.open`
-         */
-        window_features?: string | undefined;
-        /**
-         * Application-defined parameters for the request
-         */
-        params?: unknown;
-    },
-    responseCallback: (err: string | null, response?: unknown) => void,
-): {
-    /**
-     * Closes the window.
-     */
-    close: () => void;
-    /**
-     * Tries to move the focus to the window.
-     */
-    focus: () => void;
-};
-
-/**
- * Listens for a request. Call this from the "trusted" site providing the
- * window.
- *
- * @param requestCallback - Called to initiate the request
- */
-export function onOpen(
-    requestCallback: (
-        origin: string,
-        params: unknown,
-        sendResponse: (response: unknown) => void,
-    ) => void,
-): {
-    /**
-     * Detaches the channel without sending a response yet. Call this before
-     * navigating to another page in a multi-page dialog.
-     */
-    detach: () => void;
-};