Fix watch hot-reload WebSocket to use window.location.host instead of hardcoded localhost

The injected WebSocket URI was hardcoded as ws://localhost:<port>/websocket,
which breaks in GitHub Codespaces, behind reverse proxies, and over HTTPS.
Now uses window.location.host (which includes the correct hostname and port)
with the appropriate ws:/wss: protocol to match the page's scheme.

Removes the now-unused port parameter from generateWatchScript.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

RELEASE_NOTES.md

@@ -4,6 +4,7 @@
 
 ### Added
 * Add `--root` option to `fsdocs watch` to override the root URL for generated pages. Useful for serving docs via GitHub Codespaces, reverse proxies, or other remote hosting where `localhost` URLs are inaccessible. E.g. `fsdocs watch --root /` or `fsdocs watch --root https://example.com/docs/`. When not set, defaults to `http://localhost:<port>/` as before. [#924](https://github.com/fsprojects/FSharp.Formatting/issues/924)
+* Fix `fsdocs watch` hot-reload WebSocket to connect using the page's actual host (`window.location.host`) instead of a hardcoded `localhost:<port>`, so hot-reload works correctly in GitHub Codespaces, behind reverse proxies, and over HTTPS. [#924](https://github.com/fsprojects/FSharp.Formatting/issues/924)
 * Search dialog now auto-focuses the search input when opened, clears on close, and can be triggered with `Ctrl+K` / `Cmd+K` in addition to `/`.
 * Add `dotnet fsdocs convert` command to convert a single `.md`, `.fsx`, or `.ipynb` file to HTML (or another output format) without building a full documentation site. [#811](https://github.com/fsprojects/FSharp.Formatting/issues/811)
 * `fsdocs convert` now accepts the input file as a positional argument (e.g. `fsdocs convert notebook.ipynb -o notebook.html`). [#1019](https://github.com/fsprojects/FSharp.Formatting/pull/1019)

src/fsdocs-tool/BuildCommand.fs

@@ -819,11 +819,11 @@ module Serve =
     let refreshEvent = FSharp.Control.Event<string>()
 
     /// generate the script to inject into html to enable hot reload during development
-    let generateWatchScript (port: int) =
-        let tag =
-            """
+    let generateWatchScript () =
+        """
 <script type="text/javascript">
-    var wsUri = "ws://localhost:{{PORT}}/websocket";
+    var wsProtocol = window.location.protocol === "https:" ? "wss:" : "ws:";
+    var wsUri = wsProtocol + "//" + window.location.host + "/websocket";
     function init()
     {
         websocket = new WebSocket(wsUri);
@@ -850,8 +850,6 @@ module Serve =
 </script>
 """
 
-        tag.Replace("{{PORT}}", string<int> port)
-
     let connectedClients = ConcurrentDictionary<WebSocket, unit>()
 
     let socketHandler (webSocket: WebSocket) (context: HttpContext) =
@@ -1879,7 +1877,7 @@ type CoreBuildOptions(watch) =
         let getLatestWatchScript () =
             if watch then
                 // if running in watch mode, inject hot reload script
-                [ ParamKeys.``fsdocs-watch-script``, Serve.generateWatchScript this.port_option ]
+                [ ParamKeys.``fsdocs-watch-script``, Serve.generateWatchScript () ]
             else
                 // otherwise, inject empty replacement string
                 [ ParamKeys.``fsdocs-watch-script``, "" ]