docs: add js-dos player for Windows 3.x / 9x

docs/Navigation.md

@@ -50,6 +50,7 @@ search:
     - [Uploads](using/uploads.md)
     - In-Browser Play
         - [EmulatorJS](using/in-browser-play/emulatorjs.md)
+        - [`js-dos`](using/in-browser-play/js-dos.md)
         - [MS-DOS](using/in-browser-play/ms-dos.md)
         - [Ruffle](using/in-browser-play/ruffle.md)
     - [Emulator Streaming](using/emulator-streaming.md)

docs/about/credits.md

@@ -35,6 +35,8 @@ This stack stands on an enormous amount of open-source work. In rough order of "
 ### In-browser emulation
 
 - [EmulatorJS](https://emulatorjs.org/)
+- [`js-dos`](https://js-dos.com/)
+- [DOSBox-X](https://dosbox-x.com/)
 - [Ruffle](https://ruffle.rs/)
 - [dosbox-pure](https://github.com/schellingb/dosbox-pure)
 

docs/about/license.md

@@ -34,7 +34,7 @@ Companion repos use more permissive licenses AGPLv3 or MIT because they're small
 
 ## Third-party components
 
-Several third-party components ship with their own licenses: [EmulatorJS](https://emulatorjs.org/), [Ruffle](https://ruffle.rs/), Vue, FastAPI, and a long list of smaller dependencies. Their licenses apply to their respective code, and none of them override AGPLv3 on the RomM code itself. View the full list via `uv tree` in the backend and `npm ls` in the frontend. Redistribution respects each upstream's terms.
+Several third-party components ship with their own licenses: [EmulatorJS](https://emulatorjs.org/), [`js-dos`](https://js-dos.com/), [Ruffle](https://ruffle.rs/), Vue, FastAPI, and a long list of smaller dependencies. Their licenses apply to their respective code, and none of them override AGPLv3 on the RomM code itself. View the full list via `uv tree` in the backend and `npm ls` in the frontend. Redistribution respects each upstream's terms.
 
 ## FAQ
 

docs/install/image-variants.md

@@ -5,12 +5,12 @@ description: Choose between the slim and full container images
 
 # Image Variants
 
-RomM publishes two production image variants. They're interchangeable at the config level, so pick based on whether you want baked-in EmulatorJS cores or fetch them from the CDN at runtime.
+RomM publishes two production image variants. They're interchangeable at the config level, so pick based on whether you want the browser emulator runtimes baked into the image or fetched from a CDN at runtime.
 
-| Variant            | Tag                                           | Approx size | When to pick                                                                             |
-| ------------------ | --------------------------------------------- | ----------- | ---------------------------------------------------------------------------------------- |
-| **Full** (default) | `rommapp/romm:latest` `rommapp/romm:5.0.0`    | ~400MB      | You want in-browser play (most users pick this).                                         |
-| **Slim**           | `rommapp/romm:slim` `rommapp/romm:5.0.0-slim` | ~100MB      | Headless use (API + native-app clients only) or when you're running emulators elsewhere. |
+| Variant            | Tag                                           | Approx size | When to pick                                                                         |
+| ------------------ | --------------------------------------------- | ----------- | ------------------------------------------------------------------------------------ |
+| **Full** (default) | `rommapp/romm:latest` `rommapp/romm:5.0.0`    | ~400MB      | You want in-browser play with every runtime baked in (most users pick this).         |
+| **Slim**           | `rommapp/romm:slim` `rommapp/romm:5.0.0-slim` | ~100MB      | Headless use, or you're fine fetching EmulatorJS and `js-dos` from a CDN at runtime. |
 
 Both variants are published on Docker Hub (`docker.io/rommapp/romm`) and GitHub Container Registry (`ghcr.io/rommapp/romm`). The GHCR images track the same tags and are a good choice if you run into Docker Hub's rate limits.
 

docs/platforms/index.md

@@ -10,6 +10,6 @@ description: Everything about the supported platforms
 
 ## Related sections
 
-- **[In-Browser Play](../using/in-browser-play/emulatorjs.md)**: the end-user side of EmulatorJS + Ruffle
+- **[In-Browser Play](../using/in-browser-play/emulatorjs.md)**: the end-user side of EmulatorJS, `js-dos`, and Ruffle
 - **[Metadata Providers](../getting-started/metadata-providers.md)**
 - **[Folder Structure](../getting-started/folder-structure.md)**

docs/resources/snippets/env-vars.md

@@ -127,10 +127,11 @@
 
 ### Emulation
 
-| Variable              | Default | Required | Description                                    |
-| --------------------- | ------- | :------: | ---------------------------------------------- |
-| `DISABLE_EMULATOR_JS` | `false` |          | Disable in-browser play via EmulatorJS         |
-| `DISABLE_RUFFLE_RS`   | `false` |          | Disable in-browser Flash playback via RuffleRS |
+| Variable              | Default | Required | Description                                                 |
+| --------------------- | ------- | :------: | ----------------------------------------------------------- |
+| `DISABLE_EMULATOR_JS` | `false` |          | Disable in-browser play via EmulatorJS                      |
+| `DISABLE_RUFFLE_RS`   | `false` |          | Disable in-browser Flash playback via RuffleRS              |
+| `DISABLE_JSDOS`       | `false` |          | Disable in-browser Windows 3.x and 9x playback via `js-dos` |
 
 ### Integrations
 

docs/using/in-browser-play/js-dos.md

@@ -0,0 +1,61 @@
+---
+title: js-dos
+description: Play Windows 3.x and 9x games in the browser via DOSBox-X
+---
+
+# `js-dos`
+
+[`js-dos`](https://js-dos.com/) runs DOSBox-X in the browser for Windows 3.x (`win3x`) and Windows 9x (`win9x`) titles. MS-DOS games continue to use the [EmulatorJS `dosbox-pure` core](ms-dos.md).
+
+<!-- prettier-ignore -->
+!!! info "Bundled in the full image, fetched from a CDN in slim"
+    The full container image ships the `js-dos` runtime locally. The slim image has no local copy, so the player falls back to jsDelivr at runtime and needs outbound internet access from the browser (see [Image Variants](../../install/image-variants.md)).
+
+<!-- prettier-ignore -->
+!!! warning "`js-dos` requires HTTPS"
+    DOSBox-X uses the `SharedArrayBuffer` API, which browsers only expose in secure, cross-origin-isolated contexts, so RomM must be served over `https://` for these games to run. Use a [reverse proxy with TLS](../../install/reverse-proxy.md) if you're still on plain HTTP.
+
+Operators can turn the player off with `DISABLE_JSDOS=true` (see [Environment Variables](../../reference/environment-variables.md)).
+
+## Bundling a game
+
+RomM passes the selected file directly to `js-dos`, so upload a ready-to-run [`js-dos` bundle](https://js-dos.com/jsdos-bundle.html), not a regular zip of loose game files. The bundle is a zip archive carrying a `.jsdos/dosbox.conf`, and RomM only offers the player for files with a `.jsdos` extension, so rename the archive before uploading:
+
+```text
+game.jsdos
+    .jsdos/
+        dosbox.conf
+    WINDOWS/
+    ...game files
+```
+
+<!-- prettier-ignore -->
+!!! important "The file extension must be `.jsdos`"
+    A bundle left as `game.zip` scans in fine but never gets a Play button, because RomM gates the `js-dos` player on the file extension.
+
+The configuration controls how the bundle boots. For example, a Windows 3.x bundle with Windows installed in the bundle root can use:
+
+```ini
+[dosbox]
+machine=svga_s3
+memsize=32
+
+[autoexec]
+@echo off
+mount c .
+c:
+WIN GAMEDIR\GAME
+```
+
+- `mount c .` mounts the bundle root as `C:`. `js-dos` does not add this mount automatically.
+- `WIN GAMEDIR\GAME` boots Windows straight into the game instead of Program Manager.
+
+Windows 9x and disk-image layouts need different DOSBox-X configuration. Use the [`js-dos` bundle cookbook](https://js-dos.com/jsdos-bundle.html) or [`js-dos` Game Studio](https://v8.js-dos.com/studio/), its browser-based bundle builder. Upload the result under the `win3x` or `win9x` platform. RomM uses `js-dos` only for those platforms and leaves `dos` with EmulatorJS.
+
+## Saves
+
+`js-dos` stores filesystem changes in the browser, isolated by RomM user and game. They are not uploaded or synced with RomM. Quitting the player writes a final save, so wait for it to finish rather than closing the tab mid-game.
+
+<!-- prettier-ignore -->
+!!! warning "Saving depends on the application"
+    Some applications save only when you exit back to Windows. Exit the application before quitting the player.

docs/using/in-browser-play/ms-dos.md

@@ -9,6 +9,10 @@ description: Run DOS games in the browser via dosbox-pure
 
 DOS games run via the `dosbox-pure` core (part of [EmulatorJS](emulatorjs.md)). Create a DOS platform (folder named `dos`) and drop your games in. Operator tuning lives in [Configuration File → `emulatorjs`](../../reference/configuration-file.md#emulatorjs) (notably `disable_batch_bootup` for DOS-specific issues).
 
+<!-- prettier-ignore -->
+!!! info "Windows 3.x and 9x games use `js-dos`"
+    RomM keeps DOS games on `dosbox-pure` and routes Windows 3.x and 9x titles through the [`js-dos` player](js-dos.md). Put those titles under the `win3x` and `win9x` platform folders instead of `dos`.
+
 <!-- prettier-ignore -->
 !!! tip "Upload games as `.zip`"
     `dosbox-pure` knows how to unzip and auto-mount zipped DOS games, which is much easier than packaging a raw folder.

docs/using/index.md

@@ -9,6 +9,7 @@ description: Browse, play, collect, patch, and share from the UI
 
 - **[EmulatorJS](in-browser-play/emulatorjs.md)**
     - **[MS-DOS](in-browser-play/ms-dos.md)**
+- **[`js-dos`](in-browser-play/js-dos.md)**
 - **[Ruffle](in-browser-play/ruffle.md)**
 - **[Emulator Streaming](emulator-streaming.md)**
 - **[Downloads](downloads.md)**