Steam Workshop Collection Helper

When a Steam collection exceeds 1 000 items, the user interface often breaks, locks up, or fails to display additional items. This extension allows you to safely split your mods into multi-part collections (e.g. Part 1 and Part 2) without needing to unsubscribe, preserving your local mod load orders and gigabytes of local files.

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🔍 Problem

1. Steam's "Add to Collection" edit screen only displays and properply handles up to 1,000 subscribed mods. If you have 1200 mods, the last 200 are may appear invisible or/and cursed in the editor, making it incredibly infuriating to find and isolate them for a simple backup;
2. The common workaround of "unsubscribing from the first 1.000" forces Steam to delete local files, ruining custom load orders, game configurations, and forcing massive, time-consuming redownloads.

💡 Solution

This extension solves both issues purely on the client side:

• It traverses your paginated subscriptions page in the background using your active browser session;
• It fetches and parses your existing 1,000-item collection to pinpoint exactly which mods are missing;
• It keeps you subscribed throughout the entire process, meaning your local files and game configuration remain completely untouched;
• It interfaces with Steam's native endpoints to queue and batch-add only the identified missing items to your secondary backup collection. Aint it cool?

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HOW TO INSTALL

Because this is a personal-use utility i AI-slopped under 5 minutes, you cant really install it from the Web Store (only if its gonna end up really popular request, until dat imma too lazy hehehe)

Instead, load it directly as an "unpacked developer extension":

1. Download this repository code (Releases -> Assets -> Source code) or git clone it to your local machine;

   1.1. If its appeared as archive - unpack it somewhere and copy the path;

2. Open your Chromium-based browser (Chrome, Edge, Brave, etc.) and navigate to da extensions manager:

   • Chrome/Brave: chrome://extensions
   • Edge: edge://extensions
   • Yandex: browser://extensions
   • etc.

3. Toggle the "Developer mode" or smth most similar switch in the top-right corner;

4. Click "Load unpacked" or smth most similar in the top-left corner;

5. Enter the path to da extension;

6. Click the extension puzzle piece icon in your toolbar and pin the Steam Collection Helper. Done!

📖 HOW TO USE

Step 1: Find and Export the Missing Mods

1. Open your web browser and go to your game's Subscribed Items page on Steam.
   • expected URL format: https://steamcommunity.com/id/YOUR_PROFILE/myworkshopfiles/?appid=XXXXXX&browsefilter=mysubscriptions
2. Click the extension icon and select "1. Find Missing Items".
3. When prompted, paste the URL of your existing 1000-item collection.
4. The extension will crawl your subscription pages, compare them, download a missing_workshop_mods.txt file, and cache the remaining item IDs internally.

Step 2: Batch-Add to your Part 2 Collection

1. Create your new secondary collection on Steam (e.g., "My Mods - Part 2").
2. Go to its "Add / Edit Child Items" page, and make sure you are on the "Subscribed Items" tab.
3. Click the extension icon and select "2. Add Missing to Part 2".
4. Confirm the prompt. The script will automatically add only the remaining cached IDs to your new collection.
5. Once the process completes, refresh the page. And congrats!

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🛠️ Features

• No local file deletions or redownloads;
• Compares total active subscriptions against any specified Steam collection;
• Passes data between Steam sub-domains safely using localStorage under the same-origin policy;
• Automatically downloads a missing_workshop_mods.txt list of direct URLs for external backup;
• Includes safety delays between page fetches to respect Steam's server rate limits;
• Should be Millennium's mode Extendium compatible, so u can do all that right in the Steam client by producing pretty much same installation steps;

Bugs / Doesnt work / Suggestions

Feel free to visit Github Issues tab above and ur thoughts, i will look thro when got spare minute

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