🐛 Bug - Tina-docs cannot load Tina admin assets when served from sub-route

[ssw-yakshaver]

Requested by: @isaaclombardssw via YakShaver.ai 🦬
cc: @isaaclombardssw, @Marxoz, @joshbermanssw

Hi Team!

  🟥  Watch the video (1 min 4 sec)

  Url from screen share: https://tina.io/tinadocs/admin

Pain

Editing content on the live Tina-docs site is broken when Tina is served from an admin sub-route. The Tina admin UI attempts to load assets from an incorrect path (tina.io admin assets) instead of the Tina-docs sub-route, likely due to an extra or misconfigured slash in the asset path configuration. As a result, the editor cannot load and content cannot be edited on the live site.

Acceptance Criteria

1. Tina admin loads successfully when Tina-docs is served from a sub-route (e.g., /admin).
2. All Tina admin assets are requested from the Tina-docs sub-route and not from tina.io.
3. No 404 or asset-related errors appear in the browser console when opening the Tina admin.
4. Content can be edited and saved successfully on the live Tina-docs site.
5. Asset path configuration works consistently across environments (local, staging, live).

Reproduce Steps

1. Open the live Tina-docs site.
2. Navigate to the Tina admin interface served from a sub-route (e.g., /admin).
3. Open the browser developer console.
4. Observe failed network requests for Tina admin assets.
5. Note that assets are requested from tina.io instead of the Tina-docs sub-route.
6. Attempt to edit any content and observe that the editor does not function.

Screenshot

Figure: Admin assets resolving to wrong domain, breaking live editing

[isaaclombardssw]

Partially fixed – now works on staging but still not on Tina.io rewrite.

Plan: Copy what SSW Rules is doing.

[isaaclombardssw]

Partially fixed in tinacms/tina.io#4333

[isaaclombardssw]

I've realised this is as Tina in both TinaDocs and the TinaDocs landing page is being linked to tina.io/tinadocs – so only one can be linked at a time. This is TinaDocs landing for the moment.