Fix deep link installation for mods containing + (plus sign)

[mfishma]

Fixes #6295

Summary

I was having issues where deeplinks to projects that have + in the name (like modrinth://mod/vb+) were breaking the app. It was a problem because that's the best way to have an app load an Unlisted project. The other option being the ID, but that wasn't safe to have people trust this random string of characters.

As is usually the case with "+", there was a problem with URL-encoding. The app wasn't encoding the + sign before asking the API for the mod data. So then the backend thinks the + is a space (it searches for "vb " instead of "vb+".) Since the mod with a space at the end doesn't exist, it returned nothing, and the app threw a cryptic project_type-is-null error.

Changes

1. cache.rs Updated the URL builder to use url::form_urlencoded::byte_serialize(). This encodes the project ID (per RFC 3986) so the + actually makes it to the server correctly.
2. content-install.ts I added a quick safety check. If a project fails to load (like if the link is a typo or missing), it now just shows a normal "Project not found" error instead of breaking the UI. And I put quotes around the ID in the error message so it's easier to spot accidental trailing spaces later.

Testing

I tested using a minimal Rust harness to verify the API responses directly:
https://api.modrinth.com/v2/projects?ids=%5B%22vb%2B%22%5D → returns all the project metadata for ViaBackwards Plus ("slug":"vb+")
https://api.modrinth.com/v2/projects?ids=%5B%22vb%2B%22%2C%22fabric-api%22%2C%22sodium%22%5D returns all the project metadata for 3 projects
https://api.modrinth.com/v2/projects?ids=["vb+"] → returns empty string []
https://api.modrinth.com/v2/projects?ids=["vb+","fabric-api","sodium"] → partial failure, still returns the last two.

Hope this helps! Let me know if you need me to change anything.

[modrinth-bot]

Note

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Pull request changelog

App

Added

Changed

Deprecated

Removed

Fixed

• Fixed deeplink issues for slugs containing + characters.

Security

Website

Added

Changed

Deprecated

Removed

Fixed

Security

Hosting

Added

Changed

Deprecated

Removed

Fixed

Security