fix: disable packages cache when local wheels are detected

[Archmonger]

Description

Fixespyscript/pyscript#2282

When local .whl files are specified in the packages list, their dependencies fail to resolve on subsequent page loads because micropip.freeze() stores stale absolute or virtual filesystem references in IndexedDB. On the next page load, the frozen lockfile is restored instead of running micropip.install(), causing ModuleNotFoundError for the wheel's dependencies.

This is somewhat of a band-aid fix, based on the following response:

There are cache cases we were hoping to easily control out of the micropip box but if we need to orchestrate anything "that convoluted" you are actually better off without the cache because nothing else would be necessarily faster but it's something to consider/think about sooner than later.

Solution

This change automatically sets packages_cache to 'never' when local wheels are detected in the packages array. Local wheels are identified by:

• Paths starting with ./, ../, /, emfs://, file://
• URLs ending with .whl

Users can still explicitly opt into caching with packages_cache = "all".

Related

• Issue: Configuring "packages" to a local wheel causes dependency resolution failure pyscript#2282
• Previous partial fix: V0.6.x micropip often fails to discover package pyscript#2228

[WebReflection]

I think we should freeze the VFS into IndexedDB instead of using micropip because this problem has been coming up so many times already ... but this seems sensible, will have a look but I am on vacation right now, not sure if I'll manage before the 27th 'cause it needs a release via PyScript.

[Archmonger]

Agreed. I'm considering this a band-aid fix while the team decides the best direction to solve this. This isn't ideal but at least prevents unexpected broken functionality (from a user-perspective). I would assume this is worthy of creating a follow-up issue ticket to track and discuss future plans.

[WebReflection]

@Archmonger this is up and running but not published yet as PyScript ... which is coming next