Automatic fix and detection of partial installations, option to bundle extra wheels for simpler offline and monorepo builds

[Tremeschin]

Hi, I've got a fork with two interesting features that adds extra safety and flexibility for monorepos and offline installations.

Pardon the length, I like to add reasoning and context!

Partial installation detection

Problem: Whenever pyapp is closed mid-way an installation, the heuristic in ensure_ready() of checking for the existence of !app::install_dir().is_dir() fails to notice this partial installation, and subsequent runs gives module not found (as it's not.. installed). The only way out is doing a self restore or manually deleting the installation path.

While this is trivial for us programmers, giving such instructions to (Windows) users are annoying and error-prone

Solution: A ready.flag file is created in the root of the installation after install_project(), and ensure_ready() logic now checks for its existence before materialize() and creates it after so. The file works like a checkpoint ensuring previous runs reached the end of the installation correctly! :)

^{I'm not sure if this is the best place to put it, maybe calling self restore at the beginning of run_project() which also works, but could break isolation compatibility}

In the same idea, we can save the current binary hash to a file and call self restore if a same-version but different contents release was run (mostly in dev mode), I also have coded it, but within Python this time, and it works perfectly.

Bundling extra wheels

Problem: In a monorepo scenario like mine, I'm having to bundle all sub-projects packages into a monolithic wheel in PYAPP_PROJECT_PATH with [tool.hatch.build.targets.wheel], and defining main-lib[all] dependency to be installed only for executable releases (dynamically editing pyproject.toml pre-build), this is clunky to say the least.

Solution: While the previous works, having an option to bundle multiple local wheels like in PYAPP_PROJECT_PATH="/A.whl;/B.whl;C.whl.." would solve this issue, just list all wheels out of uv build --wheel --all and do a single pip install *.whl in pyapp when bootstrapping the pyapp project.

The implementation I made is slightly different, I added a PYAPP_EXTRA_WHEELS=a;b;c env that gets installed after PYAPP_PROJECT_PATH, mostly due the already implement complexity and assumptions of the later. But I think the current logic could grab the first file of this new proposed semicolon separated PYAPP_PROJECT_PATH as the main file?

The effects and possibilities of this are:

• If we bundle all packages of uv tree, we pretty much created an easier method for making offline distributions
• Simplifies the build process for monorepos substantially, which uv upstreams and promotes it a lot:
  • It now finds all workspace members than listing manually, allowing for private projects as well
  • No need to list main-lib[all], as the subprojects defines optional deps of the bundled main-lib

The important thing is to pip install all bundled wheels in a single go, as individual wheels would look for pypi for deps not already installed! So joining EXTRA_WHEELS and PROJECT_PATH could do it, we don't need to modify PROJECT_PATH, keeping current compatibility of how it works in essence.

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Thanks a lot for the work and attention, I hope you consider adding these mechanisms as they'd help me a lot ✨

You can base-off the work in my proof of concept no problem if you do it!