feat: would like a way to differentiate "app" vs "library" within pubspec.yaml

[eseidel]

App's vs. libraries have different expected usage of Pub.

For example, Apps should have a pubspec.lock, libraries typically should not.

Perhaps we should have a way to specify with pubspec.yaml if a package is a "library" vs. an "app" and then allow pub and other commands to have different behavior (e.g. warning if you do/don't have a pubspec.lock, or allowing specifying a strict version version for Flutter, etc.)

Something like this could be a solution to flutter/flutter#95472.

I discussed this in part in person with @mit-mit and @sethladd at I/O. My understanding is that Michael may have an in-progress doc. I'm filing this so we don't forget to follow-up.

[mit-mit]

I sync'ed with the pub team, and they are planning on spending some time on thinking about this later in q2 (cc @sigurdm @szakarias)

[sigurdm]

I think we will fix the flutter version bound issue more directly, but having a way of characterizing the package's intended usage is something we have discussed before.

There are several categories:

• app (never consumed except as a root package)
• library (contains stuff in lib/ that can be consumed by dependees in their lib/, we might need another word, as "library" already has a meaning in dart)
• dev_library (contains code in lib/ that can be consumed by dependees in their test/ and tool/) usually goes in dev-dependencies
• tool (contains executables in bin/)
• global_tool (same as tool, but designed for a global activation. Do we need this?)

A single package can be in multiple categories.

pub add could default to adding dev_library and tool to dev_dependencies.