[Bug]: `npmMinimalAgeGate` feature install pre-release versions of packages

[RichardCPoint]

Self-service

• I'd be willing to implement a fix

Describe the bug

The npmMinimalAgeGate feature was introduced in this PR, to block the installation of package versions that were only recently published to NPM:

• feat: implement npmMinimalAgeGate and npmPreapprovedPackages config options #6901

When installing or updating dependencies, ideally this should choose the newest compatible version that is older than the age gate, but excluding pre-release versions of the package (as is the usual behavior when using fuzzy version matching).

Instead, the newest version is installed, even if that is a pre-release version.

To reproduce

package.json

{
  "name": "test-yarn-npmMinimalAgeGate",
  "packageManager": "yarn@4.10.2"
}

.yarnrc.yml

npmMinimalAgeGate: 72000 # 50 days in minutes - adjust so cutoff date is 2025-07-31

Then install a package with plenty of pre-release versions:

yarn add @typespec/compiler

Observe that package.json is now updated to:

{
  "name": "test-yarn-npmMinimalAgeGate",
  "packageManager": "yarn@4.10.2",
  "dependencies": {
    "@typespec/compiler": "^1.3.0-dev.10"
  }
}

In this case, because version 1.3.0 would be too new (published 2025-08-07), yarn should have chosen version 1.2.1 instead (published 2025-07-15), but instead chose a pre-release version (published 2025-07-30).

Environment

System:
    OS: macOS 14.7.8
    CPU: (10) arm64 Apple M1 Pro
  Binaries:
    Node: 23.7.0 - /private/var/folders/g8/q_gt51tn1q35j19j5t87wm7r0000gp/T/xfs-13b8b091/node
    Yarn: 4.10.2 - /private/var/folders/g8/q_gt51tn1q35j19j5t87wm7r0000gp/T/xfs-13b8b091/yarn
    npm: 10.9.2 - /opt/homebrew/bin/npm

Additional context

No response