Build: Disable yarn npmMinimalAgeGate inside sandboxes

[valentinpalkovic]

Summary

Yarn 4.15.0 enables npmMinimalAgeGate: 1d by default (yarnpkg/berry#7135), which quarantines freshly-published packages from the local Verdaccio registry and breaks every sandbox build on next:

SB_CLI_0002 (MinimumReleaseAgeHandledError): yarn blocked package installation
because your project uses npmMinimalAgeGate.

Failed package: create-storybook@10.5.0-alpha.0

This PR is a minimal, fast-track unblock for the team: set npmMinimalAgeGate 0 in the sandbox yarn config (scripts/utils/yarn.ts → installYarn2) so freshly-published packages from the local Verdaccio registry aren't quarantined.

A follow-up PR (#34842) replaces this with the proper preapproval-based approach (7-day gate for unknown third-party packages, monorepo + satellite packages preapproved). This PR exists so we can ship the unblock immediately without waiting for that one to go green.

Test plan

• CI sandbox creation succeeds on previously-failing templates (e.g. lit-vite/default-ts)
• Locally: yarn task sandbox --template react-vite/default-ts --start-from auto completes without YN0016

Summary by CodeRabbit

• Chores
  • Updated Yarn configuration to improve installation compatibility and stability.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 3081a879-7f0d-4a95-85bc-1a7434a8c6d5

📥 Commits

Reviewing files that changed from the base of the PR and between b15652a and da37018.

📒 Files selected for processing (1)

• scripts/utils/yarn.ts

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📝 Walkthrough

Walkthrough

This PR modifies scripts/utils/yarn.ts to configure Yarn Berry's npmMinimalAgeGate setting. The installYarn2 function now explicitly sets npmMinimalAgeGate 0 before running the Yarn installation command, disabling the default npm minimal age gate quarantine behavior for freshly published packages in Storybook sandboxes.

Changes

Yarn Configuration

Layer / File(s)	Summary
Yarn npmMinimalAgeGate configuration scripts/utils/yarn.ts	installYarn2 adds yarn config set npmMinimalAgeGate 0 with inline documentation explaining it disables npm package age gating in Yarn 4.15.0 for sandbox environments.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• storybookjs/storybook#32551: Modifies the same installYarn2 function in scripts/utils/yarn.ts to address npm package availability issues in Storybook sandboxes (removes .yarnrc.yml file).

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[storybook-app-bot]

Package Benchmarks

^{Commit: da37018, ran on 21 May 2026 at 14:26:08 UTC}

The following packages have significant changes to their size or dependencies:

storybook

	Before	After	Difference
Dependency count	72	72	0
Self size	20.25 MB	20.30 MB	🚨 +50 KB 🚨
Dependency size	36.17 MB	36.17 MB	0 B
Bundle Size Analyzer	Link	Link

@storybook/cli

	Before	After	Difference
Dependency count	203	203	0
Self size	908 KB	908 KB	🎉 -931 B 🎉
Dependency size	87.56 MB	87.61 MB	🚨 +50 KB 🚨
Bundle Size Analyzer	Link	Link

@storybook/codemod

	Before	After	Difference
Dependency count	196	196	0
Self size	32 KB	32 KB	🚨 +36 B 🚨
Dependency size	86.05 MB	86.10 MB	🚨 +50 KB 🚨
Bundle Size Analyzer	Link	Link

create-storybook

	Before	After	Difference
Dependency count	73	73	0
Self size	1.08 MB	1.08 MB	🎉 -222 B 🎉
Dependency size	56.43 MB	56.48 MB	🚨 +50 KB 🚨
Bundle Size Analyzer	node	node