Telemetry: Fix prompting without checking isTTY

[Synar]

What I did

Most modules check both process.env.CI as well as process.env.stdout.isTTY before prompting the user. Telemetry was only checking process.env.CI.

This caused builds in non interactive environments to fail with a success code.

This commit aligns the check with the rest of storybook.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

• Put yourself in a configuration that will make building storybook fail. In our case, this was due to a storybook sub package version not being aligned with the main storybook version in our package.json
• Build storybook using npm in a docker container without the option CI=true
• Without this PR, the build should succeed, despite the build actually failing
• With this PR, the build will properly fail

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

Greptile Summary

Fixes telemetry prompting behavior by adding a process.stdout.isTTY check, preventing silent build failures in non-interactive environments like Docker containers without CI=true set.

• Added TTY check in code/core/src/core-server/withTelemetry.ts to align with other Storybook modules
• Fixed typo in SIGINT event listener removal (currently 'SIGINIT')
• Important for builds where package versions are misaligned, as it properly surfaces build failures
• Critical fix for Docker and other non-interactive environments where builds could silently fail
• Needs additional telemetry-specific unit tests to verify the new behavior

[greptile-apps]

LGTM

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[Synar]

Fixed typo in SIGINT event listener removal (currently 'SIGINIT')

This comment made it sound like it was already done, but it was not. I've now added the typo fix as requested though.

[emersion]

Thanks for fixing this! LGTM.

[shilman]

Thanks so much for the fix. Much appreciated! 🙏

[storybook-app-bot]

Package Benchmarks

^{Commit: 9e15711, ran on 17 June 2025 at 18:37:11 UTC}

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

@storybook/nextjs

	Before	After	Difference
Dependency count	531	531	0
Self size	902 KB	217 KB	🎉 -686 KB 🎉
Dependency size	58.92 MB	58.92 MB	🎉 -172 B 🎉
Bundle Size Analyzer	Link	Link

@storybook/nextjs-vite

	Before	After	Difference
Dependency count	131	131	0
Self size	3.07 MB	2.39 MB	🎉 -685 KB 🎉
Dependency size	22.30 MB	22.30 MB	🎉 -500 B 🎉
Bundle Size Analyzer	Link	Link