Core: Ensure process termination on SIGINT when telemetry is disabled

[ghengeveld]

What I did

Storybook was leaving behind lingering Node.js processes after being terminated, but only when telemetry was disabled. This PR fixes that bug.

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

Start Storybook with telemetry disabled. Kill it (Cmd+C), then use Activity Monitor to verify no node processes are left behind.

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 publish.yml --field pr=<PR_NUMBER>

Summary by CodeRabbit

• Bug Fixes
  • Improved development server shutdown reliability to ensure proper termination regardless of telemetry module state.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 1d5f0b7

Command	Status	Duration	Result
nx run-many -t compile,check,knip,test,lint,fmt...	✅ Succeeded	11m 56s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-04-17 10:06:20 UTC

[Copilot]

Pull request overview

Fixes a dev-server shutdown bug where Storybook could leave the Node.js process running after SIGINT/SIGTERM when telemetry is disabled, by ensuring the signal handler always terminates the process.

Changes:

• Refactors the cancelTelemetry signal handler so process.exit(0) runs in a finally block.
• Keeps sending the canceled telemetry event (with story index/stats) when telemetry is enabled, but still exits when it’s disabled.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[coderabbitai]

📝 Walkthrough

Walkthrough

The cancelTelemetry signal handler in the dev server was restructured to guarantee process termination by moving process.exit(0) into a finally block, ensuring exit occurs regardless of telemetry module state.

Changes

Cohort / File(s)	Summary
Signal Handler Restructuring code/core/src/core-server/dev-server.ts	Modified cancelTelemetry signal handler to relocate telemetry payload construction to execute only when telemetry is enabled, move cancellation logic inside the enabled branch, and guarantee process termination via finally block regardless of telemetry module state.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

---

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

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@code/core/src/core-server/dev-server.ts`:
- Around line 211-223: The signal shutdown currently awaits potentially-hung
operations (storyIndexGeneratorPromise / generator.getIndexAndStats() and
telemetry(...)), so change both awaits to bounded best-effort waits: wrap
awaiting storyIndexGeneratorPromise and generator.getIndexAndStats() in a
Promise.race with a small timeout (e.g., 200–500ms) so missing index data is
skipped if slow, and call telemetry('canceled', payload, { immediate: true })
via a Promise.race with a short timeout (or fire-and-forget while still
attempting a short await) to ensure the signal handler does not block
indefinitely; update references to storyIndexGeneratorPromise, getIndexAndStats,
summarizeIndex, and telemetry accordingly.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: f0a0e4cb-9196-437b-a684-4289bc756925

📥 Commits

Reviewing files that changed from the base of the PR and between 09fb0ba and 1d5f0b7.

📒 Files selected for processing (1)

• code/core/src/core-server/dev-server.ts