Telemetry: Improve dev cancellation handling

[shilman]

Closes N/A

What I did

Fix for #32168. The previous PR works when you run the process directly in node and cancel out with the keyboard. However, when you run through an outer process like nr storybook it does not get the SIGINT signal. This attempts to fix that case.

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

1. Install the canary in a project
2. Run it with STORYBOOK_TELEMETRY_DEBUG=1 nr storybook
3. Kill it with ctrl-C and verify that the canceled event is sent.

⚠️ NOTE: this does not fix the problem. But it hopefully fixes other related issues.

🦋 Canary release

This pull request has been released as version 0.0.0-pr-32218-sha-525e5323. Try it out in a new sandbox by running npx [email protected] sandbox or in an existing project with npx [email protected] upgrade.

More information

Published version	0.0.0-pr-32218-sha-525e5323
Triggered by	@shilman
Repository	storybookjs/storybook
Branch	shilman/fix-cancel-telemetry
Commit	525e5323
Datetime	Fri Aug 8 02:07:25 UTC 2025 (1754618845)
Workflow run	16820177616

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=32218

Greptile Summary

This PR adds SIGTERM signal handling to improve telemetry cancellation when Storybook is terminated through wrapper processes. The change is minimal but important - it adds a single line in code/core/src/core-server/dev-server.ts that registers the existing cancelTelemetry function to handle SIGTERM signals alongside the existing SIGINT handler.

The core issue being addressed is that when Storybook runs through process managers or wrapper commands like nr storybook, the SIGINT signal (typically sent by Ctrl-C) doesn't always propagate properly to the Node.js process. SIGTERM is the standard termination signal used by most process managers and container orchestrators for graceful shutdowns. By adding SIGTERM handling, the PR ensures telemetry data is properly sent even when Storybook is terminated through these wrapper processes.

This change integrates seamlessly with the existing signal handling architecture in Storybook's development server. The implementation follows the same pattern as the SIGINT handler, maintaining consistency in the codebase and ensuring that the same telemetry cleanup process runs regardless of which termination signal is received.

Confidence score: 5/5

• This PR is extremely safe to merge with virtually no risk of causing issues
• Score reflects the minimal, well-understood change that follows existing patterns and addresses a legitimate operational concern
• No files require special attention - the single line addition is straightforward and follows established conventions

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 525e532

Command	Status	Duration	Result
nx run-many -t check -c production --parallel=7	✅ Succeeded	1m 2s	View ↗
nx run-many -t build -c production --parallel=3	✅ Succeeded	4m 26s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-08-08 06:38:23 UTC

[storybook-pr-benchmarking]

Package Benchmarks

^{Commit: 525e532, ran on 8 August 2025 at 06:43:11 UTC}

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

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@storybook/server-webpack5

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sb

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@storybook/cli

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@storybook/codemod

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@storybook/preset-react-webpack

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