Bug: Skip re-processing already transformed config files for CSF factories

[huang-julien]

…orues

Fix in next release

What I did

configTOCsfFactories had no early return for already transformed code

THe failing test was for

import { defineMain } from '@storybook/react-vite/node';

export default defineMain({});

the test title state that there's nothing to change but the issue is that dedent applies \n to the code, then transform applies recast uppon the code which apply platform line break. on windows it would be \r\n . Then the test would break

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

• check that csf factories still works

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

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.

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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
  • Better detection of already-transformed default exports so configs are preserved and redundant wrapping/merging is skipped when appropriate.
  • Ensures required framework imports are present (inserting or updating imports as needed) even when skipping other transformations, avoiding incomplete or broken configs.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 99d3ce0

Command	Status	Duration	Result
nx run-many -t compile -c production --parallel=1	✅ Succeeded	7s	View ↗

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☁️ Nx Cloud last updated this comment at 2026-03-23 13:39:12 UTC

[Copilot]

Pull request overview

This PR optimizes the CSF factories codemod by avoiding unnecessary re-printing/re-formatting when a config file is already in the target defineMain/definePreview form, preventing platform-specific line-ending churn (notably on Windows).

Changes:

• Adds an early-return check that detects export default defineMain(...) / export default definePreview(...) and returns the original source when no named exports need merging.

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[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: e1f82462-6eec-4a1d-b7c9-fe038e0969e9

📥 Commits

Reviewing files that changed from the base of the PR and between 13a7ea6 and 99d3ce0.

📒 Files selected for processing (2)

• code/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.test.ts
• code/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.ts

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📝 Walkthrough

Walkthrough

Detects when a config file is already a CSF factory export (e.g., export default defineMain(...) / definePreview(...)) and, depending on file kind and exports, skips wrapping/merging while still ensuring the correct non-type import/specifier for the factory is present.

Changes

Cohort / File(s)	Summary
Codemod helper code/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.ts	Adds detection of an existing export default that (optionally unwrapped) is a direct call to the CSF factory (defineMain/definePreview), computes shouldSkipTransform (different rules for main vs preview), and short-circuits wrapping/merge steps while continuing import injection/cleanup when needed.
Tests code/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.test.ts	Adds tests verifying injection or augmentation of the non-type import from the framework package when a file already exports defineMain(...) (cases: missing import entirely, existing import without the factory specifier).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Core: Better handling for TypeScript satisfies/as syntaxes #32891: Similar codemod updates touching detection of default-export shapes and adding unwrapping helpers used by this helper.
• Addon-Vitest: Support vite/vitest config with deferred export #33755: Related AST codemod changes that add handling for various default-export shapes (direct calls, wrapped, identifiers), overlapping logic.
• CSF: Enhance config-to-csf-factory to support type wrappers #32543: Previous modifications to the same codemod focusing on unwrapping/typed default-export handling and import adjustments.

✨ Finishing Touches

📝 Generate docstrings

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[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/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.ts`:
- Around line 45-47: The early return that checks isAlreadyTransformed and
!hasNamedExports (returning info.source) can skip the import normalization/fixup
logic; change the guard in that conditional (around isAlreadyTransformed and
hasNamedExports) so it only returns early when the module's required framework
imports are already present and valid, or alternatively move/ensure the
import-normalization code (the import fixup block) runs before returning; locate
the conditional using the symbols isAlreadyTransformed, hasNamedExports, and
info.source and adjust it so files like export default defineMain({}) still go
through the import repair path.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 585c4df8-5b94-4fdd-a71f-a3581c66247d

📥 Commits

Reviewing files that changed from the base of the PR and between b2fb7d8 and 8a1f355.

📒 Files selected for processing (1)

• code/lib/cli-storybook/src/codemod/helpers/config-to-csf-factory.ts

[yannbf]

Thanks for the fix!