Generated by 🚫 dangerJS against 25c8224

No actionable comments were generated in the recent review. 🎉

Walkthrough

The useCode helper no longer applies sourceParameters.transform twice to regular snippets. New tests cover regular snippets, explicit transformFromProps, and originalSource fallback behavior.

Changes

Source transform handling

Priority: ➖ Normal

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to b6fe1

The Source block preserves the configured transform for service snippets and avoids applying it twice to emitted snippets, so this change is mergeable.

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Thanks for the CodeRabbit review!

Both actionable items are fixed in commit b6fe1fe:

1. Source.test.tsx — broken vi.fn mock bodies (parse errors)

All three mocks used /comment/ as the arrow-function body, which is a void block comment — not a return value. This caused Biome to report parse errors (Expected a function body, or an expression but instead found ')') and every ransform-called assertion to fail. Each mock now returns a proper string:

• Tests 1 & 3: (code) => '/transformed/ ' + code\
• Test 2: (code) => '/prop/ ' + code\

2. Source.tsx — service-snippet path skipping transform

The transformer guard \useSnippet && snippet ? undefined : sourceParameters.transform\ was incorrectly skipping the transform when a raw \serviceSnippet\ was selected as \staticSnippet. Service snippets are not pre-processed by \emitTransformCode, so they still need the transform. Added !serviceSnippet\ to the guard:

\\ s
transformFromProps ?? (useSnippet && !serviceSnippet && snippet ? undefined : sourceParameters.transform)
\\

All three tests now exercise correct paths. Thanks again for the detailed review! 🙏

Thanks @storybook-contribution-review[bot] for the thorough review and guidance!

The requested changes have been implemented in commit e747065:

1. Source.test.tsx rewrite:

   • Replaced tests with renderHook testing useSourceProps under // @vitest-environment happy-dom.
   • Render first with an empty SourceContext, then rerender with the emitted snippet, asserting result.current.code.
   • Covered all 4 requested test scenarios plus transformFromProps:
     • type: 'auto' args story and type: 'dynamic': snippet arrives after first render ? code is 'T:<Button />'.
     • Emitted snippet present, then raw service snippet '<Svc />' arrives ? 'T:<Svc />'.
     • type: 'code' with snippet present ? originalSource transformed once.
     • auto non-args story ? originalSource transformed once.
     • transformFromProps explicitly provided on props applies to snippet.
   • Replaced as any with typed mocks (PreparedStory and ReducedStoryContext).

2. Source.tsx source-kind selection & comment:

   • Decided source once via sourceKind: 'service' | 'emitted' | 'original'.
   • Skipped base transform only when sourceKind === 'emitted'.
   • Updated comment: "The emitted snippet is already transformed by emitTransformCode, so only transformFromProps applies to it."
   • Verified clean formatting with oxfmt --check.

3. emitTransformCode.ts note:

   • Added explicit note clarifying that snippet payloads emitted via SNIPPET_RENDERED are already transformed.

Thanks @storybook-contribution-review for the precise feedback! Both issues have been addressed in commit 8d56697:

1. Dynamic story sourceKind mapping:

   • In Source.tsx, when useSnippet is active and !serviceSnippet, sourceKind now maps directly to 'emitted'. This ensures type: 'dynamic' stories display an empty snippet rather than prematurely falling back to originalSource before the asynchronous snippet arrives.

2. Hook call stability across renders:

   • Kept useTransformCode invariant across renders by determining hasTransformer = Boolean(transformFromProps ?? sourceParameters.transform) unconditionally.
   • When sourceKind === 'emitted' and transformFromProps is undefined, passed an identity function (rawCode: string) => rawCode as the transformer. This avoids conditionally omitting the hook call on subsequent renders when the snippet resolves, completely eliminating the "Rendered fewer hooks than expected" error while preventing double transformation.

Verified with oxfmt --check and all tests in Source.test.tsx.

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Review phase: Runtime verification (stage 3 of 3)

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Thanks for the quick follow-up, @webdevsamran! Both blocking items are fixed: the transform hook no longer changes the hook count when the snippet arrives, and a dynamic story with no snippet renders '' again.

Result: all three review stages pass on 8d56697. No changes are requested.

• Architecture and code quality: pass. All 6 tests in Source.test.tsx pass, and the addon-docs type check, oxfmt and oxlint are clean.
• Runtime verification: we ran a React-Vite Storybook in Chromium with a transform that adds a marker line each time it runs.
  • Bug reproduced on the base branch: on the docs page, the marker appears twice (also with an async transform and in MDX <Source of={...} />).
  • Fixed on this head: the marker appears once.
  • No regressions found: type: 'code' is still transformed once, a transform prop still applies, a dynamic story shows '' until its snippet arrives, a Controls edit re-renders with one marker, and there are no console errors or hook-order warnings. The full addon-docs test suite passes (134/134). Run against the base Source.tsx, 3 of your new tests fail, so they catch the bug.
• Not covered at runtime: the docgen-server (service snippet) path did not produce a snippet in our setup, so only its unit test covers it. Other renderers were not run, but the fix is in the shared Source block.

The two optional suggestions about the test setup from earlier remain optional and are not needed for merge.

Package Benchmarks

^{Commit: 25c8224, ran on 20 October 2026 at 11:45:28 UTC}

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

@storybook/svelte-vite

@storybook/sveltekit

@storybook/svelte