Core: Restore the args a server-docgen preview cannot type

[valentinpalkovic]

Closes #

What I did

With experimentalDocgenServer enabled, the preview no longer holds a complete set of argTypes. Component metadata now lives on the server and is merged when the UI reads it, so prepareStory deliberately skips the inference pass to keep the preview's argTypes annotation-only. Consumers living in the preview still treated argTypes as "the set of args that exist", and silently dropped everything else.

                    story.argTypes under experimentalDocgenServer
                                      │
                 annotated only ──────┤ (no entry for a plain `args` key)
                                      │
        ┌─────────────────────────────┴─────────────────────────────┐
        ▼                                                           ▼
   ArgsStore                                            cleanArgsDecorator
   mapArgsToTypes / validateOptions                     kept only @Input/@Output
   drop keys with no argType                            or control/action
        │                                                           │
        ▼                                                           ▼
   url arg discarded                                    non-@Input arg stripped

The gate is in core and keyed only on the flag, so this is not Angular-specific. It applies to every renderer that enables the feature, React included:

// code/core/src/preview-api/modules/store/csf/prepareStory.ts
if (global.FEATURES?.experimentalDocgenServer && enhancer.secondPass) {
  return false;
}

1. URL args were discarded

mapArgsToTypes skips any key with no argType, and validateOptions builds its result by iterating argTypes, so a key absent from it can never come out. An arg set through the URL therefore never reached the story. The fix infers types where the validation needs them, without putting them back on the story where they would pollute the UI-read merge:

const argTypesForValidation = (story: PreparedStory<any>): ArgTypes =>
  global.FEATURES?.experimentalDocgenServer
    ? inferArgTypes({ id: story.id, argTypes: story.argTypes, initialArgs: story.initialArgs })
    : story.argTypes;

Same function, same inputs it would have had in the first pass, just called locally. This lives in core, so it covers every renderer.

2. Angular stripped args the component did not declare

cleanArgsDecorator kept an arg only when it was a component @Input/@Output or carried a control/action. Server docgen leaves the preview with no control on anything, so a public property that is not an @Input lost the value its story set.

Rather than add a third escape hatch to that filter, this deletes it. No other renderer does this: React passes every arg straight through. The behaviour arrived in 2021 with no stated rationale, and the only story it touched in that commit was a stray debug decorator:

(storyFn) => {
  const stroy = storyFn();
  console.log(stroy);
  return stroy;
},

The failure it plausibly guarded against, an invalid binding for a non-input, is prevented elsewhere: template generation starts from the component's real metadata and intersects with the props it was given.

inputs: ngComponentInputsOutputs.inputs.filter((i) => i.templateName in props)

Scoped to angular-vite. @storybook/angular keeps its decorator, so the two frameworks now differ here. That is deliberate: the webpack package has no docgen-server path, so nothing in this PR forces the change there.

The decorateStory suite was describe.skip'd as "infinitely running". It completes in under half a second, so it is enabled here. Two template expectations had silently rotted behind buildTemplate's 80-column line breaking while the suite was dark; those are corrected.

3. Two baseline re-records this PR needs to run at all

angular-vite/docgen-server-ts only runs in the daily set, so two merged changes never had their recorded baselines updated. The verification step gates every later job in that sandbox, so nothing above could be exercised until both were corrected.

Merged change	Drift
props-table visibility rules	dropped three internals from doc-button, added the three protected constructor dependencies to the DI component
"Stop marking a defaulted input as required in the props table"	flipped table.type.required on every input carrying a default value

The second is the entire diff for 16 of the 17 files, 43 lines of exactly this:

         "type": {
-          "required": true,
+          "required": false,
           "summary": "string"
         }

Both are re-records, not behaviour changes.

Effect

Reproduced against a real angular-vite/docgen-server-ts dev sandbox, before and after, same server:

Probe	Before	After
example-button--primary&args=label:Hello+world	"Button"	"Hello world"
WithComponentWrapperDecorator	"Private text:"	"Private text: Child private text"

The decorator deletion changes the legacy Compodoc path too, so both were verified against live sandboxes. WithComponentWrapperDecorator renders identically on each:

Child
Input text: Child text
Output : Click here !
Private text: Child private text

Check	Result
angular-vite/default-ts sandbox e2e (Compodoc)	59 passed, 0 failed
angular-vite/docgen-server-ts sandbox e2e	58 passed, 0 failed
@storybook/angular + @storybook/angular-vite unit	566 passed, 0 failed
code/core preview-api store unit	309 passed, 0 failed
baselines:sandbox --template angular-vite/docgen-server-ts	baselines match

Follow-up, not fixed here

#35919 tracks removing argTypes from user-facing story annotations entirely. Three internal consumers fell into this same trap, so users reading argTypes in a play function will too. inferActionsFromArgTypesRegex is a fourth case, found by inspection with no failing test today, so it is left alone here and recorded in that issue.

The ArgTypeInference template story that first surfaced this was fixed separately on next and is no longer part of this diff.

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

ArgsStore.test.ts gains types args from their initial value when the story declares no argTypes, which fails on next with:

AssertionError: expected { a: 'Button', b: 1 } to deeply equal { a: 'Hello world', b: 42 }

Note b: the initial value 1 is what identifies the arg as numeric, so the URL string '42' is coerced back to 42. decorateStory.test.ts covers the pass-through, and addon-controls.spec.ts › should apply controls automatically when passed via url covers the URL path in the sandbox.

Manual testing

1. yarn task sandbox --template angular-vite/docgen-server-ts --start-from auto
2. cd ../storybook-sandboxes/angular-vite-docgen-server-ts && yarn storybook
3. Open example/button → primary, set the label control to Hello world, then reload the page. The button must still read Hello world rather than reverting to Button.
4. Open Core / Decorators / ComponentWrapperDecorator → With Component Wrapper Decorator. The child must read Private text: Child private text, not a bare Private text:.
5. Repeat step 4 on an angular-vite/default-ts sandbox to confirm the Compodoc path is unchanged.

Note

A linked angular-vite sandbox currently cannot boot locally: yarn storybook dies with value `"builtin:vite-wasm-fallback"` does not match any variant of enum `BindingBuiltinPluginName` . Yarn's portal linking needs --preserve-symlinks, which makes the repo's nested rolldown@1.0.3 load the sandbox root's @rolldown/binding-darwin-arm64@1.2.0. Work around it by adding "resolutions": { "vite": "8.0.16", "rolldown": "1.0.3" } to the generated sandbox's package.json and re-running yarn install. Unrelated to this PR, and worth its own issue.

Documentation

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

No user-facing API changes. The behaviour restored here is what users already get from a non-docgen-server Storybook. The angular-vite arg pass-through aligns it with every other renderer.

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

• Declare whether manual QA will be needed for this PR during the next release, through qa:needed or qa:skip

• 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.

bug. These are the failures that surface once angular-vite/docgen-server-ts actually runs; they are present on next today.

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📒 Files selected for processing (16)

• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/example-button.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/example-header.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/example-page.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-argtypes-doc-button.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-argtypes-doc-directive.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-angular-forms-customcontrolvalueaccessor-custom-cva-component.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-component-with-ng-content-ng-content-about-parent.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-component-with-template-template.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-component-without-selector-without-selector-ng-component-outlet.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-component-without-selector-without-selector.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-ng-module-import-module-chip.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-ng-module-import-module-for-root.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-basics-ng-module-import-module.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-core-decorators-componentwrapperdecorator-decorators.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-others-app-initializer-use-factory.json
• code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/stories-frameworks-angular-vite-others-issues-12009-unknown-component.json

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Walkthrough

Changes

Server Docgen Argument Handling

Layer / File(s)	Summary
ArgsStore type inference and regression coverage code/core/src/preview-api/modules/store/ArgsStore.ts, code/core/src/preview-api/modules/store/ArgsStore.test.ts	ArgsStore infers argument types during server docgen for delta validation and persisted-argument mapping. Tests cover string and numeric conversion without declared argTypes.
Angular argument passthrough and test coverage code/frameworks/angular-vite/src/client/decorateStory.ts, code/frameworks/angular-vite/src/client/decorateStory.test.ts	decorateStory passes all story arguments without the removed cleaning decorator. Enabled tests cover controlled, action, and unclassified arguments.
Angular docgen metadata baselines code/lib/docgen-harness/src/sandbox-baselines/__baselines__/angular-vite-docgen-server-ts/*.json	Generated baselines update required flags and add metadata for provider-injected properties.

Merge Risk: ⚪ Minimal · up to a8b32

This PR restores untyped argument propagation for server-docgen previews and updates the affected Angular rendering and story expectations. The reported automated coverage passes, and no actionable merge-blocking risk remains beyond normal checks and review.

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