bug: babel-preset-storybook-full-source overwrites inline CSF3 story parameters

[dmytrokirpa]

Package and environment

• Package: @fluentui/babel-preset-storybook-full-source@0.1.3
• Storybook: 10.5.5

Configuration

The plugin is configured as:

[fullSourcePlugin, { importMappings: {}, storyGranularity: "story" }]

Reproduction

import type { Meta, StoryObj } from "@storybook/react";

const meta = { title: "Example" } satisfies Meta;
export default meta;
type Story = StoryObj<typeof meta>;

export const Default: Story = {
  render: () => <div>Example</div>,
  parameters: {
    docs: { description: { story: "Description" } },
  },
};

The relevant Storybook configuration includes:

import fullSourcePlugin from "@fluentui/babel-preset-storybook-full-source";

export default {
  babel: async (config: any) => ({
    ...config,
    plugins: [
      ...(config.plugins ?? []),
      [fullSourcePlugin, { importMappings: {}, storyGranularity: "story" }],
    ],
  }),
};

Expected behavior

The inline parameters.docs.description.story description survives, and parameters.fullSource is added.

Actual behavior

The description disappears, while parameters.fullSource remains.

Root cause

Verified from the package implementation: parameter detection only tracks assignment expressions such as Story.parameters = ...; it does not recognize the inline parameters property inside export const Story = { ... }. At Program exit it considers parameters missing and appends Story.parameters = {}, overwriting all inline parameters, then assigns Story.parameters.fullSource.

Proposed fix

Recognize inline CSF3 object parameters, or initialize with Story.parameters ??= {} rather than unconditionally replacing the object.

A locally verified workaround is to post-transform Story.parameters = {} into:

Story.parameters = Story.parameters ?? {};