CLI: Update AI setup instructions to msw-storybook-addon v3

[yannbf]

What I did

The storybook ai setup prompts teach the msw-storybook-addon v2 API. Under the upcoming v3 (mswjs/msw-storybook-addon#193), that preview snippet crashes at module load: initialize no longer exists, and mswLoader moved to the msw-storybook-addon/csf3 subpath. Since the install step is unpinned, the moment v3 becomes latest, every fresh setup run would produce instructions that make agents scaffold broken previews.

Changes, across all prompt variants (the shipping pattern-copy-play default plus the other variants via the shared partials):

• Register the addon with storybook add msw-storybook-addon@3 so it also lands in the main.* addons field. Pinning the major means the snippets and the installed API can't drift apart.
• CSF3 previews: loaders: [mswLoader()] imported from msw-storybook-addon/csf3, with handlers wired in beforeEach({ msw }) instead of the deprecated parameters.msw (merged into the existing beforeEach the example already had).
• CSF factories previews: branch on hasCsfFactoryPreview and wire via addonMsw() in definePreview({ addons }).
• The msw-handlers example exports a flat array now that it's spread into msw.use(...).
• For CSF factories projects, the msw step now warns that storybook add may inject a mswStorybookAddon namespace entry into definePreview.addons and instructs removing it in favor of addonMsw() — a single namespace entry collapses the whole preview's type inference to never (CSF factories codemod injects incompatible addon namespaces into definePreview, collapsing all preview types to never #35571).

How to test

• Go to a project that could use MSW but doesn't have it yet, e.g. MealDrop + Removing its storybook with npx @hipster/sb-utils uninstall --yes
• Run the Storybook AI setup
• If the generated code includes MSW and its addon, make sure that it works as intended

Summary by CodeRabbit

• New Features

  • Updated generated MSW setup guidance for modern Storybook workflows, including explicit MSW addon registration.
  • Enhanced CSF factory preview support with definePreview, mswHandlers, and session provider wiring.
  • Refreshed examples to match current MSW addon usage and handler-array patterns.

• Bug Fixes

  • Adjusted generated install commands to include only the necessary MSW-related packages (removing extra addon installation from the install step).
  • Corrected preview/MSW configuration to avoid incorrect definePreview injection and mismatched initialization style.

[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: 0354e530-d6ef-4268-8136-24e076571099

📥 Commits

Reviewing files that changed from the base of the PR and between 9200c8d and 80148d8.

📒 Files selected for processing (4)

• code/core/src/cli/ai/setup-prompts/monorepo-optimized-tests-relaxed-limits-no-story-deletion.ts
• code/core/src/cli/ai/setup-prompts/monorepo.ts
• code/core/src/cli/ai/setup-prompts/optimized-tests.ts
• code/core/src/cli/ai/setup-prompts/relaxed-limits.ts

🚧 Files skipped from review as they are similar to previous changes (4)

• code/core/src/cli/ai/setup-prompts/relaxed-limits.ts
• code/core/src/cli/ai/setup-prompts/monorepo-optimized-tests-relaxed-limits-no-story-deletion.ts
• code/core/src/cli/ai/setup-prompts/monorepo.ts
• code/core/src/cli/ai/setup-prompts/optimized-tests.ts

---

📝 Walkthrough

Walkthrough

MSW setup prompts now install msw separately from msw-storybook-addon, provide addon v3 guidance, use array-based handlers, and generate CSF3 or CSF factory preview examples with mswLoader(), beforeEach, and addonMsw().

Changes

MSW v3 setup prompts

Layer / File(s)	Summary
MSW installation and setup guidance code/core/src/cli/ai/setup-prompts/monorepo*.ts, code/core/src/cli/ai/setup-prompts/optimized-tests.ts, code/core/src/cli/ai/setup-prompts/relaxed-limits.ts, code/core/src/cli/ai/setup-prompts/partials/steps.ts, code/core/src/cli/ai/setup-prompts/pattern-copy-play.ts	MSW install commands now exclude msw-storybook-addon; setup instructions add the addon separately and include CSF factory guidance.
Handler and preview integration code/core/src/cli/ai/setup-prompts/partials/examples.ts, code/core/src/cli/ai/setup-prompts/partials/steps.ts, code/core/src/cli/ai/setup-prompts/pattern-copy-play.ts	Generated handlers use arrays, while preview examples use mswLoader(), beforeEach({ msw }), msw.use(...mswHandlers), and addonMsw() for CSF factory previews.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant StorybookPreview
  participant mswLoader
  participant beforeEach
  participant MSWHandlers
  StorybookPreview->>mswLoader: load mswLoader()
  StorybookPreview->>beforeEach: invoke async beforeEach({ msw })
  beforeEach->>MSWHandlers: msw.use(...mswHandlers)

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Possibly related PRs

• storybookjs/storybook#35409: Updates related MSW setup and verification helpers in AI setup prompts.
• storybookjs/storybook#35536: Aligns Storybook/MSW documentation with v3 handler configuration.

✨ Finishing Touches

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• Create stacked PR
• Commit on current branch

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@code/core/src/cli/ai/setup-prompts/pattern-copy-play.ts`:
- Line 147: Update the preview import snippets to include the generated
handler-file extension, using .ts for TypeScript output and .js for JavaScript
output. Apply this to both imports in pattern-copy-play.ts (lines 147-147 and
164-164) and all three imports in partials/examples.ts (lines 19-19, 48-48, and
79-79), preserving the existing generated-output language distinction.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 950d56b7-03cf-472b-9d99-f45aefe6eb7c

📥 Commits

Reviewing files that changed from the base of the PR and between e615c99 and 9200c8d.

📒 Files selected for processing (7)

• code/core/src/cli/ai/setup-prompts/monorepo-optimized-tests-relaxed-limits-no-story-deletion.ts
• code/core/src/cli/ai/setup-prompts/monorepo.ts
• code/core/src/cli/ai/setup-prompts/optimized-tests.ts
• code/core/src/cli/ai/setup-prompts/partials/examples.ts
• code/core/src/cli/ai/setup-prompts/partials/steps.ts
• code/core/src/cli/ai/setup-prompts/pattern-copy-play.ts
• code/core/src/cli/ai/setup-prompts/relaxed-limits.ts

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