feat(react): support lazy activity with internal plugin

[orionmiz]

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🦋 Changeset detected

Latest commit: 7726c76a70f3087eca117747a42204f433093b47

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@stackflow/react	Minor

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[coderabbitai[bot]]

📝 Walkthrough

Summary by CodeRabbit

• New Features
  • Added support for lazy-loaded activities on React 18–19; navigation now waits for components to load, improving transition reliability.
• Bug Fixes
  • More predictable behavior when the animation option is undefined, preventing unintended animation states.
• Chores
  • Prepared a minor release for @stackflow/react.

Walkthrough

Adds a new internal React plugin that detects React.lazy and memoized activity components, pauses navigation while unresolved lazy components load, and conditionally registers the plugin for React major versions 18–19; includes a changeset for a minor @stackflow/react release.

Changes

Cohort / File(s)	Change Summary
Lazy Activity Plugin Implementation integrations/react/src/stable/lazyActivityPlugin.ts	New file: adds lazyActivityPlugin(activityComponentMap) which detects React lazy/memo components, tracks load status, pauses navigation on onBeforePush/onBeforeReplace while awaiting the component's loading promise, and resumes navigation after resolve/reject.
Plugin Registration & Setup integrations/react/src/stable/stackflow.tsx	Modified plugin initialization: normalizes and types incoming plugins array, imports React version, conditionally appends lazyActivityPlugin(activityComponentMap) when React major version is 18–19, and tightened parsing of animate in action options.
Changeset / Release Note .changeset/small-rice-listen.md	New changeset added declaring a minor release for @stackflow/react documenting the lazy activity support addition.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant Stackflow
    participant LazyPlugin as lazyActivityPlugin
    participant ReactLazy as ReactLazyComponent

    User->>Stackflow: request navigation (push/replace)
    Stackflow->>LazyPlugin: onBeforePush/onBeforeReplace
    LazyPlugin->>ReactLazy: inspect activity component (lazy/memo)
    alt component is lazy and uninitialized
        LazyPlugin->>Stackflow: pause navigation
        LazyPlugin->>ReactLazy: start loading (invoke promise)
        ReactLazy-->>LazyPlugin: promise resolves / rejects
        LazyPlugin->>Stackflow: resume navigation
    else not lazy or already loaded
        LazyPlugin->>Stackflow: allow navigation to continue
    end

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

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📥 Commits

Reviewing files that changed from the base of the PR and between 8823102fff002f8cb556898e9a7e66976083227a and 7726c76a70f3087eca117747a42204f433093b47.

📒 Files selected for processing (1)

• integrations/react/src/stable/stackflow.tsx (2 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• integrations/react/src/stable/stackflow.tsx

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✨ Finishing Touches

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🧪 Generate unit tests

• [ ] Create PR with unit tests
• [ ] Post copyable unit tests in a comment
• [ ] Commit unit tests in branch lazy-activity

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	stackflow-docs	7726c76a	Commit Preview URL	Aug 20 2025, 06:45 AM

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@stackflow/demo

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commit: 7726c76

[orionmiz]

/oc summarize

[opencode-agent[bot]]

This PR adds support for lazy-loaded React components in Stackflow by implementing an internal plugin that handles React.lazy and React.memo components.

Key Changes

New lazy activity plugin (integrations/react/src/stable/lazyActivityPlugin.ts):

• Detects React.lazy and React.memo components using internal React symbols
• Pauses navigation during lazy component loading to prevent flicker/errors
• Handles both onBeforePush and onBeforeReplace events
• Automatically resumes navigation after component loads (success or failure)

Plugin integration (integrations/react/src/stable/stackflow.tsx):

• Conditionally registers the plugin only for React 18.x
• Appends plugin to existing plugin array
• Uses React version detection to ensure compatibility

Changeset (.changeset/small-rice-listen.md):

• Documents this as a minor version bump for @stackflow/react
• No breaking changes to public APIs

Technical Implementation

The plugin works by:

1. Inspecting activity components for lazy/memo wrappers
2. Extracting loading promises from React's internal _payload structure
3. Pausing navigation until promises resolve/reject
4. Automatically resuming navigation afterward

This is backward-compatible and requires no configuration - it's automatically applied for supported React versions.

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[orionmiz]

/oc could you review this PR line-by-line via gh api command with gh cli?

[opencode-agent[bot]]

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