Create `@fedify/fresh` package for Fresh 2.0 integration

[dahlia]

Background

Fresh 2.0 has introduced significant changes to its middleware API and overall architecture. The current Fedify integration module @fedify/fedify/x/fresh was designed for Fresh 1.x and is incompatible with these changes. We need to create a new package that properly integrates with Fresh 2.0's updated middleware system.

Key changes in Fresh 2.0

• Unified middleware signatures: Middleware now receives a single context object instead of (req, ctx) parameters
• Request object location: The Request object is now accessed via ctx.req instead of being a separate parameter
• Context consolidation: Various context interfaces (AppContext, LayoutContext, RouteContext) have been unified into a single Context interface
• Simplified configuration: No more fresh.config.ts or fresh.gen.ts files
• Vite integration: Fresh 2.0 uses Vite for development and build processes

Requirements

Package structure

• Package name: @fedify/fresh
• Target: Fresh 2.0+ compatibility
• Release timeline: Aligned with Fedify 2.0 release

Middleware implementation

The new middleware should:

• Follow Fresh 2.0's unified middleware signature pattern: (ctx: Context) => Response | Promise<Response>
• Access the request via ctx.req instead of as a separate parameter
• Properly integrate with Fresh's new context system
• Support all existing Fedify federation features

API compatibility

• Maintain feature parity with the current @fedify/fedify/x/fresh module
• Adapt to Fresh 2.0's context-based approach
• Ensure smooth migration path for existing users

Technical specifications

Middleware signature

// Fresh 1.x pattern (old)
export function federation(req: Request, ctx: FreshContext): Response | Promise<Response>

// Fresh 2.0 pattern (new)
export function federation(ctx: Context): Response | Promise<Response>

Context access patterns

• Use ctx.req for request access
• Use ctx.url for URL information
• Use ctx.state for passing data between middlewares
• Use ctx.params for route parameters

Tasks

• Create new package structure for @fedify/fresh
• Implement Fresh 2.0 compatible middleware
• Update type definitions for Fresh 2.0 context
• Migrate existing functionality from @fedify/fedify/x/fresh
• Add comprehensive tests for Fresh 2.0 integration
• Write migration guide from @fedify/fedify/x/fresh to @fedify/fresh
• Update documentation with Fresh 2.0 examples
• Ensure compatibility with Vite build process

References

• Fresh 2.0 Migration Guide
• Fresh 2.0 Context API
• Current implementation: @fedify/fedify/x/fresh

Acceptance criteria

• The package works seamlessly with Fresh 2.0
• All existing Fedify federation features are supported
• Type safety is maintained with proper TypeScript definitions
• Documentation includes clear examples for Fresh 2.0
• Migration path from the old module is documented
• Tests pass for all federation scenarios in Fresh 2.0 environment

[dodok8]

I'll work on this issue.

[dahlia]

@dodok8 Great! Note that you need to work on the next branch instead of the main branch!