Runtime Devflare

Use event-first handlers by default and mark ambiguous handler styles explicitly

Devflare runtime supports event-first handlers, request-wide middleware, route method handlers, and explicit markers for ambiguous two-argument worker-style or resolve-style functions.

This page documents , , , , event-first handlers, and route dispatch with examples that match the actual exports.

Best for: Runtime import and dispatch questions
Worker-safe import
Ambiguous case: Two-argument fetch handlers

Copy the handler style that matches the job

The ambiguous error is intentional

If a two-argument handler is not marked, Devflare cannot safely know whether it is or . Mark it instead of relying on parameter names.

Event-first and route-dispatch examples

import { defineFetchHandler, sequence, type FetchEvent, type ResolveFetch } from 'devflare/runtime'

async function requestId(event: FetchEvent, resolve: ResolveFetch): Promise<Response> {

event.locals.requestId = crypto.randomUUID()

return resolve(event)

}

export const handle = sequence(requestId)

export const fetch = defineFetchHandler(

(request: Request, env: DevflareEnv) => env.ASSETS.fetch(request),

{ style: 'worker' }

)

sequence(...)

Use from when broad HTTP concerns must wrap route resolution or another fetch handler in a clear top-to-bottom order.

transport.ts

Most workers do not need a transport file. Add one when Devflare’s local RPC-style bridge must encode and decode custom values, especially across Durable Object method calls in tests.