diff --git a/.changeset/adapters-runtime-workers-hyperdx.md b/.changeset/adapters-runtime-workers-hyperdx.md
new file mode 100644
index 0000000..753082d
--- /dev/null
+++ b/.changeset/adapters-runtime-workers-hyperdx.md
@@ -0,0 +1,5 @@
+---
+"evlog": patch
+---
+
+Resolve Nitro runtime config in drain adapters via dynamic `import()` (Cloudflare Workers and other runtimes without `require`). Cache Nitro module namespaces after first load to avoid repeated imports on every drain. Fix HyperDX drain to `await` `resolveAdapterConfig()` so env/runtime config is applied when using `createHyperDXDrain()` without inline overrides.
diff --git a/packages/evlog/src/adapters/_config.ts b/packages/evlog/src/adapters/_config.ts
index aebee8e..7a25343 100644
--- a/packages/evlog/src/adapters/_config.ts
+++ b/packages/evlog/src/adapters/_config.ts
@@ -1,24 +1,37 @@
 /**
- * Try to get runtime config from Nitro/Nuxt environment.
- * Supports both Nitro v2 (nitropack/runtime) and Nitro v3 (nitro/runtime-config).
- * Returns undefined if not in a Nitro context.
+ * Nitro runtime modules resolved via dynamic `import()` (Workers-safe: avoids a bundler-injected
+ * `createRequire` polyfill from sync `require()`). Module namespaces are cached after first
+ * successful load; `useRuntimeConfig()` is still invoked on each call so config stays current.
+ *
+ * Drain handlers remain non-blocking for the HTTP response when the host provides `waitUntil`
+ * (see Nitro plugin); the extra `await` here only sequences work inside that background drain.
  */
-export function getRuntimeConfig(): Record<string, any> | undefined {
-  try {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    const { useRuntimeConfig } = require('nitropack/runtime')
-    return useRuntimeConfig()
-  } catch {
-    // nitropack not available — try Nitro v3
+let nitropackRuntime: typeof import('nitropack/runtime') | null | undefined
+let nitroV3Runtime: typeof import('nitro/runtime-config') | null | undefined
+
+export async function getRuntimeConfig(): Promise<Record<string, any> | undefined> {
+  if (nitropackRuntime === undefined) {
+    try {
+      nitropackRuntime = await import('nitropack/runtime')
+    } catch {
+      nitropackRuntime = null
+    }
+  }
+  if (nitropackRuntime) {
+    return nitropackRuntime.useRuntimeConfig()
   }
 
-  try {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    const { useRuntimeConfig } = require('nitro/runtime-config')
-    return useRuntimeConfig()
-  } catch {
-    return undefined
+  if (nitroV3Runtime === undefined) {
+    try {
+      nitroV3Runtime = await import('nitro/runtime-config')
+    } catch {
+      nitroV3Runtime = null
+    }
   }
+  if (nitroV3Runtime) {
+    return nitroV3Runtime.useRuntimeConfig()
+  }
+  return undefined
 }
 
 export interface ConfigField<T> {
@@ -26,12 +39,12 @@ export interface ConfigField<T> {
   env?: string[]
 }
 
-export function resolveAdapterConfig<T>(
+export async function resolveAdapterConfig<T>(
   namespace: string,
   fields: ConfigField<T>[],
   overrides?: Partial<T>,
-): Partial<T> {
-  const runtimeConfig = getRuntimeConfig()
+): Promise<Partial<T>> {
+  const runtimeConfig = await getRuntimeConfig()
   const evlogNs = runtimeConfig?.evlog?.[namespace]
   const rootNs = runtimeConfig?.[namespace]
 
diff --git a/packages/evlog/src/adapters/_drain.ts b/packages/evlog/src/adapters/_drain.ts
index abfe555..ca37ccf 100644
--- a/packages/evlog/src/adapters/_drain.ts
+++ b/packages/evlog/src/adapters/_drain.ts
@@ -2,16 +2,21 @@ import type { DrainContext, WideEvent } from '../types'
 
 export interface DrainOptions<TConfig> {
   name: string
-  resolve: () => TConfig | null
+  resolve: () => TConfig | null | Promise<TConfig | null>
   send: (events: WideEvent[], config: TConfig) => Promise<void>
 }
 
+/**
+ * Build a drain callback for `evlog:drain` (or `initLogger({ drain })`).
+ * The returned function is async so `resolve` can load Nitro runtime config; hosts typically attach
+ * the resulting promise to `waitUntil` so the HTTP response is not blocked (see Nitro plugin).
+ */
 export function defineDrain<TConfig>(options: DrainOptions<TConfig>): (ctx: DrainContext | DrainContext[]) => Promise<void> {
   return async (ctx: DrainContext | DrainContext[]) => {
     const contexts = Array.isArray(ctx) ? ctx : [ctx]
     if (contexts.length === 0) return
 
-    const config = options.resolve()
+    const config = await options.resolve()
     if (!config) return
 
     try {
diff --git a/packages/evlog/src/adapters/axiom.ts b/packages/evlog/src/adapters/axiom.ts
index fd70906..5184dcc 100644
--- a/packages/evlog/src/adapters/axiom.ts
+++ b/packages/evlog/src/adapters/axiom.ts
@@ -75,8 +75,8 @@ const AXIOM_FIELDS: ConfigField<ResolvedAxiomConfig>[] = [
 export function createAxiomDrain(overrides?: Partial<AxiomConfig>) {
   return defineDrain<AxiomConfig>({
     name: 'axiom',
-    resolve: () => {
-      const config = resolveAdapterConfig<ResolvedAxiomConfig>(
+    resolve: async () => {
+      const config = await resolveAdapterConfig<ResolvedAxiomConfig>(
         'axiom',
         AXIOM_FIELDS,
         overrides as Partial<ResolvedAxiomConfig>,
diff --git a/packages/evlog/src/adapters/better-stack.ts b/packages/evlog/src/adapters/better-stack.ts
index 2e0a384..9cd8058 100644
--- a/packages/evlog/src/adapters/better-stack.ts
+++ b/packages/evlog/src/adapters/better-stack.ts
@@ -54,8 +54,8 @@ export function toBetterStackEvent(event: WideEvent): Record<string, unknown> {
 export function createBetterStackDrain(overrides?: Partial<BetterStackConfig>) {
   return defineDrain<BetterStackConfig>({
     name: 'better-stack',
-    resolve: () => {
-      const config = resolveAdapterConfig<BetterStackConfig>('betterStack', BETTER_STACK_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<BetterStackConfig>('betterStack', BETTER_STACK_FIELDS, overrides)
       if (!config.sourceToken) {
         console.error('[evlog/better-stack] Missing source token. Set NUXT_BETTER_STACK_SOURCE_TOKEN env var or pass to createBetterStackDrain()')
         return null
diff --git a/packages/evlog/src/adapters/hyperdx.ts b/packages/evlog/src/adapters/hyperdx.ts
index 290da64..befbf76 100644
--- a/packages/evlog/src/adapters/hyperdx.ts
+++ b/packages/evlog/src/adapters/hyperdx.ts
@@ -81,8 +81,8 @@ export function toHyperDXOTLPConfig(config: HyperDXConfig): OTLPConfig {
 export function createHyperDXDrain(overrides?: Partial<HyperDXConfig>) {
   return defineDrain<HyperDXConfig>({
     name: 'hyperdx',
-    resolve: () => {
-      const config = resolveAdapterConfig<HyperDXConfig>('hyperdx', HYPERDX_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<HyperDXConfig>('hyperdx', HYPERDX_FIELDS, overrides)
       if (!config.apiKey) {
         console.error('[evlog/hyperdx] Missing apiKey. Set HYPERDX_API_KEY or NUXT_HYPERDX_API_KEY, or pass to createHyperDXDrain()')
         return null
diff --git a/packages/evlog/src/adapters/otlp.ts b/packages/evlog/src/adapters/otlp.ts
index 08f2b82..ed3764c 100644
--- a/packages/evlog/src/adapters/otlp.ts
+++ b/packages/evlog/src/adapters/otlp.ts
@@ -245,8 +245,8 @@ function getHeadersFromEnv(): Record<string, string> | undefined {
 export function createOTLPDrain(overrides?: Partial<OTLPConfig>) {
   return defineDrain<OTLPConfig>({
     name: 'otlp',
-    resolve: () => {
-      const config = resolveAdapterConfig<OTLPConfig>('otlp', OTLP_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<OTLPConfig>('otlp', OTLP_FIELDS, overrides)
 
       // OTLP-specific: resolve headers from env if not provided via config
       if (!config.headers) {
diff --git a/packages/evlog/src/adapters/posthog.ts b/packages/evlog/src/adapters/posthog.ts
index 904d1c2..9aef8b7 100644
--- a/packages/evlog/src/adapters/posthog.ts
+++ b/packages/evlog/src/adapters/posthog.ts
@@ -105,8 +105,8 @@ export function toPostHogEvent(event: WideEvent, config: PostHogEventsConfig): P
 export function createPostHogDrain(overrides?: Partial<PostHogConfig>) {
   return defineDrain<PostHogConfig>({
     name: 'posthog',
-    resolve: () => {
-      const config = resolveAdapterConfig<PostHogConfig>('posthog', POSTHOG_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<PostHogConfig>('posthog', POSTHOG_FIELDS, overrides)
       if (!config.apiKey) {
         console.error('[evlog/posthog] Missing apiKey. Set NUXT_POSTHOG_API_KEY/POSTHOG_API_KEY env var or pass to createPostHogDrain()')
         return null
@@ -172,8 +172,8 @@ export async function sendBatchToPostHog(events: WideEvent[], config: PostHogCon
 export function createPostHogEventsDrain(overrides?: Partial<PostHogEventsConfig>) {
   return defineDrain<PostHogEventsConfig>({
     name: 'posthog-events',
-    resolve: () => {
-      const config = resolveAdapterConfig<PostHogEventsConfig>('posthog', POSTHOG_EVENTS_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<PostHogEventsConfig>('posthog', POSTHOG_EVENTS_FIELDS, overrides)
       if (!config.apiKey) {
         console.error('[evlog/posthog-events] Missing apiKey. Set NUXT_POSTHOG_API_KEY/POSTHOG_API_KEY env var or pass to createPostHogEventsDrain()')
         return null
diff --git a/packages/evlog/src/adapters/sentry.ts b/packages/evlog/src/adapters/sentry.ts
index 21f722d..cadbaa3 100644
--- a/packages/evlog/src/adapters/sentry.ts
+++ b/packages/evlog/src/adapters/sentry.ts
@@ -224,8 +224,8 @@ function buildEnvelopeBody(logs: SentryLog[], dsn: string): string {
 export function createSentryDrain(overrides?: Partial<SentryConfig>) {
   return defineDrain<SentryConfig>({
     name: 'sentry',
-    resolve: () => {
-      const config = resolveAdapterConfig<SentryConfig>('sentry', SENTRY_FIELDS, overrides)
+    resolve: async () => {
+      const config = await resolveAdapterConfig<SentryConfig>('sentry', SENTRY_FIELDS, overrides)
       if (!config.dsn) {
         console.error('[evlog/sentry] Missing DSN. Set NUXT_SENTRY_DSN/SENTRY_DSN env var or pass to createSentryDrain()')
         return null