diff --git a/packages/effect/src/context.test-d.ts b/packages/effect/src/context.test-d.ts
index 5cc928ffb0..71c9c3a6e0 100644
--- a/packages/effect/src/context.test-d.ts
+++ b/packages/effect/src/context.test-d.ts
@@ -100,6 +100,17 @@ describe('InferEffectServices', () => {
     expectTypeOf<InferEffectServices<{ auth: boolean }>>().toEqualTypeOf<never>()
   })
 
+  it('does not distribute over union contexts', () => {
+    expectTypeOf<InferEffectServices<WithEffectContext<Service1> | WithEffectContext<Service2>>>().toEqualTypeOf<never>()
+    expectTypeOf<InferEffectServices<WithEffectContext<Service1> | { auth: boolean }>>().toEqualTypeOf<never>()
+    expectTypeOf<InferEffectServices<WithEffectContext<Service1 | Service2> | WithEffectContext<Service1>>>().toEqualTypeOf<Service1>()
+  })
+
+  it('infers services from intersection and any contexts', () => {
+    expectTypeOf<InferEffectServices<WithEffectContext<Service1> & { auth: boolean }>>().toEqualTypeOf<Service1>()
+    expectTypeOf<InferEffectServices<any>>().toEqualTypeOf<unknown>()
+  })
+
   it('accepts a context with more services than required', () => {
     expectTypeOf<WithEffectContext<Service1 | Service2>>().toExtend<WithEffectContext<Service1>>()
   })
diff --git a/packages/effect/src/context.ts b/packages/effect/src/context.ts
index 2fddf541fb..ce41d12356 100644
--- a/packages/effect/src/context.ts
+++ b/packages/effect/src/context.ts
@@ -101,7 +101,8 @@ export interface WithEffectContext<Services> {
 
 /**
  * Infers the Effect services available in an oRPC context that extends `WithEffectContext`.
+ * For a union context, only the services every member provides are inferred.
  *
  * @see {@link https://orpc.dev/docs/integrations/effect#effect-services | Effect Integration - Effect Services}
  */
-export type InferEffectServices<T extends Context> = T extends WithEffectContext<infer Services> ? Services : never
+export type InferEffectServices<T extends Context> = [T] extends [{ 'effect/context': EffectContext.Context<infer Services> }] ? Services : never
diff --git a/packages/effect/src/extensions/effect.ts b/packages/effect/src/extensions/effect.ts
index 959ab773f5..cb91e88b6b 100644
--- a/packages/effect/src/extensions/effect.ts
+++ b/packages/effect/src/extensions/effect.ts
@@ -18,9 +18,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         TInitialContext,
         InferSchemaOutput<InitialInputSchema>,
-        TYield,
         TReturn,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        TYield
       >,
     ): DecoratedProcedure<
       TInitialContext,
@@ -43,9 +43,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         MergedContext<TInitialContext, TInjectedContext>,
         InferSchemaOutput<InitialInputSchema>,
-        TYield,
         TReturn,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        TYield
       >,
     ): DecoratedProcedure<
       TInitialContext,
@@ -69,9 +69,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         MergedContext<TInitialContext, TInjectedContext>,
         InferSchemaOutput<TInputSchema>,
-        TYield,
         TReturn,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        TYield
       >,
     ): DecoratedProcedure<
       TInitialContext,
@@ -95,9 +95,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         MergedContext<TInitialContext, TInjectedContext>,
         InferSchemaOutput<InitialInputSchema>,
-        TYield,
         TReturn,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        TYield
       >,
     ): DecoratedProcedure<
       TInitialContext,
@@ -122,9 +122,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         MergedContext<TInitialContext, TInjectedContext>,
         InferSchemaOutput<TInputSchema>,
-        TYield,
         TReturn,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        TYield
       >,
     ): DecoratedProcedure<
       TInitialContext,
@@ -146,9 +146,9 @@ declare module '@orpc/server' {
       handler: HandlerGen<
         MergedContext<TInitialContext, TInjectedContext>,
         InferSchemaOutput<TInputSchema>,
-        Effect.Effect<any, any, InferEffectServices<MergedContext<TInitialContext, TInjectedContext>>>,
         InferSchemaInput<TOutputSchema>,
-        ORPCErrorConstructorMap<TErrorMap>
+        ORPCErrorConstructorMap<TErrorMap>,
+        Effect.Effect<any, any, InferEffectServices<MergedContext<TInitialContext, TInjectedContext>>>
       >,
     ): ImplementedProcedure<
       TInitialContext,
diff --git a/packages/effect/src/handler.test-d.ts b/packages/effect/src/handler.test-d.ts
index 12f18e1b01..b33efd24f9 100644
--- a/packages/effect/src/handler.test-d.ts
+++ b/packages/effect/src/handler.test-d.ts
@@ -1,5 +1,5 @@
 import type { InitialInputSchema, Schema } from '@orpc/contract'
-import type { DecoratedProcedure, DefaultInitialContext, ORPCErrorConstructorMap } from '@orpc/server'
+import type { DecoratedProcedure, DefaultInitialContext, ORPCErrorConstructorMap, ProcedureHandler } from '@orpc/server'
 import type { WithEffectContext } from './context'
 import { ORPCError, os } from '@orpc/server'
 import { Context, Effect } from 'effect'
@@ -108,4 +108,25 @@ describe('handlerGen', () => {
         yield* Service2
       }))
   })
+
+  it('accepts explicit type arguments in ProcedureHandler order with TYield last', () => {
+    type Errors = ORPCErrorConstructorMap<typeof errorMap>
+
+    const handler = handlerGen<WithEffectContext<Service1>, { id: string }, number, Errors, Effect.Effect<any, any, Service1>>(
+      function* ({ errors }, input) {
+        expectTypeOf(input).toEqualTypeOf<{ id: string }>()
+        expectTypeOf(errors).toEqualTypeOf<Errors>()
+        yield* Service1
+        return 1
+      },
+    )
+    expectTypeOf(handler).toEqualTypeOf<ProcedureHandler<WithEffectContext<Service1>, { id: string }, number, Errors>>()
+
+    const defaults = handlerGen<WithEffectContext<Service1>>(function* () {
+      yield* Service1
+    })
+    expectTypeOf(defaults).toEqualTypeOf<
+      ProcedureHandler<WithEffectContext<Service1>, unknown, unknown, ORPCErrorConstructorMap<Record<never, never>>>
+    >()
+  })
 })
diff --git a/packages/effect/src/handler.ts b/packages/effect/src/handler.ts
index 9f7d10dc8c..c9e101f3a9 100644
--- a/packages/effect/src/handler.ts
+++ b/packages/effect/src/handler.ts
@@ -3,14 +3,12 @@ import type { InferEffectServices, WithEffectContext } from './context'
 import { Effect, Context as EffectContext } from 'effect'
 import { runPromise } from './runtime'
 
-export type InferYieldError<Eff> = [Eff] extends [never] ? never : [Eff] extends [Effect.Effect<infer _A, infer E, infer _R>] ? E : never
-
 export interface HandlerGen<
   TCurrentContext extends Context,
   TInput,
-  TYield extends Effect.Effect<any, any, InferEffectServices<TCurrentContext>>,
   TReturn,
   TErrorConstructorMap extends ORPCErrorConstructorMap<any>,
+  TYield extends Effect.Effect<any, any, InferEffectServices<TCurrentContext>>,
 > {
   (
     opts: ProcedureHandlerOptions<TCurrentContext, TInput, TErrorConstructorMap>,
@@ -22,6 +20,8 @@ export interface HandlerGen<
   >
 }
 
+export type AnyHandlerGen = HandlerGen<any, any, any, any, any>
+
 /**
  * Creates a procedure handler from an Effect generator function.
  * Inside the generator you can yield Effect operations, and `handlerGen`
@@ -31,17 +31,17 @@ export interface HandlerGen<
  */
 export function handlerGen<
   TCurrentContext extends Context,
-  TInput,
-  TErrorConstructorMap extends ORPCErrorConstructorMap<any>,
-  TYield extends Effect.Effect<any, any, InferEffectServices<TCurrentContext>>,
-  TReturn,
+  TInput = unknown,
+  TReturn = unknown,
+  TErrorConstructorMap extends ORPCErrorConstructorMap<any> = ORPCErrorConstructorMap<Record<never, never>>,
+  TYield extends Effect.Effect<any, any, InferEffectServices<TCurrentContext>> = Effect.Effect<any, any, InferEffectServices<TCurrentContext>>,
 >(
-  handler: HandlerGen<TCurrentContext, TInput, TYield, TReturn, TErrorConstructorMap>,
+  handler: HandlerGen<TCurrentContext, TInput, TReturn, TErrorConstructorMap, TYield>,
 ): ProcedureHandler<TCurrentContext, TInput, TReturn, TErrorConstructorMap> {
   return (opts, input) => {
     const effectContext = opts.context['effect/context']
     const wrap = opts.context['effect/wrap'] as WithEffectContext<any>['effect/wrap']
-    const ef = Effect.gen(() => handler(opts, input)) as Effect.Effect<TReturn, InferYieldError<TYield>>
+    const ef = Effect.gen(() => handler(opts, input)) as Effect.Effect<TReturn, unknown>
 
     return runPromise(
       typeof wrap === 'function' ? wrap(ef, { ...opts, kind: 'handler' }) : ef,
diff --git a/packages/effect/src/index.test.ts b/packages/effect/src/index.test.ts
index 4716b465a6..28adaf8475 100644
--- a/packages/effect/src/index.test.ts
+++ b/packages/effect/src/index.test.ts
@@ -3,10 +3,16 @@ it('exports', async () => {
     handlerGen: expect.any(Function),
     middlewareGen: expect.any(Function),
     EffectSchemaToJsonSchemaConverter: expect.any(Function),
-    toStandardSchema: expect.any(Function),
     catchORPCError: expect.any(Function),
     catchORPCErrorCode: expect.any(Function),
     catchORPCErrorCodes: expect.any(Function),
     createEffectClient: expect.any(Function),
   })
 })
+
+it('does not export internal helpers', async () => {
+  const mod = await import('./index')
+
+  expect(mod).not.toHaveProperty('runPromise')
+  expect(mod).not.toHaveProperty('toStandardSchema')
+})
diff --git a/packages/effect/src/index.ts b/packages/effect/src/index.ts
index c1d0e9cb19..42f4d9fea5 100644
--- a/packages/effect/src/index.ts
+++ b/packages/effect/src/index.ts
@@ -4,8 +4,6 @@ export * from './converter'
 export * from './error'
 export * from './handler'
 export * from './middleware'
-export * from './runtime'
-export * from './schema'
 
 export type {
   JsonSchema,
diff --git a/packages/effect/src/middleware.test-d.ts b/packages/effect/src/middleware.test-d.ts
index 105d14f0e6..79a972e1a5 100644
--- a/packages/effect/src/middleware.test-d.ts
+++ b/packages/effect/src/middleware.test-d.ts
@@ -1,4 +1,4 @@
-import type { ORPCErrorConstructorMap } from '@orpc/server'
+import type { Middleware, ORPCErrorConstructorMap } from '@orpc/server'
 import type { WithEffectContext } from './context'
 import { os } from '@orpc/server'
 import { Context, Effect } from 'effect'
@@ -184,4 +184,16 @@ describe('middlewareGen', () => {
         return yield* next()
       }))
   })
+
+  it('accepts explicit type arguments in Middleware order with TYield last', () => {
+    const middleware = middlewareGen<WithEffectContext<Service1>, { user: 'user' }, { id: string }, number, typeof errorMap, Effect.Effect<any, any, Service1>>(
+      function* ({ errors, next }, input) {
+        expectTypeOf(input).toEqualTypeOf<{ id: string }>()
+        expectTypeOf(errors).toEqualTypeOf<ORPCErrorConstructorMap<typeof errorMap>>()
+        yield* Service1
+        return yield* next({ context: { user: 'user' as const } })
+      },
+    )
+    expectTypeOf(middleware).toEqualTypeOf<Middleware<WithEffectContext<Service1>, { user: 'user' }, { id: string }, number, typeof errorMap>>()
+  })
 })
diff --git a/packages/effect/src/middleware.ts b/packages/effect/src/middleware.ts
index bd5f456ccc..568898cd26 100644
--- a/packages/effect/src/middleware.ts
+++ b/packages/effect/src/middleware.ts
@@ -25,8 +25,8 @@ export interface MiddlewareGen<
   TOutContext extends Context,
   TInput,
   TOutput,
-  TYield extends Effect.Effect<any, any, InferEffectServices<TInContext>>,
   TErrorConstructorMap extends ORPCErrorConstructorMap<any>,
+  TYield extends Effect.Effect<any, any, InferEffectServices<TInContext>>,
 > {
   (
     opts: MiddlewareGenOptions<TInContext, TOutput, TErrorConstructorMap>,
@@ -57,7 +57,7 @@ export function middlewareGen<
   TErrorMap extends ErrorMap = Record<never, never>,
   TYield extends Effect.Effect<any, any, InferEffectServices<TInContext>> = Effect.Effect<any, any, InferEffectServices<TInContext>>,
 >(
-  middleware: MiddlewareGen<TInContext, TOutContext, TInput, TOutput, TYield, ORPCErrorConstructorMap<TErrorMap>>,
+  middleware: MiddlewareGen<TInContext, TOutContext, TInput, TOutput, ORPCErrorConstructorMap<TErrorMap>, TYield>,
 ): Middleware<TInContext, TOutContext, TInput, TOutput, TErrorMap> {
   const mid: Middleware<TInContext, TOutContext, TInput, TOutput, TErrorMap> = (opts, input, done) => {
     const next: MiddlewareGenNext<TOutput> = <U extends Context = object>(...rest: MaybeOptionalOptions<MiddlewareNextOptions<U>>) => Effect.contextWith(