diff --git a/packages/effect/src/error.test-d.ts b/packages/effect/src/error.test-d.ts
index 65cd32dce7..05c96d8680 100644
--- a/packages/effect/src/error.test-d.ts
+++ b/packages/effect/src/error.test-d.ts
@@ -1,4 +1,5 @@
-import type { ORPCError, ORPCErrorCode } from '@orpc/server'
+import type { AnyORPCError, ORPCErrorCode } from '@orpc/client'
+import { ORPCError } from '@orpc/client'
 import { Effect } from 'effect'
 import { catchORPCError, catchORPCErrorCode, catchORPCErrorCodes } from './error'
 
@@ -22,6 +23,14 @@ const effectWithHidden = {} as Effect.Effect<
   Service1
 >
 
+const effectWithAny = Effect.fail(new Error('boom') as unknown).pipe(
+  Effect.mapError(error => error instanceof ORPCError ? error : new ORPCError('INTERNAL_SERVER_ERROR')),
+)
+
+const effectWithWide = {} as Effect.Effect<'output', ORPCError<ORPCErrorCode, unknown>>
+const effectWithString = {} as Effect.Effect<'output', ORPCError<string, unknown>>
+const effectWithUnion = {} as Effect.Effect<'output', ORPCError<'NOT_FOUND' | 'CONFLICT', { id: string }>>
+
 describe('catchORPCError', () => {
   it('catches every ORPCError and excludes them from the error channel (data-last)', () => {
     const recovered = effect.pipe(catchORPCError((error) => {
@@ -180,6 +189,81 @@ describe('catchORPCErrorCode', () => {
     // @ts-expect-error - BAD_GATEWAY is not present and the channel cannot hold hidden ORPCErrors
     void withString.pipe(catchORPCErrorCode('BAD_GATEWAY', () => Effect.succeed('recovered')))
   })
+
+  it('keeps AnyORPCError in the error channel and narrows the handler to the caught code', () => {
+    expectTypeOf(effectWithAny).toEqualTypeOf<Effect.Effect<never, AnyORPCError>>()
+
+    const recovered = effectWithAny.pipe(catchORPCErrorCode('NOT_FOUND', (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', any>>()
+      return Effect.succeed(error.code)
+    }))
+
+    expectTypeOf(recovered).toEqualTypeOf<Effect.Effect<'NOT_FOUND', AnyORPCError>>()
+  })
+
+  it('narrows wide codes to the caught code and keeps them in the error channel', () => {
+    const recoveredWide = effectWithWide.pipe(catchORPCErrorCode('NOT_FOUND', (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', unknown>>()
+      return Effect.succeed(error.code)
+    }))
+
+    expectTypeOf(recoveredWide).toEqualTypeOf<Effect.Effect<'output' | 'NOT_FOUND', ORPCError<ORPCErrorCode, unknown>>>()
+
+    const recoveredString = catchORPCErrorCode(effectWithString, 'NOT_FOUND', (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', unknown>>()
+      return Effect.succeed(error.code)
+    })
+
+    expectTypeOf(recoveredString).toEqualTypeOf<Effect.Effect<'output' | 'NOT_FOUND', ORPCError<string, unknown>>>()
+  })
+
+  it('narrows union codes to the caught code and keeps them in the error channel', () => {
+    const recovered = effectWithUnion.pipe(catchORPCErrorCode('NOT_FOUND', (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', { id: string }>>()
+      return Effect.succeed(error.data.id)
+    }))
+
+    expectTypeOf(recovered).toEqualTypeOf<
+      Effect.Effect<'output' | string, ORPCError<'NOT_FOUND' | 'CONFLICT', { id: string }>>
+    >()
+  })
+
+  it('keeps errors in the error channel when the code is not a single literal', () => {
+    const code = {} as 'NOT_FOUND' | 'CONFLICT'
+
+    const recoveredUnion = effect.pipe(catchORPCErrorCode(code, (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', { id: string }> | ORPCError<'CONFLICT', number>>()
+      return Effect.succeed('recovered' as const)
+    }))
+
+    expectTypeOf(recoveredUnion).toEqualTypeOf<
+      Effect.Effect<'output' | 'recovered', ORPCError<'NOT_FOUND', { id: string }> | ORPCError<'CONFLICT', number>, Service1>
+    >()
+
+    const recoveredString = effectWithHidden.pipe(catchORPCErrorCode({} as string, (error) => {
+      expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', { id: string }> | ORPCError<string, unknown>>()
+      return Effect.succeed('recovered' as const)
+    }))
+
+    expectTypeOf(recoveredString).toEqualTypeOf<
+      Effect.Effect<'output' | 'recovered', ORPCError<'NOT_FOUND', { id: string }> | Error, Service1>
+    >()
+  })
+
+  it('keeps ORPCError subclasses', () => {
+    class NotFoundError extends ORPCError<'NOT_FOUND', { id: string }> {
+      declare readonly extra: 'extra'
+    }
+
+    const withSubclass = {} as Effect.Effect<'output', NotFoundError | ORPCError<'CONFLICT', number>>
+
+    const recovered = withSubclass.pipe(catchORPCErrorCode('NOT_FOUND', (error) => {
+      expectTypeOf(error).toEqualTypeOf<NotFoundError>()
+      return Effect.succeed(error.extra)
+    }))
+
+    expectTypeOf(recovered).toEqualTypeOf<Effect.Effect<'output' | 'extra', ORPCError<'CONFLICT', number>>>()
+  })
 })
 
 describe('catchORPCErrorCodes', () => {
@@ -246,4 +330,100 @@ describe('catchORPCErrorCodes', () => {
     // @ts-expect-error - BAD_GATEWAY is not present and the channel cannot hold hidden ORPCErrors
     void withString.pipe(catchORPCErrorCodes({ BAD_GATEWAY: () => Effect.succeed('recovered') }))
   })
+
+  it('keeps AnyORPCError in the error channel', () => {
+    const recovered = effectWithAny.pipe(catchORPCErrorCodes({
+      NOT_FOUND: (error) => {
+        expectTypeOf(error).toEqualTypeOf<AnyORPCError>()
+        return Effect.succeed('nf' as const)
+      },
+    }))
+
+    expectTypeOf(recovered).toEqualTypeOf<Effect.Effect<'nf', AnyORPCError>>()
+  })
+
+  it('types handlers of wide codes and keeps them in the error channel', () => {
+    const recoveredWide = effectWithWide.pipe(catchORPCErrorCodes({
+      NOT_FOUND: (error) => {
+        expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', unknown>>()
+        return Effect.succeed('nf' as const)
+      },
+    }))
+
+    expectTypeOf(recoveredWide).toEqualTypeOf<Effect.Effect<'output' | 'nf', ORPCError<ORPCErrorCode, unknown>>>()
+
+    const recoveredString = catchORPCErrorCodes(effectWithString, {
+      NOT_FOUND: (error) => {
+        expectTypeOf(error).toEqualTypeOf<ORPCError<string, unknown>>()
+        return Effect.succeed('nf' as const)
+      },
+    })
+
+    expectTypeOf(recoveredString).toEqualTypeOf<Effect.Effect<'output' | 'nf', ORPCError<string, unknown>>>()
+  })
+
+  it('types handlers of undeclared keys when the channel can hold hidden ORPCErrors', () => {
+    void effectWithHidden.pipe(catchORPCErrorCodes({
+      __CUSTOM__: (error) => {
+        expectTypeOf(error).toExtend<AnyORPCError>()
+        expectTypeOf(error.code).toExtend<string>()
+        expectTypeOf(error.data).toEqualTypeOf<unknown>()
+        return Effect.succeed('recovered' as const)
+      },
+    }))
+  })
+
+  it('narrows union codes and excludes them only once every code is handled', () => {
+    const recoveredOne = effectWithUnion.pipe(catchORPCErrorCodes({
+      NOT_FOUND: (error) => {
+        expectTypeOf(error).toEqualTypeOf<ORPCError<'NOT_FOUND', { id: string }>>()
+        return Effect.succeed('nf' as const)
+      },
+    }))
+
+    expectTypeOf(recoveredOne).toEqualTypeOf<
+      Effect.Effect<'output' | 'nf', ORPCError<'NOT_FOUND' | 'CONFLICT', { id: string }>>
+    >()
+
+    const recoveredAll = effectWithUnion.pipe(catchORPCErrorCodes({
+      NOT_FOUND: () => Effect.succeed('nf' as const),
+      CONFLICT: (error) => {
+        expectTypeOf(error).toEqualTypeOf<ORPCError<'CONFLICT', { id: string }>>()
+        return Effect.succeed('cf' as const)
+      },
+    }))
+
+    expectTypeOf(recoveredAll).toEqualTypeOf<Effect.Effect<'output' | 'nf' | 'cf', never>>()
+  })
+
+  it('keeps codes whose handler can be undefined in the error channel', () => {
+    const recoveredUndefined = effect.pipe(catchORPCErrorCodes({
+      NOT_FOUND: undefined,
+      CONFLICT: () => Effect.succeed('cf' as const),
+    }))
+
+    expectTypeOf(recoveredUndefined).toEqualTypeOf<
+      Effect.Effect<'output' | 'cf', ORPCError<'NOT_FOUND', { id: string }>, Service1>
+    >()
+
+    const maybeHandler = {} as ((error: ORPCError<'NOT_FOUND', { id: string }>) => Effect.Effect<'nf', RangeError, Service2>) | undefined
+
+    const recoveredMaybe = effect.pipe(catchORPCErrorCodes({ NOT_FOUND: maybeHandler }))
+
+    expectTypeOf(recoveredMaybe).toEqualTypeOf<
+      Effect.Effect<
+        'output' | 'nf',
+        ORPCError<'NOT_FOUND', { id: string }> | ORPCError<'CONFLICT', number> | RangeError,
+        Service1 | Service2
+      >
+    >()
+
+    const optionalCases = {} as { NOT_FOUND?: (error: ORPCError<'NOT_FOUND', { id: string }>) => Effect.Effect<'nf'> }
+
+    const recoveredOptional = effect.pipe(catchORPCErrorCodes(optionalCases))
+
+    expectTypeOf(recoveredOptional).toEqualTypeOf<
+      Effect.Effect<'output' | 'nf', ORPCError<'NOT_FOUND', { id: string }> | ORPCError<'CONFLICT', number>, Service1>
+    >()
+  })
 })
diff --git a/packages/effect/src/error.test.ts b/packages/effect/src/error.test.ts
index fe6addf3bf..8b3f6ea415 100644
--- a/packages/effect/src/error.test.ts
+++ b/packages/effect/src/error.test.ts
@@ -1,4 +1,4 @@
-import { ORPCError } from '@orpc/server'
+import { ORPCError } from '@orpc/client'
 import { Cause, Effect, Exit } from 'effect'
 import { catchORPCError, catchORPCErrorCode, catchORPCErrorCodes } from './error'
 
diff --git a/packages/effect/src/error.ts b/packages/effect/src/error.ts
index 320c49a28b..989d03ae09 100644
--- a/packages/effect/src/error.ts
+++ b/packages/effect/src/error.ts
@@ -1,8 +1,50 @@
-import type { AnyORPCError, ORPCErrorCode } from '@orpc/server'
-import { ORPCError } from '@orpc/server'
+import type { AnyORPCError, ORPCErrorCode } from '@orpc/client'
+import type { Types } from 'effect'
+import { ORPCError } from '@orpc/client'
 import { getOwn } from '@orpc/shared'
 import { Effect, Function } from 'effect'
 
+type AnyEffect = Effect.Effect<any, any, any>
+
+type ORPCErrorsOf<E> = E extends AnyORPCError ? E : AnyORPCError extends E ? ORPCError<ORPCErrorCode, unknown> : never
+
+type ORPCErrorCodeOf<E> = ORPCErrorsOf<E>['code']
+
+type ORPCErrorWithCode<E, TCode extends ORPCErrorCode> = E extends ORPCError<infer UCode, infer UData>
+  ? [Exclude<UCode, TCode>] extends [never]
+      ? E
+      : [UCode & TCode] extends [never] ? never : ORPCError<TCode extends UCode ? TCode : TCode & UCode, UData>
+  : AnyORPCError extends E ? ORPCError<TCode, unknown> : never
+
+type ExcludeORPCErrorCode<E, TCode extends string> = E extends ORPCError<infer UCode, any>
+  ? [Exclude<UCode, TCode>] extends [never] ? never : E
+  : E
+
+type LiteralORPCErrorCode<TCode extends string> = Types.IsUnion<TCode> extends true
+  ? never
+  : Record<never, never> extends Record<TCode, unknown> ? never : TCode
+
+type ORPCErrorCodeCases<E, TCases> = Types.NoExcessProperties<{
+  [K in ORPCErrorCodeOf<E>]?: Record<never, never> extends Record<K, unknown>
+    ? { bivarianceHack(error: ORPCErrorWithCode<E, K>): AnyEffect }['bivarianceHack']
+    : (error: ORPCErrorWithCode<E, K>) => AnyEffect
+}, TCases>
+
+/**
+ * The codes `TCases` surely handles: required keys with a function value.
+ */
+type HandledORPCErrorCodes<TCases> = {
+  [K in keyof TCases]-?: TCases[K] extends (...args: any[]) => any ? K : never
+}[Types.RequiredKeys<TCases>] & string
+
+type ORPCErrorCodeCasesEffect<TCases> = ReturnType<Extract<TCases[keyof TCases], (...args: any[]) => any>>
+
+type CatchORPCErrorCodesEffect<A, E, R, TCases> = Effect.Effect<
+  A | Effect.Success<ORPCErrorCodeCasesEffect<TCases>>,
+  ExcludeORPCErrorCode<E, HandledORPCErrorCodes<TCases>> | Effect.Error<ORPCErrorCodeCasesEffect<TCases>>,
+  R | Effect.Services<ORPCErrorCodeCasesEffect<TCases>>
+>
+
 /**
  * Recovers from `ORPCError` failures in the error channel of an effect.
  * Other failures re-fail with their original cause. Because failure types
@@ -25,17 +67,17 @@ import { Effect, Function } from 'effect'
  */
 export const catchORPCError: {
   <E, A2, E2, R2>(
-    f: (error: E extends AnyORPCError ? E : AnyORPCError extends E ? ORPCError<ORPCErrorCode, unknown> : never) => Effect.Effect<A2, E2, R2>,
+    f: (error: ORPCErrorsOf<E>) => Effect.Effect<A2, E2, R2>,
   ): <A, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A | A2, E2 | Exclude<E, AnyORPCError>, R | R2>
   <A, E, R, A2, E2, R2>(
     self: Effect.Effect<A, E, R>,
-    f: (error: E extends AnyORPCError ? E : AnyORPCError extends E ? ORPCError<ORPCErrorCode, unknown> : never) => Effect.Effect<A2, E2, R2>,
+    f: (error: ORPCErrorsOf<E>) => Effect.Effect<A2, E2, R2>,
   ): Effect.Effect<A | A2, E2 | Exclude<E, AnyORPCError>, R | R2>
 } = Function.dual(
   2,
   (
-    self: Effect.Effect<any, any, any>,
-    f: (error: AnyORPCError) => Effect.Effect<any, any, any>,
+    self: AnyEffect,
+    f: (error: AnyORPCError) => AnyEffect,
   ) => self.pipe(
     Effect.catchIf((error): error is AnyORPCError => error instanceof ORPCError, f),
   ),
@@ -66,21 +108,21 @@ export const catchORPCError: {
  * @see {@link https://orpc.dev/docs/integrations/effect#catching-orpcerrors | Effect Integration - Catching ORPCErrors}
  */
 export const catchORPCErrorCode: {
-  <const TCode extends E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never, E, A2, E2, R2>(
+  <const TCode extends ORPCErrorCodeOf<E>, E, A2, E2, R2>(
     code: TCode,
-    f: (error: E extends AnyORPCError ? Extract<E, ORPCError<TCode, any>> : AnyORPCError extends E ? ORPCError<TCode, unknown> : never) => Effect.Effect<A2, E2, R2>,
-  ): <A, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A | A2, E2 | Exclude<E, ORPCError<TCode, any>>, R | R2>
-  <A, E, R, const TCode extends E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never, A2, E2, R2>(
+    f: (error: ORPCErrorWithCode<E, TCode>) => Effect.Effect<A2, E2, R2>,
+  ): <A, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<A | A2, E2 | ExcludeORPCErrorCode<E, LiteralORPCErrorCode<TCode>>, R | R2>
+  <A, E, R, const TCode extends ORPCErrorCodeOf<E>, A2, E2, R2>(
     self: Effect.Effect<A, E, R>,
     code: TCode,
-    f: (error: E extends AnyORPCError ? Extract<E, ORPCError<TCode, any>> : AnyORPCError extends E ? ORPCError<TCode, unknown> : never) => Effect.Effect<A2, E2, R2>,
-  ): Effect.Effect<A | A2, E2 | Exclude<E, ORPCError<TCode, any>>, R | R2>
+    f: (error: ORPCErrorWithCode<E, TCode>) => Effect.Effect<A2, E2, R2>,
+  ): Effect.Effect<A | A2, E2 | ExcludeORPCErrorCode<E, LiteralORPCErrorCode<TCode>>, R | R2>
 } = Function.dual(
   3,
   (
-    self: Effect.Effect<any, any, any>,
+    self: AnyEffect,
     code: ORPCErrorCode,
-    f: (error: AnyORPCError) => Effect.Effect<any, any, any>,
+    f: (error: AnyORPCError) => AnyEffect,
   ) => self.pipe(
     Effect.catchIf((error): error is AnyORPCError => error instanceof ORPCError && error.code === code, f),
   ),
@@ -114,48 +156,18 @@ export const catchORPCErrorCode: {
  * @see {@link https://orpc.dev/docs/integrations/effect#catching-orpcerrors | Effect Integration - Catching ORPCErrors}
  */
 export const catchORPCErrorCodes: {
-  <
-    E,
-    Cases extends
-    & { [K in E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never]?: string extends K
-      ? (error: never) => Effect.Effect<any, any, any>
-      : K extends infer C extends ORPCErrorCode
-        ? (error: E extends AnyORPCError ? Extract<E, ORPCError<C, any>> : AnyORPCError extends E ? ORPCError<C, unknown> : never) => Effect.Effect<any, any, any>
-        : never }
-        & { [K in Exclude<keyof Cases, E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never>]: never },
-  >(
+  <E, Cases extends ORPCErrorCodeCases<E, Cases>>(
     cases: Cases,
-  ): <A, R>(self: Effect.Effect<A, E, R>) => Effect.Effect<
-    A | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<infer A2, any, any> ? A2 : never }[keyof Cases],
-    | Exclude<E, ORPCError<keyof Cases & ORPCErrorCode, any>>
-    | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<any, infer E2, any> ? E2 : never }[keyof Cases],
-    R | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<any, any, infer R2> ? R2 : never }[keyof Cases]
-  >
-  <
-    A,
-    E,
-    R,
-    Cases extends
-    & { [K in E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never]?: string extends K
-      ? (error: never) => Effect.Effect<any, any, any>
-      : K extends infer C extends ORPCErrorCode
-        ? (error: E extends AnyORPCError ? Extract<E, ORPCError<C, any>> : AnyORPCError extends E ? ORPCError<C, unknown> : never) => Effect.Effect<any, any, any>
-        : never }
-        & { [K in Exclude<keyof Cases, E extends ORPCError<infer TCode, any> ? TCode : AnyORPCError extends E ? ORPCErrorCode : never>]: never },
-  >(
+  ): <A, R>(self: Effect.Effect<A, E, R>) => CatchORPCErrorCodesEffect<A, E, R, Cases>
+  <A, E, R, Cases extends ORPCErrorCodeCases<E, Cases>>(
     self: Effect.Effect<A, E, R>,
     cases: Cases,
-  ): Effect.Effect<
-    A | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<infer A2, any, any> ? A2 : never }[keyof Cases],
-    | Exclude<E, ORPCError<keyof Cases & ORPCErrorCode, any>>
-    | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<any, infer E2, any> ? E2 : never }[keyof Cases],
-    R | { [K in keyof Cases]: Cases[K] extends (...args: any[]) => Effect.Effect<any, any, infer R2> ? R2 : never }[keyof Cases]
-  >
+  ): CatchORPCErrorCodesEffect<A, E, R, Cases>
 } = Function.dual(
   2,
   (
-    self: Effect.Effect<any, any, any>,
-    cases: Record<string, ((error: AnyORPCError) => Effect.Effect<any, any, any>) | undefined>,
+    self: AnyEffect,
+    cases: Record<string, ((error: AnyORPCError) => AnyEffect) | undefined>,
   ) => self.pipe(
     Effect.catchIf(
       (error): error is AnyORPCError => error instanceof ORPCError && typeof getOwn(cases, error.code) === 'function',