diff --git a/.changeset/big-eyes-talk.md b/.changeset/big-eyes-talk.md
new file mode 100644
index 0000000000..7c8c4cb32f
--- /dev/null
+++ b/.changeset/big-eyes-talk.md
@@ -0,0 +1,5 @@
+---
+"@effect/schema": patch
+---
+
+Remove `Simplify` from `extend`, `pick`, `omit`, `pluck` APIs, closes #2989, #2990
diff --git a/packages/schema/dtslint/Context.ts b/packages/schema/dtslint/Context.ts
index 6698a29382..67aec64433 100644
--- a/packages/schema/dtslint/Context.ts
+++ b/packages/schema/dtslint/Context.ts
@@ -212,14 +212,14 @@ S.Struct({ a: aContext, b: bContext })
 // pick
 // ---------------------------------------------
 
-// $ExpectType SchemaClass<{ readonly a: string; }, { readonly a: string; }, "aContext" | "bContext">
+// $ExpectType SchemaClass<Pick<{ readonly a: string; readonly b: number; }, "a">, Pick<{ readonly a: string; readonly b: number; }, "a">, "aContext" | "bContext">
 S.Struct({ a: aContext, b: bContext }).pipe(S.pick("a"))
 
 // ---------------------------------------------
 // omit
 // ---------------------------------------------
 
-// $ExpectType SchemaClass<{ readonly a: string; }, { readonly a: string; }, "aContext" | "bContext">
+// $ExpectType SchemaClass<Omit<{ readonly a: string; readonly b: number; }, "b">, Omit<{ readonly a: string; readonly b: number; }, "b">, "aContext" | "bContext">
 S.Struct({ a: aContext, b: bContext }).pipe(S.omit("b"))
 
 // ---------------------------------------------
@@ -267,7 +267,7 @@ S.Record(aContext, bContext)
 // extend
 // ---------------------------------------------
 
-// $ExpectType Schema<{ readonly a: string; readonly b: number; readonly c: boolean; }, { readonly a: string; readonly b: number; readonly c: boolean; }, "aContext" | "bContext" | "cContext">
+// $ExpectType Schema<{ readonly a: string; readonly b: number; } & { readonly c: boolean; }, { readonly a: string; readonly b: number; } & { readonly c: boolean; }, "aContext" | "bContext" | "cContext">
 S.asSchema(S.Struct({ a: aContext, b: bContext }).pipe(S.extend(S.Struct({ c: cContext }))))
 
 // $ExpectType extend<Struct<{ a: aContext; b: bContext; }>, Struct<{ c: cContext; }>>
diff --git a/packages/schema/dtslint/Schema.ts b/packages/schema/dtslint/Schema.ts
index 7f86eb9c49..199b7785cd 100644
--- a/packages/schema/dtslint/Schema.ts
+++ b/packages/schema/dtslint/Schema.ts
@@ -863,29 +863,29 @@ S.Struct({ a: S.String.pipe(S.optional({ exact: true, nullable: true, as: "Optio
 // @ts-expect-error
 pipe(S.Struct({ a: S.propertySignature(S.Number).pipe(S.fromKey("c")) }), S.pick("a"))
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a: string; readonly b: number; }, never>
+// $ExpectType SchemaClass<Pick<{ readonly a: string; readonly b: number; readonly c: boolean; }, "a" | "b">, Pick<{ readonly a: string; readonly b: number; readonly c: boolean; }, "a" | "b">, never>
 pipe(S.Struct({ a: S.String, b: S.Number, c: S.Boolean }), S.pick("a", "b"))
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Pick<{ readonly a: string; readonly b: number; readonly c: boolean; }, "a" | "b">, Pick<{ readonly a: string; readonly b: string; readonly c: boolean; }, "a" | "b">, never>
 pipe(S.Struct({ a: S.String, b: S.NumberFromString, c: S.Boolean }), S.pick("a", "b"))
 
 // ---------------------------------------------
 // pick - optional
 // ---------------------------------------------
 
-// $ExpectType SchemaClass<{ readonly a?: string; readonly b: number; }, { readonly a?: string; readonly b: number; }, never>
+// $ExpectType SchemaClass<Pick<{ readonly a?: string; readonly b: number; readonly c: boolean; }, "a" | "b">, Pick<{ readonly b: number; readonly c: boolean; readonly a?: string; }, "a" | "b">, never>
 pipe(
   S.Struct({ a: S.optional(S.String, { exact: true }), b: S.Number, c: S.Boolean }),
   S.pick("a", "b")
 )
 
-// $ExpectType SchemaClass<{ readonly a?: string; readonly b: number; }, { readonly a?: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Pick<{ readonly a?: string; readonly b: number; readonly c: boolean; }, "a" | "b">, Pick<{ readonly b: string; readonly c: boolean; readonly a?: string; }, "a" | "b">, never>
 pipe(
   S.Struct({ a: S.optional(S.String, { exact: true }), b: S.NumberFromString, c: S.Boolean }),
   S.pick("a", "b")
 )
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a?: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Pick<{ readonly a: string; readonly b: number; readonly c: boolean; }, "a" | "b">, Pick<{ readonly b: string; readonly c: boolean; readonly a?: string; }, "a" | "b">, never>
 pipe(
   S.Struct({
     a: S.optional(S.String, { exact: true, default: () => "" }),
@@ -902,26 +902,26 @@ pipe(
 // @ts-expect-error
 pipe(S.Struct({ a: S.propertySignature(S.Number).pipe(S.fromKey("c")) }), S.omit("a"))
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a: string; readonly b: number; }, never>
+// $ExpectType SchemaClass<Omit<{ readonly a: string; readonly b: number; readonly c: boolean; }, "c">, Omit<{ readonly a: string; readonly b: number; readonly c: boolean; }, "c">, never>
 pipe(S.Struct({ a: S.String, b: S.Number, c: S.Boolean }), S.omit("c"))
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Omit<{ readonly a: string; readonly b: number; readonly c: boolean; }, "c">, Omit<{ readonly a: string; readonly b: string; readonly c: boolean; }, "c">, never>
 pipe(S.Struct({ a: S.String, b: S.NumberFromString, c: S.Boolean }), S.omit("c"))
 
 // ---------------------------------------------
 // omit - optional
 // ---------------------------------------------
 
-// $ExpectType SchemaClass<{ readonly a?: string; readonly b: number; }, { readonly a?: string; readonly b: number; }, never>
+// $ExpectType SchemaClass<Omit<{ readonly a?: string; readonly b: number; readonly c: boolean; }, "c">, Omit<{ readonly b: number; readonly c: boolean; readonly a?: string; }, "c">, never>
 pipe(S.Struct({ a: S.optional(S.String, { exact: true }), b: S.Number, c: S.Boolean }), S.omit("c"))
 
-// $ExpectType SchemaClass<{ readonly a?: string; readonly b: number; }, { readonly a?: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Omit<{ readonly a?: string; readonly b: number; readonly c: boolean; }, "c">, Omit<{ readonly b: string; readonly c: boolean; readonly a?: string; }, "c">, never>
 pipe(
   S.Struct({ a: S.optional(S.String, { exact: true }), b: S.NumberFromString, c: S.Boolean }),
   S.omit("c")
 )
 
-// $ExpectType SchemaClass<{ readonly a: string; readonly b: number; }, { readonly a?: string; readonly b: string; }, never>
+// $ExpectType SchemaClass<Omit<{ readonly a: string; readonly b: number; readonly c: boolean; }, "c">, Omit<{ readonly b: string; readonly c: boolean; readonly a?: string; }, "c">, never>
 pipe(
   S.Struct({
     a: S.optional(S.String, { exact: true, default: () => "" }),
@@ -1058,7 +1058,7 @@ S.Record(S.String.pipe(S.brand(Symbol.for("UserId"))), S.String)
 // extend
 // ---------------------------------------------
 
-// $ExpectType Schema<{ readonly a: string; readonly b: string; readonly c: string; }, { readonly a: string; readonly b: string; readonly c: string; }, never>
+// $ExpectType Schema<{ readonly a: string; readonly b: string; } & { readonly c: string; }, { readonly a: string; readonly b: string; } & { readonly c: string; }, never>
 S.asSchema(pipe(
   S.Struct({ a: S.String, b: S.String }),
   S.extend(S.Struct({ c: S.String }))
@@ -1070,19 +1070,19 @@ pipe(
   S.extend(S.Struct({ c: S.String }))
 )
 
-// $ExpectType Schema<{ readonly a: string; readonly b: string; readonly c: string; }, { readonly a: string; readonly b: string; readonly c: string; }, never>
+// $ExpectType Schema<{ readonly a: string; readonly b: string; } & { readonly c: string; }, { readonly a: string; readonly b: string; } & { readonly c: string; }, never>
 S.asSchema(S.extend(S.Struct({ a: S.String, b: S.String }), S.Struct({ c: S.String })))
 
 // $ExpectType extend<Struct<{ a: typeof String$; b: typeof String$; }>, Struct<{ c: typeof String$; }>>
 S.extend(S.Struct({ a: S.String, b: S.String }), S.Struct({ c: S.String }))
 
-// $ExpectType Schema<{ readonly a: string; readonly b: number; } | { readonly a: string; readonly c: boolean; }, { readonly a: string; readonly b: number; } | { readonly a: string; readonly c: boolean; }, never>
+// $ExpectType Schema<{ readonly a: string; } & ({ readonly b: number; } | { readonly c: boolean; }), { readonly a: string; } & ({ readonly b: number; } | { readonly c: boolean; }), never>
 S.asSchema(S.extend(S.Struct({ a: S.String }), S.Union(S.Struct({ b: S.Number }), S.Struct({ c: S.Boolean }))))
 
 // $ExpectType extend<Struct<{ a: typeof String$; }>, Union<[Struct<{ b: typeof Number$; }>, Struct<{ c: typeof Boolean$; }>]>>
 S.extend(S.Struct({ a: S.String }), S.Union(S.Struct({ b: S.Number }), S.Struct({ c: S.Boolean })))
 
-// $ExpectType Schema<{ readonly [x: string]: string; readonly a: string; readonly b: string; readonly c: string; }, { readonly [x: string]: string; readonly a: string; readonly b: string; readonly c: string; }, never>
+// $ExpectType Schema<{ readonly a: string; readonly b: string; } & { readonly c: string; } & { readonly [x: string]: string; }, { readonly a: string; readonly b: string; } & { readonly c: string; } & { readonly [x: string]: string; }, never>
 S.asSchema(pipe(
   S.Struct({ a: S.String, b: S.String }),
   S.extend(S.Struct({ c: S.String })),
@@ -1454,16 +1454,16 @@ S.asSchema(S.mutable(S.transform(S.Array(S.String), S.Array(S.String), { decode:
 // $ExpectType mutable<transform<Array$<typeof String$>, Array$<typeof String$>>>
 S.mutable(S.transform(S.Array(S.String), S.Array(S.String), { decode: identity, encode: identity }))
 
-// $ExpectType Schema<{ a: string; b: number; }, { a: string; b: number; }, never>
+// $ExpectType Schema<{ a: string; } & { b: number; }, { a: string; } & { b: number; }, never>
 S.asSchema(S.extend(S.mutable(S.Struct({ a: S.String })), S.mutable(S.Struct({ b: S.Number }))))
 
-// $ExpectType Schema<{ a: string; readonly b: number; }, { a: string; readonly b: number; }, never>
+// $ExpectType Schema<{ a: string; } & { readonly b: number; }, { a: string; } & { readonly b: number; }, never>
 S.asSchema(S.extend(S.mutable(S.Struct({ a: S.String })), S.Struct({ b: S.Number })))
 
-// $ExpectType Schema<{ [x: string]: string; a: string; }, { [x: string]: string; a: string; }, never>
+// $ExpectType Schema<{ a: string; } & { [x: string]: string; }, { a: string; } & { [x: string]: string; }, never>
 S.asSchema(S.extend(S.mutable(S.Struct({ a: S.String })), S.mutable(S.Record(S.String, S.String))))
 
-// $ExpectType Schema<{ readonly [x: string]: string; a: string; }, { readonly [x: string]: string; a: string; }, never>
+// $ExpectType Schema<{ a: string; } & { readonly [x: string]: string; }, { a: string; } & { readonly [x: string]: string; }, never>
 S.asSchema(S.extend(S.mutable(S.Struct({ a: S.String })), S.Record(S.String, S.String)))
 
 // ---------------------------------------------
diff --git a/packages/schema/dtslint/generic.ts b/packages/schema/dtslint/generic.ts
new file mode 100644
index 0000000000..2dad72b345
--- /dev/null
+++ b/packages/schema/dtslint/generic.ts
@@ -0,0 +1,37 @@
+import { Schema } from "@effect/schema"
+import { Either } from "effect"
+
+export const f1 = <A extends object, I extends object, R>(
+  resultSchema: Schema.Schema<A, I, R>
+) => {
+  const left = Schema.Struct({
+    ok: Schema.Literal(false),
+    error: Schema.String
+  })
+  const right = <A, I, R>(
+    resultSchema: Schema.Schema<A, I, R>
+  ) => Schema.extend(Schema.Struct({ ok: Schema.Literal(true) }), resultSchema)
+  const union = Schema.Union(left, right(resultSchema))
+  const out = Schema.transform(
+    union,
+    Schema.EitherFromSelf({ left: Schema.String, right: Schema.typeSchema(resultSchema) }),
+    {
+      decode: (u) => u.ok ? Either.right(u) : Either.left(u.error),
+      encode: (a) => ({ ok: true as const, ...a })
+    }
+  )
+  return out
+}
+
+type Model = { id: string } & Record<string, unknown>
+
+export const f2 = <T extends Model>(schema: Schema.Schema<T>) => {
+  type Patch = Pick<T, "id"> & Partial<Omit<T, "id">>
+
+  const patch: Schema.Schema<Patch> = schema.pipe(
+    Schema.pick("id"),
+    Schema.extend(schema.pipe(Schema.omit("id"), Schema.partial()))
+  )
+
+  return patch
+}
diff --git a/packages/schema/src/Schema.ts b/packages/schema/src/Schema.ts
index dc1556231e..d7747ef1b6 100644
--- a/packages/schema/src/Schema.ts
+++ b/packages/schema/src/Schema.ts
@@ -2632,8 +2632,7 @@ export const Record = <K extends Schema.All, V extends Schema.All>(key: K, value
 export const pick = <A, I, Keys extends ReadonlyArray<keyof A & keyof I>>(...keys: Keys) =>
 <R>(
   self: Schema<A, I, R>
-): SchemaClass<Types.Simplify<Pick<A, Keys[number]>>, Types.Simplify<Pick<I, Keys[number]>>, R> =>
-  make(AST.pick(self.ast, keys))
+): SchemaClass<Pick<A, Keys[number]>, Pick<I, Keys[number]>, R> => make(AST.pick(self.ast, keys))
 
 /**
  * @category struct transformations
@@ -2642,8 +2641,7 @@ export const pick = <A, I, Keys extends ReadonlyArray<keyof A & keyof I>>(...key
 export const omit = <A, I, Keys extends ReadonlyArray<keyof A & keyof I>>(...keys: Keys) =>
 <R>(
   self: Schema<A, I, R>
-): SchemaClass<Types.Simplify<Omit<A, Keys[number]>>, Types.Simplify<Omit<I, Keys[number]>>, R> =>
-  make(AST.omit(self.ast, keys))
+): SchemaClass<Omit<A, Keys[number]>, Omit<I, Keys[number]>, R> => make(AST.omit(self.ast, keys))
 
 /**
  * Given a schema `Schema<A, I, R>` and a key `key: K`, this function extracts a specific field from the `A` type,
@@ -2686,7 +2684,7 @@ export const pluck: {
   <A, I, R, K extends keyof A & keyof I>(
     schema: Schema<A, I, R>,
     key: K
-  ): Schema<A[K], Types.Simplify<Pick<I, K>>, R> => {
+  ): Schema<A[K], Pick<I, K>, R> => {
     const ps = AST.getPropertyKeyIndexedAccess(AST.typeAST(schema.ast), key)
     const value = make<A[K], A[K], R>(ps.isOptional ? AST.orUndefined(ps.type) : ps.type)
     return transform(
@@ -2971,8 +2969,8 @@ const intersectUnionMembers = (
 export interface extend<Self extends Schema.Any, That extends Schema.Any> extends
   AnnotableClass<
     extend<Self, That>,
-    Types.Simplify<Schema.Type<Self> & Schema.Type<That>>,
-    Types.Simplify<Schema.Encoded<Self> & Schema.Encoded<That>>,
+    Schema.Type<Self> & Schema.Type<That>,
+    Schema.Encoded<Self> & Schema.Encoded<That>,
     Schema.Context<Self> | Schema.Context<That>
   >
 {}
@@ -3007,19 +3005,11 @@ export interface extend<Self extends Schema.Any, That extends Schema.Any> extend
  * @since 0.67.0
  */
 export const extend: {
-  <That extends Schema.Any>(
-    that: That
-  ): <Self extends Schema.Any>(self: Self) => extend<Self, That>
-  <Self extends Schema.Any, That extends Schema.Any>(
-    self: Self,
-    that: That
-  ): extend<Self, That>
+  <That extends Schema.Any>(that: That): <Self extends Schema.Any>(self: Self) => extend<Self, That>
+  <Self extends Schema.Any, That extends Schema.Any>(self: Self, that: That): extend<Self, That>
 } = dual(
   2,
-  <Self extends Schema.Any, That extends Schema.Any>(
-    self: Self,
-    that: That
-  ) => make(extendAST(self.ast, that.ast, []))
+  <Self extends Schema.Any, That extends Schema.Any>(self: Self, that: That) => make(extendAST(self.ast, that.ast, []))
 )
 
 /**