diff --git a/src/documentBuilder/InferResult/OutputField.ts b/src/documentBuilder/InferResult/OutputField.ts
index 6f856570b..0f9749144 100644
--- a/src/documentBuilder/InferResult/OutputField.ts
+++ b/src/documentBuilder/InferResult/OutputField.ts
@@ -42,8 +42,8 @@ type GetCodecForCodecless<
   $Schema extends Schema,
   $Node extends Schema.Scalar.ScalarCodecless
 > =
-  $Node['name'] extends keyof $Schema['scalars']['map']
-    ? $Schema['scalars']['map'][$Node['name']]
+  $Node['name'] extends keyof $Schema['scalarRegistry']['map']
+    ? $Schema['scalarRegistry']['map'][$Node['name']]
     : Schema.Scalar.String
 
 // dprint-ignore
diff --git a/src/extensions/SchemaErrors/tests/fixture/graffle/modules/schema.ts b/src/extensions/SchemaErrors/tests/fixture/graffle/modules/schema.ts
index 2fb50a6b2..a66aca603 100644
--- a/src/extensions/SchemaErrors/tests/fixture/graffle/modules/schema.ts
+++ b/src/extensions/SchemaErrors/tests/fixture/graffle/modules/schema.ts
@@ -1732,7 +1732,22 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
     Error: Schema.Error
     Interface: Schema.Interface
   }
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Date'
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Date: Schema.Date
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: {
     SchemaErrors: {
       objectNames: 'ErrorOne' | 'ErrorTwo'
diff --git a/src/generator/generator/__snapshots__/generate.test.ts.snap b/src/generator/generator/__snapshots__/generate.test.ts.snap
index 2deb8706a..56297309a 100644
--- a/src/generator/generator/__snapshots__/generate.test.ts.snap
+++ b/src/generator/generator/__snapshots__/generate.test.ts.snap
@@ -2893,7 +2893,22 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
     Error: Schema.Error
     Interface: Schema.Interface
   }
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Date'
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Date: Schema.Date
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: $$Utilities.GlobalRegistry.TypeExtensions
 }
 "
@@ -7688,7 +7703,13 @@ export interface Schema<
   objects: {};
   unions: {};
   interfaces: {};
-  scalars: $Scalars;
+  scalarNamesUnion: "ID" | "Boolean" | "String";
+  scalars: {
+    ID: Schema.ID;
+    Boolean: Schema.Boolean;
+    String: Schema.String;
+  };
+  scalarRegistry: $Scalars;
   extensions: $$Utilities.GlobalRegistry.TypeExtensions;
 }
 "
diff --git a/src/generator/generators/Schema.ts b/src/generator/generators/Schema.ts
index 3807a40c8..34441b5da 100644
--- a/src/generator/generators/Schema.ts
+++ b/src/generator/generators/Schema.ts
@@ -262,11 +262,15 @@ export const SchemaGenerator = createCodeGenerator(
   ({ config, code }) => {
     const kindMap = config.schema.kindMap
     // dprint-ignore
-    const root = kindMap.list.Root.map(_ => [_.name, `${identifiers.Schema}.${_.name}`])
-    const objects = kindMap.list.OutputObject.map(_ => [_.name, `${identifiers.Schema}.${_.name}`])
-    const unions = kindMap.list.Union.map(_ => [_.name, `${identifiers.Schema}.${_.name}`])
-    const interfaces = kindMap.list.Interface.map(_ => [_.name, `${identifiers.Schema}.${_.name}`])
-    const enums = kindMap.list.Enum.map(_ => [_.name, `${identifiers.Schema}.${_.name}`])
+    const root = kindMap.list.Root.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const)
+    const objects = kindMap.list.OutputObject.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const)
+    const unions = kindMap.list.Union.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const)
+    const interfaces = kindMap.list.Interface.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const)
+    const enums = kindMap.list.Enum.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const)
+    const scalars = [
+      ...kindMap.list.ScalarCustom.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const),
+      ...kindMap.list.ScalarStandard.map(_ => [_.name, `${identifiers.Schema}.${_.name}`] as const),
+    ]
     const operationsAvailable = entries(kindMap.index.Root).filter(_ => _[1] !== null).map(_ => _[0])
     const schema: Code.TermObject = {
       name: `$$Data.Name`,
@@ -290,10 +294,12 @@ export const SchemaGenerator = createCodeGenerator(
         ...unions,
         ...interfaces,
       ]),
-      objects: Object.fromEntries(objects),
-      unions: Object.fromEntries(unions),
-      interfaces: Object.fromEntries(interfaces),
-      scalars: `$Scalars`,
+      objects,
+      unions,
+      interfaces,
+      scalarNamesUnion: Code.tsUnionItems(scalars.map(_ => _[0]).map(Code.string)),
+      scalars,
+      scalarRegistry: `$Scalars`,
       extensions: `${identifiers.$$Utilities}.GlobalRegistry.TypeExtensions`,
     }
 
diff --git a/src/layers/6_client/chainExtensions/scalar.test-d.ts b/src/layers/6_client/chainExtensions/scalar.test-d.ts
index 892070510..586f832e5 100644
--- a/src/layers/6_client/chainExtensions/scalar.test-d.ts
+++ b/src/layers/6_client/chainExtensions/scalar.test-d.ts
@@ -1,7 +1,8 @@
+import { DateScalar, FooScalar } from '../../../../tests/_/fixtures/scalars.js'
 import { schemaMap } from '../../../../tests/_/schemas/kitchen-sink/graffle/__.js'
 import { Graffle } from '../../../entrypoints/__Graffle.js'
 import { assertEqual } from '../../../lib/assert-equal.js'
-import type { SomeFunction } from '../../../lib/prelude.js'
+import { any, type SomeFunction } from '../../../lib/prelude.js'
 import type { TypeErrorMissingSchemaMap } from './scalar.js'
 
 const g1 = Graffle.create({ schema: `foo` })
@@ -9,3 +10,11 @@ assertEqual<typeof g1.scalar, TypeErrorMissingSchemaMap>()
 
 const g2 = Graffle.create({ schema: `foo`, schemaMap })
 assertEqual<typeof g2.scalar, SomeFunction>()
+
+// @ts-expect-error "Foo" is not a scalar name in the schema.
+Graffle.create({ schema: `foo`, schemaMap }).scalar(`Foo`, any)
+// @ts-expect-error "Foo" is not a scalar name in the schema.
+Graffle.create({ schema: `foo`, schemaMap }).scalar(FooScalar)
+Graffle.create({ schema: `foo`, schemaMap }).scalar(`Date`, any)
+Graffle.create({ schema: `foo`, schemaMap }).scalar(DateScalar)
+Graffle.create({ schema: `foo`, schemaMap }).scalar(`Int`, any)
diff --git a/src/layers/6_client/chainExtensions/scalar.ts b/src/layers/6_client/chainExtensions/scalar.ts
index 1fe3448c4..4ca0cb368 100644
--- a/src/layers/6_client/chainExtensions/scalar.ts
+++ b/src/layers/6_client/chainExtensions/scalar.ts
@@ -1,6 +1,7 @@
 import type { Simplify } from 'type-fest'
 import { Chain } from '../../../lib/chain/__.js'
 import type { ConfigManager } from '../../../lib/config-manager/__.js'
+import type { GlobalRegistry } from '../../../types/GlobalRegistry/GlobalRegistry.js'
 import { Schema } from '../../../types/Schema/__.js'
 import { type Context } from '../context.js'
 
@@ -24,11 +25,16 @@ type ScalarMethod<$Args extends Chain.Extension.Parameters<Scalar_>> = {
   /**
    * TODO Docs.
    */
-  // TODO limit $Name to what is in the schema.
-  <$Name extends string, $Decoded>(name: $Name, $Codec: {
-    decode: (value: string) => $Decoded
-    encode: (value: $Decoded) => string
-  }): Chain.Definition.MaterializeWithNewContext<
+  <
+    $Name extends GlobalRegistry.GetOrGeneric<$Args['context']['name']>['schema']['scalarNamesUnion'],
+    $Decoded,
+  >(
+    name: $Name,
+    $Codec: {
+      decode: (value: string) => $Decoded
+      encode: (value: $Decoded) => string
+    },
+  ): Chain.Definition.MaterializeWithNewContext<
     $Args['chain'],
     ConfigManager.SetAtPath<
       $Args['context'],
@@ -42,7 +48,9 @@ type ScalarMethod<$Args extends Chain.Extension.Parameters<Scalar_>> = {
   /*
    * TODO Docs.
    */
-  <$Scalar extends Schema.Scalar>(scalar: $Scalar): Chain.Definition.MaterializeWithNewContext<
+  <$Scalar extends Schema.Scalar<GlobalRegistry.GetOrGeneric<$Args['context']['name']>['schema']['scalarNamesUnion']>>(
+    scalar: $Scalar,
+  ): Chain.Definition.MaterializeWithNewContext<
     $Args['chain'],
     ConfigManager.SetAtPath<
       $Args['context'],
diff --git a/src/lib/prelude.ts b/src/lib/prelude.ts
index 47177d057..c76bd2071 100644
--- a/src/lib/prelude.ts
+++ b/src/lib/prelude.ts
@@ -636,3 +636,5 @@ export type SimplifyExcept<$ExcludeType, $Type> =
     : $Type extends $ExcludeType
       ? $Type
       : {[TypeKey in keyof $Type]: $Type[TypeKey]}
+
+export const any = undefined as any
diff --git a/src/types/Schema/__.ts b/src/types/Schema/__.ts
index e0bfbfb72..70736d592 100644
--- a/src/types/Schema/__.ts
+++ b/src/types/Schema/__.ts
@@ -6,6 +6,7 @@ import type { Enum } from './nodes/Enum.js'
 import type { Interface } from './nodes/Interface.js'
 import type { OutputObject } from './nodes/OutputObject.js'
 import type { Scalar } from './nodes/Scalar/Scalar.js'
+import type { ScalarCodecless } from './nodes/ScalarCodecless.js'
 import type { Union } from './nodes/Union.js'
 // import type { Mutation, Query, RootType, Subscription } from './StandardTypes/object.js'
 
@@ -35,9 +36,11 @@ export interface Schema<
   objects: Record<string, OutputObject>
   unions: Record<string, Union>
   interfaces: Record<string, Interface>
+  scalars: Record<string, Scalar | ScalarCodecless>
+  scalarNamesUnion: string
   /**
-   * A map of scalar definitions. Useful for custom scalars.
+   * A registry of scalar definitions. Useful for custom scalars.
    */
-  scalars: $Scalars
+  scalarRegistry: $Scalars
   extensions: $Extensions
 }
diff --git a/tests/_/fixtures/scalars.ts b/tests/_/fixtures/scalars.ts
index 7426e0933..ddc9575c2 100644
--- a/tests/_/fixtures/scalars.ts
+++ b/tests/_/fixtures/scalars.ts
@@ -4,3 +4,8 @@ export const DateScalar = Graffle.Scalars.create(`Date`, {
   encode: (value: globalThis.Date) => value.toISOString(),
   decode: (value: string) => new globalThis.Date(value),
 })
+
+export const FooScalar = Graffle.Scalars.create(`Foo`, {
+  encode: (value) => String(value),
+  decode: (value) => value,
+})
diff --git a/tests/_/schemas/kitchen-sink/graffle/modules/schema.ts b/tests/_/schemas/kitchen-sink/graffle/modules/schema.ts
index de0c1e5c4..d5ce42788 100644
--- a/tests/_/schemas/kitchen-sink/graffle/modules/schema.ts
+++ b/tests/_/schemas/kitchen-sink/graffle/modules/schema.ts
@@ -1732,6 +1732,21 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
     Error: Schema.Error
     Interface: Schema.Interface
   }
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Date'
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Date: Schema.Date
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: $$Utilities.GlobalRegistry.TypeExtensions
 }
diff --git a/tests/_/schemas/mutation-only/graffle/modules/schema.ts b/tests/_/schemas/mutation-only/graffle/modules/schema.ts
index f69de24e5..cd8e37878 100644
--- a/tests/_/schemas/mutation-only/graffle/modules/schema.ts
+++ b/tests/_/schemas/mutation-only/graffle/modules/schema.ts
@@ -266,6 +266,19 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
   objects: {}
   unions: {}
   interfaces: {}
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: $$Utilities.GlobalRegistry.TypeExtensions
 }
diff --git a/tests/_/schemas/pokemon/graffle/modules/schema.ts b/tests/_/schemas/pokemon/graffle/modules/schema.ts
index f93a82215..4c4cd66ff 100644
--- a/tests/_/schemas/pokemon/graffle/modules/schema.ts
+++ b/tests/_/schemas/pokemon/graffle/modules/schema.ts
@@ -1088,6 +1088,21 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
   interfaces: {
     Being: Schema.Being
   }
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Date'
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Date: Schema.Date
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: $$Utilities.GlobalRegistry.TypeExtensions
 }
diff --git a/tests/_/schemas/query-only/graffle/modules/schema.ts b/tests/_/schemas/query-only/graffle/modules/schema.ts
index f78380d35..86b4bf0ca 100644
--- a/tests/_/schemas/query-only/graffle/modules/schema.ts
+++ b/tests/_/schemas/query-only/graffle/modules/schema.ts
@@ -266,6 +266,19 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
   objects: {}
   unions: {}
   interfaces: {}
-  scalars: $Scalars
+  scalarNamesUnion:
+    | 'Boolean'
+    | 'Float'
+    | 'ID'
+    | 'Int'
+    | 'String'
+  scalars: {
+    Boolean: Schema.Boolean
+    Float: Schema.Float
+    ID: Schema.ID
+    Int: Schema.Int
+    String: Schema.String
+  }
+  scalarRegistry: $Scalars
   extensions: $$Utilities.GlobalRegistry.TypeExtensions
 }
diff --git a/website/graffle/modules/Schema.ts b/website/graffle/modules/Schema.ts
index ab2520e95..1b71ae7e1 100644
--- a/website/graffle/modules/Schema.ts
+++ b/website/graffle/modules/Schema.ts
@@ -1088,6 +1088,21 @@ export interface Schema<$Scalars extends $$Utilities.Schema.Scalar.Registry = $$
   interfaces: {
     Being: Schema.Being;
   };
-  scalars: $Scalars;
+  scalarNamesUnion:
+    | "Date"
+    | "Float"
+    | "ID"
+    | "String"
+    | "Int"
+    | "Boolean";
+  scalars: {
+    Date: Schema.Date;
+    Float: Schema.Float;
+    ID: Schema.ID;
+    String: Schema.String;
+    Int: Schema.Int;
+    Boolean: Schema.Boolean;
+  };
+  scalarRegistry: $Scalars;
   extensions: $$Utilities.GlobalRegistry.TypeExtensions;
 }