Declare json-schema metadata decorators with auto dec

.chronus/changes/graphql-regen-auto-accessor-docs-2026-9-2.md

@@ -0,0 +1,8 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/graphql"
+---
+
+Regenerate the decorator signatures to pick up the doc comments now emitted for auto decorator
+accessors.

.chronus/changes/json-schema-auto-decorators-2026-9-2.md

@@ -0,0 +1,27 @@
+---
+changeKind: deprecation
+packages:
+  - "@typespec/json-schema"
+---
+
+The metadata-only decorators of this library are now declared as `auto dec`, so the compiler
+synthesizes their implementation and provides typed accessors. This affects `@baseUri`, `@id`,
+`@oneOf`, `@multipleOf`, `@contains`, `@minContains`, `@maxContains`, `@uniqueItems`,
+`@minProperties`, `@maxProperties`, `@contentEncoding`, `@contentMediaType`, `@contentSchema` and
+`@prefixItems`.
+
+Nothing changes for TypeSpec authors. For JavaScript consumers, the `$baseUri`-style implementation
+functions and their `BaseUriDecorator`-style signature types are deprecated: they are no longer what
+the compiler invokes. Use the generated `set*` accessor to apply a decorator programmatically:
+
+```ts
+// Before
+context.call($minContains, target, 2);
+
+// After
+import { setMinContains } from "@typespec/json-schema";
+setMinContains(program, target, 2);
+```
+
+Applying one of these decorators twice on the same declaration now reports a `duplicate-decorator`
+warning. The last application still wins.

.chronus/changes/tspd-auto-accessor-docs-2026-9-2.md

@@ -0,0 +1,15 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/tspd"
+---
+
+Document the generated auto decorator accessors with the description of the decorator they read or
+write, so libraries re-exporting them satisfy api-extractor's `ae-undocumented` rule.
+
+```ts
+/** Mark a model as a GraphQL input type in the emitted schema. */
+export function isInputType(program: Program, target: Model): boolean {
+  return hasAutoDecorator(program, "TypeSpec.GraphQL.inputType", target);
+}
+```

.chronus/changes/tspd-honor-library-config-2026-9-2.md

@@ -0,0 +1,9 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/tspd"
+---
+
+Honor the library's own `tspconfig.yaml` when generating signatures and reference documentation, so
+libraries that opt into a compiler feature (such as `auto-decorators`) no longer report errors during
+`gen-extern-signature` and `doc`.

packages/graphql/generated-defs/TypeSpec.GraphQL.ts

@@ -184,40 +184,92 @@ export type TypeSpecGraphQLDecorators = {
   specifiedBy: SpecifiedByDecorator;
 };
 
+/**
+ * Mark a model as a GraphQL input type in the emitted schema.
+ *
+ * This decorator is applied automatically by the mutation engine when it produces
+ * a model that is used in input position. The emitter uses this to emit the model
+ * as an `input` type rather than an object `type`.
+ */
 export function isInputType(program: Program, target: Model): boolean {
   return hasAutoDecorator(program, "TypeSpec.GraphQL.inputType", target);
 }
 
+/**
+ * Mark a model as a GraphQL input type in the emitted schema.
+ *
+ * This decorator is applied automatically by the mutation engine when it produces
+ * a model that is used in input position. The emitter uses this to emit the model
+ * as an `input` type rather than an object `type`.
+ */
 export function setInputType(program: Program, target: Model): void {
   setAutoDecorator(program, "TypeSpec.GraphQL.inputType", target);
 }
 
+/**
+ * Mark a field, operation, or type as nullable in the emitted GraphQL schema.
+ *
+ * Applied automatically by the mutation engine when it strips `| null` from
+ * union types, and can also be applied directly in TypeSpec source.
+ */
 export function isNullable(
   program: Program,
   target: ModelProperty | Operation | Union | Model,
 ): boolean {
   return hasAutoDecorator(program, "TypeSpec.GraphQL.nullable", target);
 }
 
+/**
+ * Mark a field, operation, or type as nullable in the emitted GraphQL schema.
+ *
+ * Applied automatically by the mutation engine when it strips `| null` from
+ * union types, and can also be applied directly in TypeSpec source.
+ */
 export function setNullable(
   program: Program,
   target: ModelProperty | Operation | Union | Model,
 ): void {
   setAutoDecorator(program, "TypeSpec.GraphQL.nullable", target);
 }
 
+/**
+ * Mark a field or operation as having nullable array elements in the emitted GraphQL schema.
+ *
+ * Applied automatically by the mutation engine when it detects `Array<T | null>`
+ * patterns. Causes the emitter to emit `[T]` instead of `[T!]`.
+ */
 export function isNullableElements(program: Program, target: ModelProperty | Operation): boolean {
   return hasAutoDecorator(program, "TypeSpec.GraphQL.nullableElements", target);
 }
 
+/**
+ * Mark a field or operation as having nullable array elements in the emitted GraphQL schema.
+ *
+ * Applied automatically by the mutation engine when it detects `Array<T | null>`
+ * patterns. Causes the emitter to emit `[T]` instead of `[T!]`.
+ */
 export function setNullableElements(program: Program, target: ModelProperty | Operation): void {
   setAutoDecorator(program, "TypeSpec.GraphQL.nullableElements", target);
 }
 
+/**
+ * Mark a model as a `@oneOf` input object in the emitted GraphQL schema.
+ *
+ * This decorator is applied automatically by the mutation engine when it converts
+ * a union type in input context to a synthetic input object (since GraphQL unions
+ * are output-only). The emitter uses this to emit the `@oneOf` directive.
+ */
 export function isOneOf(program: Program, target: Model): boolean {
   return hasAutoDecorator(program, "TypeSpec.GraphQL.oneOf", target);
 }
 
+/**
+ * Mark a model as a `@oneOf` input object in the emitted GraphQL schema.
+ *
+ * This decorator is applied automatically by the mutation engine when it converts
+ * a union type in input context to a synthetic input object (since GraphQL unions
+ * are output-only). The emitter uses this to emit the `@oneOf` directive.
+ */
 export function setOneOf(program: Program, target: Model): void {
   setAutoDecorator(program, "TypeSpec.GraphQL.oneOf", target);
 }