Updates to derive and lift

packages/api/index.ts

@@ -452,12 +452,12 @@ export type DeriveFunction = {
     input: Opaque<SchemaWithoutCell<InputSchema>>,
     f: (
       input: Schema<InputSchema>,
-    ) => Schema<ResultSchema> | Promise<Schema<ResultSchema>>,
+    ) => Schema<ResultSchema>,
   ): OpaqueRef<SchemaWithoutCell<ResultSchema>>;
 
   <In, Out>(
     input: Opaque<In>,
-    f: (input: In) => Out | Promise<Out>,
+    f: (input: In) => Out,
   ): OpaqueRef<Out>;
 };
 

packages/runner/src/builder/module.ts

@@ -186,30 +186,30 @@ export function derive<
   input: Opaque<SchemaWithoutCell<InputSchema>>,
   f: (
     input: Schema<InputSchema>,
-  ) => Schema<ResultSchema> | Promise<Schema<ResultSchema>>,
+  ) => Schema<ResultSchema>,
 ): OpaqueRef<SchemaWithoutCell<ResultSchema>>;
 export function derive<In, Out>(
   input: Opaque<In>,
-  f: (input: In) => Out | Promise<Out>,
+  f: (input: In) => Out,
 ): OpaqueRef<Out>;
 export function derive<In, Out>(...args: any[]): OpaqueRef<any> {
   if (args.length === 4) {
     const [argumentSchema, resultSchema, input, f] = args as [
       JSONSchema,
       JSONSchema,
       Opaque<SchemaWithoutCell<any>>,
-      (input: Schema<any>) => Schema<any> | Promise<Schema<any>>,
+      (input: Schema<any>) => Schema<any>,
     ];
     return lift(
       argumentSchema,
       resultSchema,
-      f as (input: Schema<any>) => Schema<any> | Promise<Schema<any>>,
+      f as (input: Schema<any>) => Schema<any>,
     )(input);
   }
 
   const [input, f] = args as [
     Opaque<In>,
-    (input: In) => Out | Promise<Out>,
+    (input: In) => Out,
   ];
   return lift(f)(input);
 }

packages/schema-generator/src/formatters/array-formatter.ts

@@ -33,13 +33,16 @@ export class ArrayFormatter implements TypeFormatter {
       );
     }
 
-    // Handle special cases for any[] and never[] with JSON Schema shortcuts
+    // Handle special cases for any[], unknown[], and never[] with JSON Schema shortcuts
     const elementFlags = info.elementType.flags;
 
-    if (
-      (elementFlags & ts.TypeFlags.Any) || (elementFlags & ts.TypeFlags.Unknown)
-    ) {
-      // any[] or unknown[] - allow any item type
+    if (elementFlags & ts.TypeFlags.Any) {
+      // any[] - allow any item type
+      return { type: "array", items: true };
+    }
+
+    if (elementFlags & ts.TypeFlags.Unknown) {
+      // unknown[] - allow any item type (type safety at compile time)
       return { type: "array", items: true };
     }
 

packages/schema-generator/src/formatters/common-tools-formatter.ts

@@ -109,14 +109,17 @@ export class CommonToolsFormatter implements TypeFormatter {
       );
     }
 
-    // Prepare inner context (preserve node when available)
-    const innerContext = innerTypeNode
-      ? { ...context, typeNode: innerTypeNode }
-      : context;
+    // Don't pass synthetic TypeNodes - they lose type information (especially for arrays)
+    // Synthetic nodes have pos === -1 and end === -1
+    // But DO pass real TypeNodes from source code for proper type detection (e.g., Default)
+    const isSyntheticNode = innerTypeNode && innerTypeNode.pos === -1 &&
+      innerTypeNode.end === -1;
+
+    const shouldPassTypeNode = innerTypeNode && !isSyntheticNode;
     const innerSchema = this.schemaGenerator.formatChildType(
       innerType,
-      innerContext,
-      innerTypeNode,
+      context,
+      shouldPassTypeNode ? innerTypeNode : undefined,
     );
 
     // Stream<T>: do not reflect inner Cell-ness; only mark asStream
@@ -243,7 +246,18 @@ export class CommonToolsFormatter implements TypeFormatter {
       defaultTypeNode,
       context,
     );
+
     if (defaultValue !== undefined) {
+      // JSON Schema Draft 2020-12 allows default as a sibling of $ref
+      // Simply add the default property directly to the schema
+      if (typeof valueSchema === "boolean") {
+        // Boolean schemas (true/false) cannot have properties directly
+        // For true: { default: value } (any value is valid)
+        // For false: { not: true, default: value } (no value is valid)
+        return valueSchema === false
+          ? { not: true, default: defaultValue } as SchemaDefinition
+          : { default: defaultValue } as SchemaDefinition;
+      }
       (valueSchema as any).default = defaultValue;
     }
 

packages/schema-generator/src/formatters/intersection-formatter.ts

@@ -186,7 +186,7 @@ export class IntersectionFormatter implements TypeFormatter {
       typeof (schema as Record<string, unknown>).$ref === "string"
     ) {
       const ref = (schema as Record<string, unknown>).$ref as string;
-      const prefix = "#/definitions/";
+      const prefix = "#/$defs/";
       if (ref.startsWith(prefix)) {
         const name = ref.slice(prefix.length);
         const def = context.definitions[name];

packages/schema-generator/src/formatters/primitive-formatter.ts

@@ -64,20 +64,28 @@ export class PrimitiveFormatter implements TypeFormatter {
       return { type: "null" };
     }
     if (flags & ts.TypeFlags.Undefined) {
-      // undefined cannot occur in JSON - return {} which matches anything
-      return {};
+      // undefined: return true to indicate "accept any value"
+      // undefined is handled at runtime/compile time, not by JSON schema validation
+      return true;
     }
     if (flags & ts.TypeFlags.Void) {
-      // void cannot occur in JSON - return {} which matches anything
-      return {};
+      // void: return true to indicate "accept any value"
+      // void functions don't return meaningful values, so schema validation is permissive
+      return true;
     }
     if (flags & ts.TypeFlags.Never) {
-      // never cannot occur in JSON - return {} which matches anything
-      return {};
+      // never: return false to reject all values
+      // never means this type can never occur, so no value should validate
+      return false;
     }
-    if ((flags & ts.TypeFlags.Unknown) || (flags & ts.TypeFlags.Any)) {
-      // unknown/any can be any JSON value (primitive or object) - {} matches everything
-      return {};
+    if (flags & ts.TypeFlags.Any) {
+      // any: return true to indicate "allow any value"
+      return true;
+    }
+    if (flags & ts.TypeFlags.Unknown) {
+      // unknown: return true to indicate "accept any value"
+      // Type safety is enforced at compile time via TypeScript narrowing
+      return true;
     }
 
     // Fallback

packages/schema-generator/src/schema-generator.ts

@@ -156,7 +156,7 @@ export class SchemaGenerator implements ISchemaGenerator {
     // Hoist every named type (excluding wrappers filtered by getNamedTypeKey)
     // into definitions and return $ref for non-root uses. Cycle detection
     // still applies via definitionStack.
-    let namedKey = getNamedTypeKey(type);
+    let namedKey = getNamedTypeKey(type, context.typeNode);
     if (!namedKey) {
       const synthetic = context.anonymousNames.get(type);
       if (synthetic) namedKey = synthetic;
@@ -170,7 +170,7 @@ export class SchemaGenerator implements ISchemaGenerator {
         context.definitionStack.delete(
           this.createStackKey(type, context.typeNode, context.typeChecker),
         );
-        return { "$ref": `#/definitions/${namedKey}` };
+        return { "$ref": `#/$defs/${namedKey}` };
       }
       // Start building this named type; we'll store the result below
       context.inProgressNames.add(namedKey);
@@ -185,12 +185,12 @@ export class SchemaGenerator implements ISchemaGenerator {
     if (context.definitionStack.has(stackKey)) {
       if (namedKey) {
         context.emittedRefs.add(namedKey);
-        return { "$ref": `#/definitions/${namedKey}` };
+        return { "$ref": `#/$defs/${namedKey}` };
       }
       const syntheticKey = this.ensureSyntheticName(type, context);
       context.inProgressNames.add(syntheticKey);
       context.emittedRefs.add(syntheticKey);
-      return { "$ref": `#/definitions/${syntheticKey}` };
+      return { "$ref": `#/$defs/${syntheticKey}` };
     }
 
     // Push current type onto the stack
@@ -213,7 +213,7 @@ export class SchemaGenerator implements ISchemaGenerator {
           );
           if (!isRootType) {
             context.emittedRefs.add(keyForDef);
-            return { "$ref": `#/definitions/${keyForDef}` };
+            return { "$ref": `#/$defs/${keyForDef}` };
           }
           // For root, keep inline; buildFinalSchema may promote if we choose
         }
@@ -267,27 +267,29 @@ export class SchemaGenerator implements ISchemaGenerator {
       if (!definitions[namedKey]) {
         definitions[namedKey] = rootSchema;
       }
-      base = { $ref: `#/definitions/${namedKey}` } as SchemaDefinition;
+      base = { $ref: `#/$defs/${namedKey}` } as SchemaDefinition;
     } else {
       base = rootSchema;
     }
 
     // Handle boolean schemas (rare, but supported by JSON Schema)
     if (typeof base === "boolean") {
-      return base ? { $schema: "https://json-schema.org/draft-07/schema#" } : {
-        $schema: "https://json-schema.org/draft-07/schema#",
-        not: true,
-      };
+      return base
+        ? { $schema: "https://json-schema.org/draft/2020-12/schema" }
+        : {
+          $schema: "https://json-schema.org/draft/2020-12/schema",
+          not: true,
+        };
     }
 
     // Object schema: attach only the definitions actually referenced by the
     // final output
     const filtered = this.collectReferencedDefinitions(base, definitions);
     const out: Record<string, unknown> = {
-      $schema: "https://json-schema.org/draft-07/schema#",
+      $schema: "https://json-schema.org/draft/2020-12/schema",
       ...(base as Record<string, unknown>),
     };
-    if (Object.keys(filtered).length > 0) out.definitions = filtered;
+    if (Object.keys(filtered).length > 0) out.$defs = filtered;
     return out as SchemaDefinition;
   }
 
@@ -414,7 +416,7 @@ export class SchemaGenerator implements ISchemaGenerator {
     const visited = new Set<string>();
 
     const enqueueFromRef = (ref: string) => {
-      const prefix = "#/definitions/";
+      const prefix = "#/$defs/";
       if (typeof ref === "string" && ref.startsWith(prefix)) {
         const name = ref.slice(prefix.length);
         if (name) needed.add(name);
@@ -430,9 +432,9 @@ export class SchemaGenerator implements ISchemaGenerator {
       const obj = node as Record<string, unknown>;
       for (const [k, v] of Object.entries(obj)) {
         if (k === "$ref" && typeof v === "string") enqueueFromRef(v);
-        // Skip descending into existing definitions blocks to avoid pulling in
+        // Skip descending into existing $defs blocks to avoid pulling in
         // already-attached subsets recursively
-        if (k === "definitions") continue;
+        if (k === "$defs" || k === "definitions") continue;
         scan(v);
       }
     };

packages/schema-generator/src/type-utils.ts

@@ -211,7 +211,31 @@ export function getNativeTypeSchema(
  */
 export function getNamedTypeKey(
   type: ts.Type,
+  typeNode?: ts.TypeNode,
 ): string | undefined {
+  // Check if the TypeNode indicates this is a wrapper type (Default/Cell/Stream)
+  // Even if the type symbol says it's the inner type, if it's wrapped we shouldn't hoist it
+  if (
+    typeNode && ts.isTypeReferenceNode(typeNode) &&
+    ts.isIdentifier(typeNode.typeName)
+  ) {
+    const nodeTypeName = typeNode.typeName.text;
+    if (
+      nodeTypeName === "Default" || nodeTypeName === "Cell" ||
+      nodeTypeName === "Stream"
+    ) {
+      return undefined;
+    }
+  }
+
+  // Check if this is a Default/Cell/Stream wrapper type via alias
+  const aliasName = (type as TypeWithInternals).aliasSymbol?.name;
+  if (
+    aliasName === "Default" || aliasName === "Cell" || aliasName === "Stream"
+  ) {
+    return undefined;
+  }
+
   // Prefer direct symbol name; fall back to target symbol for TypeReference
   const symbol = type.symbol;
   let name = symbol?.name;
@@ -220,12 +244,13 @@ export function getNamedTypeKey(
     const ref = type as unknown as ts.TypeReference;
     name = ref.target?.symbol?.name ?? name;
   }
-  // Fall back to alias symbol when present (type aliases)
-  if (!name) {
-    const aliasName = (type as TypeWithInternals).aliasSymbol?.name;
-    if (aliasName) name = aliasName;
+  // Fall back to alias symbol when present (type aliases) if we haven't used it yet
+  if (!name && aliasName) {
+    name = aliasName;
+  }
+  if (!name || name === "__type") {
+    return undefined;
   }
-  if (!name || name === "__type") return undefined;
   // Exclude property/method-like symbols (member names), which are not real named types
   const symFlags = symbol?.flags ?? 0;
   if (

packages/schema-generator/test/fixtures/schema/cycles-multi-hop.expected.json

@@ -1,10 +1,10 @@
 {
-  "$ref": "#/definitions/SchemaRoot",
-  "definitions": {
+  "$ref": "#/$defs/SchemaRoot",
+  "$defs": {
     "B": {
       "properties": {
         "c": {
-          "$ref": "#/definitions/C"
+          "$ref": "#/$defs/C"
         }
       },
       "required": [
@@ -15,7 +15,7 @@
     "C": {
       "properties": {
         "a": {
-          "$ref": "#/definitions/SchemaRoot"
+          "$ref": "#/$defs/SchemaRoot"
         }
       },
       "required": [
@@ -26,7 +26,7 @@
     "SchemaRoot": {
       "properties": {
         "b": {
-          "$ref": "#/definitions/B"
+          "$ref": "#/$defs/B"
         }
       },
       "required": [

packages/schema-generator/test/fixtures/schema/cycles-mutual-optional.expected.json

@@ -1,18 +1,18 @@
 {
-  "$ref": "#/definitions/SchemaRoot",
-  "definitions": {
+  "$ref": "#/$defs/SchemaRoot",
+  "$defs": {
     "SchemaRoot": {
       "properties": {
         "a": {
-          "$ref": "#/definitions/SchemaRootA"
+          "$ref": "#/$defs/SchemaRootA"
         }
       },
       "type": "object"
     },
     "SchemaRootA": {
       "properties": {
         "b": {
-          "$ref": "#/definitions/SchemaRoot"
+          "$ref": "#/$defs/SchemaRoot"
         }
       },
       "type": "object"

packages/schema-generator/test/fixtures/schema/date-types.expected.json

@@ -1,5 +1,5 @@
 {
-  "definitions": {
+  "$defs": {
     "Document": {
       "properties": {
         "archivedAt": {
@@ -96,13 +96,13 @@
   },
   "properties": {
     "document": {
-      "$ref": "#/definitions/Document"
+      "$ref": "#/$defs/Document"
     },
     "eventLog": {
-      "$ref": "#/definitions/EventLog"
+      "$ref": "#/$defs/EventLog"
     },
     "userProfile": {
-      "$ref": "#/definitions/UserProfile"
+      "$ref": "#/$defs/UserProfile"
     }
   },
   "required": [