fix(server): support Zod v4 in query parameter type detection

.changeset/fix-zod4-query-param-detection.md

@@ -0,0 +1,5 @@
+---
+'@mastra/server': patch
+---
+
+Fixed "Invalid query parameters" errors that occurred in projects using Zod v4 when filtering by date ranges, tags, or metadata. Complex query parameters (objects, arrays, records) are now correctly detected and parsed for both Zod v3 and v4.

packages/server/src/server/server-adapter/routes/route-builder.ts

@@ -78,51 +78,26 @@ export function jsonQueryParam<T extends ZodTypeAny>(schema: T): z.ZodType<z.inf
   ]) as z.ZodType<z.infer<T>>;
 }
 
-/**
- * Gets the type name from a Zod schema's internal definition.
- * Works across zod v3 and v4 by checking _def.typeName (v3) and _def.type (v4).
- */
 function getZodTypeName(schema: ZodTypeAny): string | undefined {
-  const schemaAny = schema as any;
-  const def = schemaAny?._def ?? schemaAny?.def;
+  const def = (schema as any)?._def;
+  // Zod v3 uses _def.typeName ("ZodObject"), Zod v4 uses _def.type ("object")
   return def?.typeName ?? def?.type;
 }
 
-/**
- * Checks if a Zod schema represents a complex type that needs JSON parsing from query strings.
- * Complex types: arrays, objects, records (these can't be represented as simple strings)
- * Simple types: strings, numbers, booleans, enums (can use z.coerce for conversion)
- *
- * Uses _def.typeName string comparison instead of instanceof to support both zod v3 and v4,
- * since instanceof checks fail across different zod versions in bundled code.
- */
+const OPTIONAL_TYPES = new Set(['ZodOptional', 'optional', 'ZodNullable', 'nullable']);
+const COMPLEX_TYPES = new Set(['ZodArray', 'array', 'ZodRecord', 'record', 'ZodObject', 'object']);
+
 function isComplexType(schema: ZodTypeAny): boolean {
-  // Unwrap all optional/nullable layers to check the inner type
-  // Note: .partial() can create nested optionals (e.g., ZodOptional<ZodOptional<ZodObject>>)
   let inner: ZodTypeAny = schema;
   let typeName = getZodTypeName(inner);
 
-  while (
-    typeName === 'ZodOptional' ||
-    typeName === 'ZodNullable' ||
-    typeName === 'optional' ||
-    typeName === 'nullable'
-  ) {
-    // Access innerType from internals to avoid version-specific method differences
+  while (typeName && OPTIONAL_TYPES.has(typeName)) {
     const innerDef = (inner as any)._def ?? (inner as any).def;
     inner = innerDef.innerType;
     typeName = getZodTypeName(inner);
   }
 
-  // Complex types that need JSON parsing
-  return (
-    typeName === 'ZodArray' ||
-    typeName === 'ZodRecord' ||
-    typeName === 'ZodObject' ||
-    typeName === 'array' ||
-    typeName === 'record' ||
-    typeName === 'object'
-  );
+  return typeName != null && COMPLEX_TYPES.has(typeName);
 }
 
 /**