Replace Zod with TypeBox for schema validation

- Switch from Zod to TypeBox for tool parameter schemas
- TypeBox schemas can be serialized/deserialized as JSON
- Use AJV for runtime validation instead of Zod's parse
- Add StringEnum helper for Google API compatibility (avoids anyOf/const patterns)
- Export Type and Static from main package for convenience
- Update all tests and documentation to reflect TypeBox usage

packages/ai/src/validation.ts

@@ -1,32 +1,37 @@
-import { z } from "zod";
+import Ajv from "ajv";
+import addFormats from "ajv-formats";
 import type { Tool, ToolCall } from "./types.js";
 
+// Create a singleton AJV instance with formats
+const ajv = new Ajv({ allErrors: true, strict: false });
+addFormats(ajv);
+
 /**
- * Validates tool call arguments against the tool's Zod schema
- * @param tool The tool definition with Zod schema
+ * Validates tool call arguments against the tool's TypeBox schema
+ * @param tool The tool definition with TypeBox schema
  * @param toolCall The tool call from the LLM
  * @returns The validated arguments
- * @throws ZodError with formatted message if validation fails
+ * @throws Error with formatted message if validation fails
  */
 export function validateToolArguments(tool: Tool, toolCall: ToolCall): any {
-	try {
-		// Validate arguments with Zod schema
-		return tool.parameters.parse(toolCall.arguments);
-	} catch (e) {
-		if (e instanceof z.ZodError) {
-			// Format validation errors nicely
-			const errors = e.issues
-				.map((err) => {
-					const path = err.path.length > 0 ? err.path.join(".") : "root";
-					return `  - ${path}: ${err.message}`;
-				})
-				.join("\n");
+	// Compile the schema
+	const validate = ajv.compile(tool.parameters);
 
-			const errorMessage = `Validation failed for tool "${toolCall.name}":\n${errors}\n\nReceived arguments:\n${JSON.stringify(toolCall.arguments, null, 2)}`;
-
-			// Throw a new error with the formatted message
-			throw new Error(errorMessage);
-		}
-		throw e;
+	// Validate the arguments
+	if (validate(toolCall.arguments)) {
+		return toolCall.arguments;
 	}
+
+	// Format validation errors nicely
+	const errors =
+		validate.errors
+			?.map((err) => {
+				const path = err.instancePath ? err.instancePath.substring(1) : err.params.missingProperty || "root";
+				return `  - ${path}: ${err.message}`;
+			})
+			.join("\n") || "Unknown validation error";
+
+	const errorMessage = `Validation failed for tool "${toolCall.name}":\n${errors}\n\nReceived arguments:\n${JSON.stringify(toolCall.arguments, null, 2)}`;
+
+	throw new Error(errorMessage);
 }