fix(ai): coerce string numbers in tool argument validation (#786)

* fix(ai): coerce string numbers in tool argument validation

* fix(ai): clone tool arguments before AJV validation for type coercion

packages/ai/src/utils/validation.ts

@@ -19,6 +19,7 @@ if (!isBrowserExtension) {
 		ajv = new Ajv({
 			allErrors: true,
 			strict: false,
+			coerceTypes: true,
 		});
 		addFormats(ajv);
 	} catch (_e) {
@@ -46,7 +47,7 @@ export function validateToolCall(tools: Tool[], toolCall: ToolCall): any {
  * 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
+ * @returns The validated (and potentially coerced) arguments
  * @throws Error with formatted message if validation fails
  */
 export function validateToolArguments(tool: Tool, toolCall: ToolCall): any {
@@ -60,9 +61,12 @@ export function validateToolArguments(tool: Tool, toolCall: ToolCall): any {
 	// Compile the schema
 	const validate = ajv.compile(tool.parameters);
 
-	// Validate the arguments
-	if (validate(toolCall.arguments)) {
-		return toolCall.arguments;
+	// Clone arguments so AJV can safely mutate for type coercion
+	const args = structuredClone(toolCall.arguments);
+
+	// Validate the arguments (AJV mutates args in-place for type coercion)
+	if (validate(args)) {
+		return args;
 	}
 
 	// Format validation errors nicely