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addons/godot_ai/handlers/_param_validators.gd

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+@tool
+class_name McpParamValidators
+extends RefCounted
+
+const ErrorCodes := preload("res://addons/godot_ai/utils/error_codes.gd")
+
+## Type-check a JSON-decoded param Variant before assigning it into a typed
+## GDScript local. The dispatcher only catches handler crashes as an opaque
+## "malformed result" (issue #210), so a typed assignment like
+##   var group: String = params.get("group", "")
+## will runtime-error and bubble up without telling the caller which param
+## was the wrong shape. Only string params are guarded — int/bool params
+## can't be: Godot's JSON parser decodes every number as float (a wire `5`
+## arrives as `5.0`), so a strict int check would reject every legitimate
+## integer a client sends, and GDScript's typed assignment already converts
+## numeric Variants safely. Bool params arrive as real bools and a wrong
+## type surfaces through the dispatcher's malformed-result path.
+
+
+## Returns null iff `value` is a String or StringName. On any other type
+## returns an INVALID_PARAMS error dict whose message names both `name` and
+## the actual Variant type (via Godot's built-in `type_string`).
+static func require_string(name: String, value: Variant) -> Variant:
+	var t := typeof(value)
+	if t == TYPE_STRING or t == TYPE_STRING_NAME:
+		return null
+	return ErrorCodes.make(
+		ErrorCodes.WRONG_TYPE,
+		"Param '%s' must be a String, got %s" % [name, type_string(t)],
+	)