Check for local name clash with existing variables in Insert flow (#6375)

Check for local name alias clashes with extisting var in Insert flow
Fixes #6230

src/lib/commandTypes.ts

@@ -220,6 +220,13 @@ export type CommandArgumentConfig<
             machineContext?: C
           ) => OutputType)
       defaultValueFromContext?: (context: C) => OutputType
+      validation?: ({
+        data,
+        context,
+      }: {
+        data: any
+        context: CommandBarContext
+      }) => Promise<boolean | string>
     }
   | {
       inputType: 'text'
@@ -343,6 +350,13 @@ export type CommandArgument<
             commandBarContext: ContextFrom<typeof commandBarMachine>,
             machineContext?: ContextFrom<T>
           ) => OutputType)
+      validation?: ({
+        data,
+        context,
+      }: {
+        data: any
+        context: CommandBarContext
+      }) => Promise<boolean | string>
     }
   | {
       inputType: 'path'

src/lib/createMachineCommand.ts

@@ -211,6 +211,15 @@ export function buildCommandArgument<
       defaultValue: arg.defaultValue,
       ...baseCommandArgument,
     } satisfies CommandArgument<O, T> & { inputType: 'kcl' }
+  } else if (arg.inputType === 'string') {
+    return {
+      inputType: arg.inputType,
+      defaultValue: arg.defaultValueFromContext
+        ? arg.defaultValueFromContext(context)
+        : arg.defaultValue,
+      validation: arg.validation,
+      ...baseCommandArgument,
+    } satisfies CommandArgument<O, T> & { inputType: 'string' }
   } else {
     return {
       inputType: arg.inputType,

src/lib/kclCommands.ts

@@ -133,6 +133,14 @@ export function kclCommands(commandProps: KclCommandConfig): Command[] {
             const path = context.argumentsToSubmit['path'] as string
             return getPathFilenameInVariableCase(path)
           },
+          validation: async ({ data, context }) => {
+            const variableExists = kclManager.variables[data.localName]
+            if (variableExists) {
+              return 'This variable name is already in use.'
+            }
+
+            return true
+          },
         },
       },
       onSubmit: (data) => {