fix: honor explicit zero argument count

Author: posva

packages/devframe/src/__tests__/tool-input.test.ts

@@ -5,6 +5,7 @@ describe('tool input positional arguments', () => {
   it('passes arrays through and maps argN keys using the declared count', () => {
     expect(toolInputToRpcArgs([1, 2], 2)).toEqual([1, 2])
     expect(toolInputToRpcArgs({ arg0: 'a', arg1: 'b' }, 2)).toEqual(['a', 'b'])
+    expect(toolInputToRpcArgs({ arg0: 'a' }, 0)).toEqual([])
   })
 
   it('collects contiguous argN keys without a declared count', () => {

packages/devframe/src/tool-input.ts

@@ -13,7 +13,7 @@ function collectPositionalArgs(input: unknown, argumentCount: number | undefined
     return undefined
 
   const record = input as Record<string, unknown>
-  if (argumentCount)
+  if (argumentCount != null)
     return Array.from({ length: argumentCount }, (_, index) => record[`arg${index}`])
   if ('arg0' in record) {
     const positional: unknown[] = []