fix(puter-js): preserve zero amount in kv incr/decr (#3802)

parseCounterArgs used a falsy check, so incr(key, 0) sent amount 1. Only default when amount is undefined/null.

src/puter-js/src/modules/kv/kv.test.js

@@ -278,6 +278,11 @@ describe('kv.incr / kv.decr driver payloads', () => {
         expect(lastBody().args).toEqual({ key: 'n', pathAndAmountMap: { '': 5 } });
     });
 
+    it('incr(key, 0) preserves a zero amount instead of defaulting to 1', async () => {
+        await kv.incr('n', 0);
+        expect(lastBody().args).toEqual({ key: 'n', pathAndAmountMap: { '': 0 } });
+    });
+
     it('incr(key, pathAndAmountMap) passes the map through', async () => {
         await kv.incr('n', { 'user.score': 2 });
         expect(lastBody().args).toEqual({ key: 'n', pathAndAmountMap: { 'user.score': 2 } });
@@ -326,6 +331,11 @@ describe('kv.incr / kv.decr driver payloads', () => {
         await kv.decr('n', 4);
         expect(lastBody().args).toEqual({ key: 'n', pathAndAmountMap: { '': 4 } });
     });
+
+    it('decr(key, 0) preserves a zero amount instead of defaulting to 1', async () => {
+        await kv.decr('n', 0);
+        expect(lastBody().args).toEqual({ key: 'n', pathAndAmountMap: { '': 0 } });
+    });
 });
 
 describe('kv.add driver payloads', () => {

src/puter-js/src/modules/kv/lib/args.js

@@ -63,7 +63,7 @@ export const parseCounterArgs = (keyOrOptions, amountOrMap, optConfig) => {
     }
     return {
         key: keyOrOptions,
-        pathAndAmountMap: !amountOrMap ? { '': 1 } : typeof amountOrMap === 'number' ? { '': amountOrMap } : amountOrMap,
+        pathAndAmountMap: amountOrMap === undefined || amountOrMap === null ? { '': 1 } : typeof amountOrMap === 'number' ? { '': amountOrMap } : amountOrMap,
         optConfig,
     };
 };