fix: preserve fractional timestamp input compatibility

api/src/open-api/open-api-input-boundaries.spec.ts

@@ -26,6 +26,7 @@ describe('public HTTP input boundaries', () => {
     ['2026-09-14T08:00:00+08:00', '2026-09-14T00:00:00.000Z'],
     ['2026-09-14T00:00Z', '2026-09-14T00:00:00.000Z'],
     ['2000-02-29T00:00:00.123Z', '2000-02-29T00:00:00.123Z'],
+    ['2026-09-14T00:00:00.123456789Z', '2026-09-14T00:00:00.123Z'],
   ])('preserves valid calendar dates/timezones %s', (value, expected) => {
     expect(parseOpenApiDate(value).toISOString()).toBe(expected);
   });

api/src/open-api/open-api.protocol.ts

@@ -12,7 +12,7 @@ export function pinnedWebhookLookup(address: string, family: number): LookupFunc
 
 /** Validate calendar components before Date can normalize an impossible day. */
 export function parseOpenApiDate(value: string): Date {
-  const parts = /^(\d{4})-(\d{2})-(\d{2})(?:T(\d{2}):(\d{2})(?::(\d{2})(?:\.(\d{1,3}))?)?(Z|[+-]\d{2}:\d{2}))?$/.exec(
+  const parts = /^(\d{4})-(\d{2})-(\d{2})(?:T(\d{2}):(\d{2})(?::(\d{2})(?:\.(\d+))?)?(Z|[+-]\d{2}:\d{2}))?$/.exec(
     value,
   );
   if (parts) {