Dart web: i64 fields in signals silently fail deserialization

[dillon-0]

Bug

Any RustSignal struct containing i64 fields (e.g., Option<i64> for Unix-millis timestamps) silently fails deserialization on Dart web. The signal is sent successfully from Rust (send_signal_to_dart() returns Ok(())), but Dart never receives it.

Root cause

rinf uses serde-generate to produce Dart bindings. The Dart serde runtime's deserializeInt64() calls ByteData.getInt64() and serializeInt64() calls ByteData.setInt64() — both throw UnsupportedError on Dart web because JavaScript numbers are 64-bit doubles with no native 64-bit integer type.

The unsigned variant deserializeUint64() already uses a web-compatible BigInt path (_bytesToBigInt), but the signed deserializeInt64() does not.

The error occurs inside the assignRustSignal callback during bincodeDeserialize(), and is swallowed silently — no console error, no page error.

Fix

I've submitted a fix upstream: zefchain/serde-reflection#92

Once that's merged and released, updating the serde-generate dependency in rinf_cli will resolve this.

Workaround

Until the upstream fix is released, users can manually patch the generated lib/src/bindings/serde/binary_deserializer.dart after running rinf gen:

// Replace:
int deserializeInt64() {
  final result = input.getInt64(_offset, Endian.little);
  _offset += 8;
  return result;
}

// With:
int deserializeInt64() {
  final number = _bytesToBigInt(8, signed: true);
  _offset += 8;
  return number.toInt();
}

And similarly for serializeInt64 in binary_serializer.dart.

Reproduction

1. Define a signal with an i64 field: pub struct MySignal { pub timestamp: Option<i64> }
2. Send it from Rust on web: MySignal { timestamp: Some(1711282800000) }.send_signal_to_dart()
3. Observe: Rust logs success, but Dart stream listener never fires
4. Remove the i64 field → signal is received correctly

Environment

• rinf 8.10.0
• Flutter 3.38.x, Dart web (DDC debug mode)
• serde-generate 0.32.0