Lyric

What changed in v4.3.0 — 2026-08-27

A VM owns what its scripts open. The heaviest finding of the 4.2 sweep, fixed.

Added

• LangVm is IDisposable, and disposing it closes every socket, child process and file its scripts left open.

  using var vm = new LangVm(new HostOptions { Capabilities = Capability.FileAccess });
  // leaving the block closes whatever the script still held
  

  A script has no obligation to close what it opens: it may be stopped by an ExecutionBudget, it may panic, or it may simply return with a handle in hand. Until now those handles were held per THREAD, so neither dropping the VM nor collecting it released them — a host that stopped an untrusted script was left holding its resources, and on Windows a file the script opened stayed locked. That was the half of the sandbox a host could not work around.

• Two VMs never share a descriptor, on one thread or on several. The tables belong to the VM, so which thread opened a handle no longer decides who owns it, and disposing one VM cannot touch another's. The two-VMs-on-two-threads case is a deterministic test now rather than a timing argument.

Changed

• A child process is DISOWNED, not killed, when a VM is disposed — what std.process.close already does by hand. Releasing a handle automatically must not mean more than releasing it by hand; kill it from the script, or hold the pid in the host.

Deliberately unchanged

• There is no finalizer. A VM that is merely dropped keeps its handles until the process ends. A finalizer here would run against Socket, FileStream and Process objects that have their own, in an order nobody controls — a half answer that hides the case instead of closing it. Guide 14 says so plainly instead.
• The interrupt SIGNAL stays process-wide — the handler, the pending signal, the listening count and the self-pipe. Only the programmatic interrupt() and the listening flag became per-VM, which is what they had always meant; they were per-thread standing in for it.

The full changelog →