polyc-host 2026.9.4

Generic dedicated-thread bridge from the tokio control plane to a Commonware-runtime-backed durable store.
Documentation

Generic dedicated-thread bridge between the tokio control plane and a Commonware-runtime-backed durable store.

Built slice by slice against the invariants every host migration (PersonaHost, EventLogHost) depends on:

  • INV-H1: dropping a [HostHandle] never deadlocks — the command sender is dropped before the dedicated thread is joined.
  • INV-H2: an eager [Body::open] failure surfaces as [spawn_host]'s Err, before any command can be sent — never as a silently-empty host.
  • INV-H3: a lazy [Body::open] (returns Ok(()) immediately) followed by a command that fails inside [Body::handle] never crashes the command loop.
  • INV-H4: a command already queued on the channel when shutdown.cancel() fires is still processed by the post-cancellation drain, not lost.
  • INV-H5: [Body::on_drain_complete] fires strictly after the drain has run every command it queued.
  • INV-H6: a caller-supplied (Sender, Receiver) pair ([spawn_host_with_channel]) drives the exact same ready handshake/loop/drain/on_drain_complete/Drop machinery as an internally-created one ([spawn_host]) — the only difference is who constructs the channel. EventLogHost's 4 shards need this: every shard's Sender must exist and be handed to every OTHER shard's Body before any shard's thread starts (a chicken-and-egg an internally-built channel can't resolve), so the caller builds all its channels up front and hands each shard its own (Sender, Receiver) pair.