The durable process behind one browser session.

One DurableStash.Session exists per browser session; every LiveView of that session reads and writes through it. State is partitioned per view module, and the single-process actor model gives a total order over writes — per-key last-write-wins with no timestamps needed.

State shape (string keys — it round-trips through JSON object storage):

%{
  "views" => %{
    "Elixir.My.View" => %{"vsn" => 1, "data" => %{"key" => value}}
  },
  "last_seen_at" => unix_millis | nil
}

Each view slice carries the vsn its writer declared. A write with a different vsn replaces the slice wholesale instead of merging — the adapter only does that with a full, migrated key set, so a version bump can never mix old- and new-shape keys.

Writes merge in memory and reply immediately; the object-store PUT then runs in a handle_continue/2 on this same process, after the reply is sent — so a write never blocks the calling LiveView on the network round-trip. Durability lands a continue later, and DurableServer also flushes on its periodic interval and on graceful shutdown. A synchronous PUT inside every write — the previous behaviour — is what made auto_stash form views feel sluggish under per-keystroke validation.