Per-session GenServer owning a single PTY process.

Each PTY.Session holds the state previously scattered as one map entry inside Eai.Sandbox.PTYPool. Moving to a dedicated process means:

• Slow PTY init (pty_init_sleep_ms, pty_ready_sleep_ms) runs inside this process and no longer blocks other sessions.
• PTY crash → :pty_exited arrives in this process only; orphaned tasks are cleaned up immediately via ResultCollector.force_complete/1.
• :transient restart: on abnormal exit, the supervisor restarts the session with a fresh PTY. init/1 force-completes any in-flight task left over from the previous incarnation.

Graph

<<{Eai.PTY.Registry, required_by, Eai.PTY.Session}. <<{Eai.PTY.Supervisor, spawned_by, Eai.PTY.Session}. <<{Eai.Hub, required_by, Eai.PTY.Session}. <<{Eai.ResultCollector, required_by, Eai.PTY.Session}. <<{Eai.Naming, required_by, Eai.PTY.Session}. <<{Eai.PTY.Session, required_by, Eai.PTY}.

Lifecycle

start_link(pty_session_id)
  └─ init/1
       ├─ mkdir work_dir, setup symlinks
       ├─ ExPTY.spawn (shell, on_data → self, on_exit → self)
       └─ flush init noise

handle_call :exec / :force_reset / :write_raw / :interrupt_task / :clear_task / :info
handle_info {:pty_data, data} / :pty_exited

terminate/2  →  Hub.run_post_only(__MODULE__, :terminate, [reason, state])

Naming / addressing

Registered via Eai.Naming.pty_session(pty_session_id) on start. Look up by Eai.PTY.Registry.lookup(pty_session_id).