The app's end of the connection, independent of the transport, which
reaches it through Detail::Exchange: one request's way back, safe from
any thread and never blocking.
- What needs only the session's own state (hello, status, list, log,
pause, resume) is answered on the transport thread. What touches the
app (calls, get, set, trace, screenshot) queues for the next Pump and
runs on the app's thread between frames. Waits and steps reply from
the Pump that sees them satisfied, events from the thread that emits
them. No request ever holds a thread while it waits.
- A request whose timeout passes before Pump is answered Timeout and
is guaranteed not to have run, so an agent never wonders whether a
command went through; an Async result arrives on the Pump it is
ready; requests left when the Session ends are answered ShuttingDown.
- Advance() for frame loops and Paused()/TakeSteps() for fixed-step
loops hold what the app gates on them; pausing an app that gates
nothing is refused instead of silently doing nothing. pause --when
stops the frame its condition holds; pause --on-check stops before
the next Advance in the frame a check fails, optionally raising
SIGTRAP for an attached debugger.
- A wait that times out says what its condition's paths were; a log
follower gets matching entries in order, from the backlog on, and is
dropped when it cannot keep up.
- Request parameters go through Codec, so a mistyped request gets the
same did-you-mean replies a mistyped command does. The session sets
PR_SET_PTRACER_ANY so a debugger the agent starts can attach.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
