StartAsync awaited the static launch-gate semaphore with no timeout, so one
hung launch (slow disk, AV scanning claude.exe, a Porta.Pty/ConPTY hiccup)
blocked every subsequent pane open behind it indefinitely, including Retry.
Extracted the wait into WaitForLaunchGateAsync with a 30s timeout that
throws TimeoutException before the try/finally (never releasing a gate it
didn't acquire); the exception flows through StartCoreAsync's existing
catch into StartError, so the pane shows an error + Retry instead of
hanging. StartError renders ex.Message directly (no locale key involved),
so no locale changes were needed.
PtyTerminalSession.StartAsync itself needs a real TerminalControl and stays
impractical to unit-test directly, so tests target the extracted
WaitForLaunchGateAsync helper against a plain SemaphoreSlim: timeout throws,
timeout never acquires the gate, and success still acquires it.
mika kuns
4310f88ebf