Tried on the example with the app's sandbox, two things were wrong:
- `debugger` printed `flatpak enter <id> lldb -p <pid>`, and flatpak
enter runs a command without the sandbox's PATH, which /app/bin is
on: "Failed to execute child process lldb". It now prints the path
it found, /app/bin/lldb, which attached, listed threads and detached.
- With the app held by that debugger, the handshake times out, and
the client said "cannot reach basic on port ..." and exited 3, no
instance, though its lock said it lived. It now says the app is
alive but not answering, stopped in a debugger or hung, prints how
to attach, check and end it, and exits 5.
Environment::haveLldb becomes lldb, the path or empty. ShouldServeOverQuic
covers the second with an instance whose lock is held and whose port
is silent.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>