The terminal agent is intentionally detached so it survives the
short-lived CLI launcher, but its real owner is the persistent browse
server. If that server crashed or was killed before running normal
shutdown, the agent was adopted by PID 1 and lived forever (#2019).
spawnTerminalAgent now requires an ownerPid and exports it to the agent
as BROWSE_OWNER_PID; all three spawn sites pass the server PID (cli.ts
cold-start, cli.ts supervisor respawn, server.ts watchdog). The agent
polls the owner with signal 0 every 15s (GSTACK_TERMINAL_OWNER_WATCHDOG_MS
to tune) on an unref'd timer and, when the owner disappears, exits
through the SAME cleanup path as an intentional SIGTERM shutdown — now
re-entrancy-guarded and also removing the terminal-internal-token file
alongside the port file and agent record.
Runtime test spawns a real agent tied to a throwaway owner process,
kills the owner, and asserts the agent exits and its discovery files
(terminal-agent-pid, terminal-port) are gone.
Reconciled with the watchdog commit's spawnTerminalAgent contract test
(process-liveness-windows.test.ts now passes ownerPid and pins the
BROWSE_OWNER_PID env forwarding).
Closes#2019.
Contributed by @csarigoz (PR #2530).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
