`adk dev` leaks its `opencode serve` child on exit/kill — orphans accumulate at ~230 MB RSS each

[johnf]

Environment: adk CLI 2.0.1 (linux-x64 release binary); Ubuntu (kernel 6.17).

Each adk dev boot spawns an opencode serve child. When the parent adk dev dies — killed, crashed, or exited — the child is not terminated: it reparents to init/systemd and keeps running. On a day of repeated dev-server restarts (working around eval-run fragility reported separately) we accumulated 13 orphaned opencode serve processes at roughly 230 MB RSS each (~3 GB total), one per restart.

Expected: the child dies with the parent (process group kill, prctl PDEATHSIG, or an exit handler), or at minimum adk dev reaps stale instances on its next boot.

Repro:

1. adk dev (note the opencode serve child in pgrep -af 'opencode serve').
2. Kill the parent (Ctrl-C or kill <pid>; also happens when it crashes).
3. The opencode serve process is still running, now parented to init. Repeat to accumulate.

Workaround: pkill -f "opencode serve" after killing adk dev.

[johnf]

A diagnostic narrowing, from four boot/kill cycles on 2.0.3 today: no orphan was leaked in any of them.

The difference appears to be how the server is terminated. Each cycle started it as its own process-group leader and killed the group rather than the process:

setsid adk dev --non-interactive --no-watch > server.log 2>&1 &
server_pid=$!
...
kill -TERM -- "-$server_pid"     # negative PID — the whole group

Four such cycles, zero new opencode serve processes. The one orphan present on this machine (243 MB RSS, reparented to systemd --user) started well before these runs, from a server that had been stopped the ordinary way.

So the leak looks specific to the child surviving a kill aimed at the parent alone — which is consistent with the original report and suggests the fix is for adk dev to reap or process-group its opencode serve child on shutdown. A workaround that holds in the meantime: setsid + group kill.

Not claiming this is fixed — it isn't, and the pre-existing orphan is the evidence.