[rekram1-node]

Problem

opencode starts every child (MCP servers, shell tool commands, formatters, rg, git) in its own process group, and only stops those groups from scope finalizers. Several exit paths skip the finalizers:

• the 10s shutdown deadline calls process.exit(1)
• a second SIGTERM/SIGINT during shutdown exits right away
• closing the terminal sends SIGHUP, which nothing handled, so the process just died

Anything still running then gets reparented to PID 1, and MCP servers that ignore stdin EOF (npx wrappers, for example) stay there forever. Part of #50363. This replaces #59398 with something much smaller.

Change

spawn (own group)  → groups.add(pid)
leader exits       → groups.delete(pid)
process "exit"     → SIGKILL every group still in the set

• cross-spawn-spawner.ts keeps a set of live process groups and registers one synchronous exit hook that SIGKILLs whatever is left. Normal teardown already had its chance to stop things gracefully; the hook can't wait. A group is dropped as soon as its leader exits, so a finished shell command's intentional background job is left alone as before, and a reused PID can't be hit.
• shutdown-deadline.ts treats SIGHUP like SIGTERM, but only when stdin or stdout is a terminal. nohup and the background service have no terminal, and adding a listener would otherwise override nohup's ignore.
• Windows: no-op, there are no process groups there.
• A SIGKILL of opencode itself still can't run any hook. That's the remaining part of the issue.

Things meant to outlive opencode don't go through this spawner, so they need no opt-out. I checked:

• background service (serve --service): raw node:child_process in packages/client/src/service-contender.ts
• persistent terminal daemon: raw spawn in packages/core/src/persistent-pty/daemon.ts
• updater, pager, port owner lookup, standalone --stdio server: go through the spawner but are awaited or tied to the CLI's lifetime, so killing them on exit is right

Verification

serve from this branch with a stdio MCP server that ignores stdin EOF and SIGTERM and has its own child:

path	before	after
SIGTERM, then a second SIGTERM	server + child left with PPID 1	gone
SIGHUP with a terminal	left with PPID 1	gone
SIGHUP without a terminal	left	left (unchanged on purpose)
CLI command that starts the background service, then exits	service keeps running	service keeps running

Also ran bun typecheck in packages/util and packages/cli, test/shutdown-deadline.test.ts in cli, test/effect/cross-spawn-spawner.test.ts, test/mcp.test.ts and test/process in core, and bun run check from the root.

Visual

<svg xmlns="http://www.w3.org/2000/svg" width="240" height="72" viewBox="0 0 240 72" fill="none" stroke="currentColor" stroke-width="2">
<style>
.s{animation:s 4s infinite}.l{animation:l 4s infinite}.c{animation:c 4s infinite}
@keyframes s{0%,30%{opacity:1}40%,85%{opacity:.2}95%,100%{opacity:1}}
@keyframes l{0%,32%{opacity:.5}40%,85%{opacity:0}95%,100%{opacity:.5}}
@keyframes c{0%,40%{opacity:1;transform:none}50%,85%{opacity:0;transform:translateY(6px)}95%,100%{opacity:1;transform:none}}
@media (prefers-reduced-motion:reduce){.s,.l,.c{animation:none}}
</style>
<g class="s"><rect x="16" y="20" width="64" height="32" rx="6"/><path d="M32 36h32" opacity=".6"/></g>
<path class="l" d="M80 36h48" stroke-dasharray="4 4"/>
<g class="c"><rect x="128" y="20" width="44" height="32" rx="6"/><rect x="184" y="20" width="44" height="32" rx="6" opacity=".6"/><path d="M172 36h12" opacity=".6"/></g>
</svg>

---

Added by the opencode bot (AI-generated).

Related: #50363

[opencode-agent]

Looks good. I reproduced both exit paths on the base and checked them against this branch:

• process.exit() with a child that ignores SIGTERM and has a grandchild, spawned through the spawner: on the base the whole group is left with PPID 1; with this change it's killed.
• Terminal hangup (the shutdown-hang fixture under a pty): on the base the child is orphaned; here the hangup becomes a SIGTERM shutdown and the child is killed. Without a terminal, behaviour is unchanged, as intended.

shutdown-deadline and cross-spawn-spawner tests pass, and packages/util type-checks. No blocking concerns.

Public API: unchanged.

Related: #50363