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Symptom: a backend model-worker subprocess (the per-model gRPC server LocalAI spawns) can be orphaned and linger — holding VRAM and its listen port — if the LocalAI process is killed non-gracefully (e.g. a supervisor's graceful-shutdown grace period elapses and LocalAI is SIGKILLed) before its own teardown runs. Root cause: LocalAI's graceful teardown (pkg/signals/handler.go installs the SIGINT/SIGTERM handler; core/cli/run.go registers app.Shutdown -> ModelLoader.StopAllGRPC -> process.Stop in pkg/model/process.go) only runs when LocalAI receives a catchable signal and survives long enough to run its handlers. Backends are spawned via github.com/mudler/go-processmanager v0.1.1, whose getSysProcAttr() sets Setpgid:true (own process group, so the group can be signalled) but never PR_SET_PDEATHSIG/Pdeathsig, and exposes no Config field or option for a caller to inject/extend SysProcAttr. LocalAI fully delegates spawning to that library (it never builds the exec.Cmd itself), so it cannot set a kernel parent-death signal at the spawn site. If LocalAI is SIGKILLed, nothing tells the backend to exit and it is reparented to init. Fix: add a best-effort, backend-side safety net at the one shared choke point every out-of-process Go backend routes through — grpc.StartServer / RunServer in pkg/grpc. On startup it captures getppid() and polls; when the process is reparented (getppid changes / becomes 1 — the standard POSIX signal the original parent died) it logs and self-terminates. getppid() reparent detection is portable (Linux + macOS), unlike Linux-only PR_SET_PDEATHSIG. Toggle via LOCALAI_BACKEND_PARENT_WATCH (default on; off on Windows) and LOCALAI_BACKEND_PARENT_WATCH_INTERVAL. This is strictly a backstop alongside the existing graceful SIGTERM->grace->SIGKILL teardown, which is unchanged. Scope/limitations: covers Go-based backends (everything using pkg/grpc). The C++ backends (e.g. llama-cpp) and Python backends do not route through pkg/grpc and are not covered by this mechanism — they would each need an equivalent parent-death check (follow-up). The fully general fix is for go-processmanager to expose SysProcAttr injection so LocalAI can set Pdeathsig at spawn for every backend regardless of language (suggested upstream follow-up; out of scope for this LocalAI-only PR). Test: pkg/grpc/parentwatch_test.go builds a real test -> middle -> grandchild process tree, lets the middle process exit to orphan the grandchild running the real watchParentDeath, and asserts it detects the reparent and self-terminates. Unix-only (build-tagged), runs in CI (Linux). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>