feat: Log backend exit code (#9581)

Signed-off-by: Richard Palethorpe <io@richiejp.com>

Author: richiejp

go.mod

@@ -38,7 +38,7 @@ require (
 	github.com/modelcontextprotocol/go-sdk v1.5.0
 	github.com/mudler/cogito v0.9.5-0.20260315222927-63abdec7189b
 	github.com/mudler/edgevpn v0.31.1
-	github.com/mudler/go-processmanager v0.1.0
+	github.com/mudler/go-processmanager v0.1.1
 	github.com/mudler/memory v0.0.0-20260406210934-424c1ecf2cf8
 	github.com/mudler/xlog v0.0.6
 	github.com/nats-io/nats.go v1.50.0

go.sum

@@ -711,8 +711,8 @@ github.com/mudler/edgevpn v0.31.1 h1:7qegiDWd0kAg6ljhNHxqvp8hbo/6BbzSdbb7/2WZfiY
 github.com/mudler/edgevpn v0.31.1/go.mod h1:ftV5B0nKFzm4R8vR80UYnCb2nf7lxCRgAALxUEEgCf8=
 github.com/mudler/go-piper v0.0.0-20241023091659-2494246fd9fc h1:RxwneJl1VgvikiX28EkpdAyL4yQVnJMrbquKospjHyA=
 github.com/mudler/go-piper v0.0.0-20241023091659-2494246fd9fc/go.mod h1:O7SwdSWMilAWhBZMK9N9Y/oBDyMMzshE3ju8Xkexwig=
-github.com/mudler/go-processmanager v0.1.0 h1:fcSKgF9U/a1Z7KofAFeZnke5YseadCI5GqL9oT0LS3E=
-github.com/mudler/go-processmanager v0.1.0/go.mod h1:h6kmHUZeafr+k5hRYpGLMzJFH4hItHffgpRo2QIkP+o=
+github.com/mudler/go-processmanager v0.1.1 h1:c/1NRZOZpW8HuFv9RhBG57nQu1oDMRomEHedwBFMlrw=
+github.com/mudler/go-processmanager v0.1.1/go.mod h1:h6kmHUZeafr+k5hRYpGLMzJFH4hItHffgpRo2QIkP+o=
 github.com/mudler/localrecall v0.5.9-0.20260415164846-8ad831f840fc h1:p1ucQ2rbU4mhG2Xl1Emg5Q6QCYCjI+fvMF9KTek/+sY=
 github.com/mudler/localrecall v0.5.9-0.20260415164846-8ad831f840fc/go.mod h1:xuPtgL9zUyiQLmspYzO3kaboYrGbWmwi8BQPt1aCAcs=
 github.com/mudler/memory v0.0.0-20260406210934-424c1ecf2cf8 h1:Ry8RiWy8fZ6Ff4E7dPmjRsBrnHOnPeOOj2LhCgyjQu0=

pkg/model/process.go

@@ -204,5 +204,30 @@ func (ml *ModelLoader) startProcess(grpcProcess, id string, serverAddress string
 		}
 	}()
 
+	// Surface backend exits in the log. Without this, a crash (SIGSEGV
+	// from a missing shared library, a Python ImportError, etc.) is
+	// invisible at every log level — the only signal is a delayed
+	// "connection refused" from the gRPC dial, which doesn't say
+	// whether the child is alive.
+	go func() {
+		<-grpcControlProcess.Done()
+		fields := []any{
+			"id", id,
+			"address", serverAddress,
+			"process", filepath.Base(grpcProcess),
+		}
+		code, codeErr := grpcControlProcess.ExitCode()
+		if codeErr == nil {
+			fields = append(fields, "exitCode", code)
+		}
+		// 143 = 128 + SIGTERM, the signal sent during graceful stop / model unload.
+		// Treat that and a clean 0 as expected; everything else is a likely crash.
+		if codeErr == nil && (code == "0" || code == "143") {
+			xlog.Info("Backend process exited", fields...)
+		} else {
+			xlog.Warn("Backend process exited unexpectedly", fields...)
+		}
+	}()
+
 	return grpcControlProcess, nil
 }