fix(agent): recover OpenResty runtime after invalid PID (#45)

* fix(agent): recover OpenResty runtime after invalid PID

* fix(agent): scope OpenResty shutdown to instance processes

---------

Co-authored-by: Noru Wyrms <wyrmsnoru@gmail.com>

internal/apps/agent/nginx/runtime_process_ps.go

@@ -0,0 +1,49 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package nginx
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+//nolint:unused // Used by the non-Linux Unix inspector.
+const (
+	psCommandIndex      = 8
+	psMasterBinaryIndex = 11
+)
+
+//nolint:unused // Used by the non-Linux Unix inspector; portable for fixture tests.
+func parsePSRuntime(output, binary, configPath string, owner int) ([]runtimeProcess, error) {
+	var processes []runtimeProcess
+	for _, line := range strings.Split(output, "\n") {
+		fields := strings.Fields(line)
+		if len(fields) <= psCommandIndex {
+			continue
+		}
+		uid, err := strconv.Atoi(fields[2])
+		if err != nil {
+			continue
+		}
+		title := strings.Join(fields[psCommandIndex:], " ")
+		if !strings.HasPrefix(title, "nginx: ") && !strings.HasPrefix(title, "openresty: ") {
+			continue
+		}
+		master := uid == owner && matchesRuntimeMaster(title, configPath)
+		if master && (len(fields) <= psMasterBinaryIndex || fields[psMasterBinaryIndex] != binary) {
+			return nil, fmt.Errorf("cannot verify openresty master invocation %s", fields[0])
+		}
+		pid, err := strconv.Atoi(fields[0])
+		if err != nil {
+			return nil, err
+		}
+		parentPID, err := strconv.Atoi(fields[1])
+		if err != nil {
+			return nil, err
+		}
+		processes = append(processes, runtimeProcess{PID: pid, ParentPID: parentPID, Master: master, StartTime: strings.Join(fields[3:psCommandIndex], " ")})
+	}
+	return processes, nil
+}