feat: podman-compose stack units and root/user execution scopes

- syncup: podman first, docker only as fallback (podman wins on name clash;
  existing docker units found in podman switch to podman)
- syncup: group podman-compose containers into one `kind: stack` unit per
  project (project, working_dir, compose_files, compose_bin from labels);
  disable existing member units ("part of stack <project>")
- generator: compose mode (podman-compose up/stop, WorkingDirectory) with
  pod start/stop fallback when compose binary/dir/files are missing
- reconcile: stacks disabled with "stack not found" when neither compose
  files nor pod exist
- root: scan root + rootless users listed in `users:` (podman only)
- non-root: config ~/.config/unitdore/units.yaml, own user units only
- sysuser package: runuser with XDG_RUNTIME_DIR/DBUS env, home/linger lookup
- install: warn when linger is not enabled for user units
- testdata/stack: podman-compose test stack and captured podman ps fixture
- docs: README, generated-units, man page, AGENTS, PLAN

systemd/generator.go

@@ -2,6 +2,8 @@ package systemd
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 	"text/template"
 
@@ -12,12 +14,18 @@ const systemUnitTemplate = `# /etc/systemd/system/{{.ServiceName}}
 # Generated by unitdore — do not edit manually
 
 [Unit]
-Description=Unitdore: {{.Unit.Name}} ({{.Unit.Runtime}})
+Description=Unitdore: {{.Unit.Name}} ({{.Label}})
 After=network.target{{with .RuntimeService}} {{.}}
 Requires={{.}}{{end}}
 
 [Service]
-Type=simple
+Type={{.ServiceType}}
+{{- if eq .ServiceType "oneshot"}}
+RemainAfterExit=yes
+{{- end}}
+{{- with .WorkingDir}}
+WorkingDirectory={{.}}
+{{- end}}
 ExecStart={{.ExecStart}}
 ExecStop={{if .ExecStop}}-{{.ExecStop}}{{end}}
 {{- if .Unit.Restart}}
@@ -36,11 +44,17 @@ const userUnitTemplate = `# ~/.config/systemd/user/{{.ServiceName}}
 # Generated by unitdore — do not edit manually
 
 [Unit]
-Description=Unitdore: {{.Unit.Name}} ({{.Unit.Runtime}})
+Description=Unitdore: {{.Unit.Name}} ({{.Label}})
 After=default.target
 
 [Service]
-Type=simple
+Type={{.ServiceType}}
+{{- if eq .ServiceType "oneshot"}}
+RemainAfterExit=yes
+{{- end}}
+{{- with .WorkingDir}}
+WorkingDirectory={{.}}
+{{- end}}
 ExecStart={{.ExecStart}}
 ExecStop={{if .ExecStop}}-{{.ExecStop}}{{end}}
 {{- if .Unit.Restart}}
@@ -61,6 +75,9 @@ type templateData struct {
 	ExecStart      string
 	ExecStop       string
 	RuntimeService string
+	Label          string // shown in Description
+	ServiceType    string // simple | oneshot
+	WorkingDir     string
 }
 
 // ServiceName returns the systemd service name for a unit, with optional prefix/suffix.
@@ -70,14 +87,25 @@ func ServiceName(u config.Unit, prefix, suffix string) string {
 
 // Generate produces the .service file content for a unit.
 func Generate(u config.Unit, prefix, suffix string) (string, error) {
-	execStart, execStop := buildExecCommands(u)
-
 	data := templateData{
 		ServiceName:    ServiceName(u, prefix, suffix),
 		Unit:           u,
-		ExecStart:      execStart,
-		ExecStop:       execStop,
 		RuntimeService: runtimeService(u.Runtime),
+		Label:          u.Runtime,
+		ServiceType:    "simple",
+	}
+
+	switch {
+	case u.IsStack() && u.Command == "" && StackMode(u) == StackModeCompose:
+		data.ExecStart, data.ExecStop = buildComposeCommands(u)
+		data.Label = "podman-compose stack"
+		data.WorkingDir = u.WorkingDir
+	case u.IsStack() && u.Command == "":
+		data.ExecStart, data.ExecStop = buildPodCommands(u)
+		data.Label = "podman pod"
+		data.ServiceType = "oneshot"
+	default:
+		data.ExecStart, data.ExecStop = buildExecCommands(u)
 	}
 
 	tmplStr := systemUnitTemplate
@@ -125,3 +153,66 @@ func buildExecCommands(u config.Unit) (start, stop string) {
 	}
 	return start, stop
 }
+
+// Stack modes: compose (podman-compose up/stop) with pod start/stop as fallback.
+const (
+	StackModeCompose = "compose"
+	StackModePod     = "pod"
+)
+
+// StackMode picks how a stack unit is started: compose when the compose binary,
+// working dir and compose files all exist; otherwise pod start/stop.
+func StackMode(u config.Unit) string {
+	if ComposeAvailable(u) {
+		return StackModeCompose
+	}
+	return StackModePod
+}
+
+// ComposeAvailable reports whether the stack can be driven by podman-compose.
+func ComposeAvailable(u config.Unit) bool {
+	if u.ComposeBin == "" || u.WorkingDir == "" {
+		return false
+	}
+	if !exists(u.ComposeBin) || !exists(u.WorkingDir) {
+		return false
+	}
+	for _, f := range u.ComposeFiles {
+		if !filepath.IsAbs(f) {
+			f = filepath.Join(u.WorkingDir, f)
+		}
+		if !exists(f) {
+			return false
+		}
+	}
+	return true
+}
+
+func exists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+func buildComposeCommands(u config.Unit) (start, stop string) {
+	args := []string{quoteArg(u.ComposeBin), "-p", quoteArg(u.Project)}
+	for _, f := range u.ComposeFiles {
+		args = append(args, "-f", quoteArg(f))
+	}
+	base := strings.Join(args, " ")
+	return base + " up", base + " stop"
+}
+
+func buildPodCommands(u config.Unit) (start, stop string) {
+	pod := quoteArg("pod_" + u.Project)
+	return "/usr/bin/podman pod start " + pod, "/usr/bin/podman pod stop " + pod
+}
+
+// quoteArg double-quotes an argument for systemd command lines if it
+// contains whitespace or quotes.
+func quoteArg(s string) string {
+	if !strings.ContainsAny(s, " \t\"'\\") {
+		return s
+	}
+	r := strings.NewReplacer(`\`, `\\`, `"`, `\"`)
+	return `"` + r.Replace(s) + `"`
+}