From df9b226c7ed5c1660483cc8560e5152ca2add1ec Mon Sep 17 00:00:00 2001
From: Hein <hein.puth@gmail.com>
Date: Mon, 12 Oct 2026 20:19:58 +0200
Subject: [PATCH] feat: OpenRC and runit init backends behind an Init interface

Extract init-neutral unit resolution into service/, add initsys.Init with systemd, openrc and runit backends, selected by 'init:' config or autodetect. OpenRC and runit are root only; rootless units run as system services as that user. Add docs and generated examples for all three.
---
 AGENTS.md                  |  17 +-
 README.md                  |  25 ++-
 cmd/helpers.go             |   5 +-
 cmd/install.go             |  24 ++-
 cmd/installall.go          |  24 ++-
 cmd/list.go                |  10 +-
 cmd/root.go                |   5 +-
 cmd/start.go               |  12 +-
 cmd/startall.go            |  12 +-
 cmd/status.go              |  12 +-
 cmd/stop.go                |  12 +-
 cmd/stopall.go             |  12 +-
 cmd/syncup.go              |   4 +-
 cmd/uninstall.go           |  16 +-
 cmd/uninstallall.go        |  16 +-
 cmd/update.go              |  12 +-
 config/config.go           |   3 +
 docs/generated-units.md    | 324 ++++++++++++++++++++++++++++++++-
 docs/unitdore.1            |  11 +-
 initsys/initsys.go         |  77 ++++++++
 initsys/initsys_test.go    |  52 ++++++
 openrc/openrc.go           | 279 ++++++++++++++++++++++++++++
 openrc/openrc_test.go      | 221 ++++++++++++++++++++++
 runit/runit.go             | 364 +++++++++++++++++++++++++++++++++++++
 runit/runit_test.go        | 295 ++++++++++++++++++++++++++++++
 service/spec.go            | 294 ++++++++++++++++++++++++++++++
 service/spec_test.go       | 215 ++++++++++++++++++++++
 systemd/backend.go         |  37 ++++
 systemd/generator.go       | 155 +---------------
 systemd/generator_test.go  |  81 ---------
 systemd/start_stop_test.go |  25 ---
 typescript                 |   0
 32 files changed, 2329 insertions(+), 322 deletions(-)
 create mode 100644 initsys/initsys.go
 create mode 100644 initsys/initsys_test.go
 create mode 100644 openrc/openrc.go
 create mode 100644 openrc/openrc_test.go
 create mode 100644 runit/runit.go
 create mode 100644 runit/runit_test.go
 create mode 100644 service/spec.go
 create mode 100644 service/spec_test.go
 create mode 100644 systemd/backend.go
 create mode 100644 typescript

diff --git a/AGENTS.md b/AGENTS.md
index 4a2b89a..9277441 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -1,6 +1,6 @@
 ## Project Overview
 
-**Unitdore** is a Go CLI tool that bridges container runtimes (Podman, Docker) and systemd. It discovers running containers, stores them in a YAML config, and generates + manages systemd `.service` unit files for each one.
+**Unitdore** is a Go CLI tool that bridges container runtimes (Podman, Docker) and the init system (systemd, OpenRC, runit). It discovers running containers, stores them in a YAML config, and generates + manages service files for each one.
 
 # Agent Rules
 
@@ -33,7 +33,11 @@ config/        # Config struct + YAML load/save (units.yaml)
 runtime/       # Docker and Podman runtime abstraction, compose labels
 sysuser/       # run commands as root/user (runuser), home/linger lookup
 testdata/stack # podman-compose test stack + captured `podman ps` fixture
-systemd/       # .service file generator and systemd manager
+service/       # init-neutral unit resolution: commands, quoting, user env
+initsys/       # Init interface, backend selection (config init: / autodetect)
+systemd/       # .service generator + systemctl manager (Backend)
+openrc/        # /etc/init.d script generator + rc-service manager (Backend)
+runit/         # /etc/sv run/finish generator + sv manager (Backend)
 docs/          # generated-units.md (unit file examples), unitdore.1 (man page)
 ```
 
@@ -41,13 +45,18 @@ docs/          # generated-units.md (unit file examples), unitdore.1 (man page)
 
 - **`config`** — `Unit` and `Config` structs; `Load`, `Save`, `FindUnit`, `AddUnit`
 - **`runtime`** — `ContainerRuntime` interface; `docker.go`, `podman.go` implementations
+- **`service`** — `Resolve(unit)` → start/stop commands, type, workdir; shared by all backends
+- **`initsys`** — `Init` interface; `New(cfg)` picks backend; cmd/ only talks to `Init`
 - **`systemd`** — `generator.go` builds `.service` file content; `manager.go` calls `systemctl`
+- **`openrc`**, **`runit`** — same role; root only; tests stub command execution via package vars
 
 ### Config file
 
 **Location:** `/etc/unitdore/units.yaml`
 
 ```yaml
+init: ""        # systemd | openrc | runit (empty = autodetect)
+service_dir: ""  # runit: supervised dir (empty = autodetect)
 prefix: ""      # prepended to service file name (e.g. "prod-")
 suffix: ""      # appended to service file name (e.g. "-svc")
 users: []       # root only: rootless users scanned by syncup
@@ -101,6 +110,10 @@ Tests exist in:
 - `runtime/runtime_test.go`
 - `cmd/syncup_test.go`
 - `sysuser/sysuser_test.go`
+- `service/spec_test.go`
+- `initsys/initsys_test.go`
+- `openrc/openrc_test.go`
+- `runit/runit_test.go`
 - `systemd/generator_test.go`
 
 Always run `make test` before marking a task complete. Add tests for new behaviour in the same package as the code under test.
diff --git a/README.md b/README.md
index b390c13..3e6e054 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 > *A door you open and close for container units.*
 
-Unitdore bridges your container runtime (Podman, Docker) and systemd. It discovers running containers and podman-compose stacks, stores them in a config file, and generates + manages systemd `.service` units for each one.
+Unitdore bridges your container runtime (Podman, Docker) and your init system (systemd, OpenRC, runit). It discovers running containers and podman-compose stacks, stores them in a config file, and generates + manages a service for each one.
 
 ## Install
 
@@ -107,6 +107,8 @@ oldthing   podman    hein    no        no          —                 container
 **Location:** `/etc/unitdore/units.yaml`
 
 ```yaml
+init: ""                     # optional: systemd | openrc | runit (empty = autodetect)
+service_dir: ""              # optional: runit supervised dir (empty = /var/service or /etc/service)
 prefix: ""                   # optional: prepended to all service names, e.g. "prod-"
 suffix: ""                   # optional: appended to all service names, e.g. "-svc"
 users: [hein]                # root only: rootless users scanned by syncup
@@ -158,6 +160,27 @@ units:
     enabled: true
 ```
 
+### Init systems
+
+Set `init:` in the config, or leave empty to autodetect (`/run/systemd/system` → systemd, `/run/openrc` → openrc, `/etc/runit` → runit, else systemd).
+
+| | systemd | openrc | runit |
+|---|---|---|---|
+| Service file | `/etc/systemd/system/unitdore-<n>.service` | `/etc/init.d/unitdore-<n>` | `/etc/sv/unitdore-<n>/{run,finish}` + symlink in `service_dir` |
+| Start / stop | `systemctl` | `rc-service` | `sv` |
+| Enable at boot | `systemctl enable` | `rc-update add … default` | remove `down` file |
+| Installed state | disabled until enabled | not in runlevel | symlinked with `down` file (no autostart) |
+| Rootless `user:` | `systemctl --user` unit (needs linger) | system service, `command_user` | system service, `chpst -u` |
+| Non-root use | yes (own user units) | **root only** | **root only** |
+| `restart*` | `Restart=on-failure`, `StartLimitBurst` | `supervise-daemon` `respawn_*` (always respawns) | `finish`: on-failure, `RestartSec`; **no retry limit** |
+| `docker` dependency | `Requires=docker.service` | `need docker` | none |
+| `oneshot` | `RemainAfterExit` | `start()`/`stop()` functions | run once, then `tail -f /dev/null` |
+
+- Rootless units on openrc/runit set `HOME` and `XDG_RUNTIME_DIR=/run/user/<uid>` and create that dir if missing.
+- `command` / `args` use systemd quoting; they are re-quoted for sh on openrc/runit.
+- No log redirection is generated on openrc; use the runtime's own logs.
+- `docs/generated-units.md` shows systemd output only.
+
 ### Script / executable units
 
 Added manually (`unitdore edit`); syncup never creates or disables them.
diff --git a/cmd/helpers.go b/cmd/helpers.go
index 3cfcbd9..e3237d5 100644
--- a/cmd/helpers.go
+++ b/cmd/helpers.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/initsys"
 	"github.com/warkanum/unitdore/sysuser"
 )
 
@@ -16,8 +17,8 @@ func runtimeLabel(u config.Unit) string {
 }
 
 // lingerHint prints, once per user, how to make user units start at boot.
-func lingerHint(seen map[string]bool, u config.Unit) {
-	if u.User == "" || seen[u.User] || sysuser.LingerEnabled(u.User) {
+func lingerHint(ini initsys.Init, seen map[string]bool, u config.Unit) {
+	if !ini.SupportsLinger() || u.User == "" || seen[u.User] || sysuser.LingerEnabled(u.User) {
 		return
 	}
 	seen[u.User] = true
diff --git a/cmd/install.go b/cmd/install.go
index 7c8e528..38b08fa 100644
--- a/cmd/install.go
+++ b/cmd/install.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var dryRun bool
@@ -32,6 +32,10 @@ func runInstall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 	installed := 0
 	skipped := 0
 	removed := 0
@@ -40,14 +44,14 @@ func runInstall(cmd *cobra.Command, args []string) error {
 	for _, u := range cfg.Units {
 		if !u.Enabled {
 			// Remove unit file if it exists for disabled units
-			if systemd.IsInstalled(u, prefix, suffix) {
+			if ini.IsInstalled(u, prefix, suffix) {
 				if dryRun {
-					fmt.Printf("  ~ would remove: %s\n", systemd.ServiceName(u, prefix, suffix))
+					fmt.Printf("  ~ would remove: %s\n", ini.ServiceName(u, prefix, suffix))
 				} else {
-					if err := systemd.Uninstall(u, prefix, suffix); err != nil {
+					if err := ini.Uninstall(u, prefix, suffix); err != nil {
 						fmt.Printf("  ✗ failed to remove %s: %v\n", u.Name, err)
 					} else {
-						fmt.Printf("  - removed: %s (disabled)\n", systemd.ServiceName(u, prefix, suffix))
+						fmt.Printf("  - removed: %s (disabled)\n", ini.ServiceName(u, prefix, suffix))
 						removed++
 					}
 				}
@@ -58,23 +62,23 @@ func runInstall(cmd *cobra.Command, args []string) error {
 		}
 
 		if dryRun {
-			content, err := systemd.Generate(u, prefix, suffix)
+			content, err := ini.Generate(u, prefix, suffix)
 			if err != nil {
 				fmt.Printf("  ✗ %s: %v\n", u.Name, err)
 				continue
 			}
-			path, _ := systemd.UnitPath(u, prefix, suffix)
+			path, _ := ini.UnitPath(u, prefix, suffix)
 			fmt.Printf("\n--- %s ---\n%s\n", path, content)
 			installed++
 			continue
 		}
 
-		if err := systemd.Install(u, prefix, suffix); err != nil {
+		if err := ini.Install(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed: %s: %v\n", u.Name, err)
 		} else {
-			path, _ := systemd.UnitPath(u, prefix, suffix)
+			path, _ := ini.UnitPath(u, prefix, suffix)
 			fmt.Printf("  ✓ installed: %s\n", path)
-			lingerHint(lingerSeen, u)
+			lingerHint(ini, lingerSeen, u)
 			installed++
 		}
 	}
diff --git a/cmd/installall.go b/cmd/installall.go
index 202dd8e..a690772 100644
--- a/cmd/installall.go
+++ b/cmd/installall.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var installallDryRun bool
@@ -32,6 +32,10 @@ func runInstallall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 	installed := 0
 	skipped := 0
 	removed := 0
@@ -39,14 +43,14 @@ func runInstallall(cmd *cobra.Command, args []string) error {
 
 	for _, u := range cfg.Units {
 		if !u.Enabled {
-			if systemd.IsInstalled(u, prefix, suffix) {
+			if ini.IsInstalled(u, prefix, suffix) {
 				if installallDryRun {
-					fmt.Printf("  ~ would remove: %s\n", systemd.ServiceName(u, prefix, suffix))
+					fmt.Printf("  ~ would remove: %s\n", ini.ServiceName(u, prefix, suffix))
 				} else {
-					if err := systemd.Uninstall(u, prefix, suffix); err != nil {
+					if err := ini.Uninstall(u, prefix, suffix); err != nil {
 						fmt.Printf("  ✗ failed to remove %s: %v\n", u.Name, err)
 					} else {
-						fmt.Printf("  - removed: %s (disabled)\n", systemd.ServiceName(u, prefix, suffix))
+						fmt.Printf("  - removed: %s (disabled)\n", ini.ServiceName(u, prefix, suffix))
 						removed++
 					}
 				}
@@ -57,23 +61,23 @@ func runInstallall(cmd *cobra.Command, args []string) error {
 		}
 
 		if installallDryRun {
-			content, err := systemd.Generate(u, prefix, suffix)
+			content, err := ini.Generate(u, prefix, suffix)
 			if err != nil {
 				fmt.Printf("  ✗ %s: %v\n", u.Name, err)
 				continue
 			}
-			path, _ := systemd.UnitPath(u, prefix, suffix)
+			path, _ := ini.UnitPath(u, prefix, suffix)
 			fmt.Printf("\n--- %s ---\n%s\n", path, content)
 			installed++
 			continue
 		}
 
-		if err := systemd.Install(u, prefix, suffix); err != nil {
+		if err := ini.Install(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed: %s: %v\n", u.Name, err)
 		} else {
-			path, _ := systemd.UnitPath(u, prefix, suffix)
+			path, _ := ini.UnitPath(u, prefix, suffix)
 			fmt.Printf("  ✓ installed: %s\n", path)
-			lingerHint(lingerSeen, u)
+			lingerHint(ini, lingerSeen, u)
 			installed++
 		}
 	}
diff --git a/cmd/list.go b/cmd/list.go
index 90508a3..b1824df 100644
--- a/cmd/list.go
+++ b/cmd/list.go
@@ -7,7 +7,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var listCmd = &cobra.Command{
@@ -41,6 +41,10 @@ func runList(cmd *cobra.Command, args []string) error {
 	})
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
 	type row struct{ name, runtime, enabled, installed, path string }
 
@@ -53,9 +57,9 @@ func runList(cmd *cobra.Command, args []string) error {
 
 		installed := "no"
 		unitPath := "—"
-		if p, err := systemd.UnitPath(u, prefix, suffix); err == nil {
+		if p, err := ini.UnitPath(u, prefix, suffix); err == nil {
 			unitPath = p
-			if systemd.IsInstalled(u, prefix, suffix) {
+			if ini.IsInstalled(u, prefix, suffix) {
 				installed = "yes"
 			}
 		}
diff --git a/cmd/root.go b/cmd/root.go
index f8552a7..6b35419 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -16,10 +16,11 @@ var configPath string
 var rootCmd = &cobra.Command{
 	Use:   "unitdore",
 	Short: "A door you open and close for container units",
-	Long: `Unitdore manages container units via systemd.
+	Long: `Unitdore manages container units via the system init (systemd, OpenRC or runit).
 
 It discovers running containers and podman-compose stacks, stores them in a
-config file, and generates + manages systemd .service units for each one.
+config file, and generates + manages init service units for each one (systemd by default;
+set 'init:' in the config for openrc or runit).
 
 As root: system units, plus user units for users listed in 'users:'.
 As a normal user: own config and user units only.`,
diff --git a/cmd/start.go b/cmd/start.go
index 033436a..15fc541 100644
--- a/cmd/start.go
+++ b/cmd/start.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var startCmd = &cobra.Command{
@@ -32,13 +32,17 @@ func runStart(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
-	if !systemd.IsInstalled(*u, prefix, suffix) {
+	if !ini.IsInstalled(*u, prefix, suffix) {
 		return fmt.Errorf("%s is not installed — run 'unitdore install' first", name)
 	}
 
-	fmt.Printf("  ▶ starting %s...\n", systemd.ServiceName(*u, prefix, suffix))
-	if err := systemd.Start(*u, prefix, suffix); err != nil {
+	fmt.Printf("  ▶ starting %s...\n", ini.ServiceName(*u, prefix, suffix))
+	if err := ini.Start(*u, prefix, suffix); err != nil {
 		return err
 	}
 	fmt.Printf("  ✓ started: %s\n", name)
diff --git a/cmd/startall.go b/cmd/startall.go
index fffbda8..9b4c44f 100644
--- a/cmd/startall.go
+++ b/cmd/startall.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var startallCmd = &cobra.Command{
@@ -28,6 +28,10 @@ func runStartall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
 	units := make([]config.Unit, len(cfg.Units))
 	copy(units, cfg.Units)
@@ -45,12 +49,12 @@ func runStartall(cmd *cobra.Command, args []string) error {
 		if !u.Enabled {
 			continue
 		}
-		if !systemd.IsInstalled(u, prefix, suffix) {
+		if !ini.IsInstalled(u, prefix, suffix) {
 			fmt.Printf("  ! %s: not installed — run 'unitdore install' first\n", u.Name)
 			continue
 		}
-		fmt.Printf("  ▶ starting: %s...\n", systemd.ServiceName(u, prefix, suffix))
-		if err := systemd.Start(u, prefix, suffix); err != nil {
+		fmt.Printf("  ▶ starting: %s...\n", ini.ServiceName(u, prefix, suffix))
+		if err := ini.Start(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed: %s: %v\n", u.Name, err)
 			failed++
 		} else {
diff --git a/cmd/status.go b/cmd/status.go
index f66cf09..641699e 100644
--- a/cmd/status.go
+++ b/cmd/status.go
@@ -7,7 +7,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var statusCmd = &cobra.Command{
@@ -37,6 +37,10 @@ func runStatus(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
 	if len(cfg.Units) == 0 {
 		fmt.Println("No units configured. Run 'unitdore syncup' to discover containers.")
@@ -65,13 +69,13 @@ func runStatus(cmd *cobra.Command, args []string) error {
 		}
 
 		installed := "yes"
-		if !systemd.IsInstalled(u, prefix, suffix) {
+		if !ini.IsInstalled(u, prefix, suffix) {
 			installed = "no"
 		}
 
 		state := "—"
-		if systemd.IsInstalled(u, prefix, suffix) {
-			state = systemd.Status(u, prefix, suffix)
+		if ini.IsInstalled(u, prefix, suffix) {
+			state = ini.Status(u, prefix, suffix)
 		}
 
 		rows = append(rows, statusRow{
diff --git a/cmd/stop.go b/cmd/stop.go
index a95f23c..8ad4d8b 100644
--- a/cmd/stop.go
+++ b/cmd/stop.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var stopCmd = &cobra.Command{
@@ -32,13 +32,17 @@ func runStop(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
-	if !systemd.IsInstalled(*u, prefix, suffix) {
+	if !ini.IsInstalled(*u, prefix, suffix) {
 		return fmt.Errorf("%s is not installed", name)
 	}
 
-	fmt.Printf("  ■ stopping %s...\n", systemd.ServiceName(*u, prefix, suffix))
-	if err := systemd.Stop(*u, prefix, suffix); err != nil {
+	fmt.Printf("  ■ stopping %s...\n", ini.ServiceName(*u, prefix, suffix))
+	if err := ini.Stop(*u, prefix, suffix); err != nil {
 		return err
 	}
 	fmt.Printf("  ✓ stopped: %s\n", name)
diff --git a/cmd/stopall.go b/cmd/stopall.go
index f3515bb..c91ba56 100644
--- a/cmd/stopall.go
+++ b/cmd/stopall.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var stopallCmd = &cobra.Command{
@@ -27,6 +27,10 @@ func runStopall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
 	// Reverse order for shutdown
 	units := make([]config.Unit, len(cfg.Units))
@@ -42,11 +46,11 @@ func runStopall(cmd *cobra.Command, args []string) error {
 	failed := 0
 
 	for _, u := range units {
-		if !systemd.IsInstalled(u, prefix, suffix) {
+		if !ini.IsInstalled(u, prefix, suffix) {
 			continue
 		}
-		fmt.Printf("  ■ stopping: %s...\n", systemd.ServiceName(u, prefix, suffix))
-		if err := systemd.Stop(u, prefix, suffix); err != nil {
+		fmt.Printf("  ■ stopping: %s...\n", ini.ServiceName(u, prefix, suffix))
+		if err := ini.Stop(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed: %s: %v\n", u.Name, err)
 			failed++
 		} else {
diff --git a/cmd/syncup.go b/cmd/syncup.go
index 0e52539..4cd54e2 100644
--- a/cmd/syncup.go
+++ b/cmd/syncup.go
@@ -9,7 +9,7 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
 	"github.com/warkanum/unitdore/runtime"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/service"
 	"github.com/warkanum/unitdore/sysuser"
 )
 
@@ -221,7 +221,7 @@ func mergeDiscovered(cfg *config.Config, containers []runtime.Container, compose
 // unitExists checks whether a unit's container or stack still exists.
 func unitExists(u config.Unit) (bool, error) {
 	if u.IsStack() {
-		if systemd.ComposeAvailable(u) {
+		if service.ComposeAvailable(u) {
 			return true, nil
 		}
 		return (&runtime.Podman{}).PodExists(u.User, runtime.PodName(u.Project))
diff --git a/cmd/uninstall.go b/cmd/uninstall.go
index 1456372..1a2be9e 100644
--- a/cmd/uninstall.go
+++ b/cmd/uninstall.go
@@ -5,7 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var uninstallCmd = &cobra.Command{
@@ -32,21 +32,25 @@ func runUninstall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
-	if !systemd.IsInstalled(*u, prefix, suffix) {
+	if !ini.IsInstalled(*u, prefix, suffix) {
 		return fmt.Errorf("%s is not installed", name)
 	}
 
-	svcName := systemd.ServiceName(*u, prefix, suffix)
+	svcName := ini.ServiceName(*u, prefix, suffix)
 
 	fmt.Printf("  ■ disabling %s...\n", svcName)
-	if err := systemd.Disable(*u, prefix, suffix); err != nil {
+	if err := ini.Disable(*u, prefix, suffix); err != nil {
 		return fmt.Errorf("disabling unit: %w", err)
 	}
 
-	path, _ := systemd.UnitPath(*u, prefix, suffix)
+	path, _ := ini.UnitPath(*u, prefix, suffix)
 	fmt.Printf("  ✗ removing %s...\n", path)
-	if err := systemd.Uninstall(*u, prefix, suffix); err != nil {
+	if err := ini.Uninstall(*u, prefix, suffix); err != nil {
 		return fmt.Errorf("removing service file: %w", err)
 	}
 
diff --git a/cmd/uninstallall.go b/cmd/uninstallall.go
index 0989224..164614a 100644
--- a/cmd/uninstallall.go
+++ b/cmd/uninstallall.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var uninstallallCmd = &cobra.Command{
@@ -27,6 +27,10 @@ func runUninstallall(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
 	units := make([]config.Unit, len(cfg.Units))
 	copy(units, cfg.Units)
@@ -41,19 +45,19 @@ func runUninstallall(cmd *cobra.Command, args []string) error {
 	failed := 0
 
 	for _, u := range units {
-		if !systemd.IsInstalled(u, prefix, suffix) {
+		if !ini.IsInstalled(u, prefix, suffix) {
 			continue
 		}
-		svcName := systemd.ServiceName(u, prefix, suffix)
+		svcName := ini.ServiceName(u, prefix, suffix)
 		fmt.Printf("  ■ disabling %s...\n", svcName)
-		if err := systemd.Disable(u, prefix, suffix); err != nil {
+		if err := ini.Disable(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed to disable %s: %v\n", u.Name, err)
 			failed++
 			continue
 		}
-		path, _ := systemd.UnitPath(u, prefix, suffix)
+		path, _ := ini.UnitPath(u, prefix, suffix)
 		fmt.Printf("  ✗ removing %s...\n", path)
-		if err := systemd.Uninstall(u, prefix, suffix); err != nil {
+		if err := ini.Uninstall(u, prefix, suffix); err != nil {
 			fmt.Printf("  ✗ failed to remove %s: %v\n", u.Name, err)
 			failed++
 			continue
diff --git a/cmd/update.go b/cmd/update.go
index 19f48f3..fc43b5c 100644
--- a/cmd/update.go
+++ b/cmd/update.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warkanum/unitdore/config"
-	"github.com/warkanum/unitdore/systemd"
+	"github.com/warkanum/unitdore/initsys"
 )
 
 var (
@@ -64,12 +64,16 @@ func runUpdate(cmd *cobra.Command, args []string) error {
 	}
 
 	prefix, suffix := cfg.Prefix, cfg.Suffix
+	ini, err := initsys.New(cfg)
+	if err != nil {
+		return err
+	}
 
-	if systemd.IsInstalled(*u, prefix, suffix) {
-		if err := systemd.Install(*u, prefix, suffix); err != nil {
+	if ini.IsInstalled(*u, prefix, suffix) {
+		if err := ini.Install(*u, prefix, suffix); err != nil {
 			return fmt.Errorf("recreating service file: %w", err)
 		}
-		path, _ := systemd.UnitPath(*u, prefix, suffix)
+		path, _ := ini.UnitPath(*u, prefix, suffix)
 		fmt.Printf("  ✓ service file recreated: %s\n", path)
 	}
 
diff --git a/config/config.go b/config/config.go
index 3991f7b..1d39678 100644
--- a/config/config.go
+++ b/config/config.go
@@ -87,6 +87,9 @@ type Config struct {
 	Prefix string   `yaml:"prefix,omitempty"` // prepended to generated service name, e.g. "prod-"
 	Suffix string   `yaml:"suffix,omitempty"` // appended to generated service name, e.g. "-svc"
 	Users  []string `yaml:"users,omitempty"`  // rootless users scanned by syncup when run as root
+
+	Init       string `yaml:"init,omitempty"`        // systemd | openrc | runit (empty = autodetect)
+	ServiceDir string `yaml:"service_dir,omitempty"` // runit: supervised service dir (empty = autodetect)
 }
 
 // Load reads and parses the config file at path.
diff --git a/docs/generated-units.md b/docs/generated-units.md
index 0f33548..a1af1bb 100644
--- a/docs/generated-units.md
+++ b/docs/generated-units.md
@@ -1,4 +1,4 @@
-# Generated Systemd Unit Files
+# Generated Unit Files (systemd, OpenRC, runit)
 
 Unitdore generates `.service` files from your `units.yaml` config.
 This document shows every combination with annotated examples.
@@ -330,6 +330,326 @@ ExecStop=-/usr/bin/podman pod stop pod_shop
 
 ---
 
+## Config Behind the Init System Examples
+
+```yaml
+init: systemd   # systemd | openrc | runit
+units:
+  - {name: nginx,  runtime: podman, order: 1, enabled: true}
+  - {name: redis,  runtime: docker, order: 2, enabled: true, restart: true, restart_sec: 5, restart_retries: 3}
+  - {name: myapp,  runtime: podman, user: alice, order: 3, enabled: true}
+  - {name: backup, runtime: script, script: /opt/scripts/backup.sh, stop_script: /opt/scripts/stop.sh, shell: /bin/sh, working_dir: /opt/scripts, order: 4, enabled: true}
+  - {name: agent,  runtime: exec, executable: /opt/agent/bin/agent, args: [--config, /etc/agent.toml], service_type: oneshot, order: 5, enabled: true}
+  - {name: shop,   runtime: podman, kind: stack, project: shop, order: 6, enabled: true}
+```
+
+---
+
+## Script and Executable Units (systemd)
+
+`script` runs `<shell> <script>` (default shell `/bin/bash`); `exec` runs the binary directly.
+
+```ini
+# /etc/systemd/system/unitdore-backup.service
+# Generated by unitdore — do not edit manually
+
+[Unit]
+Description=Unitdore: backup (sh script)
+After=network.target
+
+[Service]
+Type=simple
+WorkingDirectory=/opt/scripts
+ExecStart=/bin/sh /opt/scripts/backup.sh
+ExecStop=-/bin/sh /opt/scripts/stop.sh
+
+[Install]
+WantedBy=multi-user.target
+```
+
+```ini
+# /etc/systemd/system/unitdore-agent.service
+# Generated by unitdore — do not edit manually
+
+[Unit]
+Description=Unitdore: agent (executable)
+After=network.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/opt/agent/bin/agent --config /etc/agent.toml
+ExecStop=
+
+[Install]
+WantedBy=multi-user.target
+```
+
+---
+
+## OpenRC
+
+Root only. Files in `/etc/init.d/`. Rootless `user:` units run as a system service via `command_user`.
+
+### nginx
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-nginx
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: nginx (podman)"
+
+command_background=yes
+pidfile="/run/${RC_SVCNAME}.pid"
+command="/usr/bin/podman"
+command_args="start -a nginx"
+
+depend() {
+	need net
+}
+
+stop_pre() {
+	/usr/bin/podman stop nginx || true
+}
+```
+
+### redis
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-redis
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: redis (docker)"
+
+supervisor=supervise-daemon
+respawn_delay=5
+respawn_max=3
+command="/usr/bin/docker"
+command_args="start -a redis"
+
+depend() {
+	need net
+	need docker
+}
+
+stop_pre() {
+	/usr/bin/docker stop redis || true
+}
+```
+
+### myapp
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-myapp
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: myapp (podman)"
+export HOME=/home/alice
+export XDG_RUNTIME_DIR=/run/user/1000
+
+command_background=yes
+pidfile="/run/${RC_SVCNAME}.pid"
+command="/usr/bin/podman"
+command_args="start -a myapp"
+command_user="alice"
+
+depend() {
+	need net
+}
+
+start_pre() {
+	checkpath -d -m 0700 -o alice /run/user/1000
+}
+
+stop_pre() {
+	su -m -s /bin/sh -c '/usr/bin/podman stop myapp' alice || true
+}
+```
+
+### backup
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-backup
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: backup (sh script)"
+
+command_background=yes
+pidfile="/run/${RC_SVCNAME}.pid"
+command="/bin/sh"
+command_args="/opt/scripts/backup.sh"
+directory="/opt/scripts"
+
+depend() {
+	need net
+}
+
+stop_pre() {
+	/bin/sh /opt/scripts/stop.sh || true
+}
+```
+
+### agent
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-agent
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: agent (executable)"
+
+start() {
+	ebegin "Starting $RC_SVCNAME"
+	/opt/agent/bin/agent --config /etc/agent.toml
+	eend $?
+}
+
+depend() {
+	need net
+}
+```
+
+### shop
+
+```sh
+#!/sbin/openrc-run
+# /etc/init.d/unitdore-shop
+# Generated by unitdore — do not edit manually
+
+description="Unitdore: shop (podman pod)"
+
+start() {
+	ebegin "Starting $RC_SVCNAME"
+	/usr/bin/podman pod start pod_shop
+	eend $?
+}
+
+stop() {
+	ebegin "Stopping $RC_SVCNAME"
+	/usr/bin/podman pod stop pod_shop
+	eend $?
+}
+
+depend() {
+	need net
+}
+```
+
+---
+
+## runit
+
+Root only. Each unit is `/etc/sv/unitdore-<name>/{run,finish}` symlinked into the service dir. Install adds a `down` file (no autostart until started/enabled). Both files are shown per unit.
+
+### nginx
+
+```sh
+# ===== /etc/sv/unitdore-nginx/run =====
+#!/bin/sh
+# unitdore-nginx — generated by unitdore, do not edit manually
+exec 2>&1
+exec /usr/bin/podman start -a nginx
+
+# ===== /etc/sv/unitdore-nginx/finish =====
+#!/bin/sh
+# unitdore-nginx — generated by unitdore, do not edit manually
+/usr/bin/podman stop nginx || true
+exec sv down .
+```
+
+### redis
+
+```sh
+# ===== /etc/sv/unitdore-redis/run =====
+#!/bin/sh
+# unitdore-redis — generated by unitdore, do not edit manually
+exec 2>&1
+exec /usr/bin/docker start -a redis
+
+# ===== /etc/sv/unitdore-redis/finish =====
+#!/bin/sh
+# unitdore-redis — generated by unitdore, do not edit manually
+/usr/bin/docker stop redis || true
+[ "$1" = 0 ] && exec sv down .
+sleep 5
+```
+
+### myapp
+
+```sh
+# ===== /etc/sv/unitdore-myapp/run =====
+#!/bin/sh
+# unitdore-myapp — generated by unitdore, do not edit manually
+exec 2>&1
+[ -d /run/user/1000 ] || install -d -m 0700 -o alice /run/user/1000
+export HOME=/home/alice
+export XDG_RUNTIME_DIR=/run/user/1000
+exec chpst -u alice /usr/bin/podman start -a myapp
+
+# ===== /etc/sv/unitdore-myapp/finish =====
+#!/bin/sh
+# unitdore-myapp — generated by unitdore, do not edit manually
+chpst -u alice /usr/bin/podman stop myapp || true
+exec sv down .
+```
+
+### backup
+
+```sh
+# ===== /etc/sv/unitdore-backup/run =====
+#!/bin/sh
+# unitdore-backup — generated by unitdore, do not edit manually
+exec 2>&1
+cd /opt/scripts || exit 1
+exec /bin/sh /opt/scripts/backup.sh
+
+# ===== /etc/sv/unitdore-backup/finish =====
+#!/bin/sh
+# unitdore-backup — generated by unitdore, do not edit manually
+cd /opt/scripts 2>/dev/null
+/bin/sh /opt/scripts/stop.sh || true
+exec sv down .
+```
+
+### agent
+
+```sh
+# ===== /etc/sv/unitdore-agent/run =====
+#!/bin/sh
+# unitdore-agent — generated by unitdore, do not edit manually
+exec 2>&1
+/opt/agent/bin/agent --config /etc/agent.toml || exit 1
+exec tail -f /dev/null
+
+# ===== /etc/sv/unitdore-agent/finish =====
+#!/bin/sh
+# unitdore-agent — generated by unitdore, do not edit manually
+exec sv down .
+```
+
+### shop
+
+```sh
+# ===== /etc/sv/unitdore-shop/run =====
+#!/bin/sh
+# unitdore-shop — generated by unitdore, do not edit manually
+exec 2>&1
+/usr/bin/podman pod start pod_shop || exit 1
+exec tail -f /dev/null
+
+# ===== /etc/sv/unitdore-shop/finish =====
+#!/bin/sh
+# unitdore-shop — generated by unitdore, do not edit manually
+/usr/bin/podman pod stop pod_shop || true
+exec sv down .
+```
+
+---
+
 ## Quick Reference: Service File Locations
 
 | Scenario | Path |
@@ -339,3 +659,5 @@ ExecStop=-/usr/bin/podman pod stop pod_shop
 | With prefix `prod-` | `/etc/systemd/system/unitdore-prod-<name>.service` |
 | With suffix `-svc` | `/etc/systemd/system/unitdore-<name>-svc.service` |
 | With both | `/etc/systemd/system/unitdore-prod-<name>-svc.service` |
+| OpenRC | `/etc/init.d/unitdore-<name>` |
+| runit | `/etc/sv/unitdore-<name>/` (+ symlink in `/var/service` or `/etc/service`) |
diff --git a/docs/unitdore.1 b/docs/unitdore.1
index 2511bb5..3bb8ea1 100644
--- a/docs/unitdore.1
+++ b/docs/unitdore.1
@@ -1,6 +1,6 @@
 .TH UNITDORE 1 "2026-04-08" "0.1.0" "User Commands"
 .SH NAME
-unitdore \- manage container units via systemd
+unitdore \- manage container units via systemd, OpenRC or runit
 .SH SYNOPSIS
 .B unitdore
 [\fB\-\-config\fR \fIpath\fR]
@@ -106,6 +106,13 @@ units:
 Stack units run \fBpodman\-compose up\fR/\fBstop\fR when compose_bin,
 working_dir and compose_files exist; otherwise \fBpodman pod start\fR/\fBstop
 pod_\fR\fIproject\fR.
+.SH INIT SYSTEMS
+The \fBinit:\fR config key selects \fBsystemd\fR, \fBopenrc\fR or \fBrunit\fR.
+Empty means autodetect, falling back to systemd. OpenRC and runit are root only;
+rootless units run as system services as that user. runit service links go in
+\fBservice_dir:\fR (default \fI/var/service\fR or \fI/etc/service\fR).
+OpenRC scripts are written to \fI/etc/init.d/unitdore\-*\fR and runit services to
+\fI/etc/sv/unitdore\-*\fR.
 .SH GENERATED SERVICE FILES
 System units are written to \fI/etc/systemd/system/\fR and user units to
 \fI~/.config/systemd/user/\fR.
@@ -156,7 +163,7 @@ Generated system unit files.
 .I ~/.config/systemd/user/unitdore-*.service
 Generated rootless user unit files.
 .SH REQUIREMENTS
-systemd; Podman and/or Docker (only installed runtimes are used);
+systemd, OpenRC or runit; Podman and/or Docker (only installed runtimes are used);
 podman\-compose for compose\-mode stacks.
 User units need linger to start at boot: \fBloginctl enable\-linger\fR \fIuser\fR.
 Root is required for system units; the relevant user for rootless units.
diff --git a/initsys/initsys.go b/initsys/initsys.go
new file mode 100644
index 0000000..2d7f820
--- /dev/null
+++ b/initsys/initsys.go
@@ -0,0 +1,77 @@
+// Package initsys selects the init system backend that installs and controls
+// unitdore services.
+package initsys
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/openrc"
+	"github.com/warkanum/unitdore/runit"
+	"github.com/warkanum/unitdore/systemd"
+)
+
+// Backend names.
+const (
+	Systemd = "systemd"
+	OpenRC  = "openrc"
+	Runit   = "runit"
+)
+
+// Init is implemented by every init system backend. u.User selects the scope;
+// backends that cannot do per-user managers run user units as system services.
+type Init interface {
+	Name() string
+	ServiceName(u config.Unit, prefix, suffix string) string
+	UnitPath(u config.Unit, prefix, suffix string) (string, error)
+	Generate(u config.Unit, prefix, suffix string) (string, error)
+	Install(u config.Unit, prefix, suffix string) error
+	Uninstall(u config.Unit, prefix, suffix string) error
+	Enable(u config.Unit, prefix, suffix string) error
+	Disable(u config.Unit, prefix, suffix string) error
+	Start(u config.Unit, prefix, suffix string) error
+	Stop(u config.Unit, prefix, suffix string) error
+	// Status returns active | inactive | failed | activating | deactivating | unknown.
+	Status(u config.Unit, prefix, suffix string) string
+	IsInstalled(u config.Unit, prefix, suffix string) bool
+	// SupportsLinger reports whether user units need systemd-style linger.
+	SupportsLinger() bool
+}
+
+// New returns the backend named in cfg.Init, or the detected one.
+func New(cfg *config.Config) (Init, error) {
+	name := cfg.Init
+	if name == "" {
+		name = Detect("/")
+	}
+	switch name {
+	case Systemd:
+		return systemd.Backend{}, nil
+	case OpenRC:
+		return openrc.Backend{}, nil
+	case Runit:
+		return runit.Backend{ServiceDir: cfg.ServiceDir}, nil
+	default:
+		return nil, fmt.Errorf("unknown init %q (want systemd, openrc or runit)", name)
+	}
+}
+
+// Detect guesses the running init system below root. Falls back to systemd.
+func Detect(root string) string {
+	has := func(p string) bool {
+		_, err := os.Stat(filepath.Join(root, p))
+		return err == nil
+	}
+	switch {
+	case has("run/systemd/system"):
+		return Systemd
+	case has("run/openrc"), has("sbin/openrc-run"):
+		return OpenRC
+	case has("run/runit"), has("etc/runit"):
+		return Runit
+	default:
+		return Systemd
+	}
+}
diff --git a/initsys/initsys_test.go b/initsys/initsys_test.go
new file mode 100644
index 0000000..fd4a652
--- /dev/null
+++ b/initsys/initsys_test.go
@@ -0,0 +1,52 @@
+package initsys
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/warkanum/unitdore/config"
+)
+
+func TestDetect(t *testing.T) {
+	tests := []struct {
+		name  string
+		paths []string
+		want  string
+	}{
+		{"systemd", []string{"run/systemd/system"}, Systemd},
+		{"openrc", []string{"run/openrc"}, OpenRC},
+		{"openrc binary", []string{"sbin/openrc-run"}, OpenRC},
+		{"runit", []string{"etc/runit"}, Runit},
+		{"systemd wins", []string{"run/systemd/system", "etc/runit"}, Systemd},
+		{"fallback", nil, Systemd},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			root := t.TempDir()
+			for _, p := range tt.paths {
+				if err := os.MkdirAll(filepath.Dir(filepath.Join(root, p)), 0755); err != nil {
+					t.Fatal(err)
+				}
+				if err := os.WriteFile(filepath.Join(root, p), nil, 0644); err != nil {
+					t.Fatal(err)
+				}
+			}
+			if got := Detect(root); got != tt.want {
+				t.Errorf("Detect() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestNew(t *testing.T) {
+	for _, name := range []string{Systemd, OpenRC, Runit} {
+		ini, err := New(&config.Config{Init: name})
+		if err != nil || ini.Name() != name {
+			t.Errorf("New(%q) = %v, %v", name, ini, err)
+		}
+	}
+	if _, err := New(&config.Config{Init: "sysv"}); err == nil {
+		t.Error("New() should reject an unknown init")
+	}
+}
diff --git a/openrc/openrc.go b/openrc/openrc.go
new file mode 100644
index 0000000..d92068b
--- /dev/null
+++ b/openrc/openrc.go
@@ -0,0 +1,279 @@
+// Package openrc generates and manages OpenRC init scripts.
+//
+// Services run at system level (root only). Units with a user run as that
+// user through command_user, with HOME and XDG_RUNTIME_DIR set.
+package openrc
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/service"
+)
+
+const runlevel = "default"
+
+// Overridable for tests.
+var (
+	initDir = "/etc/init.d"
+
+	// runCmd runs a command with stdio passed through.
+	runCmd = func(name string, args ...string) error {
+		cmd := exec.Command(name, args...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		return cmd.Run()
+	}
+	// outCmd runs a command and returns its combined output.
+	outCmd = func(name string, args ...string) ([]byte, error) {
+		return exec.Command(name, args...).CombinedOutput()
+	}
+)
+
+// Backend is the OpenRC implementation of the init interface.
+type Backend struct{}
+
+func (Backend) Name() string { return "openrc" }
+
+// SupportsLinger is false: OpenRC services need no linger.
+func (Backend) SupportsLinger() bool { return false }
+
+func (Backend) ServiceName(u config.Unit, prefix, suffix string) string {
+	return service.BaseName(u, prefix, suffix)
+}
+
+func (b Backend) UnitPath(u config.Unit, prefix, suffix string) (string, error) {
+	return filepath.Join(initDir, b.ServiceName(u, prefix, suffix)), nil
+}
+
+func (b Backend) IsInstalled(u config.Unit, prefix, suffix string) bool {
+	path, _ := b.UnitPath(u, prefix, suffix)
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+func (b Backend) Install(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	content, err := b.Generate(u, prefix, suffix)
+	if err != nil {
+		return err
+	}
+	path, _ := b.UnitPath(u, prefix, suffix)
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return fmt.Errorf("creating init dir: %w", err)
+	}
+	if err := os.WriteFile(path, []byte(content), 0755); err != nil {
+		return fmt.Errorf("writing init script: %w", err)
+	}
+	return nil
+}
+
+func (b Backend) Uninstall(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	name := b.ServiceName(u, prefix, suffix)
+	_ = runCmd("rc-update", "del", name, runlevel) // not in runlevel is fine
+	path, _ := b.UnitPath(u, prefix, suffix)
+	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("removing init script: %w", err)
+	}
+	return nil
+}
+
+// Enable adds the service to the default runlevel and starts it.
+func (b Backend) Enable(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	name := b.ServiceName(u, prefix, suffix)
+	if err := runCmd("rc-update", "add", name, runlevel); err != nil {
+		return err
+	}
+	return runCmd("rc-service", name, "start")
+}
+
+// Disable stops the service and removes it from the default runlevel.
+func (b Backend) Disable(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	name := b.ServiceName(u, prefix, suffix)
+	if err := runCmd("rc-service", name, "stop"); err != nil {
+		return err
+	}
+	_ = runCmd("rc-update", "del", name, runlevel) // not in runlevel is fine
+	return nil
+}
+
+func (b Backend) Start(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	return runCmd("rc-service", b.ServiceName(u, prefix, suffix), "start")
+}
+
+func (b Backend) Stop(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("openrc"); err != nil {
+		return err
+	}
+	return runCmd("rc-service", b.ServiceName(u, prefix, suffix), "stop")
+}
+
+func (b Backend) Status(u config.Unit, prefix, suffix string) string {
+	// rc-service status exits non-zero for stopped services but still prints
+	out, _ := outCmd("rc-service", b.ServiceName(u, prefix, suffix), "status")
+	return parseStatus(string(out))
+}
+
+// parseStatus maps `rc-service <name> status` output to a systemd-like state.
+func parseStatus(out string) string {
+	out = strings.ToLower(out)
+	switch {
+	case strings.Contains(out, "crashed"):
+		return "failed"
+	case strings.Contains(out, "starting"):
+		return "activating"
+	case strings.Contains(out, "stopping"):
+		return "deactivating"
+	case strings.Contains(out, "started"):
+		return "active"
+	case strings.Contains(out, "stopped"):
+		return "inactive"
+	default:
+		return "unknown"
+	}
+}
+
+// Generate produces the init script for a unit.
+func (b Backend) Generate(u config.Unit, prefix, suffix string) (string, error) {
+	if err := service.Validate(u); err != nil {
+		return "", err
+	}
+	user, err := service.LookupUser(u.User)
+	if err != nil {
+		return "", err
+	}
+	spec := service.Resolve(u)
+
+	var w strings.Builder
+	w.WriteString("#!/sbin/openrc-run\n")
+	w.WriteString("# " + filepath.Join(initDir, b.ServiceName(u, prefix, suffix)) + "\n")
+	w.WriteString("# Generated by unitdore — do not edit manually\n\n")
+	fmt.Fprintf(&w, "description=%s\n", dq(fmt.Sprintf("Unitdore: %s (%s)", u.Name, spec.Label)))
+
+	if user != nil {
+		fmt.Fprintf(&w, "export HOME=%s\n", service.ShellQuote(user.Home))
+		fmt.Fprintf(&w, "export XDG_RUNTIME_DIR=%s\n", service.ShellQuote(user.RuntimeDir))
+	}
+
+	start, err := service.ShellCommand(spec.Start)
+	if err != nil {
+		return "", fmt.Errorf("unit %s: %w", u.Name, err)
+	}
+	stop := ""
+	if spec.Stop != "" {
+		if stop, err = service.ShellCommand(spec.Stop); err != nil {
+			return "", fmt.Errorf("unit %s: %w", u.Name, err)
+		}
+	}
+
+	if spec.Type == service.TypeOneshot {
+		writeOneshot(&w, spec, user, start, stop)
+	} else if err := writeSupervised(&w, u, spec, user); err != nil {
+		return "", err
+	}
+
+	w.WriteString("\ndepend() {\n\tneed net\n")
+	if u.Runtime == "docker" {
+		w.WriteString("\tneed docker\n")
+	}
+	w.WriteString("}\n")
+
+	if spec.Type != service.TypeOneshot {
+		if user != nil {
+			fmt.Fprintf(&w, "\nstart_pre() {\n\tcheckpath -d -m 0700 -o %s %s\n}\n",
+				service.ShellQuote(user.Name), service.ShellQuote(user.RuntimeDir))
+		}
+		if stop != "" {
+			fmt.Fprintf(&w, "\nstop_pre() {\n\t%s || true\n}\n", asUser(user, stop))
+		}
+	}
+	return w.String(), nil
+}
+
+// writeSupervised writes the variables for a long-running foreground command.
+func writeSupervised(w *strings.Builder, u config.Unit, spec service.Spec, user *service.UserEnv) error {
+	argv, err := service.SplitCommand(spec.Start)
+	if err != nil {
+		return fmt.Errorf("unit %s: %w", u.Name, err)
+	}
+	if len(argv) == 0 {
+		return fmt.Errorf("unit %s: empty command", u.Name)
+	}
+
+	w.WriteString("\n")
+	if u.Restart {
+		w.WriteString("supervisor=supervise-daemon\n")
+		fmt.Fprintf(w, "respawn_delay=%d\n", u.RestartSec)
+		if u.RestartRetries > 0 {
+			fmt.Fprintf(w, "respawn_max=%d\n", u.RestartRetries)
+		}
+	} else {
+		w.WriteString("command_background=yes\n")
+		w.WriteString("pidfile=\"/run/${RC_SVCNAME}.pid\"\n")
+	}
+
+	fmt.Fprintf(w, "command=%s\n", dq(argv[0]))
+	if len(argv) > 1 {
+		quoted := make([]string, len(argv)-1)
+		for i, a := range argv[1:] {
+			quoted[i] = service.ShellQuote(a)
+		}
+		fmt.Fprintf(w, "command_args=%s\n", dq(strings.Join(quoted, " ")))
+	}
+	if spec.WorkingDir != "" {
+		fmt.Fprintf(w, "directory=%s\n", dq(spec.WorkingDir))
+	}
+	if user != nil {
+		fmt.Fprintf(w, "command_user=%s\n", dq(user.Name))
+	}
+	return nil
+}
+
+// writeOneshot writes start/stop functions; OpenRC tracks the started state.
+func writeOneshot(w *strings.Builder, spec service.Spec, user *service.UserEnv, start, stop string) {
+	w.WriteString("\nstart() {\n\tebegin \"Starting $RC_SVCNAME\"\n")
+	if spec.WorkingDir != "" {
+		fmt.Fprintf(w, "\tcd %s || return 1\n", service.ShellQuote(spec.WorkingDir))
+	}
+	fmt.Fprintf(w, "\t%s\n\teend $?\n}\n", asUser(user, start))
+	if stop != "" {
+		w.WriteString("\nstop() {\n\tebegin \"Stopping $RC_SVCNAME\"\n")
+		if spec.WorkingDir != "" {
+			fmt.Fprintf(w, "\tcd %s || return 1\n", service.ShellQuote(spec.WorkingDir))
+		}
+		fmt.Fprintf(w, "\t%s\n\teend $?\n}\n", asUser(user, stop))
+	}
+}
+
+// asUser wraps a shell command line so it runs as the unit's user, keeping the
+// exported HOME / XDG_RUNTIME_DIR.
+func asUser(user *service.UserEnv, cmd string) string {
+	if user == nil {
+		return cmd
+	}
+	return fmt.Sprintf("su -m -s /bin/sh -c %s %s", service.ShellQuote(cmd), service.ShellQuote(user.Name))
+}
+
+// dq double-quotes s for an OpenRC (sh) variable assignment.
+func dq(s string) string {
+	r := strings.NewReplacer(`\`, `\\`, `"`, `\"`, "$", `\$`, "`", "\\`")
+	return `"` + r.Replace(s) + `"`
+}
diff --git a/openrc/openrc_test.go b/openrc/openrc_test.go
new file mode 100644
index 0000000..92f6180
--- /dev/null
+++ b/openrc/openrc_test.go
@@ -0,0 +1,221 @@
+package openrc
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/service"
+)
+
+// setup points the backend at a temp init dir with recorded commands.
+func setup(t *testing.T) *[]string {
+	t.Helper()
+	oldDir, oldRun, oldOut, oldRoot := initDir, runCmd, outCmd, service.IsRoot
+	t.Cleanup(func() { initDir, runCmd, outCmd, service.IsRoot = oldDir, oldRun, oldOut, oldRoot })
+	initDir = t.TempDir()
+	service.IsRoot = func() bool { return true }
+	var calls []string
+	runCmd = func(name string, args ...string) error {
+		calls = append(calls, name+" "+strings.Join(args, " "))
+		return nil
+	}
+	return &calls
+}
+
+func mustContain(t *testing.T, content string, wants ...string) {
+	t.Helper()
+	for _, w := range wants {
+		if !strings.Contains(content, w) {
+			t.Errorf("missing %q in:\n%s", w, content)
+		}
+	}
+}
+
+func TestGenerate_Container(t *testing.T) {
+	setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman", Enabled: true}
+	got, err := Backend{}.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"#!/sbin/openrc-run",
+		`description="Unitdore: nginx (podman)"`,
+		"command_background=yes",
+		`pidfile="/run/${RC_SVCNAME}.pid"`,
+		`command="/usr/bin/podman"`,
+		`command_args="start -a nginx"`,
+		"need net",
+		"stop_pre() {\n\t/usr/bin/podman stop nginx || true\n}",
+	)
+	if strings.Contains(got, "supervise-daemon") || strings.Contains(got, "need docker") {
+		t.Errorf("unexpected supervisor or docker dep:\n%s", got)
+	}
+}
+
+func TestGenerate_DockerRestart(t *testing.T) {
+	setup(t)
+	u := config.Unit{Name: "redis", Runtime: "docker", Restart: true, RestartSec: 5, RestartRetries: 3}
+	got, err := Backend{}.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got, "supervisor=supervise-daemon", "respawn_delay=5", "respawn_max=3", "need docker")
+	if strings.Contains(got, "command_background") {
+		t.Errorf("supervised unit must not background:\n%s", got)
+	}
+}
+
+func TestGenerate_ScriptCustomShellAndDir(t *testing.T) {
+	setup(t)
+	u := config.Unit{
+		Name: "job", Runtime: config.RuntimeScript, Shell: "/bin/sh",
+		Script: "/opt/my jobs/run.sh", WorkingDir: "/opt",
+	}
+	got, err := Backend{}.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"(sh script)",
+		`command="/bin/sh"`,
+		`command_args="'/opt/my jobs/run.sh'"`,
+		`directory="/opt"`,
+	)
+}
+
+func TestGenerate_OneshotStack(t *testing.T) {
+	setup(t)
+	u := config.Unit{Name: "shop", Runtime: "podman", Kind: config.KindStack, Project: "shop"}
+	got, err := Backend{}.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"start() {",
+		"/usr/bin/podman pod start pod_shop",
+		"stop() {",
+		"/usr/bin/podman pod stop pod_shop",
+	)
+	if strings.Contains(got, "command=") {
+		t.Errorf("oneshot must not set command:\n%s", got)
+	}
+}
+
+func TestGenerate_RootlessUser(t *testing.T) {
+	setup(t)
+	u := config.Unit{Name: "app", Runtime: "podman", User: "root"}
+	got, err := Backend{}.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"export HOME=/root",
+		"export XDG_RUNTIME_DIR=/run/user/0",
+		`command_user="root"`,
+		"checkpath -d -m 0700 -o root /run/user/0",
+		"su -m -s /bin/sh -c '/usr/bin/podman stop app' root",
+	)
+}
+
+func TestGenerate_Invalid(t *testing.T) {
+	setup(t)
+	if _, err := (Backend{}).Generate(config.Unit{Name: "x", Runtime: config.RuntimeExec}, "", ""); err == nil {
+		t.Error("expected validation error")
+	}
+	if _, err := (Backend{}).Generate(config.Unit{Name: "x", Runtime: "podman", Command: `/bin/x "open`}, "", ""); err == nil {
+		t.Error("expected quote error")
+	}
+}
+
+func TestInstallUninstall(t *testing.T) {
+	calls := setup(t)
+	b := Backend{}
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+
+	if b.IsInstalled(u, "", "") {
+		t.Fatal("should not be installed yet")
+	}
+	if err := b.Install(u, "p-", ""); err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(initDir, "unitdore-p-nginx")
+	fi, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fi.Mode().Perm()&0111 == 0 {
+		t.Errorf("init script must be executable, mode %v", fi.Mode())
+	}
+	if !b.IsInstalled(u, "p-", "") {
+		t.Error("should be installed")
+	}
+	if err := b.Uninstall(u, "p-", ""); err != nil {
+		t.Fatal(err)
+	}
+	if b.IsInstalled(u, "p-", "") {
+		t.Error("should be uninstalled")
+	}
+	if got := strings.Join(*calls, "|"); got != "rc-update del unitdore-p-nginx default" {
+		t.Errorf("calls = %q", got)
+	}
+}
+
+func TestControlCommands(t *testing.T) {
+	calls := setup(t)
+	b := Backend{}
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+
+	_ = b.Start(u, "", "")
+	_ = b.Stop(u, "", "")
+	_ = b.Enable(u, "", "")
+	_ = b.Disable(u, "", "")
+
+	want := []string{
+		"rc-service unitdore-nginx start",
+		"rc-service unitdore-nginx stop",
+		"rc-update add unitdore-nginx default",
+		"rc-service unitdore-nginx start",
+		"rc-service unitdore-nginx stop",
+		"rc-update del unitdore-nginx default",
+	}
+	if got := strings.Join(*calls, "|"); got != strings.Join(want, "|") {
+		t.Errorf("calls =\n%q\nwant\n%q", *calls, want)
+	}
+}
+
+func TestRequiresRoot(t *testing.T) {
+	setup(t)
+	service.IsRoot = func() bool { return false }
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	b := Backend{}
+	for name, err := range map[string]error{
+		"install": b.Install(u, "", ""), "uninstall": b.Uninstall(u, "", ""),
+		"start": b.Start(u, "", ""), "stop": b.Stop(u, "", ""),
+		"enable": b.Enable(u, "", ""), "disable": b.Disable(u, "", ""),
+	} {
+		if err == nil {
+			t.Errorf("%s should require root", name)
+		}
+	}
+}
+
+func TestParseStatus(t *testing.T) {
+	tests := map[string]string{
+		" * status: started":    "active",
+		" * status: stopped":    "inactive",
+		" * status: crashed":    "failed",
+		" * status: starting":   "activating",
+		" * status: stopping":   "deactivating",
+		"":                      "unknown",
+		"rc-service: not found": "unknown",
+	}
+	for in, want := range tests {
+		if got := parseStatus(in); got != want {
+			t.Errorf("parseStatus(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
diff --git a/runit/runit.go b/runit/runit.go
new file mode 100644
index 0000000..c55fd09
--- /dev/null
+++ b/runit/runit.go
@@ -0,0 +1,364 @@
+// Package runit generates and manages runit service directories.
+//
+// Each unit is a directory /etc/sv/<name> (run, finish) linked into the
+// supervised service dir. Services run at system level (root only). Units with
+// a user run as that user through chpst, with HOME and XDG_RUNTIME_DIR set.
+//
+// Install links the service with a `down` file: it is supervised but does not
+// start until started or enabled. Enable removes `down`, Disable restores it.
+package runit
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/service"
+)
+
+// Overridable for tests.
+var (
+	svDir = "/etc/sv"
+
+	// serviceDirCandidates are probed in order when no service_dir is set.
+	serviceDirCandidates = []string{"/var/service", "/etc/service"}
+
+	// superviseWait is how long Start waits for runsvdir to pick up a new link.
+	superviseWait = 10 * time.Second
+
+	runCmd = func(name string, args ...string) error {
+		cmd := exec.Command(name, args...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		return cmd.Run()
+	}
+	outCmd = func(name string, args ...string) ([]byte, error) {
+		return exec.Command(name, args...).CombinedOutput()
+	}
+)
+
+// Backend is the runit implementation of the init interface.
+type Backend struct {
+	ServiceDir string // supervised dir; empty = autodetect
+}
+
+func (Backend) Name() string { return "runit" }
+
+// SupportsLinger is false: runit services need no linger.
+func (Backend) SupportsLinger() bool { return false }
+
+func (Backend) ServiceName(u config.Unit, prefix, suffix string) string {
+	return service.BaseName(u, prefix, suffix)
+}
+
+// UnitPath is the service definition directory under /etc/sv.
+func (b Backend) UnitPath(u config.Unit, prefix, suffix string) (string, error) {
+	return filepath.Join(svDir, b.ServiceName(u, prefix, suffix)), nil
+}
+
+func (b Backend) IsInstalled(u config.Unit, prefix, suffix string) bool {
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	_, err := os.Stat(filepath.Join(dir, "run"))
+	return err == nil
+}
+
+// serviceDir returns the supervised dir that gets the symlinks.
+func (b Backend) serviceDir() string {
+	if b.ServiceDir != "" {
+		return b.ServiceDir
+	}
+	for _, d := range serviceDirCandidates {
+		if fi, err := os.Stat(d); err == nil && fi.IsDir() {
+			return d
+		}
+	}
+	return serviceDirCandidates[0]
+}
+
+func (b Backend) link(u config.Unit, prefix, suffix string) string {
+	return filepath.Join(b.serviceDir(), b.ServiceName(u, prefix, suffix))
+}
+
+type file struct {
+	name    string
+	content string
+}
+
+// Generate produces the run and finish scripts, separated by marker lines.
+func (b Backend) Generate(u config.Unit, prefix, suffix string) (string, error) {
+	files, err := b.files(u, prefix, suffix)
+	if err != nil {
+		return "", err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	var w strings.Builder
+	for _, f := range files {
+		fmt.Fprintf(&w, "# ===== %s =====\n%s\n", filepath.Join(dir, f.name), f.content)
+	}
+	return w.String(), nil
+}
+
+func (b Backend) files(u config.Unit, prefix, suffix string) ([]file, error) {
+	if err := service.Validate(u); err != nil {
+		return nil, err
+	}
+	user, err := service.LookupUser(u.User)
+	if err != nil {
+		return nil, err
+	}
+	spec := service.Resolve(u)
+
+	start, err := service.ShellCommand(spec.Start)
+	if err != nil {
+		return nil, fmt.Errorf("unit %s: %w", u.Name, err)
+	}
+	stop := ""
+	if spec.Stop != "" {
+		if stop, err = service.ShellCommand(spec.Stop); err != nil {
+			return nil, fmt.Errorf("unit %s: %w", u.Name, err)
+		}
+	}
+
+	header := "#!/bin/sh\n# " + b.ServiceName(u, prefix, suffix) + " — generated by unitdore, do not edit manually\n"
+
+	run := header + "exec 2>&1\n" + preamble(user, spec.WorkingDir)
+	if spec.Type == service.TypeOneshot {
+		// Run once, then stay up (like RemainAfterExit) until stopped
+		run += asUser(user, start) + " || exit 1\nexec tail -f /dev/null\n"
+	} else {
+		run += "exec " + asUser(user, start) + "\n"
+	}
+
+	files := []file{{"run", run}}
+	if fin := finishScript(header, u, user, spec.WorkingDir, stop); fin != "" {
+		files = append(files, file{"finish", fin})
+	}
+	return files, nil
+}
+
+// preamble prepares the environment: working dir and rootless user runtime.
+func preamble(user *service.UserEnv, workDir string) string {
+	var s string
+	if workDir != "" {
+		s += "cd " + service.ShellQuote(workDir) + " || exit 1\n"
+	}
+	if user != nil {
+		s += fmt.Sprintf("[ -d %[1]s ] || install -d -m 0700 -o %[2]s %[1]s\n",
+			service.ShellQuote(user.RuntimeDir), service.ShellQuote(user.Name))
+		s += "export HOME=" + service.ShellQuote(user.Home) + "\n"
+		s += "export XDG_RUNTIME_DIR=" + service.ShellQuote(user.RuntimeDir) + "\n"
+	}
+	return s
+}
+
+func asUser(user *service.UserEnv, cmd string) string {
+	if user == nil {
+		return cmd
+	}
+	return "chpst -u " + service.ShellQuote(user.Name) + " " + cmd
+}
+
+// finishScript runs after the service exits: best-effort stop command, then
+// the restart policy. runit restarts by default, so no-restart stops it.
+func finishScript(header string, u config.Unit, user *service.UserEnv, workDir, stop string) string {
+	var body string
+	if workDir != "" {
+		body += "cd " + service.ShellQuote(workDir) + " 2>/dev/null\n"
+	}
+	if stop != "" {
+		body += asUser(user, stop) + " || true\n"
+	}
+	switch {
+	case !u.Restart:
+		body += "exec sv down .\n"
+	default:
+		// Restart=on-failure: a clean exit stays down
+		body += "[ \"$1\" = 0 ] && exec sv down .\n"
+		if u.RestartSec > 0 {
+			body += fmt.Sprintf("sleep %d\n", u.RestartSec)
+		}
+	}
+	return header + body
+}
+
+func (b Backend) Install(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	files, err := b.files(u, prefix, suffix)
+	if err != nil {
+		return err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	link := b.link(u, prefix, suffix)
+
+	// A re-install keeps an already enabled service enabled
+	wasEnabled := isLinked(link, dir) && !exists(filepath.Join(dir, "down"))
+
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("creating service dir: %w", err)
+	}
+	for _, f := range files {
+		if err := os.WriteFile(filepath.Join(dir, f.name), []byte(f.content), 0755); err != nil {
+			return fmt.Errorf("writing %s: %w", f.name, err)
+		}
+	}
+	if !hasFile(files, "finish") {
+		_ = os.Remove(filepath.Join(dir, "finish"))
+	}
+	if !wasEnabled {
+		if err := setDown(dir, true); err != nil {
+			return err
+		}
+	}
+	return ensureLink(dir, link)
+}
+
+func (b Backend) Uninstall(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	link := b.link(u, prefix, suffix)
+
+	_ = runCmd("sv", "stop", link) // not running is fine
+	if err := os.Remove(link); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("removing service link: %w", err)
+	}
+	if err := os.RemoveAll(dir); err != nil {
+		return fmt.Errorf("removing service dir: %w", err)
+	}
+	return nil
+}
+
+// Enable makes the service start with runsvdir and starts it now.
+func (b Backend) Enable(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	link := b.link(u, prefix, suffix)
+	if err := setDown(dir, false); err != nil {
+		return err
+	}
+	if err := ensureLink(dir, link); err != nil {
+		return err
+	}
+	return startLink(link)
+}
+
+// Disable stops the service and keeps it from starting with runsvdir.
+func (b Backend) Disable(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	if err := setDown(dir, true); err != nil {
+		return err
+	}
+	_ = runCmd("sv", "stop", b.link(u, prefix, suffix)) // not running is fine
+	return nil
+}
+
+func (b Backend) Start(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	dir, _ := b.UnitPath(u, prefix, suffix)
+	link := b.link(u, prefix, suffix)
+	if err := ensureLink(dir, link); err != nil {
+		return err
+	}
+	return startLink(link)
+}
+
+func (b Backend) Stop(u config.Unit, prefix, suffix string) error {
+	if err := service.RequireRoot("runit"); err != nil {
+		return err
+	}
+	return runCmd("sv", "stop", b.link(u, prefix, suffix))
+}
+
+func (b Backend) Status(u config.Unit, prefix, suffix string) string {
+	out, _ := outCmd("sv", "status", b.link(u, prefix, suffix))
+	return parseStatus(string(out))
+}
+
+// parseStatus maps `sv status` output to a systemd-like state.
+func parseStatus(out string) string {
+	out = strings.TrimSpace(out)
+	switch {
+	case strings.HasPrefix(out, "run:"):
+		return "active"
+	case strings.HasPrefix(out, "down:"):
+		return "inactive"
+	case strings.HasPrefix(out, "finish:"):
+		return "deactivating"
+	case strings.Contains(out, "runsv not running"):
+		return "inactive"
+	default:
+		return "unknown"
+	}
+}
+
+// startLink waits until runsvdir supervises the link, then starts it.
+func startLink(link string) error {
+	deadline := time.Now().Add(superviseWait)
+	for !exists(filepath.Join(link, "supervise", "ok")) {
+		if time.Now().After(deadline) {
+			return fmt.Errorf("%s is not supervised yet (is runsvdir running?)", link)
+		}
+		time.Sleep(200 * time.Millisecond)
+	}
+	return runCmd("sv", "start", link)
+}
+
+func ensureLink(dir, link string) error {
+	if isLinked(link, dir) {
+		return nil
+	}
+	if err := os.MkdirAll(filepath.Dir(link), 0755); err != nil {
+		return fmt.Errorf("creating service dir: %w", err)
+	}
+	if err := os.Symlink(dir, link); err != nil {
+		return fmt.Errorf("linking service: %w", err)
+	}
+	return nil
+}
+
+func isLinked(link, dir string) bool {
+	target, err := os.Readlink(link)
+	return err == nil && target == dir
+}
+
+func setDown(dir string, down bool) error {
+	path := filepath.Join(dir, "down")
+	if !down {
+		if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("removing down file: %w", err)
+		}
+		return nil
+	}
+	if err := os.WriteFile(path, nil, 0644); err != nil {
+		return fmt.Errorf("writing down file: %w", err)
+	}
+	return nil
+}
+
+func exists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+func hasFile(files []file, name string) bool {
+	for _, f := range files {
+		if f.name == name {
+			return true
+		}
+	}
+	return false
+}
diff --git a/runit/runit_test.go b/runit/runit_test.go
new file mode 100644
index 0000000..c79d6f3
--- /dev/null
+++ b/runit/runit_test.go
@@ -0,0 +1,295 @@
+package runit
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/service"
+)
+
+// setup points the backend at temp dirs with recorded commands.
+func setup(t *testing.T) (b Backend, calls *[]string) {
+	t.Helper()
+	oldSv, oldRun, oldOut, oldRoot, oldWait := svDir, runCmd, outCmd, service.IsRoot, superviseWait
+	t.Cleanup(func() { svDir, runCmd, outCmd, service.IsRoot, superviseWait = oldSv, oldRun, oldOut, oldRoot, oldWait })
+	svDir = t.TempDir()
+	superviseWait = 300 * time.Millisecond
+	service.IsRoot = func() bool { return true }
+	var recorded []string
+	runCmd = func(name string, args ...string) error {
+		recorded = append(recorded, name+" "+strings.Join(args, " "))
+		return nil
+	}
+	return Backend{ServiceDir: t.TempDir()}, &recorded
+}
+
+func mustContain(t *testing.T, content string, wants ...string) {
+	t.Helper()
+	for _, w := range wants {
+		if !strings.Contains(content, w) {
+			t.Errorf("missing %q in:\n%s", w, content)
+		}
+	}
+}
+
+func read(t *testing.T, path string) string {
+	t.Helper()
+	b, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(b)
+}
+
+func TestGenerate_Container(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	got, err := b.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"===== "+filepath.Join(svDir, "unitdore-nginx", "run")+" =====",
+		"exec 2>&1",
+		"exec /usr/bin/podman start -a nginx",
+		"===== "+filepath.Join(svDir, "unitdore-nginx", "finish")+" =====",
+		"/usr/bin/podman stop nginx || true",
+		"exec sv down .",
+	)
+}
+
+func TestGenerate_RestartPolicy(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "app", Runtime: "podman", Restart: true, RestartSec: 7}
+	got, err := b.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got, `[ "$1" = 0 ] && exec sv down .`, "sleep 7")
+	if strings.Contains(got, "\nexec sv down .\n") {
+		t.Errorf("restarting unit must not always go down:\n%s", got)
+	}
+}
+
+func TestGenerate_ScriptExecAndWorkingDir(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{
+		Name: "agent", Runtime: config.RuntimeExec, Executable: "/opt/agent",
+		Args: []string{"--config", "/etc/my agent.toml"}, WorkingDir: "/opt",
+	}
+	got, err := b.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got, "cd /opt || exit 1", `exec /opt/agent --config '/etc/my agent.toml'`)
+}
+
+func TestGenerate_Oneshot(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "shop", Runtime: "podman", Kind: config.KindStack, Project: "shop"}
+	got, err := b.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"/usr/bin/podman pod start pod_shop || exit 1\nexec tail -f /dev/null",
+		"/usr/bin/podman pod stop pod_shop || true",
+	)
+}
+
+func TestGenerate_RootlessUser(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "app", Runtime: "podman", User: "root"}
+	got, err := b.Generate(u, "", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustContain(t, got,
+		"[ -d /run/user/0 ] || install -d -m 0700 -o root /run/user/0",
+		"export HOME=/root",
+		"export XDG_RUNTIME_DIR=/run/user/0",
+		"exec chpst -u root /usr/bin/podman start -a app",
+		"chpst -u root /usr/bin/podman stop app || true",
+	)
+}
+
+func TestGenerate_Invalid(t *testing.T) {
+	b, _ := setup(t)
+	if _, err := b.Generate(config.Unit{Name: "x", Runtime: config.RuntimeScript}, "", ""); err == nil {
+		t.Error("expected validation error")
+	}
+}
+
+func TestInstall_WritesDirLinkAndDown(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	dir := filepath.Join(svDir, "unitdore-nginx")
+	link := filepath.Join(b.ServiceDir, "unitdore-nginx")
+
+	if b.IsInstalled(u, "", "") {
+		t.Fatal("should not be installed yet")
+	}
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{"run", "finish"} {
+		fi, err := os.Stat(filepath.Join(dir, name))
+		if err != nil || fi.Mode().Perm()&0111 == 0 {
+			t.Errorf("%s missing or not executable: %v", name, err)
+		}
+	}
+	if _, err := os.Stat(filepath.Join(dir, "down")); err != nil {
+		t.Error("fresh install must write a down file")
+	}
+	if target, err := os.Readlink(link); err != nil || target != dir {
+		t.Errorf("link = %q, %v", target, err)
+	}
+	if !b.IsInstalled(u, "", "") {
+		t.Error("should be installed")
+	}
+}
+
+func TestInstall_ReinstallKeepsEnabled(t *testing.T) {
+	b, _ := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	dir := filepath.Join(svDir, "unitdore-nginx")
+
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := b.Enable(u, "", ""); err == nil {
+		t.Log("enable ok") // may time out waiting for supervise; down file still removed
+	}
+	if _, err := os.Stat(filepath.Join(dir, "down")); !os.IsNotExist(err) {
+		t.Fatal("enable must remove the down file")
+	}
+
+	u.Restart = true
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "down")); !os.IsNotExist(err) {
+		t.Error("re-install must keep an enabled service enabled")
+	}
+	if !strings.Contains(read(t, filepath.Join(dir, "finish")), `"$1" = 0`) {
+		t.Error("re-install must rewrite scripts")
+	}
+}
+
+func TestDisable_WritesDownAndStops(t *testing.T) {
+	b, calls := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	dir := filepath.Join(svDir, "unitdore-nginx")
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	*calls = nil
+	if err := b.Disable(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "down")); err != nil {
+		t.Error("disable must write a down file")
+	}
+	if got := strings.Join(*calls, "|"); got != "sv stop "+filepath.Join(b.ServiceDir, "unitdore-nginx") {
+		t.Errorf("calls = %q", got)
+	}
+}
+
+func TestStartStop_UseSv(t *testing.T) {
+	b, calls := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	link := filepath.Join(b.ServiceDir, "unitdore-nginx")
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+
+	// Not supervised yet: Start must give up with a clear error
+	if err := b.Start(u, "", ""); err == nil || !strings.Contains(err.Error(), "not supervised") {
+		t.Errorf("Start() err = %v", err)
+	}
+
+	if err := os.MkdirAll(filepath.Join(link, "supervise"), 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(link, "supervise", "ok"), nil, 0644); err != nil {
+		t.Fatal(err)
+	}
+	*calls = nil
+	if err := b.Start(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if err := b.Stop(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if got := strings.Join(*calls, "|"); got != "sv start "+link+"|sv stop "+link {
+		t.Errorf("calls = %q", got)
+	}
+}
+
+func TestUninstall_RemovesDirAndLink(t *testing.T) {
+	b, calls := setup(t)
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	if err := b.Install(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	*calls = nil
+	if err := b.Uninstall(u, "", ""); err != nil {
+		t.Fatal(err)
+	}
+	if b.IsInstalled(u, "", "") {
+		t.Error("should be uninstalled")
+	}
+	if _, err := os.Lstat(filepath.Join(b.ServiceDir, "unitdore-nginx")); !os.IsNotExist(err) {
+		t.Error("link should be gone")
+	}
+	if len(*calls) != 1 || !strings.HasPrefix((*calls)[0], "sv stop ") {
+		t.Errorf("calls = %q", *calls)
+	}
+}
+
+func TestServiceDirAutodetect(t *testing.T) {
+	old := serviceDirCandidates
+	t.Cleanup(func() { serviceDirCandidates = old })
+	existing := t.TempDir()
+	serviceDirCandidates = []string{filepath.Join(existing, "nope"), existing}
+	if got := (Backend{}).serviceDir(); got != existing {
+		t.Errorf("serviceDir() = %q, want %q", got, existing)
+	}
+	if got := (Backend{ServiceDir: "/custom"}).serviceDir(); got != "/custom" {
+		t.Errorf("explicit serviceDir() = %q", got)
+	}
+}
+
+func TestRequiresRoot(t *testing.T) {
+	b, _ := setup(t)
+	service.IsRoot = func() bool { return false }
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	for name, err := range map[string]error{
+		"install": b.Install(u, "", ""), "uninstall": b.Uninstall(u, "", ""),
+		"start": b.Start(u, "", ""), "stop": b.Stop(u, "", ""),
+		"enable": b.Enable(u, "", ""), "disable": b.Disable(u, "", ""),
+	} {
+		if err == nil {
+			t.Errorf("%s should require root", name)
+		}
+	}
+}
+
+func TestParseStatus(t *testing.T) {
+	tests := map[string]string{
+		"run: /var/service/x: (pid 123) 5s":       "active",
+		"down: /var/service/x: 3s, normally up":   "inactive",
+		"finish: /var/service/x: (pid 9) 1s":      "deactivating",
+		"fail: /var/service/x: runsv not running": "inactive",
+		"warning: weird":                          "unknown",
+	}
+	for in, want := range tests {
+		if got := parseStatus(in); got != want {
+			t.Errorf("parseStatus(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
diff --git a/service/spec.go b/service/spec.go
new file mode 100644
index 0000000..315147b
--- /dev/null
+++ b/service/spec.go
@@ -0,0 +1,294 @@
+// Package service resolves a config.Unit into init-system-neutral run
+// instructions (commands, working dir, type) shared by every init backend.
+package service
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/sysuser"
+)
+
+// Service types.
+const (
+	TypeSimple  = "simple"
+	TypeOneshot = "oneshot"
+)
+
+// Stack modes: compose (podman-compose up/stop) with pod start/stop as fallback.
+const (
+	StackModeCompose = "compose"
+	StackModePod     = "pod"
+)
+
+// Spec is what an init backend needs to run a unit. Start and Stop are
+// command lines in systemd quoting; use SplitCommand to get argv.
+type Spec struct {
+	Start      string
+	Stop       string // empty = none
+	Label      string
+	WorkingDir string
+	Type       string // TypeSimple | TypeOneshot
+}
+
+// BaseName returns the init-neutral service name: unitdore-<prefix><name><suffix>.
+func BaseName(u config.Unit, prefix, suffix string) string {
+	return fmt.Sprintf("unitdore-%s%s%s", prefix, u.Name, suffix)
+}
+
+// Validate reports unit configs that cannot be turned into a service.
+func Validate(u config.Unit) error {
+	if u.Command != "" {
+		return nil
+	}
+	if u.IsScript() && u.Script == "" {
+		return fmt.Errorf("unit %s: runtime script requires 'script' (or 'command')", u.Name)
+	}
+	if u.IsExec() && u.Executable == "" {
+		return fmt.Errorf("unit %s: runtime exec requires 'executable' (or 'command')", u.Name)
+	}
+	return nil
+}
+
+// Resolve builds the run instructions for a unit. Call Validate first.
+func Resolve(u config.Unit) Spec {
+	spec := Spec{Label: u.Runtime, Type: TypeSimple}
+
+	switch {
+	case u.IsScript() && u.Command == "":
+		spec.Start, spec.Stop = buildScriptCommands(u)
+		spec.Label = filepath.Base(u.ShellPath()) + " script"
+		spec.WorkingDir = u.WorkingDir
+		spec.Type = serviceType(u)
+	case u.IsExec() && u.Command == "":
+		spec.Start, spec.Stop = buildExecutableCommands(u)
+		spec.Label = "executable"
+		spec.WorkingDir = u.WorkingDir
+		spec.Type = serviceType(u)
+	case u.IsStack() && u.Command == "" && StackMode(u) == StackModeCompose:
+		spec.Start, spec.Stop = buildComposeCommands(u)
+		spec.Label = "podman-compose stack"
+		spec.WorkingDir = u.WorkingDir
+	case u.IsStack() && u.Command == "":
+		spec.Start, spec.Stop = buildPodCommands(u)
+		spec.Label = "podman pod"
+		spec.Type = TypeOneshot
+	default:
+		spec.Start, spec.Stop = buildExecCommands(u)
+	}
+	return spec
+}
+
+func serviceType(u config.Unit) string {
+	if u.ServiceType == TypeOneshot {
+		return TypeOneshot
+	}
+	return TypeSimple
+}
+
+func buildScriptCommands(u config.Unit) (start, stop string) {
+	shell := QuoteArg(u.ShellPath())
+	start = shell + " " + QuoteArg(u.Script)
+	if u.StopScript != "" {
+		stop = shell + " " + QuoteArg(u.StopScript)
+	}
+	return start, stop
+}
+
+func buildExecutableCommands(u config.Unit) (start, stop string) {
+	parts := []string{QuoteArg(u.Executable)}
+	for _, a := range u.Args {
+		parts = append(parts, QuoteArg(a))
+	}
+	if u.StopExecutable != "" {
+		stop = QuoteArg(u.StopExecutable)
+	}
+	return strings.Join(parts, " "), stop
+}
+
+func buildExecCommands(u config.Unit) (start, stop string) {
+	// If a custom command is provided, use it directly
+	if u.Command != "" {
+		return u.Command, ""
+	}
+
+	switch u.Runtime {
+	case "podman":
+		start = fmt.Sprintf("/usr/bin/podman start -a %s", u.Name)
+		stop = fmt.Sprintf("/usr/bin/podman stop %s", u.Name)
+	case "docker":
+		start = fmt.Sprintf("/usr/bin/docker start -a %s", u.Name)
+		stop = fmt.Sprintf("/usr/bin/docker stop %s", u.Name)
+	default:
+		start = fmt.Sprintf("/usr/bin/%s start %s", u.Runtime, u.Name)
+		stop = fmt.Sprintf("/usr/bin/%s stop %s", u.Runtime, u.Name)
+	}
+	return start, stop
+}
+
+// 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) + `"`
+}
+
+// SplitCommand splits a systemd-style command line into argv. It understands
+// double quotes, single quotes and backslash escapes.
+func SplitCommand(s string) ([]string, error) {
+	var (
+		args   []string
+		cur    strings.Builder
+		inArg  bool
+		quote  rune
+		escape bool
+	)
+	for _, r := range s {
+		switch {
+		case escape:
+			cur.WriteRune(r)
+			escape = false
+		case r == '\\' && quote != '\'':
+			escape = true
+			inArg = true
+		case quote != 0:
+			if r == quote {
+				quote = 0
+			} else {
+				cur.WriteRune(r)
+			}
+		case r == '"' || r == '\'':
+			quote = r
+			inArg = true
+		case r == ' ' || r == '\t' || r == '\n':
+			if inArg {
+				args = append(args, cur.String())
+				cur.Reset()
+				inArg = false
+			}
+		default:
+			cur.WriteRune(r)
+			inArg = true
+		}
+	}
+	if quote != 0 {
+		return nil, fmt.Errorf("unterminated quote in command: %s", s)
+	}
+	if escape {
+		return nil, fmt.Errorf("trailing backslash in command: %s", s)
+	}
+	if inArg {
+		args = append(args, cur.String())
+	}
+	return args, nil
+}
+
+// ShellQuote quotes s for a POSIX shell, only when needed.
+func ShellQuote(s string) string {
+	if s != "" && strings.Trim(s, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_@%+=:,./-") == "" {
+		return s
+	}
+	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
+}
+
+// ShellCommand converts a systemd-style command line into a POSIX shell line.
+func ShellCommand(s string) (string, error) {
+	argv, err := SplitCommand(s)
+	if err != nil {
+		return "", err
+	}
+	for i, a := range argv {
+		argv[i] = ShellQuote(a)
+	}
+	return strings.Join(argv, " "), nil
+}
+
+// UserEnv holds what a system-level service needs to run a command as a
+// rootless user (podman needs HOME and XDG_RUNTIME_DIR).
+type UserEnv struct {
+	Name       string
+	UID        string
+	Home       string
+	RuntimeDir string
+}
+
+// LookupUser resolves the account behind a unit's user. Empty user returns nil.
+func LookupUser(user string) (*UserEnv, error) {
+	if user == "" {
+		return nil, nil
+	}
+	uid, err := sysuser.UID(user)
+	if err != nil {
+		return nil, err
+	}
+	home, err := sysuser.HomeDir(user)
+	if err != nil {
+		return nil, err
+	}
+	return &UserEnv{Name: user, UID: uid, Home: home, RuntimeDir: "/run/user/" + uid}, nil
+}
+
+// IsRoot is sysuser.IsRoot; a variable so tests can override it.
+var IsRoot = sysuser.IsRoot
+
+// RequireRoot errors unless running as root. Non-systemd backends write to
+// system directories and manage system-level services only.
+func RequireRoot(backend string) error {
+	if !IsRoot() {
+		return fmt.Errorf("%s backend requires root", backend)
+	}
+	return nil
+}
diff --git a/service/spec_test.go b/service/spec_test.go
new file mode 100644
index 0000000..e4a39aa
--- /dev/null
+++ b/service/spec_test.go
@@ -0,0 +1,215 @@
+package service
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/warkanum/unitdore/config"
+)
+
+func TestBuildExecCommands(t *testing.T) {
+	tests := []struct {
+		name      string
+		unit      config.Unit
+		wantStart string
+		wantStop  string
+	}{
+		{
+			name:      "podman",
+			unit:      config.Unit{Name: "app", Runtime: "podman"},
+			wantStart: "/usr/bin/podman start -a app",
+			wantStop:  "/usr/bin/podman stop app",
+		},
+		{
+			name:      "docker",
+			unit:      config.Unit{Name: "app", Runtime: "docker"},
+			wantStart: "/usr/bin/docker start -a app",
+			wantStop:  "/usr/bin/docker stop app",
+		},
+		{
+			name:      "custom command",
+			unit:      config.Unit{Name: "app", Runtime: "podman", Command: "/bin/custom"},
+			wantStart: "/bin/custom",
+			wantStop:  "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			start, stop := buildExecCommands(tt.unit)
+			if start != tt.wantStart {
+				t.Errorf("start = %q, want %q", start, tt.wantStart)
+			}
+			if stop != tt.wantStop {
+				t.Errorf("stop = %q, want %q", stop, tt.wantStop)
+			}
+		})
+	}
+}
+
+func TestStackMode(t *testing.T) {
+	u := newComposeStack(t)
+	if StackMode(u) != StackModeCompose {
+		t.Errorf("StackMode() = %q, want compose", StackMode(u))
+	}
+
+	missingFile := u
+	missingFile.ComposeFiles = []string{"gone.yaml"}
+	if StackMode(missingFile) != StackModePod {
+		t.Error("missing compose file should fall back to pod mode")
+	}
+
+	missingBin := u
+	missingBin.ComposeBin = ""
+	if StackMode(missingBin) != StackModePod {
+		t.Error("missing compose binary should fall back to pod mode")
+	}
+
+	missingDir := u
+	missingDir.WorkingDir = "/nonexistent/unitdore-test"
+	if StackMode(missingDir) != StackModePod {
+		t.Error("missing working dir should fall back to pod mode")
+	}
+}
+
+func TestBuildComposeCommands_Quoting(t *testing.T) {
+	u := config.Unit{
+		Project:      "shop",
+		ComposeBin:   "/usr/bin/podman-compose",
+		ComposeFiles: []string{"compose.yaml", "my override.yaml"},
+	}
+	start, stop := buildComposeCommands(u)
+	wantBase := `/usr/bin/podman-compose -p shop -f compose.yaml -f "my override.yaml"`
+	if start != wantBase+" up" {
+		t.Errorf("start = %q", start)
+	}
+	if stop != wantBase+" stop" {
+		t.Errorf("stop = %q", stop)
+	}
+}
+
+// newComposeStack creates a stack unit whose compose binary, working dir and
+// compose file exist on disk (compose mode).
+func newComposeStack(t *testing.T) config.Unit {
+	t.Helper()
+	dir := t.TempDir()
+	bin := filepath.Join(dir, "podman-compose")
+	if err := os.WriteFile(bin, []byte("#!/bin/sh\n"), 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "compose.yaml"), []byte("services: {}\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	return config.Unit{
+		Name:         "shop",
+		Runtime:      "podman",
+		Kind:         config.KindStack,
+		Project:      "shop",
+		WorkingDir:   dir,
+		ComposeFiles: []string{"compose.yaml"},
+		ComposeBin:   bin,
+		Enabled:      true,
+	}
+}
+
+func TestSplitCommand(t *testing.T) {
+	tests := []struct {
+		in      string
+		want    []string
+		wantErr bool
+	}{
+		{in: "/usr/bin/podman start -a app", want: []string{"/usr/bin/podman", "start", "-a", "app"}},
+		{in: `/bin/x "my file.txt" 'a b'`, want: []string{"/bin/x", "my file.txt", "a b"}},
+		{in: `/bin/x "say \"hi\""`, want: []string{"/bin/x", `say "hi"`}},
+		{in: `/bin/x ""`, want: []string{"/bin/x", ""}},
+		{in: "  ", want: nil},
+		{in: `/bin/x "open`, wantErr: true},
+		{in: `/bin/x \`, wantErr: true},
+	}
+	for _, tt := range tests {
+		got, err := SplitCommand(tt.in)
+		if (err != nil) != tt.wantErr {
+			t.Errorf("SplitCommand(%q) err = %v, wantErr %v", tt.in, err, tt.wantErr)
+			continue
+		}
+		if len(got) != len(tt.want) {
+			t.Errorf("SplitCommand(%q) = %q, want %q", tt.in, got, tt.want)
+			continue
+		}
+		for i := range got {
+			if got[i] != tt.want[i] {
+				t.Errorf("SplitCommand(%q)[%d] = %q, want %q", tt.in, i, got[i], tt.want[i])
+			}
+		}
+	}
+}
+
+func TestQuoteArg_SplitCommand_RoundTrip(t *testing.T) {
+	for _, arg := range []string{"plain", "with space", `a"b`, `back\slash`, "it's"} {
+		got, err := SplitCommand("x " + QuoteArg(arg))
+		if err != nil || len(got) != 2 || got[1] != arg {
+			t.Errorf("round trip %q = %q, %v", arg, got, err)
+		}
+	}
+}
+
+func TestShellQuote(t *testing.T) {
+	tests := map[string]string{
+		"plain-1.0/x": "plain-1.0/x",
+		"":            "''",
+		"a b":         "'a b'",
+		"it's":        `'it'\''s'`,
+		"$HOME":       "'$HOME'",
+	}
+	for in, want := range tests {
+		if got := ShellQuote(in); got != want {
+			t.Errorf("ShellQuote(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestShellCommand(t *testing.T) {
+	got, err := ShellCommand(`/opt/agent --config "/etc/my agent.toml"`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if want := `/opt/agent --config '/etc/my agent.toml'`; got != want {
+		t.Errorf("ShellCommand() = %q, want %q", got, want)
+	}
+}
+
+func TestValidate(t *testing.T) {
+	bad := []config.Unit{
+		{Name: "a", Runtime: config.RuntimeScript},
+		{Name: "b", Runtime: config.RuntimeExec},
+	}
+	for _, u := range bad {
+		if Validate(u) == nil {
+			t.Errorf("Validate(%s) should fail", u.Name)
+		}
+	}
+	ok := []config.Unit{
+		{Name: "a", Runtime: config.RuntimeScript, Command: "/x"},
+		{Name: "b", Runtime: "podman"},
+	}
+	for _, u := range ok {
+		if err := Validate(u); err != nil {
+			t.Errorf("Validate(%s) = %v", u.Name, err)
+		}
+	}
+}
+
+func TestBaseName(t *testing.T) {
+	if got := BaseName(config.Unit{Name: "x"}, "p-", "-s"); got != "unitdore-p-x-s" {
+		t.Errorf("BaseName() = %q", got)
+	}
+}
+
+func TestResolve_PodFallbackIsOneshot(t *testing.T) {
+	u := config.Unit{Name: "shop", Runtime: "podman", Kind: config.KindStack, Project: "shop"}
+	spec := Resolve(u)
+	if spec.Type != TypeOneshot || spec.Start != "/usr/bin/podman pod start pod_shop" {
+		t.Errorf("Resolve() = %+v", spec)
+	}
+}
diff --git a/systemd/backend.go b/systemd/backend.go
new file mode 100644
index 0000000..212ea52
--- /dev/null
+++ b/systemd/backend.go
@@ -0,0 +1,37 @@
+package systemd
+
+import "github.com/warkanum/unitdore/config"
+
+// Backend is the systemd implementation of the init interface.
+type Backend struct{}
+
+func (Backend) Name() string { return "systemd" }
+
+func (Backend) ServiceName(u config.Unit, prefix, suffix string) string {
+	return ServiceName(u, prefix, suffix)
+}
+
+func (Backend) UnitPath(u config.Unit, prefix, suffix string) (string, error) {
+	return UnitPath(u, prefix, suffix)
+}
+
+func (Backend) Generate(u config.Unit, prefix, suffix string) (string, error) {
+	return Generate(u, prefix, suffix)
+}
+
+func (Backend) Install(u config.Unit, prefix, suffix string) error { return Install(u, prefix, suffix) }
+func (Backend) Uninstall(u config.Unit, prefix, suffix string) error {
+	return Uninstall(u, prefix, suffix)
+}
+func (Backend) Enable(u config.Unit, prefix, suffix string) error  { return Enable(u, prefix, suffix) }
+func (Backend) Disable(u config.Unit, prefix, suffix string) error { return Disable(u, prefix, suffix) }
+func (Backend) Start(u config.Unit, prefix, suffix string) error   { return Start(u, prefix, suffix) }
+func (Backend) Stop(u config.Unit, prefix, suffix string) error    { return Stop(u, prefix, suffix) }
+func (Backend) Status(u config.Unit, prefix, suffix string) string { return Status(u, prefix, suffix) }
+
+func (Backend) IsInstalled(u config.Unit, prefix, suffix string) bool {
+	return IsInstalled(u, prefix, suffix)
+}
+
+// SupportsLinger reports that user units need loginctl linger to start at boot.
+func (Backend) SupportsLinger() bool { return true }
diff --git a/systemd/generator.go b/systemd/generator.go
index 2e3d09e..e5fb079 100644
--- a/systemd/generator.go
+++ b/systemd/generator.go
@@ -2,12 +2,11 @@ package systemd
 
 import (
 	"fmt"
-	"os"
-	"path/filepath"
 	"strings"
 	"text/template"
 
 	"github.com/warkanum/unitdore/config"
+	"github.com/warkanum/unitdore/service"
 )
 
 const systemUnitTemplate = `# /etc/systemd/system/{{.ServiceName}}
@@ -82,49 +81,25 @@ type templateData struct {
 
 // ServiceName returns the systemd service name for a unit, with optional prefix/suffix.
 func ServiceName(u config.Unit, prefix, suffix string) string {
-	return fmt.Sprintf("unitdore-%s%s%s.service", prefix, u.Name, suffix)
+	return service.BaseName(u, prefix, suffix) + ".service"
 }
 
 // Generate produces the .service file content for a unit.
 func Generate(u config.Unit, prefix, suffix string) (string, error) {
-	if u.Command == "" {
-		if u.IsScript() && u.Script == "" {
-			return "", fmt.Errorf("unit %s: runtime script requires 'script' (or 'command')", u.Name)
-		}
-		if u.IsExec() && u.Executable == "" {
-			return "", fmt.Errorf("unit %s: runtime exec requires 'executable' (or 'command')", u.Name)
-		}
+	if err := service.Validate(u); err != nil {
+		return "", err
 	}
 
+	spec := service.Resolve(u)
 	data := templateData{
 		ServiceName:    ServiceName(u, prefix, suffix),
 		Unit:           u,
+		ExecStart:      spec.Start,
+		ExecStop:       spec.Stop,
 		RuntimeService: runtimeService(u.Runtime),
-		Label:          u.Runtime,
-		ServiceType:    "simple",
-	}
-
-	switch {
-	case u.IsScript() && u.Command == "":
-		data.ExecStart, data.ExecStop = buildScriptCommands(u)
-		data.Label = filepath.Base(u.ShellPath()) + " script"
-		data.WorkingDir = u.WorkingDir
-		data.ServiceType = serviceType(u)
-	case u.IsExec() && u.Command == "":
-		data.ExecStart, data.ExecStop = buildExecutableCommands(u)
-		data.Label = "executable"
-		data.WorkingDir = u.WorkingDir
-		data.ServiceType = serviceType(u)
-	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)
+		Label:          spec.Label,
+		ServiceType:    spec.Type,
+		WorkingDir:     spec.WorkingDir,
 	}
 
 	tmplStr := systemUnitTemplate
@@ -152,113 +127,3 @@ func runtimeService(runtime string) string {
 	}
 	return ""
 }
-
-func serviceType(u config.Unit) string {
-	if u.ServiceType == "oneshot" {
-		return "oneshot"
-	}
-	return "simple"
-}
-
-func buildScriptCommands(u config.Unit) (start, stop string) {
-	shell := quoteArg(u.ShellPath())
-	start = shell + " " + quoteArg(u.Script)
-	if u.StopScript != "" {
-		stop = shell + " " + quoteArg(u.StopScript)
-	}
-	return start, stop
-}
-
-func buildExecutableCommands(u config.Unit) (start, stop string) {
-	parts := []string{quoteArg(u.Executable)}
-	for _, a := range u.Args {
-		parts = append(parts, quoteArg(a))
-	}
-	if u.StopExecutable != "" {
-		stop = quoteArg(u.StopExecutable)
-	}
-	return strings.Join(parts, " "), stop
-}
-
-func buildExecCommands(u config.Unit) (start, stop string) {
-	// If a custom command is provided, use it directly
-	if u.Command != "" {
-		return u.Command, ""
-	}
-
-	switch u.Runtime {
-	case "podman":
-		start = fmt.Sprintf("/usr/bin/podman start -a %s", u.Name)
-		stop = fmt.Sprintf("/usr/bin/podman stop %s", u.Name)
-	case "docker":
-		start = fmt.Sprintf("/usr/bin/docker start -a %s", u.Name)
-		stop = fmt.Sprintf("/usr/bin/docker stop %s", u.Name)
-	default:
-		start = fmt.Sprintf("/usr/bin/%s start %s", u.Runtime, u.Name)
-		stop = fmt.Sprintf("/usr/bin/%s stop %s", u.Runtime, u.Name)
-	}
-	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) + `"`
-}
diff --git a/systemd/generator_test.go b/systemd/generator_test.go
index 62ccd5e..4e791bc 100644
--- a/systemd/generator_test.go
+++ b/systemd/generator_test.go
@@ -226,46 +226,6 @@ func TestGenerate_WithPrefixSuffix(t *testing.T) {
 	}
 }
 
-func TestBuildExecCommands(t *testing.T) {
-	tests := []struct {
-		name      string
-		unit      config.Unit
-		wantStart string
-		wantStop  string
-	}{
-		{
-			name:      "podman",
-			unit:      config.Unit{Name: "app", Runtime: "podman"},
-			wantStart: "/usr/bin/podman start -a app",
-			wantStop:  "/usr/bin/podman stop app",
-		},
-		{
-			name:      "docker",
-			unit:      config.Unit{Name: "app", Runtime: "docker"},
-			wantStart: "/usr/bin/docker start -a app",
-			wantStop:  "/usr/bin/docker stop app",
-		},
-		{
-			name:      "custom command",
-			unit:      config.Unit{Name: "app", Runtime: "podman", Command: "/bin/custom"},
-			wantStart: "/bin/custom",
-			wantStop:  "",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			start, stop := buildExecCommands(tt.unit)
-			if start != tt.wantStart {
-				t.Errorf("start = %q, want %q", start, tt.wantStart)
-			}
-			if stop != tt.wantStop {
-				t.Errorf("stop = %q, want %q", stop, tt.wantStop)
-			}
-		})
-	}
-}
-
 // newComposeStack creates a stack unit whose compose binary, working dir and
 // compose file exist on disk (compose mode).
 func newComposeStack(t *testing.T) config.Unit {
@@ -290,31 +250,6 @@ func newComposeStack(t *testing.T) config.Unit {
 	}
 }
 
-func TestStackMode(t *testing.T) {
-	u := newComposeStack(t)
-	if StackMode(u) != StackModeCompose {
-		t.Errorf("StackMode() = %q, want compose", StackMode(u))
-	}
-
-	missingFile := u
-	missingFile.ComposeFiles = []string{"gone.yaml"}
-	if StackMode(missingFile) != StackModePod {
-		t.Error("missing compose file should fall back to pod mode")
-	}
-
-	missingBin := u
-	missingBin.ComposeBin = ""
-	if StackMode(missingBin) != StackModePod {
-		t.Error("missing compose binary should fall back to pod mode")
-	}
-
-	missingDir := u
-	missingDir.WorkingDir = "/nonexistent/unitdore-test"
-	if StackMode(missingDir) != StackModePod {
-		t.Error("missing working dir should fall back to pod mode")
-	}
-}
-
 func TestGenerate_StackCompose(t *testing.T) {
 	u := newComposeStack(t)
 	content, err := Generate(u, "", "")
@@ -376,22 +311,6 @@ func TestGenerate_StackCustomCommand(t *testing.T) {
 	}
 }
 
-func TestBuildComposeCommands_Quoting(t *testing.T) {
-	u := config.Unit{
-		Project:      "shop",
-		ComposeBin:   "/usr/bin/podman-compose",
-		ComposeFiles: []string{"compose.yaml", "my override.yaml"},
-	}
-	start, stop := buildComposeCommands(u)
-	wantBase := `/usr/bin/podman-compose -p shop -f compose.yaml -f "my override.yaml"`
-	if start != wantBase+" up" {
-		t.Errorf("start = %q", start)
-	}
-	if stop != wantBase+" stop" {
-		t.Errorf("stop = %q", stop)
-	}
-}
-
 func TestGenerate_Script(t *testing.T) {
 	u := config.Unit{
 		Name:       "backup",
diff --git a/systemd/start_stop_test.go b/systemd/start_stop_test.go
index 502caa6..658a8f0 100644
--- a/systemd/start_stop_test.go
+++ b/systemd/start_stop_test.go
@@ -2,36 +2,11 @@ package systemd
 
 import (
 	"sort"
-	"strings"
 	"testing"
 
 	"github.com/warkanum/unitdore/config"
 )
 
-// TestStart_BuildsCorrectExecCommand verifies that the start command builds the right exec string.
-func TestStart_BuildsCorrectExecCommand(t *testing.T) {
-	u := config.Unit{Name: "nginx", Runtime: "podman"}
-	start, stop := buildExecCommands(u)
-	if !strings.Contains(start, "/usr/bin/podman start -a nginx") {
-		t.Errorf("expected podman start command in %q", start)
-	}
-	if !strings.Contains(stop, "/usr/bin/podman stop nginx") {
-		t.Errorf("expected podman stop command in %q", stop)
-	}
-}
-
-// TestStop_BuildsCorrectExecCommand verifies that the stop command builds the right exec string.
-func TestStop_BuildsCorrectExecCommand(t *testing.T) {
-	u := config.Unit{Name: "nginx", Runtime: "podman"}
-	start, stop := buildExecCommands(u)
-	if !strings.Contains(start, "/usr/bin/podman start -a nginx") {
-		t.Errorf("expected podman start command in %q", start)
-	}
-	if !strings.Contains(stop, "/usr/bin/podman stop nginx") {
-		t.Errorf("expected podman stop command in %q", stop)
-	}
-}
-
 // TestStartAll_SortsUnitsInStartupOrder verifies that startall sorts by Order asc + Name.
 func TestStartAll_SortsUnitsInStartupOrder(t *testing.T) {
 	u1 := config.Unit{Name: "app2", Runtime: "podman", Order: 5, Enabled: true}
diff --git a/typescript b/typescript
new file mode 100644
index 0000000..e69de29