feat(maestro): make installer re-run safe (auto-detect = update)

The wizard now treats existing state as "we're updating, not installing":

- If `~/.config/maestrod/config.toml` exists, skip the configure prompt with
  a clear notice. Sets `configured = true` so the systemd start logic still
  makes sense.
- If the systemd user unit already exists, refresh the file in place, skip
  the enable prompt (it's either already enabled or the user said no last
  time), and ask to `restart` instead of `start` — so the new binary
  actually takes effect.

Adds `SystemctlAction::Restart` and a test for it. Same `./install.sh` works
for both first install and subsequent updates; no `--update` flag.

Refs NAP-225.

crates/maestro-installer/src/install.rs

@@ -20,6 +20,7 @@ pub enum SystemctlAction {
     DaemonReload,
     Enable,
     Start,
+    Restart,
 }
 
 impl SystemctlAction {
@@ -28,6 +29,7 @@ impl SystemctlAction {
             Self::DaemonReload => "daemon-reload",
             Self::Enable => "enable",
             Self::Start => "start",
+            Self::Restart => "restart",
         }
     }
 
@@ -164,6 +166,12 @@ mod tests {
         assert_eq!(args, vec!["--user", "start", "maestrod.service"]);
     }
 
+    #[test]
+    fn systemctl_restart_includes_unit() {
+        let args = systemctl_user_args(SystemctlAction::Restart, "maestrod.service");
+        assert_eq!(args, vec!["--user", "restart", "maestrod.service"]);
+    }
+
     #[test]
     fn cargo_bin_honors_env_var() {
         // Save & restore $CARGO to keep the test hermetic.

crates/maestro-installer/src/main.rs

@@ -96,18 +96,23 @@ fn run(args: Args) -> Result<(), Box<dyn std::error::Error>> {
 
     // 2. Offer to run `maestrod configure` now (must happen before systemd
     //    start, since the daemon refuses to run without registry_url / token).
-    // In non-interactive mode (--yes / no TTY) we skip — `maestrod configure`
+    // Re-runs of the wizard auto-skip when the config already exists; that's
-    // would prompt for required fields and we don't want to surprise scripts.
+    // what makes "re-run to update" pleasant. In non-interactive mode (--yes /
-    let want_configure = interactive
+    // no TTY) we also skip — `maestrod configure` would prompt for required
-        && !args.no_configure
+    // fields and we don't want to surprise scripts.
-        && confirm(
+    let configured = if let Some(path) = maestrod_config_path() {
-            "Run `maestrod configure` now (writes ~/.config/maestrod/config.toml)?",
+        if path.exists() {
-            true,
+            eprintln!(
-        )?;
+                "\nconfig already exists at {} — skipping configure step.",
-    let configured = if want_configure {
+                path.display()
-        run_configure_passthrough()?
+            );
+            eprintln!("(run `maestrod configure --force` to rewrite it.)");
+            true
         } else {
-        false
+            run_configure_step(&args, interactive)?
+        }
+    } else {
+        run_configure_step(&args, interactive)?
     };
 
     // 3. systemd integration.
@@ -170,6 +175,24 @@ fn install_crate(
     Ok(())
 }
 
+fn maestrod_config_path() -> Option<PathBuf> {
+    Some(dirs::config_dir()?.join("maestrod").join("config.toml"))
+}
+
+fn run_configure_step(args: &Args, interactive: bool) -> Result<bool, Box<dyn std::error::Error>> {
+    let want = interactive
+        && !args.no_configure
+        && confirm(
+            "Run `maestrod configure` now (writes ~/.config/maestrod/config.toml)?",
+            true,
+        )?;
+    if want {
+        run_configure_passthrough()
+    } else {
+        Ok(false)
+    }
+}
+
 fn run_configure_passthrough() -> Result<bool, Box<dyn std::error::Error>> {
     // Run the freshly-installed `maestrod configure` interactively. We don't
     // hard-code the path; rely on it being on PATH after `cargo install`.
@@ -203,8 +226,18 @@ fn handle_systemd(
     };
 
     eprintln!();
+    let already_installed = unit_path.exists();
+    if already_installed {
+        eprintln!(
+            "systemd unit already present at {} — refreshing.",
+            unit_path.display()
+        );
+    } else {
         eprintln!("systemd detected.");
-    let want_unit = if !interactive {
+    }
+
+    // First-install: ask before dropping the unit. Update: just refresh it.
+    let want_unit = if already_installed || !interactive {
         true
     } else {
         confirm(
@@ -225,6 +258,7 @@ fn handle_systemd(
 
     run_systemctl(SystemctlAction::DaemonReload, UNIT_FILE_NAME)?;
 
+    if !already_installed {
         let want_enable = if !interactive {
             true
         } else {
@@ -233,10 +267,19 @@ fn handle_systemd(
         if want_enable {
             run_systemctl(SystemctlAction::Enable, UNIT_FILE_NAME)?;
         }
+    }
 
-    // Auto-start only when the user actually ran configure this session;
+    // Update path: restart so the freshly-installed binary actually runs.
-    // otherwise the daemon will fail immediately for lack of credentials.
+    // First-install path: only start if the user has a config to start with.
-    let want_start = if !interactive {
+    let (action, want) = if already_installed {
+        let want = if !interactive {
+            true
+        } else {
+            confirm("Restart maestrod.service to pick up the new binary?", true)?
+        };
+        (SystemctlAction::Restart, want)
+    } else {
+        let want = if !interactive {
             false
         } else if !configured {
             eprintln!(
@@ -247,8 +290,10 @@ fn handle_systemd(
         } else {
             confirm("Start maestrod.service now?", true)?
         };
-    if want_start {
+        (SystemctlAction::Start, want)
-        run_systemctl(SystemctlAction::Start, UNIT_FILE_NAME)?;
+    };
+    if want {
+        run_systemctl(action, UNIT_FILE_NAME)?;
     }
 
     Ok(())

docs/INSTALL.md

@@ -14,7 +14,12 @@ The repo is private, so grab `install.sh` while signed in to gitea, then run it:
 
 The bootstrap script builds `maestro-installer` into a temp directory, runs the
 wizard, and cleans up — only `maestrod` and `maestro` end up persisted in
-`~/.cargo/bin`. Re-run any time to update; `cargo install` overwrites in place.
+`~/.cargo/bin`.
+
+**Updating is the same command.** Re-running `./install.sh` detects an
+existing `~/.config/maestrod/config.toml` and existing systemd unit, skips the
+configure prompt, refreshes the unit, and runs `systemctl --user restart
+maestrod` instead of `start`. No `--update` flag needed.
 
 Inside the script, `cargo install --git https://git.naps.pt/naps62/maestro …`
 uses your already-configured git credentials for this host (HTTPS helper or