fix: separate root provisioning from user shell sessions on Incus

src/runtime/incus.rs

@@ -217,34 +217,42 @@ impl Runtime for IncusRuntime {
         let vm = Self::vm_name(name);
 
         if interactive {
-            // For interactive sessions (shell attach, etc.), run as the
-            // non-root user with correct HOME and working directory.
-            let uid_str = Self::detect_vm_uid(&vm).await.unwrap_or("1000".to_string());
-            let home_env = Self::detect_vm_home(&vm, &uid_str).await;
-
-            let mut args = vec![
-                "exec".to_string(),
-                vm,
-                "--user".to_string(),
-                uid_str,
-                "--cwd".to_string(),
-                "/workspace".to_string(),
-                "--env".to_string(),
-                home_env,
-                "--".to_string(),
-            ];
-            for c in cmd {
-                args.push(c.to_string());
-            }
-            let arg_refs: Vec<&str> = args.iter().map(|s| s.as_str()).collect();
-            run_interactive("incus", &arg_refs).await
+            let mut args = vec!["exec", &vm, "--"];
+            args.extend_from_slice(cmd);
+            run_interactive("incus", &args).await
         } else {
             let mut args = vec!["exec", &vm, "--"];
             args.extend_from_slice(cmd);
             run_cmd("incus", &args).await
         }
     }
 
+    /// Execute an interactive command as the non-root user.
+    /// Incus exec defaults to root, so we detect the first UID >= 1000
+    /// and set --user, HOME, and CWD for proper user sessions.
+    async fn exec_as_user(&self, name: &str, cmd: &[&str]) -> Result<ExecResult> {
+        let vm = Self::vm_name(name);
+        let uid_str = Self::detect_vm_uid(&vm).await.unwrap_or("1000".to_string());
+        let home_env = Self::detect_vm_home(&vm, &uid_str).await;
+
+        let mut args = vec![
+            "exec".to_string(),
+            vm,
+            "--user".to_string(),
+            uid_str,
+            "--cwd".to_string(),
+            "/workspace".to_string(),
+            "--env".to_string(),
+            home_env,
+            "--".to_string(),
+        ];
+        for c in cmd {
+            args.push(c.to_string());
+        }
+        let arg_refs: Vec<&str> = args.iter().map(|s| s.as_str()).collect();
+        run_interactive("incus", &arg_refs).await
+    }
+
     async fn destroy(&self, name: &str) -> Result<()> {
         let vm = Self::vm_name(name);
         // Stop first (ignore errors if already stopped)

src/runtime/mod.rs

@@ -126,4 +126,11 @@ pub trait Runtime: Send + Sync {
     /// Update mount points for an existing sandbox.
     /// Stops the VM, updates mounts in the config, and restarts.
     async fn update_mounts(&self, name: &str, mounts: &[Mount]) -> Result<()>;
+
+    /// Execute an interactive command as the non-root user.
+    /// Used for shell attach — defaults to exec_cmd with interactive=true.
+    /// Runtimes like Incus override this to set --user, HOME, and CWD.
+    async fn exec_as_user(&self, name: &str, cmd: &[&str]) -> Result<ExecResult> {
+        self.exec_cmd(name, cmd, true).await
+    }
 }

src/sandbox/mod.rs

@@ -237,7 +237,7 @@ impl SandboxManager {
         if layout == "plain" {
             println!("Attaching to sandbox '{name}'...");
             let shell = Self::probe_shell(runtime.as_ref(), name).await;
-            runtime.exec_cmd(name, &[&shell, "-l"], true).await?;
+            runtime.exec_as_user(name, &[&shell, "-l"]).await?;
             return Ok(());
         }
 
@@ -249,7 +249,7 @@ impl SandboxManager {
             // No Zellij — fall back to raw shell
             println!("Attaching to sandbox '{name}'...");
             let shell = Self::probe_shell(runtime.as_ref(), name).await;
-            runtime.exec_cmd(name, &[&shell, "-l"], true).await?;
+            runtime.exec_as_user(name, &[&shell, "-l"]).await?;
             return Ok(());
         }
 
@@ -317,7 +317,7 @@ impl SandboxManager {
             // Reattach to existing live session
             println!("Reattaching to sandbox '{name}'...");
             runtime
-                .exec_cmd(name, &["zellij", "attach", &session_name], true)
+                .exec_as_user(name, &["zellij", "attach", &session_name])
                 .await?;
         } else {
             // Create new named session with layout.
@@ -336,10 +336,9 @@ impl SandboxManager {
 
             println!("Attaching to sandbox '{name}' (layout: {effective_layout})...");
             runtime
-                .exec_cmd(
+                .exec_as_user(
                     name,
                     &["zellij", "--config", &config_path, "--layout", &layout_path],
-                    true,
                 )
                 .await?;
         }