Tidy up plan / install UX

src/cli/subcommand/install.rs

@@ -29,7 +29,7 @@ pub struct Install {
     pub plan: Option<PathBuf>,
 
     #[clap(subcommand)]
-    pub planner: BuiltinPlanner,
+    pub planner: Option<BuiltinPlanner>,
 }
 
 #[async_trait::async_trait]
@@ -43,6 +43,13 @@ impl CommandExecute for Install {
             explain,
         } = self;
 
+        let planner = match planner {
+            Some(planner) => planner,
+            None => BuiltinPlanner::default()
+                .await
+                .map_err(|e| eyre::eyre!(e))?,
+        };
+
         let mut plan = match &plan {
             Some(plan_path) => {
                 let install_plan_string = tokio::fs::read_to_string(&plan_path)

src/cli/subcommand/plan.rs

@@ -9,11 +9,10 @@ use crate::cli::CommandExecute;
 
 /// Plan an install that can be repeated on an identical host later
 #[derive(Debug, Parser)]
-#[command(args_conflicts_with_subcommands = true, arg_required_else_help = true)]
 pub struct Plan {
     #[clap(subcommand)]
     pub planner: Option<BuiltinPlanner>,
-    #[clap(env = "HARMONIC_PLAN")]
+    #[clap(env = "HARMONIC_PLAN", default_value = "/dev/stdout")]
     pub output: PathBuf,
 }