feat(claudbg-ltt0): sessions with no subcommand defaults to list

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.beans/claudbg-ltt0--sessions-no-sub-command-defaults-to-sessions-list.md

@@ -0,0 +1,10 @@
+---
+# claudbg-ltt0
+title: 'sessions: no sub-command defaults to sessions list'
+status: todo
+type: feature
+created_at: 2026-03-31T00:32:35Z
+updated_at: 2026-03-31T00:32:35Z
+---
+
+Running `claudbg sessions` with no sub-command should behave identically to `claudbg sessions list`. Note: `claudbg agents` does NOT get this treatment since agents list requires a session ID.

src/cli.rs

@@ -82,10 +82,11 @@ pub struct GlobalOpts {
 #[derive(Debug, clap::Subcommand)]
 pub enum Commands {
     /// List, dump, and transcribe sessions.
+    #[command(subcommand_required = false)]
     Sessions {
-        /// Sessions subcommand.
+        /// Sessions subcommand (defaults to `list` when omitted).
         #[command(subcommand)]
-        cmd: SessionsCmd,
+        cmd: Option<SessionsCmd>,
     },
     /// List, dump, and transcribe sub-agent runs.
     Agents {

src/main.rs

@@ -8,7 +8,7 @@ use claudbg::error::Result;
 async fn main() -> Result<()> {
     let cli = Cli::parse();
     match cli.command {
-        Commands::Sessions { cmd } => match cmd {
+        Commands::Sessions { cmd } => match cmd.unwrap_or(SessionsCmd::List) {
             SessionsCmd::List => claudbg::commands::sessions::list(&cli.global).await?,
             SessionsCmd::Dump { id, follow } => {
                 claudbg::commands::sessions::dump(&id, follow, &cli.global).await?