From 1aaeb53ead7e544588f02f408e8cd2e79956cb8e Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Thu, 19 Feb 2026 09:56:04 -0800
Subject: [PATCH] Auto-derive branch name from `-p` prompt when branch arg is
 omitted

---
 src/cli.ts | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/src/cli.ts b/src/cli.ts
index 67dc353..e6767c5 100755
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -18,23 +18,33 @@ program.name("sandlot").description("Branch-based development with git worktrees
 
 // ── sandlot new <branch> ──────────────────────────────────────────────
 
+function branchFromPrompt(text: string): string {
+  return text
+    .toLowerCase()
+    .replace(/[^a-z0-9\s-]/g, "")
+    .trim()
+    .replace(/\s+/g, "-")
+    .slice(0, 20)
+    .replace(/-$/, "")
+}
+
 program
   .command("new")
-  .argument("<branch>", "branch name or prompt (if it contains spaces)")
+  .argument("[branch]", "branch name or prompt (if it contains spaces)")
   .argument("[prompt]", "initial prompt for Claude")
   .option("-p, --print <prompt>", "run Claude in non-interactive mode with -p")
   .description("Create a new session and launch Claude")
-  .action(async (branch: string, prompt: string | undefined, opts: { print?: string }) => {
-    // If the "branch" contains spaces, it's actually a prompt — derive the branch name
-    if (branch.includes(" ")) {
+  .action(async (branch: string | undefined, prompt: string | undefined, opts: { print?: string }) => {
+    // No branch given — derive from -p prompt
+    if (!branch && opts.print) {
+      branch = branchFromPrompt(opts.print)
+    } else if (!branch) {
+      console.error("Branch name or prompt is required.")
+      process.exit(1)
+    } else if (branch.includes(" ")) {
+      // If the "branch" contains spaces, it's actually a prompt — derive the branch name
       prompt = branch
-      branch = branch
-        .toLowerCase()
-        .replace(/[^a-z0-9\s-]/g, "")
-        .trim()
-        .replace(/\s+/g, "-")
-        .slice(0, 20)
-        .replace(/-$/, "")
+      branch = branchFromPrompt(branch)
     }
     const root = await git.repoRoot()
     const worktreeAbs = join(homedir(), '.sandlot', basename(root), branch)