diff --git a/src/cli.ts b/src/cli.ts
index 7494a02..6ef7db8 100755
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -115,6 +115,21 @@ const closeAction = async (branch: string) => {
   }
 }
 
+// ── sandlot merge <branch> ──────────────────────────────────────────
+
+program
+  .command("merge")
+  .argument("<branch>", "branch name")
+  .description("Merge a branch into main and close the session")
+  .action(async (branch: string) => {
+    const root = await git.repoRoot()
+
+    await git.merge(branch, root)
+    console.log(`Merged ${branch} into current branch`)
+
+    await closeAction(branch)
+  })
+
 program
   .command("close")
   .argument("<branch>", "branch name")
diff --git a/src/git.ts b/src/git.ts
index 48b1634..f2f04ae 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -80,3 +80,11 @@ export async function checkout(branch: string, cwd: string): Promise<void> {
     throw new Error(`Failed to checkout branch "${branch}": ${result.stderr.toString().trim()}`)
   }
 }
+
+/** Merge a branch into the current branch. */
+export async function merge(branch: string, cwd: string): Promise<void> {
+  const result = await $`git merge ${branch}`.cwd(cwd).nothrow().quiet()
+  if (result.exitCode !== 0) {
+    throw new Error(`Failed to merge branch "${branch}": ${result.stderr.toString().trim()}`)
+  }
+}