Add diff command to show unstaged changes in a session's worktree

src/cli.ts

@@ -225,6 +225,27 @@ program
     spin.succeed(`Saved: ${msg}`)
   })
 
+// ── sandlot diff <branch> ───────────────────────────────────────────
+
+program
+  .command("diff")
+  .argument("<branch>", "branch name")
+  .description("Show unstaged changes in a session's worktree")
+  .action(async (branch: string) => {
+    const root = await git.repoRoot()
+    const session = await state.getSession(root, branch)
+    if (!session) {
+      console.error(`No session found for branch "${branch}".`)
+      process.exit(1)
+    }
+
+    const result = await $`git -C ${session.worktree} diff`.nothrow()
+    if (result.exitCode !== 0) {
+      console.error("git diff failed")
+      process.exit(1)
+    }
+  })
+
 // ── sandlot vm ───────────────────────────────────────────────────────
 
 const vmCmd = program.command("vm").description("Manage the sandlot VM")