Add --install flag to completions command that outputs an install script

src/cli.ts

@@ -161,8 +161,9 @@ registerVmCommands(program)
 
 program
   .command("completions")
+  .option("--install", "Output a shell script that installs the completions file")
   .description("Output fish shell completions")
-  .action(() => completionsAction(program))
+  .action((opts: { install?: boolean }) => completionsAction(program, opts))
 
 // ── Default: show list if sessions exist, otherwise help ─────────────
 

src/commands/completions.ts

@@ -1,7 +1,19 @@
 import type { Command, Option } from "commander"
 
 /** Generate fish completions dynamically from the Commander program tree. */
-export function action(program: Command) {
+export function action(program: Command, opts: { install?: boolean } = {}) {
+  if (opts.install) {
+    const dest = "~/.config/fish/completions/sandlot.fish"
+    const lines = [
+      "#!/bin/sh",
+      `mkdir -p ~/.config/fish/completions`,
+      `sandlot completions > ${dest}`,
+      `echo "Installed fish completions to ${dest}"`,
+    ]
+    process.stdout.write(lines.join("\n") + "\n")
+    return
+  }
+
   const lines: string[] = [
     "# Fish completions for sandlot (auto-generated)",
     "# Install: sandlot completions > ~/.config/fish/completions/sandlot.fish",