Show stderr output in debug mode

src/spinner.ts

@@ -1,7 +1,25 @@
 const frames = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"]
+const DEBUG = !!process.env.DEBUG
 
 export function spinner(text: string, prefix?: string) {
   const tag = prefix ? `\x1b[2m[${prefix}]\x1b[22m ` : ""
+
+  if (DEBUG) {
+    process.stderr.write(`▸ ${tag}${text}\n`)
+    return {
+      set text(t: string) {
+        process.stderr.write(`▸ ${tag}${t}\n`)
+      },
+      succeed(msg: string) {
+        process.stderr.write(`✔ ${tag}${msg}\n`)
+      },
+      fail(msg: string) {
+        process.stderr.write(`✖ ${tag}${msg}\n`)
+      },
+      stop() {},
+    }
+  }
+
   let i = 0
   const id = setInterval(() => {
     process.stderr.write(`\r\x1b[2K${frames[i++ % frames.length]} ${tag}${text}`)

src/vm.ts

@@ -4,6 +4,7 @@ import { dirname, join } from "path"
 import { getApiKey } from "./env.ts"
 import { info } from "./fmt.ts"
 
+const DEBUG = !!process.env.DEBUG
 const CONTAINER_NAME = "sandlot"
 const USER = "ubuntu"
 const CLAUDE_BIN = `/home/${USER}/.local/bin/claude`
@@ -33,7 +34,8 @@ function requireContainer(): void {
 
 /** Run a shell command, logging stderr on failure. */
 async function run(cmd: ReturnType<typeof $>, step: string): Promise<void> {
-  const result = await cmd.nothrow().quiet()
+  const prepared = DEBUG ? cmd.nothrow() : cmd.nothrow().quiet()
+  const result = await prepared
   if (result.exitCode !== 0) {
     const stderr = result.stderr.toString().trim()
     const stdout = result.stdout.toString().trim()
@@ -60,7 +62,8 @@ async function createContainer(home: string): Promise<void> {
   if (mounts.dev) args.push("--mount", `type=bind,source=${home}/dev,target=/host/dev,readonly`)
   if (mounts.code) args.push("--mount", `type=bind,source=${home}/code,target=/host/code,readonly`)
   args.push("-v", `${home}/.sandlot:/sandlot`, "ubuntu:24.04", "sleep", "infinity")
-  const result = await $`${args}`.nothrow().quiet()
+  const prepared = DEBUG ? $`${args}`.nothrow() : $`${args}`.nothrow().quiet()
+  const result = await prepared
   if (result.exitCode !== 0) {
     const stderr = result.stderr.toString().trim()
     const stdout = result.stdout.toString().trim()
@@ -234,7 +237,8 @@ export async function ensure(log?: (msg: string) => void): Promise<void> {
   requireContainer()
 
   // Ensure the container daemon is running
-  await $`container system start`.nothrow().quiet()
+  if (DEBUG) await $`container system start`.nothrow()
+  else await $`container system start`.nothrow().quiet()
 
   const s = await status()
   if (s === "running") return