Function runDevMode

packages/cli/src/commands/preview.ts:749–782

* Dev mode: spawn the studio dev server from the monorepo.

(dir: string, options?: StudioLaunchOptions)

 * Dev mode: spawn the studio dev server from the monorepo.
 */
async function runDevMode(dir: string, options?: StudioLaunchOptions): Promise<void> {
  // Find monorepo root by navigating from packages/cli/src/commands/
  const thisFile = fileURLToPath(import.meta.url);
  const repoRoot = resolve(dirname(thisFile), "..", "..", "..", "..");

  // Symlink project into the studio's data directory
  const projectsDir = join(repoRoot, "packages", "studio", "data", "projects");
  const pName = options?.projectName ?? basename(dir);
  const { symlinkPath, createdSymlink } = linkProjectIntoStudioData(dir, projectsDir, pName);

  clack.intro(c.bold("hyperframes preview"));

  const s = clack.spinner();
  s.start("Starting studio...");

  // Run the new consolidated studio (single Vite dev server with API plugin)
  const studioPkgDir = join(repoRoot, "packages", "studio");
  const child = spawn("bun", ["run", "dev"], {
    cwd: studioPkgDir,
    stdio: ["ignore", "pipe", "pipe"],
  });

  attachStudioReadyHandler(child, s, pName, options);
  removeSymlinkOnExit(createdSymlink, symlinkPath);

  // Kill the child's entire process tree on SIGTERM/SIGINT. Ctrl+C sends
  // SIGINT to the foreground process group (covers the common case), but
  // `kill <pid>` only targets this process — the child tree (Vite + Chrome)
  // would survive without explicit cleanup.
  // On Windows, killProcessTree is a no-op (pgrep/ps unavailable); Ctrl+C
  // propagates via the console process group instead.
  registerChildTreeShutdown(child);
  return waitForChildClose(child);
}

/**
 * Check if @hyperframes/studio is installed locally in the project's node_modules.