Linux; ordinary non-root account; fresh isolated T3 home; no imported data.
Command: t3 serve --tailscale-serve --tailscale-serve-port 19443 --port 19159 --host 127.0.0.1 --base-dir <isolated-home>

[04:40:40.376] INFO (#567): Listening on http://127.0.0.1:19159
T3 Code server is ready.

[04:40:40.505] WARN (#573): Failed to configure Tailscale Serve
  {
    cause: {
      _tag: 'TailscaleCommandExitError',
      executable: 'tailscale',
      subcommand: 'serve',
      argumentCount: 4,
      exitCode: 1,
      stderrLength: 197,
      stderrDiagnostic: 'permission-denied'
    },
    localPort: 19159,
    servePort: 19443
  }


GET http://127.0.0.1:19159/ => 200 text/html; charset=utf-8
HTML document received: true
Server still running after Tailscale Serve failure: true
Command: t3 pair --tailscale --tailscale-serve-port 19443 --base-dir <isolated-home>
[04:40:40.809] ERROR (#2): TailscaleServeFailedError: tailscale serve failed for HTTPS port 19443. Run `tailscale serve --https=19443 --bg <local-url>` by hand to see why.
  [cause]: TailscaleCommandExitError: tailscale serve exited with code 1.
Pair command exit status: 1
Stopped only this driver's server with SIGINT.