Swyd - Show What You Doing

Deprecated

The features here were all merged to airc and extended further.

Overview

Swyd mirrors a tmux session, read-only, into a web page. The target viewer is the Tesla browser; the terminal session runs on the laptop sitting in the car (driven by voice via dais). There is deliberately no browser-to-terminal input path.

Tesla browser -> ngrok HTTPS dev domain -> laptop localhost server -> tmux

The server follows the active pane of one tmux session (a specific pane can be pinned from the viewer), converts tmux capture-pane -e output to HTML server-side, and the page polls it with ETag/304 suppression and an adaptive interval. The server also spawns and supervises the ngrok agent as a child process, so one systemd unit is the whole system.

Usage

tools/swyd on        # start unit, wait for tunnel, print the bookmark URL
tools/swyd off       # stop everything (server + ngrok child); nothing stays running
tools/swyd status    # one-line status; --json for machines (dais)
tools/swyd url       # print the bookmark URL without starting anything

One-time install of the user unit:

systemctl --user link /home/k/swyd/tools/swyd.service
systemctl --user daemon-reload

Logs: journalctl --user -u swyd -f.

The Tesla bookmark is the URL printed by swyd on/swyd url: https://<domain>/?k=<token>. The token persists as a cookie after the first visit; the bookmark re-authenticates with zero typing even when the cookie is gone. Everything except fonts/static assets answers plain 404 without the token. /healthz is open to local loopback only (for dais-top), and requires the token through the tunnel.

Configuration

config.json (gitignored; see config.example.json for all keys with their defaults). The auth token is generated and written there on first run.

{
  "session": "swyd-test",
  "port": 8080,
  "resizeToViewport": false,
  "ngrok": { "enabled": true, "domain": "carrousel-value-recipient.ngrok-free.dev" }
}

CLI flags override the config per-invocation:

node src/server.js --session app --no-ngrok --port 8090   # local dev
node src/server.js --print-url                            # bookmark URL, then exit
yarn dev                                                  # server without tunnel

resizeToViewport (opt-in): the viewer reports its cols/rows and the server runs tmux resize-window to match the car screen exactly. Off by default because it reshapes the same session shown on the laptop. The default sizing is client-side: the page scales the font so the captured pane fits the viewport (Fit), with manual A−/A+ override.

Pages and endpoints

• / viewer: terminal + status strip (live/idle/stale dot, pane label → pane picker overlay, font controls, day/night theme, pause).
• /probe browser capability probe (kept for in-car diagnostics).
• /api/tmux/frame one frame as JSON (?pane=%5 pins a pane); supports If-None-Match/304. /api/tmux/panes lists panes. /api/config viewer settings. /healthz rich status JSON (tunnel URL, last-capture age, viewers in the last minute).

Note lastCaptureAgeMs in /healthz grows when no viewer is polling - capture is request-driven, so "old but ngrok up" means no viewer, not broken.

Development

Node >= 20, dependency-free (built-in modules only). tmux >= 3.x, ngrok agent on PATH (~/bin/ngrok).

yarn check    # node --check over all server/client JS + inline scripts in public/*.html

Layout: src/server.js (routes, lifecycle), src/tmux.js (capture, pane resolution - note tmux exits 0 with empty fields for unknown targets, the empty pane id is the "not found" signal), src/ansi.js (SGR -> HTML: 16-color palette as themable CSS classes, 256/truecolor inline, bold/dim/ italic/underline/reverse), src/auth.js, src/ngrok.js (child supervision, URL discovery via the agent API on :4040), src/config.js. Viewer in public/ (index.html, app.js, app.css).

More complete context for humans and fresh-context coding agents lives in docs/: project brief, architecture, operations, Tesla browser findings, implementation notes, and future work.

A color-cycling test session for poking at the viewer:

tmux new -d -s swyd-test -x 100 -y 30 \
  'while true; do printf "\033[32mgreen\033[0m \033[38;5;208m256\033[0m \033[38;2;255;105;180mrgb\033[0m\n"; date; sleep 2; done'

Tesla findings (POC, 2026-06)

Network:

• Direct hotspot LAN access did not work from Tesla (10.204.192.28:8080); the same URL worked from laptop and phone. Tesla appears to block hotspot-local/private addresses, at least 10.0.0.0/8.
• Cloudflare TryCloudflare worked; ngrok preferred because the assigned free dev domain is a stable bookmark.
• ngrok free tier: interstitial on first visit (cookie expires after ~1 week in Firefox), and only one agent session - a stray manually started ngrok blocks the supervised child (its error is logged verbatim).

Browser (Chrome 140-based, X11 UA):

• Viewport (fixed, confirmed in car): 1180x919 css px, devicePixelRatio: 1 (physical == css, no scaling). Fullscreen-stretched in Park is 1920x1089 (available 1920x1200) but still shows a location bar — not true fullscreen.
• fetch, WebSocket-through-ngrok, EventSource, cookies, and localStorage all work. navigator.language = fi.

Rendering:

• Tesla's generic monospace and Courier New stacks do NOT render fixed-width; the bundled Fira Code (public/fonts/) renders aligned. The terminal must use the web font.

Confirmed in car (2026-06-12):

• Stays live while driving, not just in Park — minor latency, works well.
• Blinking cursor is visible and correctly positioned.
• Pane switching from the top pane-picker works well.

Still open — text sizing / pane fit:

• A quarter-size Konsole window fit the car screen well; a full half window was too much (too many cols/rows → client auto-fit shrinks the font too small). Raising the Konsole font (fewer cols/rows) helped.
• The lever is the source pane's cols/rows, not just font scaling. Likely direction: the opt-in resizeToViewport or a target cols/rows cap. Being tested before committing to an approach.

Transport notes

Polling at 1 Hz (stretching to pollIdleMaxMs after unchanged frames, 304s in between) is simple and tunnel-friendly for a passive viewer. WebSocket verified working through ngrok and can replace polling later as an optimization, keeping polling as the fallback.