Screener
Screener is a private, low-latency screen-sharing project for one game player and a small group of friends. Its accepted media target is WebRTC P2P-first, with an SFU virtual parent feeding only the necessary roots and optional authenticated TURN for explicitly supported restrictive networks. Roots continue distributing to bounded peer descendants; this is not an always-SFU conferencing design. Viewers should be able to join from a desktop or mobile browser without installing the sender application.
The first measurable Web proof of concept is implemented. A host captures a screen, window, or browser tab and shares a numeric room code. Rooms default to a private fragment invitation whose capability authorizes only one room; a Host may explicitly choose public watching by room code after site access. During a share, the host can change between three ceiling profiles without reopening the source picker: 1080p60 at 8 Mbps, 1080p30 at 5 Mbps, and 720p30 at 3 Mbps. The host can also temporarily pause the picture or switch sources. Rooms are random and temporary by default. A site-access-protected deployment can optionally use SQLite-backed room numbers starting at 1, reusable links, and a waiting state after sharing stops. Lightweight deployments may keep independent direct WebRTC connections. The flagship deployment enables the all-room controller with bounded peer descendants and LiveKit SFU roots; short-lived TURN may be authorized only for a controller-selected exceptional media edge. The default room capacity is eight viewers and deployments may configure 1 through 16, but that admission limit is not a performance promise.
This is not yet a broadly validated production release; Current status owns the deployed revision and validation evidence. The current flagship boundary is the all-room bounded peer/SFU-UDP controller, with ordinary peer ICE kept STUN-only and short-lived TURN limited to controller-selected exceptional media edges. The optional Windows native sender remains source-only and is not a production runtime. Mobile devices are Web viewers only; ordinary Android and iOS browsers do not expose reliable screen capture for a Web Host. Real cross-network SFU/TURN media, game audio, a sustained 1:8 room, mobile browser lifecycle behavior, and latency targets still require the documented manual test matrix.
Run locally
Node.js 24 and npm 11 are required.
npm ci
npm run dev
Production requires an independent 8-128 byte visible-ASCII SITE_ACCESS_PASSWORD. It protects room creation, Host role, and code-only Viewer entry. A valid room-scoped fragment grant enters directly without it; otherwise public-watch needs site access plus the room code, and private code-only entry additionally needs the room password. Local development and tests may leave it empty.
Open http://localhost:8787. The server listens on 0.0.0.0 by default so a
phone on the same LAN can load http://<computer-lan-ip>:8787. To generate an
invite that the phone can open while the host keeps using secure-context
localhost capture, set PUBLIC_BASE_URL to that LAN URL and include both
origins in ALLOWED_ORIGINS. LAN viewers can join over HTTP; the sharing page
must remain on localhost or HTTPS because screen capture requires a secure
context. The local default has no STUN, so cross-network use still requires
HTTPS and the production ICE configuration documented separately.
Production keeps a stopped v1 SQLite backup and restore boundary as documented
in Deployment. SITE_ACCESS_PASSWORD supplies site access;
valid private fragment grants bypass that gate, while code-only entry requires site access before
public/private room policy is evaluated. The release has no v1 parser, old cookie, or
dual-schema runtime. Ordinary ICE contains only self-hosted STUN. LiveKit serves
normally one or two SFU/UDP roots; the controller may authorize short-lived TURN
only for a selected exceptional media edge. HTTPS/WSS remains TLS/TCP independently.
Run the complete automated validation with:
npm run check
Start here: