Glossary

Index

Agent folder · Agent Folder Share · <ai-agent> · Authored source · Deployment · Edge worker · Editor (deployment) · Elefunc · Export · File Sync · Freeze · Full reload · <fs-explorer> · GitFar · Hot patch · Input · Instant I ⇄ O Sync · IOSync · KV scope · Locate · ML-KEM and ML-DSA · Output · Output service worker · Owner · Permit · Pin · Playground · Public Suffix List and rt.ht · Redaction · Remote Output · Route · Router · RTCode.ai · RTCode.io · RTEdge.net · Saver · Shell · Sibling route · Smart Undo · Source view · Symbols · Sync-safe custom element · URL suffix · Utilities · Version · Web Push · Worker · Workers for Platforms · X25519MLKEM768

Products and names

RTCode.io: Elefunc's live, bidirectional playground for HTML, CSS, JavaScript and Workers, at https://rtcode.io/x/. It combines a Monaco input, an isolated live output with its own service worker, custom HTML attributes for files and access, in-editor Workers, Agent Folder Share, and one-keystroke deploys (Ctrl+S / ⌘+S) to RTEdge.net.
RTEdge.net: Elefunc's deployment network. It serves what you deploy from RTCode.io on name.rt.ht or your own domain, runs edge workers on Cloudflare Workers for Platforms, and adds sign-in suffixes, scoped KV storage, versions and screenshots. Its figures are 337 cities, 125+ countries, 500 Tbps and under 50 ms for 95% of Internet users. https://rtedge.net/ is its live network map.
Elefunc: Elefunc, Inc., the company behind RTCode.io and RTEdge.net. The name stands for "Elemental Functions", and its glyph is <λ>.
Workers for Platforms: The Cloudflare product that hosts RTEdge.net's per-route edge workers: one isolated script for each route. The router dispatches each request to its route's worker.
Router: The single shared Cloudflare Worker that serves every RTEdge.net route, on every name.rt.ht address and every custom domain. It reads the route's deployment, then answers with the root document or an exported file, or dispatches the request to the route's edge worker. See Request routing.
GitFar: Elefunc's GitHub-compatible REST facade over git repositories on disk. RTEdge.net stores every deployment version and screenshot in GitFar repositories, and the versions page and edge.versions() read them through it. The Elefunc blog describes it.
Public Suffix List and rt.ht: rt.ht is in the private section of the Public Suffix List, submitted by Elefunc, Inc. Browsers therefore treat every name.rt.ht as its own site, and deployments share no cookies, storage or sign-in sessions. Path routes on the same host do share one origin.
Utilities: The public helper hosts that complement RTCode.io and RTEdge.net, such as ip.rt.ht, q.cf.rt.ht, logo.rt.ht and lt.rt.ht.

The playground

Playground: An RTCode.io session at https://rtcode.io/x/, made of one HTML input document, its live output and their settings. Most of the session state is encoded in the playground URL, so a link reopens it: the source, the title, the routes, the editors, the selections, the layout and the output settings. The split position is not stored, and Chromium pauses address-bar updates while Agent Folder Share is active. See The playground interface.
Input: The authored HTML document that you edit in the playground's Monaco editor. It needs no <!doctype>, <html>, <head> or <body>. During Agent Folder Share it is mirrored both ways as 📄.html, with the live selections in the read-only 📄.sel.
Output: The live document that is rendered from the input, in a separate, process-isolated iframe origin: https://out.rtcode.io, or https://out.rtcode.net when the playground is embedded, for popup and tab outputs, and in some browsers. Its own service worker serves the document, your exported files and your worker, so /name.ext and : URLs behave locally the way they do after a deploy.
Output service worker: The service worker on each output origin. It serves the output document and your exported files, and runs the code of <script type=worker> elements in the playground.
Locate: F8, Toggle Locate. It links editor cursors to the output elements they produced, and lets you point at output elements to reveal their source. elefunc.com markets it as "Instant I ⇄ O Locate".
Authored source: The exact source text that produced an output element, as IOSync's source map tracks it. o.input.pos, sel, inner, outer and their *All variants return it in the playground, and sync.input.* does the same inside the output. Elements that only exist at run time yield null.
Remote Output Experimental: Mirroring the live output to another device through a short https://rt.ht/<id> link or a QR code (Alt+Q). The playground itself labels it work in progress.
Freeze Experimental: Freeze All Windows (Ctrl+Alt+F / ⌘+Alt+F) and Freeze This Window (Ctrl+Alt+D / ⌘+Alt+D) respawn the playground on frozen.rt.ht. It shows "Code is frozen." above a non-interactive preview, so that you can review scripts for infinite loops before you unfreeze it.

Live sync

Instant I ⇄ O Sync: The public name of RTCode.io's two-way, reload-free sync. Input to output (I→O, Alt+I) patches the live page as you type. Output to input (O→I, Alt+O) writes live DOM changes back into the source as exact text edits. Each direction has a Live toggle and a Once command, and Load (F5) reloads the output fully. <meta io:sync>, sync=reload and oi:exclude tune it.
Hot patch: An incremental input-to-output update that changes only the DOM that differs, without reloading. Form values, focus, selection, media state and DOM that scripts created survive it, and it never runs scripts.
Full reload: Rebuilding the output from scratch. It happens on Load (F5) and whenever a reload trigger applies: a change to an executable script, a <script reload> or sync=reload element, a custom element that is not sync-safe, or a changed <base href>. A full reload resets page state, and it is the only time the playground refreshes exported files, worker:fs assets and worker code.
IOSync: Elefunc's proprietary engine that binds every live DOM node and attribute to the exact source range it came from, in both directions. FastPath is a verified hot path for text and attribute edits that falls back to IOSync, and FastPath Strict is FastPath without the fallback. All three run behind Instant I ⇄ O Sync. See The IOSync model.
Sync-safe custom element: A custom element whose edits hot-patch instead of forcing a full reload. An element qualifies when its tag or prefix is built in, when its tag or prefix is listed in a <meta io:sync>, or when the instance carries sync=pure Experimental.

A file made from an element's content with o:=name.ext, served at /name.ext on the output and on every deployment route. For example, o:=nav.js on the route new is served at https://new.rt.ht/nav.js. The colon is attribute syntax only. Names must contain a . and must not contain a /. o:type, o:content and h:* set the MIME type, the body and the headers. In the playground, exports refresh only on full reloads.

Worker

Code in <script type=worker>: an ES module with export default { fetch } that answers requests in the output's service worker. URLs that start with :, such as <iframe src=:1.json>, reach the worker, which sees the part after the : as its path. With the edge attribute the same code is deployed. request.rt.code is true in the playground, and request.rt.edge is true on RTEdge.net. See Using workers.

Edge worker

A worker marked edge. On deploy, all of a playground's <script type=worker edge> elements are merged, their static URL imports are bundled, and the result is wrapped in the RTEdge.net shell and uploaded for each route to Workers for Platforms. The edge worker answers the route's : paths and fallbacks, and its source is never served in the page. See Edge worker runtime.

Shell

The dated RTEdge.net wrapper that is compiled around your edge worker. It builds request.rt, exposes only env.KV and env.FS, patches fetch and handles errors. The upload records the shell date, and redeploying picks up the current shell.

KV scope

One of six owner-prefixed key spaces that env.KV.open({ user, domain, route }) returns:

UG: user and global.
UD: user and domain.
UR: user and route.
OG: global.
OD: domain.
OR: route.

A falsy user opens the shared owner scope, so check request.rt.user first.

Sibling route

Another playground, open in the same browser profile, whose route in Code.D shares your host. Your output can fetch() or import() its exported files at /<its path>/<name>, as on the deployed origin. Your own files win, and sibling root documents and workers are never served.

Deployment and routes

Route: Where a deployment is served: a host and an optional path, set in Code.D. A bare name such as new means https://new.rt.ht/, and a dotted host such as example.com/docs is a custom domain. Each path route is an independent deployment, with no fallback to its parent. The grammar is ( subdomain / domain "." tld ) [ "/" pathname ].
Deployment: The saved, served state of one playground on one route, created by Edge: Deploy (Ctrl+S / ⌘+S). It consists of a root document, the exported files, an optional edge worker, route metadata (the owner, the editors, the deploy time and digest, and the last saver), a version and a screenshot. One deploy publishes the same build to every route in Code.D.
Version: One deploy or delete, recorded as a GitFar commit. Its first line is ✔️ <route> or ❌ <route>, optionally followed by 💬 <note> from Deploy with Message (Ctrl+Alt+S / ⌘+Alt+S). Versions are listed in the version viewer, which ?? opens on a deployment, walked by Smart Undo and read by edge.versions(). Every list stops at the latest deletion.
Smart Undo: Undo and Redo that carry on past the editor's own history into the first route's deployed versions. When the editor has nothing left to undo, Undo loads the previous version whose source differs. Redo moves forward again, and finally returns to where you started.
URL suffix: Text appended to a deployment URL, and to many other platform URLs, that triggers platform behavior. Examples are ::si, ::sa, ::su and ::so for sign-in, ? for the source, ?? for versions, * for the index, /: for the worker, and ::qr and /::edge. Platform snippets and the edge router handle suffixes before your code runs.
Source view: Appending ? to a deployment URL reopens its exact deployed playground state in RTCode.io. ?io, ?sync and ::i, ::e and ::c do the same. It is public unless the deployment restricts its source. See Restricting access.

Access

Owner: The account that first deployed a route. Only the owner can delete the deployment or change its editors, and the deploys of editors count against the owner's quota and domain claim.
Editor (deployment): An entry in the editors list, Code.W. An entry is person@domain.tld, that exact account; domain.tld, any account at exactly that domain; or *, any signed-in account. Entries are compared without case and with whitespace removed. Editors can view and edit deployments, but cannot delete them or change their editors. Do not confuse this with the input editor.
Saver: The account that saved a particular deployment: an editor, or else the owner. It is recorded as the version's commit author, with the owner as committer, and shown with ✏️ in the version viewer.
Permit: An entry in edge:user, io:user or the editors list. It is an exact email, a domain that matches the accounts at that domain, or *, which means any signed-in user and never an anonymous visitor.
Redaction: Three ways to keep content out of copies or served pages. copy:redact masks an element when you copy or cut from the editor. edge:redact replaces the element in the served page with a line-preserving  comment, and its exports still work. edge:remove blanks the element. None of them hides content from the source view.

AI agents

Agent Folder Share (Agent Share™): Sharing the live playground with any coding agent through a local folder, started with ✨ Agent: 📂 Share (Alt+A). RTCode.io writes the source, selections, console, screenshots, pins and instructions there, applies the agent's file edits live, and runs io.eval.js and o.eval.js requests. It is marketed as Agent 📂 Share™ and is patent-pending. It needs FileSystemObserver, which means Chrome or Edge on a computer, and a playground that is not embedded.
Agent folder: The local root folder you pick for Agent Folder Share, plus a work folder for each route inside it. The work folder is named after Code.D[0], or Unrouted when there is no route, and nested by path, so the route example.com/docs becomes <root>/example.com/docs/. It holds 📄.html, 📄.sel, 📜.json, 📸.png, 📍.<N>.*, AGENTS.md, CLAUDE.md and the agent skills. See Agent files.
File Sync: While Agent Folder Share is active, every o:= export is written to the agent folder under its own name, and each <script type=worker> as ⚙️.js. Edits to those files flow back into the input. File Sync is on by default, and ✨ Agent: File Sync: Toggle switches it.
Pin: A marked output element or region (📍), with an optional comment, geometry and an optional crop image. People create pins with Ctrl+P / ⌘+P, and agents with o.pins.add(…). Each pin is saved as 📍.<N>.json, and 📍.<N>.png too, in the agent folder, and its image needs active output screen capture. See PinList.

Network and security

X25519MLKEM768: The hybrid post-quantum key agreement that RTEdge.net hosts negotiate in TLS, TLS group id 4588. You can check a host with qi.rt.ht.
ML-KEM and ML-DSA: The post-quantum algorithms for key encapsulation, ML-KEM, and for signatures, ML-DSA. Edge workers uploaded since 2026-10-01 can use ML-KEM-768, ML-KEM-1024 and ML-DSA-44, ML-DSA-65 and ML-DSA-87 through Web Crypto.
Web Push Experimental: An app on push.rt.ht and wp.rt.ht where you subscribe your devices to topics, and then send notifications to yourself from pages and workers.

Announced

RTCode.ai Coming soon: Elefunc's upcoming AI services brand: agents that will help you in the playground and at the edge.
<ai-agent> Coming soon: An Elefunc AI agent built as a web component.
<fs-explorer> Coming soon: A file explorer web component, and the filesystem layer for <ai-agent>. It is unrelated to Agent Folder Share.

Symbols

⚡: RTCode.io and real time.
🌐: RTEdge.net and the edge.
✨: AI, and the ✨ Agent: commands.
📂: Agent Share and the agent folder.
📍: Pins.
📸: Screenshots and capture.
📜: The console log.
🕐: Saved versions.
🛎️⚙️: Console lines from the service worker, which runs the playground worker.
⚙️: Worker code.
💬: A deploy note.
✔️ and ❌: Deploy and delete commits.
<Ϟ>: The bracket-bolt mark of RTCode.io and RTEdge.net.
<λ>: Elefunc.
I ⇄ O: Two-way input and output sync.