vapor

You paste a draft into chat and now there are two copies, both going stale. vapor gives the draft one URL instead: a live markdown document anyone can open and edit, people and AI agents side by side, each with a cursor. It deletes itself after 99 hours.

Running at vapor.fyi. A fork of mist.

Documents

Anyone with the URL can read and edit. Live markdown with track changes (CriticMarkup), comments anchored to highlights, and a rendered preview. No accounts required, no save button, nothing kept past 99 hours—export before then.

curl https://vapor.fyi/new -T notes.md    # create from a file
curl https://vapor.fyi/<id>.md            # raw markdown back

People and agents

Sign-in (Google) is optional and only changes attribution:

	Human	Agent
Anonymous	Curious Ladybug 🐞	Agentic Butterfly 🦋
Signed in	Ada Lovelace	Ada's Agent

Your anonymous animal lives in localStorage and follows you between documents. Sign in and your name takes over, earlier comments included.

Connecting an agent

vapor is an MCP server. Two ways in:

# signed in: stable identity, write access if you grant it
claude mcp add --transport http vapor https://vapor.fyi/mcp

# anonymous: no setup, suggest and comment only
claude mcp add --transport http vapor https://vapor.fyi/mcp/anonymous

Agents get suggest and comment by default; full write is a separate grant on the consent screen. Their edits type in at human pace with a visible cursor (pace: "instant" skips the show). Mention @agent-name in a document to wake an agent waiting on await_events.

Tools: read_document · insert · replace · suggest · comment · reply · join · leave · await_events · create_document. Each document's Agents panel lists who's enrolled, with revoke.

The drafting habit

The vapor plugin for Claude Code bundles the MCP connection with a skill that changes where drafts live: plans and proposals go up as vapor docs instead of chat walls, Claude answers comments over MCP, and the settled document is exported to the repo before the 99-hour cliff. The bundled connection is the signed-in door (/mcp) — the first tool call prompts a Google sign-in and consent screen.

claude plugin marketplace add arfct/vapor
claude plugin install vapor@vapor

Just the skill, no plugin (source in plugin/skills/vapor/SKILL.md, served at vapor.fyi/skill.md):

curl -s https://vapor.fyi/skill.md --create-dirs -o ~/.claude/skills/vapor/SKILL.md

How it's built

Each document is one Cloudflare Durable Object holding the Yjs doc, agent roster, and event log. TipTap and React Router 7 on the front, the Agents SDK underneath, and a dependency-free auth stack (Google sign-in, OAuth 2.1 with PKCE and CIMD) ported from subpixel.

agents/    Durable Objects: DocumentAgent, VaporMcp, Registry
app/       React Router app
workers/   Worker entry, routes, OAuth server
tests/     Unit + integration

Developing

Node 22+.

npm install
npm run dev      # local server
npm run test     # also: typecheck, lint
npm run deploy   # needs CLOUDFLARE_ACCOUNT_ID

Sign-in needs GOOGLE_CLIENT_ID (a wrangler var) and SESSION_SECRET (a Workers secret); both optional in development. See .dev.vars.example. Design docs live in docs/plans/.

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