How unsurf works

The problem

Agents often need to use websites that are already authenticated in a real browser. Fresh headless containers do not inherit that state, and copied credentials create a new security problem.

Unsurf starts from a different premise:

the browser is the auth

The model

authenticated browser
        ↓
agent action
        ↓
video + trace + receipt
        ↓
optional typed API seam

1. Browser runtime

The local runtime attaches to an already-open Chrome/CDP session. Nearby agents can discover it through unsurf-local-mcp, or application code can use recordAttachedLocal(...) directly.

2. Proof artifacts

Recording wraps a browser run and produces:

video
action trace
result metadata
viewer links with grant-gated access

observeVideo() inspects those recordings. loop() composes record + observe + refine until a yes/no North Star is met.

3. Reusable seams

When a website reveals a stable API beneath the UI, Unsurf can capture it:

scout observes traffic and stores a typed seam
worker replays it directly over HTTP
heal repairs it when the site drifts

That path still matters. It is now one layer in a broader browser-runtime product, not the entire pitch.

Hosted vs local

Surface	Best for
cmux browser	Canonical local authenticated investigation, snapshots, screenshots, and human takeover
Local browser MCP	Driving an attached Chrome/CDP session when that adapter is needed
Browser Run provider	Hosted isolated Cloudflare Worker-side BrowserHandle flows and native replay
`record` / `loop`	Producing inspectable proof from video-capable browser work
Hosted MCP / REST	Scouting, search, planning, and shared hosted surfaces
API replay	Repeated work that can skip the browser after discovery

Infrastructure

Hosted Unsurf runs on Cloudflare:

Workers
Workers AI
Browser Rendering for hosted scouting
D1 + R2 for stored specs, runs, and trace bundles

Browser providers are swappable behind Unsurf’s browser abstraction. The canonical local investigation provider is now cmux’s in-app browser. The agent-browser adapter remains available for attached Chrome/CDP and playable local video; it is not required for the normal investigation workflow.

Why this shape

real browser auth beats invented delegation layers
video makes browser work reviewable
loops turn visual evidence into a stop condition
typed API seams reduce repeat browser work when the web app gives you one