Stagely

Let a coding agent test its own pull request

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A coding agent deploys the pull request it opened over MCP, opens the running app and tests its change. Then a person reviews the same stagelet.

A coding agent can write a change and open a pull request. Before a person reviews it, the agent must show that the change works in the running app. With Stagely, the agent deploys its pull request as a stagelet over MCP, opens the stagelet and tests it. Then a person reviews the same stagelet.

The loop

  1. The agent opens a pull request. When the project deploys on push, the default, this starts a deploy, unless the pull request comes from a fork. The agent can also call deploy_pull_request.
  2. The agent calls get_stagelet until the state is running and ready is true. While it waits, get_operation shows the steps and the log.
  3. When a deploy fails, get_operation gives the failed step, its error and the last 200 log lines. The agent fixes the change and pushes again.
  4. open_stagelet gives the agent a URL that works once, within 30 seconds. The agent tests the app at that URL.
  5. A person opens the same stagelet from its page in the console. The pull request’s commit status links to that page.

A session

This session is shortened. The agent gets one request in plain words:

> List my Stagely projects. Deploy pull request 1 of acme/web.
> Wait until the stagelet is ready, then open it.

list_projects
  "name": "acme/web"
deploy_pull_request {"repository":"acme/web","pull_request":1}
  "state": "deploying"
  "ready": true
get_operation {"stagelet_id":"f543a41f9949"}
  "[start stderr]  Container stagelet-web-1 Recreate"
get_stagelet {"stagelet_id":"f543a41f9949"}
  "state": "running"
  "outcome": "applied"
open_stagelet {"stagelet_id":"f543a41f9949"}
  "expires_in_seconds": 30
  "url": "https://f543a41f9949.stagelets.acme.dev/_stagely/handoff?token=‹redacted›"

Here, ready is true right after the deploy starts, because the previous revision still serves. So the agent also waits until the requested revision’s outcome is applied. Only then does the new commit serve.

What the agent can do

  • The agent signs in with OAuth through a consent page. It acts as you, in the one account that you choose, with your role in that account.
  • Its token works only at the MCP endpoint, never at the API. Access tokens last 15 minutes. A grant lasts at most one hour.
  • A stagelet session that the agent opens never outlives its grant.
  • To end the agent’s access, open Settings, then Access. Under Connected apps, click Revoke. The stagelet sessions that the agent opened stop within about 50 seconds.

Connect Claude Code

claude mcp add --transport http \
  stagely https://app.stagely.dev/mcp
claude mcp login stagely

Other MCP clients connect the same way: Stagely’s endpoint uses Streamable HTTP and OAuth with PKCE.

Start

  1. Set up Stagely once with the Quickstart.
  2. Connect a coding agent. That page lists every tool.
  3. Show reviewers how to review a stagelet.