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JetBrains Junie browser MCP

Give local Junie sessions a browser that survives the task.

Hronaut runs a separate visible Chromium application. Local Junie CLI and IDE sessions connect over loopback MCP while named browser workspaces remain available after one task ends or another compatible local MCP client takes over.

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Hronaut is an independent project and is not affiliated with or endorsed by JetBrains or Junie.

Local MCP endpoint

http://127.0.0.1:47812/mcp

The loopback endpoint exists only on the computer running Hronaut. It works with Junie running on that same computer; it is not a hosted remote-browser service.

One local configuration

CLI and IDE use the same MCP file.

Junie CLI uses the same MCP JSON configuration as Junie in JetBrains IDEs. Put a user-level server in ~/.junie/mcp/mcp.json when you want it available to both surfaces. A project-specific .junie/mcp/mcp.json can be shared with a repository, but should not contain secrets. Official Junie MCP configuration ↗

User-level local setup

Add Hronaut as a remote MCP server.

Start Hronaut first, then add this server to ~/.junie/mcp/mcp.json. The JSON shape below follows Junie's documented remote-server format.

Authentication disabled

~/.junie/mcp/mcp.json

{
  "mcpServers": {
    "hronaut": {
      "url": "http://127.0.0.1:47812/mcp"
    }
  }
}

This snippet intentionally contains no bearer token.

Authentication enabled

Use a private literal header or Junie's assistant

Enable Require MCP authentication in Hronaut. Open Hronaut Home to find the current protected setup, then either use Junie's /mcp Installation Assistant or place the literal bearer value in the user-level file's documented headers object. Keep it out of project configuration, chat, screenshots, and source control.

Junie's public MCP guide does not document file or environment interpolation for static header values, so this guide does not invent token placeholders.

Verify before using a login

Confirm the server, then prove one observable browser action.

  1. 1

    Open Junie's MCP status

    Run /mcp in Junie and confirm hronaut reports Active. In ACP clients, /mcp is a read-only listing; edit the JSON file or use a supported Junie management surface when configuration must change.

  2. 2

    Keep approval on

    Review the MCP server and tool list before allowing calls automatically.

  3. 3

    Create a clean first workspace

    Ask: “Create a Hronaut workspace named first-check, open https://example.com inside it, and tell me the page title and workspace ID. Do not use my Default workspace.”

  4. 4

    Confirm the visible result

    A separate visible first-check workspace opens Example Domain, and Junie reports its stable workspace ID.

Security boundary

Treat a persistent browser as durable authority.

A new Hronaut profile starts without MCP authentication for simple local setup. In that mode, any process running as your user can control the browser profile. Before using valuable signed-in sessions, enable Require MCP authentication. Websites can contain prompt injection, so review surprising calls and pause MCP before entering passwords, security keys, payment details, or other human-only information.

Official reference

Check JetBrains' current Junie behavior at the source.

JetBrains documents the shared CLI/IDE configuration, user and project scopes, remote URL and header fields, and /mcp status behavior. The IDE integration guide explains how the same Junie CLI session appears in supported JetBrains IDEs.

Junie MCP configurationJunie IDE integrationJunie CLI quickstartAll client setup

Last verified against JetBrains' official Junie documentation on August 28, 2026.