Ghostlight README

Ghostlight MCP

Give your agent a visible place in the browser you already use.

_{A launch brief moves from empty form to ready for review, in full view.}

Install Ghostlight | See where it fits | Installation guide | Trust Center

Your agent needs a page you are signed in to. The usual answer is a second, empty browser that knows none of your sessions, driven by a model that has to learn Chrome internals to get anything done.

Ghostlight gives it a tab group inside the Chromium you already have open. The work happens in front of you: watch it, pause it, take the wheel, or end the session. The model says what it wants, and Ghostlight does the browser part.

Ask an agent to read a page, complete a form, handle a file, follow a popup, or investigate a failed web workflow. Ghostlight carries the task across tabs and browser changes while keeping the browser work and its controls on your machine.

A light left burning, so the halls stay safe.

Where it stands today

The published release is 2.0.1. It is available as the GitHub release v2.0.1, the npm package ghostlight@2.0.1, the Chrome Web Store adapter v2.0.1, and the MCP Registry record org.sylin/ghostlight 2.0.1, all observed on 2026-10-22 and recorded in docs/public-status.json and the release custody record.

What you get

• 23 catalog tools: 22 browser tools covering tabs, navigation, reading a page, screenshots, semantic clicks and hovers, form input, file upload, scripts, waits, short flows, dialogs, and diagnostics, plus one policy tool that explains the authority in force. One call carries the intent; Ghostlight performs the browser steps behind it.
• One truthful answer per call: what happened, what changed in the browser, what is ready, and whether running it again is safe. Ghostlight writes that answer, never the page, and adds at most two recovery steps of its own. When an effect is uncertain it says so rather than guessing, and never proposes a replay that could submit a form twice.
• A desktop workbench in the tray that shows work as it happens.
• Your machine, and only your machine. Ghostlight runs as you, reaches your browser over local IPC, and keeps a payload-free local record. No account, no telemetry, no activation service, no update ping, no hosted control plane, and no second hidden browser. The only network traffic is the browsing you asked for.

Your first five minutes

You need Chrome, Edge, Brave, or Chromium 125+ and an MCP client. The npx installer needs Node.js; the one-line installers do not. The service you run afterward is native Rust. Agent setup supports Windows and Linux; macOS is not supported yet.

1. Install Ghostlight. It registers the MCP clients it finds and opens the Ghostlight window on its setup steps:

   TerminalCopy

   npx -y ghostlight install
   

   Without Node.js, use the one-liner for your system. On Windows, in PowerShell:

   powershellCopy

   irm https://sylin.org/ghostlight/get.ps1 | iex
   

   On Linux:

   TerminalCopy

   curl -fsSL https://sylin.org/ghostlight/get.sh | sh
   

2. Add Ghostlight in Browser from the step the window shows. It lists the browsers on your computer. Add opens the Chrome Web Store listing in that browser, which is also where Edge gets the extension. If the browser already holds the extension, the row reads Open instead.

3. Ask your agent:

   Open sylin.org/ghostlight/demo/desk and ring the bell.

If the install named an agent to restart, restart it first; the install says so. There is no other restart step.

A sky-blue Ghostlight group appears in your browser, the agent rings the bell on a demo page that submits and stores nothing, and the window shows Ready. That one prompt proves the whole connection. For a read-only first task instead, ask:

Open https://example.com/ in a new Ghostlight tab, summarize the page, and tell me which tab you used. Do not click, type, submit, or change the page.

When a session ends, the tabs Ghostlight keeps open leave its group and stay where they are, so no idle group is saved to your bookmarks bar. Next time, the same agent gets its group back and reuses a tab Ghostlight opened for it on that site and left open, so repeated work stops littering your tab strip. It never takes over a tab you opened, or a tab another agent left open. After a browser restart, an agent's remembered tab is used only when the browser still shows that tab at the page Ghostlight last saw there; otherwise the agent opens a fresh tab. The one case it cannot tell apart is a tab of yours that the restarted browser gave the same id and that shows the same address, such as a restored copy of the agent's page.

If a step needs attention, run:

ghostlight doctor

If you installed with npm and ghostlight is not on your PATH, npx -y ghostlight doctor runs the same check.

doctor checks the client entry, local service, browser connection, and extension, then names the next action. The installation guide covers targeted clients, source builds, updates, uninstall, and symptom-led recovery.

From one page to a whole workflow

Ghostlight is at its best when browser work has a thread to follow:

• Pick up where you are signed in. Open an application in the Chromium profile you chose and work with the session already there. Credentials stay with the browser.
• Finish the interaction. Navigate, fill forms, upload files, resolve dialogs, wait for page state, and carry results from one step into the next.
• Follow the browser. Keep working when a site opens a supported child tab or when a known workspace changes underneath the task.
• See what failed. Bring page state, console messages, and network requests together so the next debugging step comes from evidence instead of guesswork.

Use the same browser capability from any agent Ghostlight sets up (the installation guide lists every one), or from another compatible stdio MCP client. Agents receive structured page reads, exact element references, bounded action receipts, and specific recovery guidance. They can ask the policy tool to explain the authority in force at any moment.

The browser stays a shared space

Ghostlight works in a dedicated sky-blue tab group inside the browser window you chose. Page scans, clicks, typing, drags, and longer phases share one visual language, so the movement on screen has an explanation.

Pause the workspace, take over for a delicate step, or stop it. Move its tabs where you want them; Ghostlight follows the workspace instead of snapping it back. Ordinary tabs remain outside the agent's owned set: a tab you opened is never reused, regrouped, or navigated, even on the same site, and loading a page yourself in a tab Ghostlight left open takes that tab back.

Closing a tab needs two independent yes votes: the orchestrator's authority, which needs Action on that tab's site, and the browser's own preserve-tabs setting, which ships on. That keeps the evidence of what happened in front of you. Closing a tab yourself always works.

Personal use is complete without a policy manifest. Start with the full browser engine and get useful work done. When a workflow needs stronger boundaries, grant read, action, write, and execute by domain. Add sacred domains and structured audit, and preview a policy against your own history before you apply it, with Check in the window or ghostlight policy simulate, while the browser experience stays the same. The governance guide shows the operating model, and the Trust Center carries the security, privacy, continuity, deployment, and procurement evidence.

What it will and will not do

With no policy configured, HTTP(S) browsing is allowed, including localhost, loopback, and link-local destinations. Host restrictions belong to policy. Non-HTTP schemes and stale handles remain restricted. Optional local and managed policy layers can only take capability away.

Credential input requires your explicit instruction. Fill and typing accept a per-request acknowledgement from the agent; without it, the call returns guidance without pausing the session. That acknowledgement cannot override policy or your Pause and End session controls. Repeated policy refusals also leave later permitted work available; a tab that policy refused a landing on stays held until the agent moves it to an allowed page or closes it. Browser messages and animations remain passive, with no buttons or interference with your input; interactive runtime control belongs in the workbench.

The audit record holds identifiers, decisions, and content-minimized measurements: which tool ran, whether authority allowed it, how long it took, and what it did -- 3 fields, 1,240 words, 1280x720. The site an action landed on is named, because that answers where your agent went and is already in your own tab strip. Paths, queries, fragments, page text, field values, screenshots, selectors, and dialog text never enter it. docs/guides/siem-integration.md is the exact record shape.

The full catalog is in docs/1.0/LANGUAGE.md, and the exact policy schema is in docs/guides/governance-configuration.md.

The workbench

Open the tray icon and you land At a glance: the action running right now in full, finished actions stacking below it, newest first, each in Ghostlight's own words -- "Opened example.com.", "Read 1,240 words.", "Filled 3 fields and submitted the form." -- never the page's. Beside it sit Integrations, which connects the coding clients you already have and merges into their configuration with a backup (goose and Continue get Copy setup to paste, never an edit); Status, which answers whether the stack is healthy; Policy, which states what the current rules allow, one plain line per capability, naming the layer that decided each one; Settings, a tab with a rail for this screen, who else can watch, browser work, notifications and diagnostics, and where you can quit Ghostlight; and About, which carries the promise underneath it: it never phones home.

Pause and resume sit in the header beside the lamp on every tab, the same control the tray offers. They work with or without a connected browser, because Ghostlight itself holds the pause. When configured policy is not valid, Ghostlight refuses all browser work and the header never reads Ready. It reads Policy not valid and points to Policy, unless a more urgent state such as Not connected or Paused comes first. A broken edit to a local policy that is already in force is different: the last valid version stays in force, Status warns about the edit, and the header does not change. Closing the window leaves the icon in the tray and Ghostlight running, and the first time it says so in one notification. The service serves with no display, so if the window program cannot start, or the computer has no display, web view or tray, Ghostlight keeps working and ghostlight status says why there is no window.

Build it from source

Rust 1.89 or newer, plus Chromium 125 or newer for browser validation.

cargo build --workspace

Three executables land side by side:

• ghostlight-service -- the orchestrator and the workbench it serves on loopback. It links no UI toolkit and runs with no display;
• ghostlight -- the edge: the MCP stdio relay (ghostlight mcp), the Chromium native-messaging relay, and the front door that hands every other command to the service;
• ghostlight-desktop -- the shell: the window, the tray and the notices. On Linux building it needs the WebKitGTK 4.1, GTK 3 and AppIndicator development packages; running the service does not.

Deploy a build with pwsh scripts/dev-loop.ps1: it installs your build into ~/.ghostlight/bin as the development channel, because a build directory never serves on its own. docs/DEV-LOOP.md covers the loop, browser registration and the full validation loop.

After setup there is no startup ritual: launching a connected MCP client or Chromium demand-starts Ghostlight when it is not already running.

On Windows, WinGet is another way to install: winget install Sylin.Ghostlight, then run ghostlight install once. The self-contained Claude Desktop MCPB is a third. Every route puts the three executables in ~/.ghostlight/bin: WinGet only delivers them, and ghostlight install copies them there. After winget upgrade, the next ghostlight install carries the newer version there. An older copy never replaces a newer one. WinGet serves 2.0.0 until its 2.0.1 manifest is accepted into winget-pkgs; the one-line installer serves 2.0.1.

MCP Client <--stdio--> ghostlight mcp <--relay--> ghostlight-service
    <--relay--> ghostlight (browser) <--native messaging--> Extension <--CDP--> Browser

Choose your next step

License and continuity

Ghostlight is entirely free and open source: everything in this repository, including the governance module, is Apache-2.0 OR MIT. LICENSING.md explains what that covers. The former open-core split and its paid tiers were withdrawn by ADR-0140.

License state never reaches runtime -- there is no license check to reach it. An installed copy keeps working on its own terms, with no check-in and no expiry. The Continuity Promise carries the durable version of that.

Questions and contributions

GitHub Issues for reproducible defects, GitHub Discussions for questions and ideas, and hello@sylin.org for security, licensing, or anything that should not be public.

I build Ghostlight in partnership with AI coding agents. CONTRIBUTING.md explains the current boundaries and the gates every change passes.