Lumo Userscripts

Scripts you can ask for.

A native MV3 userscript manager with a standard MCP endpoint. Lumo can create, edit and enable scripts through it — with your approval.

Get from GitHub Read the agent docs

MCP endpointchrome.userScriptsGM APILocal-first

Scripts

New scriptCheck updates

Search scripts, namespaces, @match…AllEnabledUpdatesImportTrash

GitHub focus modeUpdate available

v1.4.2 · northwind · @match

3m ago

Reader cleanup

v0.9.0 · northwind · @match

3m ago

Bilibili quietPending review

v2.1.0 · personal · @match

3m ago

Docs keyboard nav

v1.0.3 · personal · @match

3m ago

Pricing table captureCreated by agent

v0.1.0 · lumo · @match

3m ago

MCP provider

lumo:mcp

Agent integration

An extension agents can operate.

Lumo connects over MCP, asks once for approval, then creates, edits and enables scripts inside the same conversation that read the page.

Read-only until you allow writes
Review mode keeps new scripts disabled
Every write is audited

Read the connection guide

Scripts

New scriptCheck updates

Search scripts, namespaces, @match…AllEnabledUpdatesImportTrash

GitHub focus modeUpdate available

v1.4.2 · northwind · @match

3m ago

Reader cleanup

v0.9.0 · northwind · @match

3m ago

Bilibili quietPending review

v2.1.0 · personal · @match

3m ago

Docs keyboard nav

v1.0.3 · personal · @match

3m ago

Pricing table captureCreated by agent

v0.1.0 · lumo · @match

3m ago

Allow agent access?

Lumo wants to connect to the userscript endpoint. Approving adds its extension ID to the allowlist.

Lumo

1.0.19

cgfnadidpooocnkalljpdmelmaponefa

Read tools are granted immediately. Writes stay off until you enable them, and every write is audited.

LaterApprove

Agent protocol

Read, write, review.

A probe decides whether the provider is usable; three independent switches decide what the agent may do.

Lumo

MCP client

Lumo Userscripts

MCP provider

L0 probe: installed, enabled, authorized?

sendMessage(extId, { channel: 'lumo:probe' })

Stateless service + status

{ service, status: { enabled, authorized, ready } }

—

You approve the caller once

settings → agent → allowedExtensionIds

L1 session: MCP over a runtime port

connect(extId, { name: 'lumo:mcp' })

The agent calls the tool surface

tools/list · tools/call

Authorized by sender.id

Policy re-checked per call

Writes audited

Endpoint

Off by default.

Writes

A second switch.

Review

New scripts stay disabled.

The tool surfacenamespace: userscripts

list

The library, or the scripts that run on a URL.

read

get

Metadata and paged source code.

read

diagnostics

Runtime availability, registrations and errors.

read

set_enabled

Enable or disable a script.

write

create

Validate metadata and save a new script.

write

edit

Atomic anchored edits.

write

update

Replace the source or metadata overrides.

write

install

Install from a URL with its dependencies.

write

delete

Move a script to the recycle bin.

write

Read tools need authorization. Writes need a separate switch and are audited.

Install

Install once. Run everywhere.

Paste a URL, drop a file or use the clipboard. The install page shows the script's reach first.

URL, file and clipboard install
@require and @resource resolution
Permission-aware updates

Read documentation

Editor

A real editor, not a textarea.

CodeMirror 6, metadata validation, overrides, values and resources — the same script the agent can edit.

CodeMirror 6
Metadata validation and overrides
Values and resources in place

Read documentation

Runtime

Native registration, two engines.

Scripts run through chrome.userScripts. A MAIN-world runner serves page scripts; an isolated host runs sandboxed ones.

EnginesMAIN + USER_SCRIPT

Matching@match · @include

Dependencies@require · @resource

StorageIndexedDB

GM_setValue

Per-script storage

GM_xmlhttpRequest

Cross-origin requests

GM_cookie

Cookie access

GM_download

Managed downloads

GM_notification

System notifications

GM_registerMenuCommand

Script commands

GM_addStyle

Scoped styles

GM_addElement

DOM injection

GM_setClipboard

Clipboard write

GM_getTab

Tab state

unsafeWindow

Page-world access

GM.* aliases

Promised API

Values survive updates

1// Read once, write on change.
2const theme = GM_getValue('theme', 'system');
3GM_registerMenuCommand('Toggle theme', () => {
4  GM_setValue('theme', theme === 'dark' ? 'light' : 'dark');
5});

Control

Nothing runs without your say.

Permissions are visible before install. Updates wait for approval. Logs and the recycle bin are one click away.

Permission	Why
userScripts	Dynamic script registration
storage, unlimitedStorage	Settings and bounded metadata
tabs, activeTab, webNavigation, scripting	Tab context and diagnostics
declarativeNetRequest	Redirect .user.js navigations to install
cookies, downloads	GM_cookie, GM_download
notifications, contextMenus, alarms, clipboardWrite	GM APIs and background jobs

Recycle bin

Deleted scripts stay recoverable.

Backups

Export and restore JSON or ZIP.

Update checks

New permissions need a decision.

Logs

Registration and runtime diagnostics.

Install

Chrome 138+ and one switch.

Chrome requires you to allow user scripts for the extension once.

Open the releases

Download the archive or unpacked build.

Open GitHub Releases

Load unpacked

Enable Developer mode, then Load unpacked.

Read the docs

Allow user scripts

Enable Allow User Scripts on the extension card.

Read the docs

Chrome 138+. Node 22+ only when building from source.Privacy

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