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This page has a stable machine-readable Markdown route for AI assistants and developer agents. The human-visible page remains the same source of truth.
Security model
Deny-by-default allow-list
The extension will only control pages on hosts that were explicitly allow-listed. This prevents accidental automation on the wrong site.
- Allow-list entries are host-based (example:
example.com). - On local dev setups you may use host:port (example:
localhost:3000).
DOMAIN_NOT_ALLOWED, your first fix is usually: add the host to the allow-list.
In 8.4.0, page-side add requests remain visible: the page asks through allowlistAddRequest,
then the user confirms on the matching master tab before the host is really added.
External add-on Trust Policy — introduced in v8.4.0, current in v8.5.0
RTO v8.4.0 added a Trust Policy for official external add-ons. It remains current in RTO v8.5.0. Other extensions cannot use RTO as an open automation port: RTO Original checks the sender extension ID and still applies RTO Lock, allow-list and capability checks before any sensitive action.
- Unknown external extensions are refused by default.
- Trusted add-ons receive only the capabilities RTO original grants.
- Direct allow-list mutation is not exposed to add-ons; visible requests must use
allowlistAddRequest. - Normal RTO usage works without Bridge or any add-on.
Controlled tabs
RTO runs actions only inside a tab it controls. You typically create one with openTab (using a tabKey you choose).
NO_CONTROLLED_TAB or TAB_NOT_FOUND.- Controlled tabs now show the visible banner
WARNING : This tab is controlled by RTO. - Banner state is tracked by the background per controlled tab, not via
window.name. - Master ownership is tracked per controlled tab, which keeps multi-tab workflows separated.
Rule of thumb: most real flows require allow-list + controlled tab + stable selectors.
Origin handshake (page identity)
RTO uses window.postMessage. To avoid a fixed magic page name (and reduce accidental collisions), the helper sets a page-side identifier:
- Docs pages usually set
window.RTO_PAGE_ORIGIN(example:"rto-docs"). - The extension replies only to the page origin it saw during the initial handshake/detect (the helpers manage this).
RTO_form_api.js so you do not have to manage raw messaging details by hand.Safe DOM actions (no arbitrary code execution)
DOM automation is done through named actions (click, setValue, getText, …). This is safer than evaluating arbitrary JavaScript on the target page.
- No generic “eval” channel.
- Actions validate inputs (tabKey, selector, payload fields) and return structured errors.
Browser security limits
- The helper scripts run in your page; the extension runs in a different context.
- Normal web security still applies (same-origin policy, permission prompts, browser internal pages).
- Some pages cannot be controlled at all (example: browser settings pages).
- Incognito requires explicit permission (otherwise content scripts do not run there).
Next
- Allow-list
- Messaging protocol (if you want to understand raw messages)