Chrome extension: security and privacy

The Chimera Browser extension lets Chimera Desktop read and act on tabs that Chimera opens in its own Chimera tab group. It works only when paired with the local desktop app. The owner chooses site access explicitly. Page content—including accessibility trees, page text, and screenshots—travels from the extension to the local app and then to the AI model provider configured by the owner (for example, OpenRouter). This is the store's “Website content” data category. The extension does not inspect the owner's other tabs.

Permissions

• debugger — Chrome permits this permission to read and change any tab. The extension's code restricts its own operations to the Chimera tab group and to origins the owner granted (checkCurrentOrigin); that restriction is enforced by the extension, not by Chrome's permission system. Chrome displays its debugger warning whenever debugging is active.
• nativeMessaging — communicates with the local Chimera native host and paired desktop app; it does not open a network listener.
• tabs — creates, navigates, and closes tabs belonging to the Chimera group.
• tabGroups — creates and maintains the group named “Chimera”.
• storage — remembers the group and active tab across service-worker restarts.
• Optional http://*/* and https://*/* host access — Chrome requests access only after the owner allows a site. Access is optional and granted site by site; the extension does not declare <all_urls>.

The extension itself makes no network requests, has no analytics, and does not read or export cookies, passwords, browsing history, or autofill data. Sensitive fields and CAPTCHA challenges are refused. Irreversible actions such as payments, purchases, sending, deletion, publishing, and non-search form submissions require owner confirmation, including on trusted sites. Downloads and uploads are refused. Content the owner asks Chimera to read is provided to the configured model provider through the app.

Google search. Off by default (CHIMERA_BROWSER_GOOGLE=off). When the owner turns it to ask, each search is a card the owner approves; the extension then opens Google's results page in a visible tab of the Chimera group and reads the titles, links and snippets of the results, which go to the app and on to the model provider like any other page. It runs at a person's pace (at most one search every 20 seconds, five per conversation turn, 30 a day), sends no extra parameters, and at a CAPTCHA or "unusual traffic" page it stops, does not retry for 30 minutes, and hands the tab back to the owner.

Privacy policy

The extension communicates with the local app through Chrome Native Messaging and makes no network requests of its own. It has no analytics and does not read or export cookies, passwords, or browsing history. When the owner asks the app to inspect a page, the page content returned by the extension is sent onward by the app to the owner's configured AI model provider; it is not accurate to describe that content as staying on the computer.

Install, pair, and unpair

1. Install the extension from the Chrome Web Store, or for a local build open chrome://extensions, enable Developer mode, select Load unpacked, and choose the extensions/chrome directory.
2. Copy the extension ID shown by Chrome. From the repository root, run python scripts/register_chrome_host.py <extension-id> to review the registration plan. Apply registration only when the native host executable is installed and the owner is ready to pair. The Web Store extension ID differs from a locally loaded extension ID; run python scripts/register_chrome_host.py <store-extension-id> --apply again to register the store ID. The registration records which program the host will accept as the app on the other end of the local pipe: by default the Python interpreter that runs Chimera from source (a virtual environment's python.exe resolved to the interpreter it launches). For the installed desktop build, pass its backend executable with --server-executable <path>. Pass it too when Python comes from the Microsoft Store, whose interpreter runs from a path the default cannot resolve. A wrong value fails closed: the host refuses to talk to the app and pairing never starts.
3. In Chimera Desktop, open Settings → Browser and choose Pair. The app displays a six-digit code valid for two minutes. In the Chrome extension popup, enter that code and choose Pair. The code can be tried at most five times and is consumed on success. The app stores the resulting key in the operating-system vault when one is available; otherwise the status warns that it is in the local CHIMERA_HOME/browser/pairing.key file.
4. The extension popup names the site requesting permission in its Allow button and provides Stop. To stop navigation, use Stop; this drops the current connection but leaves pairing in place. To unpair, use the desktop's Unpair action; this removes the key and requires a new code to pair again.
5. The vault and one-time code make direct access harder, not impossible. A malicious program running as your Windows user can read the pairing key and control the paired Chrome. The Windows Credential Manager is readable by any process of the same user, and the native-host registration (HKCU) and its wrapper are files that user can rewrite. The key is kept out of the environment of the commands Chimera runs and is masked in their output, which closes the easiest path, the agent's own shell; it does not close the others. This design does not claim to isolate the extension from that user.
6. Remove the native-host registration and unpacked extension separately if they are no longer needed.

The extension's manifest version must track the Chimera package version. For this release it is 0.72.0; update manifest.json and extensions/chrome/README.md together when the package version changes. The package-generation scripts do not upload or publish anything. Store submission and publication are owner-only actions.