Claude’s Chrome side panel is now a full Cowork session

What happened

I’ll pull the 9to5Mac piece and any official Claude/Cowork details so the paragraphs stay factual and specific.The 9to5Mac write-up and Anthropic’s own notes should give the product mechanics without inventing numbers.Anthropic is turning the Claude in Chrome side panel into a full Cowork session, so a browser task is no longer a dead-end chat that lives only in the sidebar. Conversations started in the panel now save to Claude history and can be resumed from the Claude desktop, web, and mobile apps. Skills and connectors already configured on the account work from the browser without a second setup step. The Cowork side panel is available on Max and Team today, with a Pro rollout planned over the coming weeks. On Enterprise plans the feature is off by default; administrators can enable it and restrict it to approved domains. Claude in Chrome still does not run on other Chromium browsers or on mobile.

The change is a session-model change, not a new set of page-click tools. Claude in Chrome already could see the current page and act on it with the user’s existing logins, including clicking links, moving between pages, entering text, and filling out forms. What it could not do was treat that work as the same Cowork session used on other Claude apps, so context and conversation stayed behind when the user left Chrome. The side panel now starts a Cowork session directly, with no selector to switch between chat and Cowork. Sessions live with the account rather than a single device, which is what lets a task begun in a tab continue later on desktop, web, or phone. Anthropic’s example is asking Claude to collect invoice amounts and dates from several vendor portals, open the tabs, read each invoice, and build a spreadsheet, then picking the same session up in the desktop app to add local files or compare the result with last month’s budget. Local files and other desktop applications still require the Claude desktop app. The side panel can read the tab the user is on without that app; Claude driving the browser as part of a longer task still needs the desktop app open.

The technical detail

For engineers and builders, the useful part is the class of systems that never get a first-class connector: internal dashboards, vendor portals, and legacy admin pages that only exist as authenticated HTML. Direct Claude connectors cover a lot of SaaS, but a large share of operational work still sits behind a login Claude cannot call as an API. A Cowork session in the real browser can operate those pages with the cookies and SSO the user already has, and it can do so with the same skills, connectors, and history as the rest of the account. That changes how you design a multi-step job. You can start the scrape or form-fill where the page is, then finish the spreadsheet, file merge, or comparison on desktop without rebuilding the prompt or losing the thread. The remaining split is the one to design around, not ignore. Chrome is the authenticated front door. Desktop is still the layer for local files, local connectors, and computer use. If your workflow assumes the side panel is a full laptop agent, it is not.

Why it matters for builders

The competitive fight is over whether a browser agent is a disposable sidebar or the same durable session as the rest of the assistant. Anthropic is attaching Cowork, its existing longer-running work product, to the browser where people already have sessions and cookies. That is a different bet from an isolated in-app browser. Anthropic has already drawn the contrast with Claude Code’s in-app browser, which uses an isolated profile; the Chrome extension works on sites where the user is already signed in. Signed-in access is the product advantage and the security cost. Assistants that stay in a sandboxed browser avoid some of the prompt-injection and account-abuse surface, and they also cannot operate the internal tools a person is already logged into. Assistants that sit in the real browser inherit cookies, SSO, and those internal apps, and they inherit the injection problem Anthropic is documenting in public. The market question is no longer whether a sidebar can click a page. Every major assistant is shipping some version of that. The question is whether the click stream shares identity, skills, connectors, and later desktop work with the rest of the product, or whether it remains a second, weaker chat.

Market and competitive context

If you are on Max or Team, the test is whether a real job survives the hop between surfaces. Start a task that needs a live logged-in page, confirm the conversation appears in history, then resume it on desktop or mobile and check that skills and connectors fire without reconfiguration. Watch the Pro rollout if that is your plan. If you run Enterprise, the default-off switch and the domain allowlist are the controls to set before the extension lands on a work Chrome profile. Do not assume Chrome-only shops are covered, because other Chromium browsers and mobile are still out. Keep the desktop app in the loop for anything that needs local files, local connectors, or Claude driving the browser as part of a longer Cowork task. What to watch next is whether the side panel stays Cowork-only or later grows a lighter chat mode back, and whether Enterprise domain restrictions stay coarse, whole-site allowlists, or get precise enough for teams that want Claude on a vendor portal and not on mail or billing.

What to watch next

The risk Anthropic names is prompt injection. Hidden instructions in a page, an email, or a document can push Claude toward actions the user did not ask for. The company added a second check on Claude’s own actions. In automatically approve mode, Claude works through a task without stopping at every step, but before consequential moves such as submitting a form, sending a message, or downloading a file, that check reviews the action against the original request and blocks mismatches. Claude still asks before purchases or sharing personal data. Anthropic says these measures reduce risk and cannot eliminate it. That is the right engineering claim. An agent holding the user’s real logins is a confused-deputy problem, not a chatbot problem. Open questions are how often the consequential-action check misses a crafted page, whether account-scoped session portability now means a poisoned browser thread can be resumed on mobile or desktop with the same tools attached, and how Enterprise domain allowlists treat redirects and embedded third-party origins. Related prior art is every browser copilot that promised to use the live page, plus Anthropic’s own earlier Claude in Chrome pilot and the isolated-profile browser inside Claude Code. The durable design choice here is account-scoped Cowork identity for the sidebar, not a new click API.