plat 624

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PLAT-624: Code side chats cannot share an extension browser controlled by another project chat

Field	Value
State	fixed on main
Priority	P2
Product	browser
Area	browser
Summary	Code side chats share a project extension binding, but its persistent controller permits only the first chat.

What happened

The owner asked whether the multiple Code chat tabs added in PLAT-571 cause browser issues. Reviewed against main 2dd249b9c, including the five-chat UI change 956d4d177. This issue is confirmed by code inspection, not a live Code UI run.

• Each side chat resolves its own conversation/session in the same project directory (resolveProductProjectBindingWithStore). Browser isolation is project-scoped, so each chat finds the same account/project extension binding.
• handleExtensionBrowser passes its trusted workflow root or chat session ID to AcquireForActive. Separate Code chats have separate controller IDs.
• AcquireForActive permanently assigns b.owner on the first page command. Releasing its tool gate does not release that assignment. Another chat is rejected with CHROME_EXTENSION_BUSY, including after the first chat's tool call has completed. The existing relay test explicitly checks that rejection.
• The connection status can still show connected because it reports the live project socket rather than whether the current chat may control it.

This is a compatibility gap with the new multi-chat feature, not evidence of a cross-account grant or commands interleaving. The rejection protects cached element references and the one native CDP controller.

Fix

• Code uses a server-registered private client for each trusted root chat within the authorized account/project binding. Each client gets a separate native CLI session, CDP capability, selected targets, element-reference cache and recording lease. The project tool gate still serializes complete actions.
• Extension 0.4.6 routes requests/replies and flattened page events by client ID, discards late disconnected-client replies, and verifies target/session ownership. Manually shared tabs are claimed on first attach. Other chats create their own tabs. The account code and project tab group remain shared.
• Client IDs are stable server-derived routing labels; private capabilities and native sessions are fresh on reconnect. Ownership/created flags survive network, worker and server reconnect in trusted session storage, never browser restart.
• Closing an idle Code side chat calls the authenticated Stop endpoint before dismissing its UI; a working chat still must be stopped before closing.
• Stop/clear releases only the chat capability and native runtime, discards its unfinished recording, closes its agent-created tabs and unshares manual pages. It leaves the other chats, account pairing and project socket live.
• status distinguishes this chat's shared_tabs from project_shared_tabs. Existing Crew/workflow root handoff, account authorization, background default, screenshot guards and headless-limit exemptions remain enforced.
• Older extensions refuse Code page actions with an explicit 0.4.6 reload message.

Verification

• Real Chrome 154.0.4258.53 with the unpacked 0.4.6 extension, guarded workspace shell and native agent-browser 0.38.2: PASS (43 s). Two Code chats kept their own tabs, selection and saved references; foreign physical targets were refused. A delegate retained its parent chat's client. Both chats recorded independent, nonempty decodable WebMs concurrently; releasing B left A and the project live. B reconnected first after server restart without receiving A's page. Closing a restored chat before it re-registers its native client also released only its own agent-created tabs.
• Existing real-path checks passed: workflow step and paused cross-site iframe handoff, Code/Crew/account separation, screenshots, interrupted-take rejection, headless-limit exemption, background focus/explicit activation, delayed reply rejection, failed-init recovery, browser restart and account reset.
• go test -race ./pkg/browserrelay: PASS. Live sockets route identical request IDs only to the originating private client and revoke one without stopping the other; an older extension refuses Code page actions explicitly.
• go test ./pkg/browser ./pkg/browserrelay: PASS.
• Five server regressions covering project isolation, workflow runtime/HTTP account binding and session ownership: PASS.
• Frontend tsc -b and WorkSurface/chat-selection tests (12): PASS.
• JavaScript syntax, embedded ZIP byte equality and ticket index/check: PASS.

Rollout

Use Browser Bridge 0.4.6 with the updated server. The download ZIP is included. Local source checkouts are fast-forwarded after push; running servers need their normal restart/rebuild. RTS deployment is separate and has not been performed.

Shared-file writes between Code chats are independent of browser tab isolation and remain tracked in PLAT-571.