The daemon dispatched inbound `session.window_closed` and
`session.user_interrupt` events using only the payload — the sending
browser's identity was never checked against the session's owner.
Any connected extension could therefore emit window_closed with
another browser's session_id to tear down its session (forgetting it,
dropping its tool queue + interrupt marker), or emit user_interrupt
to cancel every inflight tool of another browser's session and arm
its interrupt marker. This is a cross-tenant integrity/DoS hole that
is exploitable even between two legitimate extensions, independent of
the (separately tracked) WS Origin allow-list gap.
Thread the sender's BrowserId (already in scope as `client.id` in
handle_inbound_text) into both handlers and ignore the event when the
named session is live and owned by a different browser. A session
that is already gone is left to the existing no-op forget path.
Adds four ownership tests (owner honoured / non-owner ignored for each
event); updated two existing tests for the new signature. Full bsk
suite green (165 lib + integration), no new clippy warnings.
Co-Authored-By: Claude <noreply@anthropic.com>
