• A transient WebAssembly fetch failure no longer leaves Firefox permanently broken.
• The fork ledger repairs itself when a forked tab is closed, instead of holding a dead entry. A fork name that owns no live fork is now an error (FORK_NOT_FOUND, newly declared) rather than a silent fall-back to the wrong tab, and both killFork parameter spellings answer it.
• TAB_LOAD_TIMEOUT is correctly non-retriable on Firefox, as it already was elsewhere.
• An oversize result can no longer kill the bridge; the response producer is capped.
• Chromium: an injection argument MV3 would silently mangle is now refused outright, and an absent scroll id crosses the MV3 boundary intact instead of being dropped.
• Firefox screenshots are bounded, and the refusal is consistent across forks.

Wire protocol 4 → 6. Supersedes 0.6.0. Protocol 6 is required on both sides. Clients pinned to protocol 5 must be updated together with the extension — the bridge, the browser packages, the official clients and the Safari path all move at once.