[TheCryptoDonkey]

Late viewers can receive cached-object availability before the holder’s ephemeral presence, leaving an open connection without framing-2 knowledge. The zero-budget cached race then downloads from HTTP until another presence arrives.

Advertise optional obj: 2 in the existing encrypted SDP offer/answer and accept it only after admission, current-negotiation checks and successful remote SDP installation. Missing or invalid metadata preserves existing presence-derived behaviour. This adds no signalling messages or timers and preserves verification, upload limits and HTTP deadlines.

Validation:

• 661 JavaScript tests and 16 focused capability controls passed; syntax and documentation checks passed.
• Two real SDK factories reproduce the cold-race failure before the fix, with missing, invalid, legacy, denied and stale negotiation controls.
• M4 Chrome with native SCTP and the committed WASM delivered a verified 6 MiB object while all receiver presence was withheld; the single HTTP backstop aborted after the client read 320 KiB. Origin-win and reused-connection controls also passed. This is a synthetic protocol fixture; real 4K playback, physical devices and public NAT remain separate acceptance gates.