pub const NO_ALERT_KEY: &str = "no_alert";Expand description
Metadata key marking a frame the SDK sent on its own: control traffic, key packages, data-sync frames, receipts, typing, presence, and a 1:1 Welcome no user message is waiting on.
Set to "1" in the cleartext envelope so the relay can tell these from
the user’s own messages (both are opaque __MLS_ENC__ ciphertext to it)
and skip the “new message” push for an offline recipient. Frames built
for the application’s user-content sends never carry it. Unsigned like
all metadata; receivers ignore it.