Codec only — the app does not pin yet — but without this branch an
inbound pin falls through parse to the attachment path and comes back
renderable, so every pin the iPhone app sets would draw an empty bubble
in the conversation.
isRenderable excludes it for the same reason it excludes a reaction, and
it is NOT in Kind.CONTROL: a build that swallowed it as generic control
would drop every pin while looking like it worked.
🔴 The envelope carries an id and never a copy of the message. A pin
carrying the text would keep a message readable after its own timer had
removed it, so pinning would quietly defeat disappearing messages.
Refs paulhitt/flamenet-messenger-ios#50
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
