root cause (proven, not inferred): contentDetails.boundStreamId on
liveBroadcasts.insert does NOT bind the broadcast. Our diagnostic reads
lifeCycle=created privacy=private autoStart=true bound=NONE
boundMatches=NO-BINDING | streamStatus=active
created is Google's "incomplete settings" state, so enableAutoStart has no
bound stream to fire from; close-out then 403s invalidTransition because
created -> complete is not a legal edge. A reusable stream accepts bytes for
a broadcast that isn't watching it, so a perfectly healthy 99MB RTMP session
is exactly what an unbound broadcast looks like -- every observable pointed
away from the binding.
Google's migration guide states the rule outright: a liveBroadcast must be
bound to exactly one stream before it can start, and is not bound at creation.
That was in the docs read during the original design and was not applied.
Shipped:
- BindBroadcastAsync -> POST liveBroadcasts/bind?part=id&id&streamId (no body),
called from PrepareAndStartLiveAsync right after CreateBroadcast, before the pump.
Failure is fatal to the session: an unbound broadcast can never go live, so a
live-looking UI over one is a lie.
- boundStreamId removed from the insert body, and the streamId parameter removed
from CreateBroadcast. A parameter that looks meaningful but cannot affect the
outcome is what made the misdiagnosis possible.
- Replaced CreateBroadcast_With_StreamId_Binds_Reusable_Stream_At_Insert, which
asserted the disproven behaviour and therefore laundered a guess into a
guarantee, with tests for the omitted field and the real bind endpoint.
Error messages (creator ruling 2026-10-04): bind failures are not all "check the
sign-in". Six documented reasons exist and only one is auth; BindFailureMessage
gives each its own text, and the fallback passes the raw reason through verbatim
so an unmapped reason stays greppable. liveBroadcastBindingNotAllowed matters
most -- it means our ordering is wrong, and a generic re-auth message would hide
a bug in our own code behind a plausible excuse. See MyMistakes.md.
ai.md: also corrects the TASK 44 claim that liveChatId is only populated once the
broadcast is live. The diagnostic shows it present while lifecycle is created.
That claim was inferred from a sample's active-status guard, which is not a spec.
Suite 395/395, 0 warnings.
gramps
07a088a23f