pi streams AssistantMessages with NO id (verified against a captured
live stream and pi-ai's AssistantMessage type): the id exists only once
the server's persistTurn stamps the record. applyWireEvent minted a
FRESH c_ id per event, so message_start appended, every message_update
found no match and APPENDED another full copy, and message_end appended
again - the tail grew one message per chunk. projectView's step
separators + thinking blocks then filled the transcript with dividers
and thinking indicators mid-stream (with fresh React keys remounting
the whole subtree per chunk), cleaned up only by the settle sync's
setMessages(record).
The fix: the in-flight assistant message is tracked by SLOT -
message_start mints and remembers one client id; message_update and
message_end REPLACE that same tail entry (pi guarantees exactly one
streaming message at a time via its strict start-updates-end ordering;
the reattach replay replays the same sequence). An explicit
message.id on the wire still wins; the slot clears at message_end,
stop(), and setMessages().
Tests: all streaming fixtures rewritten to pi's real shape (no
message.id) - the old ones encoded the wrong assumption - plus a
regression pin asserting N id-less updates leave exactly ONE assistant
message in the tail with a stable slot id.
Verified live mid-stream (DOM sampled every 500ms during a teaching
turn): 0 separators throughout, thinking blocks 1-2 (one per step, not
per chunk), text growing smoothly.
amosblomqvist
8e097752da