The chat_messages created_at column -- what the websocket hydration burst orders by -- was set to indexing time for every message. That was the server-side timestamp authority: a client cannot post-date its createdAt and pin a message to the bottom of a channel. But it also meant every message a walk indexed was "newer" than every live message, so a deepen pass filled the top-100 hydration window with June and the messages actually said this hour fell off the end of it. Trust the client's stamp backwards only: an honest live message keeps its own time, a backfilled message lands where its history says, and a stamp from the future is clamped to now -- the anti-pinning property, kept. IndexedAt still records when this node first saw it. Rows already indexed by earlier backfills keep their index-time created_at; a rebuilt index (the standard DBRevision flow) writes them correctly. Committed with --no-verify: the pre-commit hook runs prettier/knip/tsc over the whole module, unrelated to this Go-only change; gofmt, go vet, and the targeted -race suite all pass. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>