[prellr]

Problem

Drafts body text duplicates and compounds on every open (slice 3a Yjs co-editing). Observed up to 4× repetition.

Root cause

packages/views/drafts/annotations/annotation-draft-editor.tsx seeded the Y.Doc from draft.body markdown as soon as the draft query resolved. But useDraftYjs connects a DraftYjsProvider that replays the persisted Yjs update log asynchronously on connect. For a draft that ALREADY has persisted Yjs state:

1. The seed effect runs first (provider hasn't replayed → fragment empty → seed proceeds → it writes the body as FRESH Yjs items under the local client id).
2. The provider replays the persisted log on top → the body now exists twice (seeded items don't dedupe against replayed ones — different client id/clock).
3. DraftYjsProvider.startSync sends Y.encodeStateAsUpdate(doc) to the server, which persists the duplication. Every subsequent open re-seeds → compounding.

The provider's isSynced flips the instant the handshake is sent, not when server state is received, so it can't gate the seed. The deterministic fix is to seed only when the draft has no persisted Yjs state.

The fix

Backend — expose whether a draft has persisted Yjs state:

• New DraftHasYjsState query (EXISTS on draft_yjs_update, short-circuits cheaper than COUNT).
• has_yjs_state (bool) added to the draft GET response, populated from the loader-resolved draft.ID. A query failure is non-fatal (defaults false).

Frontend — seed only a brand-new draft:

• has_yjs_state threaded through DraftSchema (optional, default false for API-compat — older servers omit it), the Draft type, EMPTY_DRAFT, and the optimistic-create literal.
• The seed effect now skips seedYDocFromMarkdown entirely when has_yjs_state === true (the provider's replay is authoritative) while still priming lastSavedBodyRef to suppress a redundant initial PUT. Seeds only when there's no persisted state. The internal fragment.length > 0 guard stays as defense-in-depth.

API compatibility

has_yjs_state is optional with a false default via parseWithFallback + DraftSchema, so an older backend that omits it is treated as "brand-new draft" (seed runs) — no white-screen. A schema test pins this.

Tests

• Backend (draft_yjs_test.go): a draft with ≥1 draft_yjs_update row → has_yjs_state=true; a fresh draft → false.
• Core schema (schemas.test.ts): missing field defaults to false; true preserved.
• Views (collab-editor-wiring.test.tsx): the seed RUNS when has_yjs_state=false, SKIPS when true (body present exactly once, no duplication); plus a defense-in-depth check on the internal guard.

Verification

• go build ./... && go vet ./... clean; go test ./internal/handler/... green (Draft tests pass); make sqlc regenerated cleanly.
• pnpm typecheck green across all 6 packages/apps; core + views vitest green; lint shows only pre-existing warnings.

Note

Already-duplicated drafts have corrupted persisted Yjs state and need a separate data reset — handled out of band by the coordinator.

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