docs: say handed over, not landed, for the row-baseline ordering token

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/lib/itemStore.svelte.ts

@@ -88,7 +88,8 @@ export type ItemRowPort = {
 	/** Send what `write` queued for `key` now; resolves once it landed. */
 	flush(key: ItemKey): Promise<void>
 	overwrite(key: ItemKey, value: unknown | null): Promise<void>
-	/** Rows landed for `key` so far, by any writer. Handed back to `seedSync` to order it. */
+	/** Rows handed to the syncer for `key` so far, by any writer, counted before the debounce
+	 *  rather than on the response. Handed back to `seedSync` to order it. */
 	rowMark(key: ItemKey): number
 	seedSync(key: ItemKey, draftSavedAt: string | undefined, since: number): void
 	conflicted(key: ItemKey): boolean

frontend/src/lib/userDraftDbSyncer.svelte.ts

@@ -538,12 +538,10 @@ export const UserDraftDbSyncer = {
 	},
 
 	/**
-	 * Seed the per-tab `last_sync` after an editor reads a draft from the
-	 * server. Pass the response's `draft_saved_at` so the next save sends a
-	 * matching `last_sync`; pass `undefined` when no draft existed (next
-	 * save omits `last_sync`, the backend's first-push branch). Pass the
-	 * `sendsSoFar` taken before the read as `since`: a row handed over after
-	 * that puts the syncer ahead of this response, which is then ignored.
+	 * Seed the per-tab `last_sync` from a read: its `draft_saved_at`, or
+	 * `undefined` when no draft existed (the backend's first-push branch).
+	 * `since` is the `sendsSoFar` taken before that read; a row handed over
+	 * after it leaves this response behind, so it is ignored.
 	 */
 	recordRemoteSync(
 		query: UserDraftLastSyncQuery,