fix(orm): read a wide index union from its probes instead of scanning

.agents/skills/kitcn/references/features/orm.md

@@ -695,7 +695,7 @@ const page = await ctx.orm.query.users.withIndex("by_status").findMany({
 });
 ```
 
-Falls back to a bounded scan (needs `maxScan`) when the probed index cannot supply the requested `orderBy`, or when the union is wider than 64 ranges.
+Falls back to a bounded scan (needs `maxScan`) when the probed index cannot supply the requested `orderBy`, or when a union wider than 64 ranges is asked for an `orderBy` that sorts across values, such as `createdAt`. Up to 64 ranges are read as one merged stream; a wider union is read one range after another, which keeps it index-bounded at any list length but can only produce the index's own order.
 
 Without an `orderBy`, an index-union page is in the order of the index it walks — grouped by the probed value — not in creation order.
 

.changeset/wide-index-union-stays-indexed.md

@@ -0,0 +1,34 @@
+---
+"kitcn": minor
+---
+
+## Breaking changes
+
+- Support index-ordered pagination for indexed filters with more than 64 values. Pages follow index order, grouped by the filtered value, rather than creation order. Add `orderBy` and `maxScan` to preserve newest-first paging.
+
+```ts
+// Before
+const page = await db.query.users.withIndex("by_status").findMany({
+  where: { status: { in: manyStatuses } },
+  cursor: null,
+  limit: 20,
+  maxScan: 500,
+});
+
+// After
+const page = await db.query.users.withIndex("by_status").findMany({
+  where: { status: { in: manyStatuses } },
+  orderBy: { createdAt: "desc" },
+  cursor: null,
+  limit: 20,
+  maxScan: 500,
+});
+```
+
+## Patches
+
+- Fix unnecessary full-table reads for `select()` filters containing more than 64 values.
+- Fix unnecessary full-table reads for long `in` lists combined with another condition, such as `name: { contains: 'x' }`.
+- Improve limited reads with additional conditions so they stop after enough matching rows are found when index order satisfies the requested sort.
+- Support index-bounded reads for indexed `in`, `notIn`, `ne`, and same-field equality `OR` filters regardless of list length.
+- Support pagination without `maxScan` for wide filters whose requested order follows their indexed values; cross-value sorting, such as `orderBy: { createdAt: 'desc' }`, still requires `maxScan` past 64 values.