@@ -0,0 +1,38 @@
+---
+'@object-ui/data-objectstack': patch
+---
+
+data-objectstack: type `queryDataset(selection)` as the spec's `DatasetSelection` instead of a hand-written copy
+
+The adapter restated the selection contract inline, field by field, and the copy
+had drifted three ways from the pinned `@objectstack/spec@17.0.0-rc.5`:
+
+- **`compareTo.dimension` was required.** It has been optional since
+  objectstack#5011, *because the executor resolves it*: exactly one time
+  dimension carrying a `dateRange` is the one shifted, and zero or several
+  raises a loud error naming the candidates. Requiring it made the compiler
+  demand from every typed caller precisely the consumer-side dimension guess
+  that change forbids — trading a loud executor error for a silently wrong
+  comparison window. No runtime path hit this yet (the dashboard's
+  `DatasetWidget` passes `selection` as `unknown`), but a declaration is a live
+  instruction to anyone calling this client from TypeScript.
+- **`timeDimensions` was widened to `unknown[]`**, erasing the very entry shape
+  the executor's resolution reads (`{ dimension, granularity?, dateRange? }`),
+  and **`runtimeFilter` to `Record<string, unknown>`**, erasing the
+  `$and`/`$or`/`$not` vocabulary the server parses.
+- **`dateGranularity` was missing entirely** — the copy had simply stopped at
+  whatever the contract looked like the day it was written, so a typed caller
+  could not bucket a trend by month at all.
+
+The parameter is now the spec type by reference, so there is nothing left to
+re-sync. The fix is the removal of the dialect rather than a correction to it:
+restating a contract owned elsewhere creates a second de-facto dialect of it, and
+drift is then only a matter of time (AGENTS.md #0/#0.1). `queryDataset.test.ts`
+pins structural identity with `DatasetSelection` plus each of the three drifts
+individually, checked by this package's `tsc --noEmit`; a runtime test pins that
+a dimension-less `compareTo` reaches the server untouched, so the adapter can
+never start guessing on the executor's behalf.
+
+The response type is deliberately left alone — it is the REST envelope
+(`object` / `dimensionFields` / `drillRawRows`), not a restatement of
+`AnalyticsResult`.
@@ -8,6 +8,7 @@
 
 import { ObjectStackClient, type QueryOptions as ObjectStackQueryOptions } from '@objectstack/client';
 import type { DroppedFieldsEvent } from '@objectstack/spec/data';
+import type { DatasetSelection } from '@objectstack/spec/contracts';
 import type {
   DataSource,
   BatchTransactionOperation,
@@ -3190,25 +3191,21 @@ export class ObjectStackAdapter<T = unknown> implements DataSource<T> {
    * silently returning wrong numbers.
    *
    * @param dataset - An inline dataset definition (draft) OR a saved dataset name.
-   * @param selection - Dimension/measure names to project + runtime directives.
+   * @param selection - The spec's {@link DatasetSelection} — dimension/measure
+   *   names to project plus runtime directives. This parameter IS the spec type
+   *   by reference, never a local restatement of it (objectui#3613): a hand
+   *   copy of a contract is a second dialect of it, and the copy this replaced
+   *   had already drifted three ways from `@objectstack/spec` — it required
+   *   `compareTo.dimension` (optional since objectstack#5011, and resolved by
+   *   the EXECUTOR, so requiring it pushed callers into exactly the
+   *   consumer-side dimension guess AGENTS.md #0.1 forbids), it widened
+   *   `timeDimensions` to `unknown[]` and `runtimeFilter` to
+   *   `Record<string, unknown>`, and it had never grown `dateGranularity` at
+   *   all. Pinned in `queryDataset.test.ts`.
    */
   async queryDataset(
     dataset: Record<string, unknown> | string,
-    selection: {
-      dimensions?: string[];
-      measures: string[];
-      runtimeFilter?: Record<string, unknown>;
-      timeDimensions?: unknown[];
-      compareTo?: { kind: 'previousPeriod' | 'previousYear'; dimension: string };
-      order?: Record<string, 'asc' | 'desc'>;
-      limit?: number;
-      offset?: number;
-      timezone?: string;
-      /** Marginal-aggregate groupings (e.g. `[rows, [colDim], []]`) — server
-       *  computes each subtotal with the measure's TRUE aggregate (never client
-       *  re-derived). `[]` is the grand total. */
-      totals?: { groupings: string[][] };
-    },
+    selection: DatasetSelection,
   ): Promise<{
     rows: Array<Record<string, unknown>>;
     /** Column metadata: a display `label` (dimensions and measures), and a
 
@@ -7,6 +7,11 @@
  */
 
 import { describe, it, expect, beforeEach, vi } from 'vitest';
+import type {
+  AnalyticsQuery as SpecAnalyticsQuery,
+  DatasetCompareTo as SpecDatasetCompareTo,
+  DatasetSelection as SpecDatasetSelection,
+} from '@objectstack/spec/contracts';
 import {
   ObjectStackAdapter,
   clearSharedDiscoveryCache,
@@ -130,3 +135,122 @@ describe('ObjectStackAdapter.queryDataset', () => {
     });
   });
 });
+
+/* -------------------------------------------------------------------------- */
+/* objectui#3613 — the `selection` parameter IS the spec type, not a copy.      */
+/*                                                                             */
+/* Compile-time pins. A violation is a `tsc --noEmit` error, not a runtime      */
+/* failure: this package's tsconfig.json includes its whole `src/**` (tests     */
+/* included), so these are checked by `pnpm --filter @object-ui/data-objectstack*/
+/* type-check` with no separate tsconfig.typetests.json — the same property     */
+/* spec-symbol-batch6.test.ts documents and relies on.                          */
+/* -------------------------------------------------------------------------- */
+
+type Assert<T extends true> = T;
+type IsAny<T> = 0 extends 1 & T ? true : false;
+type Equal<A, B> = (<T>() => T extends A ? 1 : 2) extends <T>() => T extends B ? 1 : 2
+  ? true
+  : false;
+type HasKey<T, K extends PropertyKey> = K extends keyof T ? true : false;
+
+/** The declared type of `queryDataset`'s second parameter, read off the method. */
+type SelectionParam = Parameters<ObjectStackAdapter['queryDataset']>[1];
+
+describe('queryDataset(selection) is @objectstack/spec DatasetSelection itself', () => {
+  it('is pinned at compile time', () => {
+    type _SpecNotAny = Assert<Equal<IsAny<SpecDatasetSelection>, false>>;
+
+    // THE pin. `Equal` rather than a two-way `extends` on purpose: a
+    // restatement that merely *overlaps* the contract satisfies mutual
+    // assignability in the drifted direction too (a required `dimension` is
+    // still assignable TO an optional one). Structural identity is the only
+    // assertion a hand copy cannot pass while drifting.
+    type _IsTheSpecType = Assert<Equal<SelectionParam, SpecDatasetSelection>>;
+
+    expect(true).toBe(true);
+  });
+
+  // The three drifts the deleted copy had accumulated, named individually so a
+  // future reader learns what a restatement costs — not just that one existed.
+  it('pins compareTo as the spec DatasetCompareTo, with dimension OPTIONAL', () => {
+    type CompareTo = NonNullable<SelectionParam['compareTo']>;
+    type _IsSpecCompareTo = Assert<Equal<CompareTo, SpecDatasetCompareTo>>;
+
+    // objectstack#5011 made `dimension` optional BECAUSE the executor resolves
+    // it (exactly one dated time dimension → that one; zero or several → a loud
+    // error listing the candidates). The copy declared it required, so the
+    // compiler demanded from every typed caller precisely the consumer-side
+    // dimension guess that change forbids — turning a loud executor error into
+    // a silently wrong comparison window.
+    type _DimensionOptional = Assert<Equal<CompareTo['dimension'], string | undefined>>;
+    type _DimensionWasNotRequired = Assert<Equal<Equal<CompareTo['dimension'], string>, false>>;
+    // …and the shape with no `dimension` at all is a legal authoring surface.
+    type _KindOnlyIsValid = Assert<
+      { kind: 'previousPeriod' } extends CompareTo ? true : false
+    >;
+
+    expect(true).toBe(true);
+  });
+
+  it('pins timeDimensions at the spec shape, not `unknown[]`', () => {
+    type _IsSpecTimeDimensions = Assert<
+      Equal<SelectionParam['timeDimensions'], SpecAnalyticsQuery['timeDimensions']>
+    >;
+    type _NotUnknownArray = Assert<
+      Equal<Equal<SelectionParam['timeDimensions'], unknown[] | undefined>, false>
+    >;
+    // The entry shape the executor's compareTo resolution reads (`dateRange`
+    // present ⇒ shiftable) — invisible through `unknown[]`.
+    type Entry = NonNullable<SelectionParam['timeDimensions']>[number];
+    type _EntryHasDimension = Assert<Equal<Entry['dimension'], string>>;
+    type _EntryHasDateRange = Assert<HasKey<Entry, 'dateRange'>>;
+
+    expect(true).toBe(true);
+  });
+
+  it('pins runtimeFilter as a FilterCondition and carries dateGranularity', () => {
+    // The copy widened `runtimeFilter` to `Record<string, unknown>`, which
+    // erases the `$and`/`$or`/`$not` vocabulary the server parses.
+    type _RuntimeFilterNarrowed = Assert<
+      Equal<Equal<SelectionParam['runtimeFilter'], Record<string, unknown> | undefined>, false>
+    >;
+    type _RuntimeFilterKnowsLogicalOps = Assert<
+      HasKey<NonNullable<SelectionParam['runtimeFilter']>, '$and'>
+    >;
+
+    // `dateGranularity` (framework#3588) is the drift nobody had noticed: the
+    // copy never grew the key, so a typed caller could not bucket a trend by
+    // month at all. A restatement does not only drift on the fields it has — it
+    // also stops at whatever the contract looked like the day it was written.
+    type _HasDateGranularity = Assert<HasKey<SelectionParam, 'dateGranularity'>>;
+    type _DateGranularityEnum = Assert<
+      Equal<
+        SelectionParam['dateGranularity'],
+        'day' | 'week' | 'month' | 'quarter' | 'year' | undefined
+      >
+    >;
+
+    expect(true).toBe(true);
+  });
+
+  // The runtime half of the same fact: the adapter must forward `compareTo`
+  // VERBATIM. If it ever "helpfully" filled a `dimension` in to satisfy its own
+  // old declaration, the executor would stop resolving and every caller's
+  // comparison window would depend on the adapter's guess.
+  it('forwards a dimension-less compareTo to the server untouched', async () => {
+    const { fetchImpl, calls } = makeFetch({ ok: true, body: { rows: [], fields: [] } });
+    const adapter = new ObjectStackAdapter({ baseUrl: 'http://localhost:3000', autoReconnect: false, fetch: fetchImpl as any });
+
+    await adapter.queryDataset('sales', {
+      dimensions: ['region'],
+      measures: ['revenue'],
+      timeDimensions: [{ dimension: 'closedAt', granularity: 'month', dateRange: ['2026-01-01', '2026-03-31'] }],
+      compareTo: { kind: 'previousPeriod' },
+    });
+
+    const post = calls.find((c) => c.url.includes('/analytics/dataset/query'))!;
+    const sent = JSON.parse(post.init.body);
+    expect(sent.selection.compareTo).toEqual({ kind: 'previousPeriod' });
+    expect(sent.selection.compareTo).not.toHaveProperty('dimension');
+  });
+});