diff --git a/.changeset/temporal-hooks-on-contract.md b/.changeset/temporal-hooks-on-contract.md
new file mode 100644
index 0000000000..4a8992c485
--- /dev/null
+++ b/.changeset/temporal-hooks-on-contract.md
@@ -0,0 +1,25 @@
+---
+"@objectstack/spec": minor
+"@objectstack/service-analytics": patch
+---
+
+feat(spec): promote the temporal storage hooks onto the IDataDriver contract (ADR-0053 D-A2)
+
+`temporalFilterValue` and `temporalFilterColumnSql` — the pair that closed
+#3912's storage-form drift — were duck-typed: analytics probed
+`typeof driver.x === 'function'` against a locally-invented interface, and
+nothing at the type level said a driver must implement both or neither. The
+lesson of #3912 is precisely that coercing the comparand without normalising
+the column reintroduces half the bug, so a driver implementing one hook alone
+would silently regress.
+
+Both are now optional members of `IDataDriver`
+(`@objectstack/spec/contracts`), documented as a pair with "absent = identity"
+semantics for drivers whose storage form is the wire form (memory, mongo).
+`SqlDriver implements IDataDriver`, so its signatures are compile-checked from
+here on; analytics derives its driver seam by `Pick`-ing the contract instead
+of a local duck type. Runtime `typeof` guards remain — that is the correct way
+to consume an optional contract member — but the shape they guard now has one
+authoritative definition.
+
+No runtime behaviour change. ADR-0053 D-A2 is recorded as resolved.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8edab5b992..d688e7592d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -196,6 +196,126 @@ jobs:
           path: .turbo/cache
           key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
 
+
+  # ── Temporal conformance against live, non-UTC servers (ADR-0053 D-A3) ─────
+  #
+  # The datetime storage work (#3912/#3942) was verified against real servers
+  # because every one of its bugs was invisible on all-UTC infrastructure: a
+  # zone-naive write resolved in the SERVER's zone on Postgres, mysql2 rendered
+  # a Date in the HOST's zone, and a bare YYYY-MM-DD comparand meant a
+  # different midnight per dialect. The committed suites are opt-in
+  # (OS_TEST_POSTGRES_URL / OS_TEST_MYSQL_URL) and skip without a server, so
+  # without this job they would never run in CI and the seam could regress
+  # silently — D-A3's exact concern.
+  #
+  # Every timezone here is deliberately DIFFERENT: servers at +08:00, the Node
+  # process at America/New_York, assertions in UTC. Both suites assert they
+  # are pointed at a non-UTC server, so a mis-provisioned service fails loudly
+  # instead of letting the job pass vacuously.
+  temporal-conformance:
+    name: Temporal Conformance (live PG + MySQL)
+    needs: filter
+    if: needs.filter.outputs.core == 'true'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    services:
+      postgres:
+        image: postgres:16
+        env:
+          POSTGRES_PASSWORD: postgres
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd="pg_isready -U postgres"
+          --health-interval=5s
+          --health-timeout=5s
+          --health-retries=12
+      mysql:
+        # Real MySQL 8.0. The hands-on verification of #3942 ran on MariaDB
+        # 10.11 — the stricter dialect for datetime literals — so this job is
+        # the other half of the compatibility claim. `-h 127.0.0.1` forces the
+        # ping over TCP: the image's init phase runs mysqld with networking
+        # disabled, so a socket ping would report healthy before init finishes.
+        image: mysql:8.0
+        env:
+          MYSQL_ROOT_PASSWORD: root
+          MYSQL_DATABASE: conformance
+        ports:
+          - 3306:3306
+        options: >-
+          --health-cmd="mysqladmin ping -h 127.0.0.1 -uroot -proot"
+          --health-interval=5s
+          --health-timeout=5s
+          --health-retries=24
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      # Service containers cannot override the image command, so the non-UTC
+      # zones are set post-start through each server's own mechanism. Echoed
+      # back so a provisioning failure is visible in the log — though the
+      # suites' own non-UTC guards are the real gate.
+      - name: Point both servers at a non-UTC timezone
+        run: |
+          docker exec ${{ job.services.postgres.id }} psql -U postgres -c "ALTER SYSTEM SET timezone='Asia/Shanghai'"
+          docker exec ${{ job.services.postgres.id }} psql -U postgres -c "SELECT pg_reload_conf()"
+          docker exec ${{ job.services.postgres.id }} psql -U postgres -tAc "SHOW timezone"
+          docker exec ${{ job.services.mysql.id }} mysql -uroot -proot -e "SET GLOBAL time_zone = '+08:00'"
+          docker exec ${{ job.services.mysql.id }} mysql -uroot -proot -N -e "SELECT @@global.time_zone"
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v7
+        with:
+          node-version: '22'
+
+      - name: Enable Corepack
+        run: corepack enable
+
+      - name: Get pnpm store directory
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v6
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-v3-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-v3-
+
+      # Restore-only (same policy as every other job); falls back to the Test
+      # Core namespace because that job builds a superset of what this one
+      # needs and its cache is seeded from main.
+      - name: Restore Turbo cache
+        uses: actions/cache/restore@v6
+        with:
+          path: .turbo/cache
+          key: ${{ runner.os }}-turbo-${{ github.job }}-${{ github.ref_name }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-turbo-${{ github.job }}-
+            ${{ runner.os }}-turbo-test-${{ github.ref_name }}-
+            ${{ runner.os }}-turbo-test-
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Build driver-sql and its dependencies
+        run: pnpm exec turbo run build --filter=@objectstack/driver-sql... --concurrency=4
+
+      # The whole driver-sql suite runs under the skewed process zone — not
+      # just the live-server files — so a TZ-sensitive assumption anywhere in
+      # the driver's tests fails here before it can ship.
+      - name: Run driver-sql suite against both live servers
+        env:
+          TZ: America/New_York
+          OS_TEST_POSTGRES_URL: postgres://postgres:postgres@127.0.0.1:5432/postgres
+          OS_TEST_MYSQL_URL: mysql://root:root@127.0.0.1:3306/conformance
+        run: pnpm --filter @objectstack/driver-sql test
+
   dogfood:
     # Sharded 2-way: the suite is ~60 independent test files, each booting its
     # own in-process app, and a single 4-vCPU runner needed ~7½ minutes for the
diff --git a/docs/adr/0053-date-and-datetime-semantics.md b/docs/adr/0053-date-and-datetime-semantics.md
index b5ab1d8358..7c0a22c5e9 100644
--- a/docs/adr/0053-date-and-datetime-semantics.md
+++ b/docs/adr/0053-date-and-datetime-semantics.md
@@ -1,6 +1,6 @@
 # ADR-0053: `date` is a timezone-naive calendar day; `datetime` is an instant rendered in a reference timezone
 
-**Status**: Accepted (2026-06-16) — Phase 1 + addendum D-A1 implemented (`sql-driver.ts` `toDateOnly` write/read/filter normalization; analytics `coerceTemporalFilterValue`), Phase 2 landing incrementally; D-A2 (`temporalFilterValue` promotion onto the `IDataDriver` contract) still open as the ADR predicted. **Partly superseded (2026-07-29, addendum D-B1..D-B4):** Phase 1's "`Field.datetime` stays stored as UTC epoch ms" is replaced by one canonical UTC instant per dialect — `YYYY-MM-DDTHH:MM:SS.sssZ` text on SQLite, `timestamptz` on Postgres, `DATETIME(3)` on MySQL — applied on write and to filter comparands alike (#3912, #3942).
+**Status**: Accepted (2026-06-16) — Phase 1 + addendum D-A1 implemented (`sql-driver.ts` `toDateOnly` write/read/filter normalization; analytics `coerceTemporalFilterValue`), Phase 2 landing incrementally; D-A2 resolved 2026-07-30: `temporalFilterValue` + `temporalFilterColumnSql` are optional `IDataDriver` contract members with identity semantics, and analytics types its driver seam from the contract. **Partly superseded (2026-07-29, addendum D-B1..D-B4):** Phase 1's "`Field.datetime` stays stored as UTC epoch ms" is replaced by one canonical UTC instant per dialect — `YYYY-MM-DDTHH:MM:SS.sssZ` text on SQLite, `timestamptz` on Postgres, `DATETIME(3)` on MySQL — applied on write and to filter comparands alike (#3912, #3942).
 **Deciders**: ObjectStack Protocol Architects
 **Builds on**: [ADR-0032](./0032-unified-expression-layer.md) (unified expression layer — CEL dialect, `today()`/`daysFromNow()`), [ADR-0014](./0014-record-form-field-type.md) (field types)
 **Consumers**: `@objectstack/spec` (`Field.date`/`Field.datetime`), `@objectstack/driver-sql` (`coerceFilterValue`, `formatInput`/`formatOutput`, `dateFields`/`datetimeFields`), `@objectstack/formula` (`stdlib` time functions, `cel-engine` hydration), `@objectstack/objectql` (`applyFormulaPlan`), schedule/cron executors, report/analytics date bucketing, `sys-user-preference.timezone`.
@@ -387,6 +387,19 @@ that is not on the driver contract. Promote it to a first-class
 retire it)** once the contract method is universal. (If an in-flight
 `IDataDriver`-interface change is open, align this with it; do not block on it.)
 
+> **Resolved (2026-07-30).** Both hooks — `temporalFilterValue` and the D-B
+> column-side companion `temporalFilterColumnSql` — are optional members of
+> `IDataDriver` (`spec/contracts/data-driver.ts`), documented as a PAIR:
+> implementing one without the other reintroduces half of #3912, so the
+> contract says implement both or neither, with "absent = identity" semantics
+> for drivers whose storage form is the wire form. `SqlDriver implements
+> IDataDriver`, so its signatures are compile-checked; analytics derives its
+> driver seam by `Pick`-ing the contract instead of a local duck type, keeping
+> the runtime `typeof` guards as the (correct) way to consume an optional
+> member. `coerceFilterValueForSql` already sits behind the hook as the
+> last-resort boolean/number recovery for non-temporal columns — the demotion
+> this decision asked for — and is retained for exactly that role.
+
 **D-A3 — Add a temporal conformance matrix as the runtime regression backstop.**
 Cover `field-type {date, datetime} × operator {eq, gte/lte/gt/lt, in, dateRange} ×
 relative-token {today, N_days_ago, N_months_ago, …} × driver {SQLite, Postgres at
@@ -400,8 +413,9 @@ time, the matrix proves runtime correctness across drivers.
 - The `datetime`-on-raw-SQL filter bug is closed at the driver boundary, mirroring
   Phase 1's "align the consumer with the driver's existing contract rather than
   inventing a semantic" stance. No change to Phase 2's reference-timezone plan.
-- Until D-A2 lands, the hook depends on a duck-typed driver method — a known,
-  intentionally-temporary seam tracked here.
+- ~~Until D-A2 lands, the hook depends on a duck-typed driver method — a known,
+  intentionally-temporary seam tracked here.~~ Landed 2026-07-30; see the
+  resolution note under D-A2.
 
 ---
 
@@ -503,7 +517,8 @@ is clean.
   companion threaded to analytics as
   `StrategyContext.coerceTemporalFilterColumn`. Coercing the value alone is not
   sufficient on a mixed-form column, so any surface that binds a comparand into
-  raw SQL must wrap its column reference too. Both remain duck-typed until D-A2.
+  raw SQL must wrap its column reference too. Both promoted onto the contract
+  2026-07-30 — see the resolution note under D-A2.
 - D-A3's conformance matrix should gain a **storage-form** axis (canonical,
   legacy-epoch, legacy-naive) and a **server-timezone** axis, since both are now
   known to have produced dialect-divergent row results.
diff --git a/packages/services/service-analytics/src/plugin.ts b/packages/services/service-analytics/src/plugin.ts
index 5adbb5a582..b44adf61cc 100644
--- a/packages/services/service-analytics/src/plugin.ts
+++ b/packages/services/service-analytics/src/plugin.ts
@@ -3,7 +3,7 @@
 import type { Plugin, PluginContext } from '@objectstack/core';
 import type { Cube, FilterCondition } from '@objectstack/spec/data';
 import type { ExecutionContext } from '@objectstack/spec/kernel';
-import type { IAnalyticsService } from '@objectstack/spec/contracts';
+import type { IAnalyticsService, IDataDriver } from '@objectstack/spec/contracts';
 import { AnalyticsService } from './analytics-service.js';
 import type { AnalyticsServiceConfig } from './analytics-service.js';
 import type { DriverCapabilities } from './strategies/types.js';
@@ -45,31 +45,27 @@ interface DataEngineLike {
   } | undefined;
   /**
    * Resolve the storage driver backing an object (public ObjectQL accessor).
-   * Used to delegate temporal filter-value coercion to the driver, which is the
+   * Used to delegate temporal storage-form coercion to the driver, which is the
    * single source of truth for how a `Field.date`/`Field.datetime` is stored on
-   * the active dialect. The driver may expose `temporalFilterValue(object, field,
-   * value)` (SqlDriver does); when absent we leave the value untouched.
+   * the active dialect. When the hooks are absent, values and column SQL pass
+   * through untouched — the contract's identity semantics.
    */
-  getDriverForObject?(objectName: string): DriverLike | undefined;
+  getDriverForObject?(objectName: string): TemporalDriverSurface | undefined;
 }
 
-/** Minimal driver surface the analytics layer probes for temporal coercion. */
-interface DriverLike {
-  /**
-   * Coerce a filter comparand to the column's on-disk storage form
-   * (SQLite `Field.datetime` → epoch ms; `Field.date` → YYYY-MM-DD; native
-   * timestamp / non-temporal → unchanged). Optional — only SqlDriver implements it.
-   */
-  temporalFilterValue?(objectName: string, field: string, value: unknown): unknown;
-  /**
-   * Normalise the column reference to that same storage form. Required alongside
-   * `temporalFilterValue` on any dialect whose column is mixed-form — a SQLite
-   * `Field.datetime` holds an INTEGER epoch and ISO TEXT at once, so coercing
-   * only the value fixes one half and leaves the other empty (#3912). Optional —
-   * only SqlDriver implements it.
-   */
-  temporalFilterColumnSql?(objectName: string, field: string, columnSql: string): string;
-}
+/**
+ * The slice of the `IDataDriver` CONTRACT the analytics layer consumes —
+ * `temporalFilterValue` / `temporalFilterColumnSql` are first-class contract
+ * members since ADR-0053 D-A2, no longer a duck-typed local invention. Picked
+ * (rather than using `IDataDriver` whole) because `getDriverForObject` hands
+ * back whatever the engine registered, and this seam only needs the temporal
+ * surface; the runtime `typeof` guards below remain the correct way to consume
+ * an optional contract member.
+ */
+type TemporalDriverSurface = Pick<
+  IDataDriver,
+  'temporalFilterValue' | 'temporalFilterColumnSql'
+>;
 
 /**
  * Configuration for AnalyticsServicePlugin.
diff --git a/packages/spec/src/contracts/data-driver.ts b/packages/spec/src/contracts/data-driver.ts
index 73380a443b..9db000c45f 100644
--- a/packages/spec/src/contracts/data-driver.ts
+++ b/packages/spec/src/contracts/data-driver.ts
@@ -127,6 +127,47 @@ export interface IDataDriver {
   /** Delete multiple records matching a query (optional) */
   deleteMany?(object: string, query: QueryAST, options?: DriverOptions): Promise<number>;
 
+  // ===========================================================================
+  // Temporal Storage Convention (ADR-0053 D-A1/D-A2, #3912)
+  // ===========================================================================
+  //
+  // A driver is the single source of truth for how a `Field.date` /
+  // `Field.datetime` value is physically stored on its dialect. Any surface
+  // that builds queries OUTSIDE the driver's own find()/filter path — the
+  // analytics native-SQL strategy today, any future raw-query strategy — must
+  // route its temporal comparands AND its column references through these two
+  // hooks rather than re-deriving the storage form from the value's textual
+  // shape (the drift that produced #3912).
+  //
+  // The two hooks are a pair on purpose: #3912's lesson is that coercing the
+  // comparand alone is NOT sufficient on a dialect whose stored form can
+  // diverge from the bound form — the column side of the comparison has to be
+  // normalised by the same authority. A driver that implements one without
+  // the other reintroduces half the bug, so implement both or neither.
+  //
+  // Both are optional with identity semantics: a driver whose storage form IS
+  // the wire form (memory, mongo) simply omits them, and callers treat
+  // "absent" exactly like "returns the input unchanged".
+
+  /**
+   * Coerce a filter comparand to the on-disk storage form of `field` on
+   * `objectName` — e.g. an ISO instant for a canonical-text datetime column,
+   * `YYYY-MM-DD` text for a `Field.date`, a dialect-spelled datetime literal
+   * where the dialect cannot parse ISO-8601. Non-temporal fields and
+   * uninterpretable values are returned unchanged.
+   */
+  temporalFilterValue?(objectName: string, field: string, value: unknown): unknown;
+
+  /**
+   * The companion for the LEFT side of the same comparison: given the SQL the
+   * caller was going to emit for the column (an already-quoted, possibly
+   * qualified reference), return the SQL it must emit instead so the column
+   * reads in the same storage form {@link temporalFilterValue} coerces the
+   * comparand into. Returns `columnSql` verbatim for every column that needs
+   * no normalisation — which is every column on a fully-converged database.
+   */
+  temporalFilterColumnSql?(objectName: string, field: string, columnSql: string): string;
+
   // ===========================================================================
   // Transaction Management
   // ===========================================================================