diff --git a/.changeset/fix-1530-date-formula-cel.md b/.changeset/fix-1530-date-formula-cel.md
new file mode 100644
index 000000000..998f56f41
--- /dev/null
+++ b/.changeset/fix-1530-date-formula-cel.md
@@ -0,0 +1,15 @@
+---
+"@objectstack/formula": patch
+---
+
+fix(formula): hydrate ISO date/datetime strings on CEL `no such overload` fault (#1530)
+
+Date-typed formula fields and date predicates always evaluated to `null`:
+`Field.date`/`Field.datetime` serialize to ISO strings, and cel-js compared the
+raw string against the `google.protobuf.Timestamp` from `today()`/`now()`/
+`daysFromNow()`, raising `no such overload` (swallowed to null). The existing
+numeric-string fault-retry (#1534) is now extended to also coerce strict ISO-8601
+date/date-time strings to `Date` before retrying once, fixing every caller
+(formula fields, flow conditions, validation/workflow predicates). Hydration runs
+only after a fault, so clean expressions are never re-interpreted and genuine
+non-temporal strings still fault loudly.
diff --git a/packages/formula/src/cel-engine.test.ts b/packages/formula/src/cel-engine.test.ts
index 2180a750b..6a3776aed 100644
--- a/packages/formula/src/cel-engine.test.ts
+++ b/packages/formula/src/cel-engine.test.ts
@@ -147,4 +147,79 @@ describe('celEngine', () => {
       expect(r.ok).toBe(false);
     });
   });
+
+  // ADR-0032 §1c — string-serialized date/datetime fields (#1530). Field.date
+  // serializes to "YYYY-MM-DD" and Field.datetime to a full ISO string; cel-js
+  // compares those raw strings against the google.protobuf.Timestamp returned by
+  // today()/now()/daysFromNow() and faults `no such overload`, which previously
+  // surfaced as a silent `null`.
+  describe('date/datetime-string field hydration (#1530)', () => {
+    const now = new Date('2026-06-02T08:00:00Z');
+
+    it('compares a date-only field against today()/daysFromNow() (is_expiring_soon)', () => {
+      const r = celEngine.evaluate(
+        cel('record.end_date >= today() && record.end_date <= daysFromNow(60)'),
+        { now, record: { end_date: '2026-06-20' } },
+      );
+      expect(r).toEqual({ ok: true, value: true });
+    });
+
+    it('returns false (not a fault) when the date compare is unmet', () => {
+      const r = celEngine.evaluate(cel('record.end_date <= daysFromNow(60)'), {
+        now,
+        record: { end_date: '2027-01-01' },
+      });
+      expect(r).toEqual({ ok: true, value: false });
+    });
+
+    it('handles is_overdue: a past date-only field < today()', () => {
+      const r = celEngine.evaluate(cel('record.due_date < today()'), {
+        now,
+        record: { due_date: '2026-05-31' },
+      });
+      expect(r).toEqual({ ok: true, value: true });
+    });
+
+    it('hydrates a full ISO datetime field against now()', () => {
+      const r = celEngine.evaluate(cel('record.resolution_due_at < now()'), {
+        now,
+        record: { resolution_due_at: '2026-06-01T08:15:35.244Z' },
+      });
+      expect(r).toEqual({ ok: true, value: true });
+    });
+
+    it('supports timestamp arithmetic on hydrated date fields (today() - hire_date)', () => {
+      // hire_date ~2.4y before `now` → tenure exceeds 2 years (17520h).
+      const r = celEngine.evaluate(
+        cel('(today() - record.hire_date) > duration("17520h")'),
+        { now, record: { hire_date: '2024-01-01' } },
+      );
+      expect(r).toEqual({ ok: true, value: true });
+    });
+
+    it('hydrates date + numeric strings together in one record', () => {
+      const r = celEngine.evaluate(
+        cel('record.amount >= 1000 && record.end_date >= today()'),
+        { now, record: { amount: '2500.00', end_date: '2026-06-20' } },
+      );
+      expect(r).toEqual({ ok: true, value: true });
+    });
+
+    it('does not coerce non-temporal strings (still faults loudly)', () => {
+      const r = celEngine.evaluate(cel('record.end_date <= today()'), {
+        now,
+        record: { end_date: 'soon' },
+      });
+      expect(r.ok).toBe(false);
+    });
+
+    it('leaves genuine date-string equality untouched (no spurious coercion)', () => {
+      // string == string type-checks, so the retry never runs and the value
+      // stays a string.
+      const r = celEngine.evaluate(cel('record.end_date == "2026-06-20"'), {
+        record: { end_date: '2026-06-20' },
+      });
+      expect(r).toEqual({ ok: true, value: true });
+    });
+  });
 });
diff --git a/packages/formula/src/cel-engine.ts b/packages/formula/src/cel-engine.ts
index 9081357fa..e52981b1d 100644
--- a/packages/formula/src/cel-engine.ts
+++ b/packages/formula/src/cel-engine.ts
@@ -71,6 +71,17 @@ function coerce(value: unknown): unknown {
 // digit runs (CodeQL ReDoS). This matches the same strings without the hazard.
 const NUMERIC_STRING_RE = /^[+-]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][+-]?\d+)?$/;
 
+/**
+ * A string that is an ISO-8601 date (`"2026-06-20"`) or date-time
+ * (`"2026-06-20T08:15:35.244Z"`, `"2026-06-20 08:15"`, `"...+02:00"`). Strict
+ * and anchored — no nested unbounded quantifiers, so no ReDoS hazard (every
+ * sub-group is bounded or a single `\.\d+`). `Field.date` / `Field.datetime`
+ * serialize to these; cel-js compares them as `string` and faults against the
+ * `google.protobuf.Timestamp` returned by `today()` / `now()` / `daysFromNow()`.
+ */
+const ISO_TEMPORAL_STRING_RE =
+  /^\d{4}-\d{2}-\d{2}(?:[T ]\d{2}:\d{2}(?::\d{2})?(?:\.\d+)?(?:Z|[+-]\d{2}:?\d{2})?)?$/;
+
 /**
  * cel-js raises `no such overload: dyn <op> int` (and kin) when a comparison
  * or arithmetic operator sees a `string` on one side and a number on the
@@ -85,27 +96,33 @@ function isNumericOverloadError(err: unknown): boolean {
 }
 
 /**
- * Recursively coerce string values that are *entirely* numeric literals into
- * numbers. Used only on the {@link isNumericOverloadError} retry path, so it
- * can never change a comparison that already evaluated cleanly — it only
- * rescues one that already faulted. Dates and non-numeric strings pass through
- * untouched (a zip like `"02134"` only changes if the surrounding expression
- * already faulted, in which case the original loud error is preserved when the
- * retry still cannot type-check).
+ * Recursively coerce string values that faulted a CEL overload into their
+ * intended primitive: entirely-numeric literals → `number` (#1534), and
+ * ISO-8601 date / date-time strings → `Date` (cel-js `google.protobuf.Timestamp`)
+ * (#1530). Used only on the {@link isNumericOverloadError} retry path, so it can
+ * never change a comparison that already evaluated cleanly — it only rescues one
+ * that already faulted. Strings that are neither (a zip like `"02134"`, free
+ * text) pass through untouched; if the retry still cannot type-check, the
+ * original loud error is preserved.
  */
-function hydrateNumericStrings(value: unknown): unknown {
+function hydrateOverloadStrings(value: unknown): unknown {
   if (typeof value === 'string') {
     const trimmed = value.trim();
-    if (trimmed.length > 0 && NUMERIC_STRING_RE.test(trimmed)) {
-      const n = Number(trimmed);
-      if (Number.isFinite(n)) return n;
+    if (trimmed.length > 0) {
+      if (NUMERIC_STRING_RE.test(trimmed)) {
+        const n = Number(trimmed);
+        if (Number.isFinite(n)) return n;
+      } else if (ISO_TEMPORAL_STRING_RE.test(trimmed)) {
+        const ms = Date.parse(trimmed);
+        if (!Number.isNaN(ms)) return new Date(ms);
+      }
     }
     return value;
   }
-  if (Array.isArray(value)) return value.map(hydrateNumericStrings);
+  if (Array.isArray(value)) return value.map(hydrateOverloadStrings);
   if (value && typeof value === 'object' && !(value instanceof Date)) {
     const out: Record<string, unknown> = {};
-    for (const [k, v] of Object.entries(value)) out[k] = hydrateNumericStrings(v);
+    for (const [k, v] of Object.entries(value)) out[k] = hydrateOverloadStrings(v);
     return out;
   }
   return value;
@@ -170,14 +187,18 @@ export const celEngine: DialectEngine = {
         const raw = env.evaluate(source, scope);
         return { ok: true, value: coerce(raw) as T };
       } catch (err) {
-        // ADR-0032 §1c — string-serialized numeric fields (`rating` → `"5.0"`,
-        // `amount` → `"250000.00"`) make `record.rating >= 4` raise CEL's
-        // `no such overload: dyn >= int`. Hydrate purely-numeric strings to
-        // numbers and retry ONCE. This only runs after a fault, so a comparison
-        // that already evaluated cleanly is never re-interpreted; if the retry
-        // still cannot type-check, the original loud error is reported (#1534).
+        // ADR-0032 §1c — string-serialized fields make CEL raise
+        // `no such overload`: numeric fields (`rating` → `"5.0"`,
+        // `amount` → `"250000.00"`) on `record.rating >= 4` (#1534), and
+        // date/datetime fields (`end_date` → `"2026-06-20"`) on
+        // `record.end_date <= daysFromNow(60)` (#1530), since cel-js compares the
+        // raw string against the `google.protobuf.Timestamp` from `today()` etc.
+        // Hydrate those strings to number / Date and retry ONCE. This only runs
+        // after a fault, so a comparison that already evaluated cleanly is never
+        // re-interpreted; if the retry still cannot type-check, the original loud
+        // error is reported.
         if (!isNumericOverloadError(err)) throw err;
-        const hydrated = hydrateNumericStrings(scope) as Record<string, unknown>;
+        const hydrated = hydrateOverloadStrings(scope) as Record<string, unknown>;
         try {
           const raw = env.evaluate(source, hydrated);
           return { ok: true, value: coerce(raw) as T };