diff --git a/package.json b/package.json
index b1e7d500..b62b2ad7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-monorepo",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "private": true,
   "scripts": {
     "build": "pnpm -r run build",
diff --git a/packages/data-gpu-samples/package.json b/packages/data-gpu-samples/package.json
index 05a1019e..58f9c704 100644
--- a/packages/data-gpu-samples/package.json
+++ b/packages/data-gpu-samples/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-gpu-samples",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "WebGPU samples built on @adobe/data-gpu",
   "type": "module",
   "private": true,
diff --git a/packages/data-gpu/package.json b/packages/data-gpu/package.json
index ff157484..2dcd0eaf 100644
--- a/packages/data-gpu/package.json
+++ b/packages/data-gpu/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/data-gpu",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Adobe data WebGPU plugins and types for graphics and compute",
   "type": "module",
   "private": false,
diff --git a/packages/data-lit-tictactoe/package.json b/packages/data-lit-tictactoe/package.json
index 51bb046b..56dbaf0f 100644
--- a/packages/data-lit-tictactoe/package.json
+++ b/packages/data-lit-tictactoe/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-lit-tictactoe",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Tic-Tac-Toe sample - Lit web components with @adobe/data-lit and AgenticService",
   "type": "module",
   "private": true,
diff --git a/packages/data-lit-todo/package.json b/packages/data-lit-todo/package.json
index 4ed39ecf..1ea781f0 100644
--- a/packages/data-lit-todo/package.json
+++ b/packages/data-lit-todo/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-lit-todo",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Todo sample app demonstrating @adobe/data with Lit",
   "type": "module",
   "private": true,
diff --git a/packages/data-lit/package.json b/packages/data-lit/package.json
index 4c8b9a39..e23bd1d3 100644
--- a/packages/data-lit/package.json
+++ b/packages/data-lit/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/data-lit",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Adobe data Lit bindings - hooks, elements, decorators",
   "type": "module",
   "private": false,
diff --git a/packages/data-p2p-tictactoe/package.json b/packages/data-p2p-tictactoe/package.json
index c0c890f8..a8f2d59e 100644
--- a/packages/data-p2p-tictactoe/package.json
+++ b/packages/data-p2p-tictactoe/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-p2p-tictactoe",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Serverless P2P tic-tac-toe — WebRTC DataChannel + @adobe/data-sync",
   "type": "module",
   "private": true,
diff --git a/packages/data-persistence/package.json b/packages/data-persistence/package.json
index aa859ccf..443cd8ea 100644
--- a/packages/data-persistence/package.json
+++ b/packages/data-persistence/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@adobe/data-persistence",
-    "version": "0.9.69",
+    "version": "0.9.70",
     "description": "Worker-based incremental persistence layer for @adobe/data ECS over OPFS (browser) and node:fs (server).",
     "type": "module",
     "sideEffects": false,
diff --git a/packages/data-react-hello/package.json b/packages/data-react-hello/package.json
index 8da0b0fa..2de3676c 100644
--- a/packages/data-react-hello/package.json
+++ b/packages/data-react-hello/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-react-hello",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Hello World sample - click counter using @adobe/data-react",
   "type": "module",
   "private": true,
diff --git a/packages/data-react-pixie/package.json b/packages/data-react-pixie/package.json
index cef08f53..29cbe8b7 100644
--- a/packages/data-react-pixie/package.json
+++ b/packages/data-react-pixie/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-react-pixie",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "PixiJS React sample - ECS sprites (bunny, fox) with @adobe/data-react",
   "type": "module",
   "private": true,
diff --git a/packages/data-react/package.json b/packages/data-react/package.json
index 181e4872..eabca7e3 100644
--- a/packages/data-react/package.json
+++ b/packages/data-react/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/data-react",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Adobe data React bindings — hooks and context for ECS database",
   "type": "module",
   "private": false,
diff --git a/packages/data-solid-dashboard/package.json b/packages/data-solid-dashboard/package.json
index 2d294252..378c7b1a 100644
--- a/packages/data-solid-dashboard/package.json
+++ b/packages/data-solid-dashboard/package.json
@@ -1,6 +1,6 @@
 {
   "name": "data-solid-dashboard",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Mini dashboard sample — multiple components sharing one @adobe/data ECS database with SolidJS",
   "type": "module",
   "private": true,
diff --git a/packages/data-solid/package.json b/packages/data-solid/package.json
index 5298254f..6247aa37 100644
--- a/packages/data-solid/package.json
+++ b/packages/data-solid/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/data-solid",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Adobe data SolidJS bindings — context and provider for ECS database",
   "type": "module",
   "private": false,
diff --git a/packages/data-sync/package.json b/packages/data-sync/package.json
index 743e0d50..cec0f674 100644
--- a/packages/data-sync/package.json
+++ b/packages/data-sync/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@adobe/data-sync",
-    "version": "0.9.69",
+    "version": "0.9.70",
     "description": "Multi-user real-time synchronisation for @adobe/data ECS — server, client, and in-process loopback.",
     "type": "module",
     "sideEffects": false,
diff --git a/packages/data/package.json b/packages/data/package.json
index e3b093c4..9e8f968c 100644
--- a/packages/data/package.json
+++ b/packages/data/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/data",
-  "version": "0.9.69",
+  "version": "0.9.70",
   "description": "Adobe data oriented programming library",
   "type": "module",
   "sideEffects": false,
diff --git a/packages/data/src/observe/with-batch.test.ts b/packages/data/src/observe/with-batch.test.ts
index 5e253448..408ef6e0 100644
--- a/packages/data/src/observe/with-batch.test.ts
+++ b/packages/data/src/observe/with-batch.test.ts
@@ -1,5 +1,5 @@
 // © 2026 Adobe. MIT License. See /LICENSE for details.
-import { describe, it, expect, vi } from 'vitest';
+import { describe, it, expect } from 'vitest';
 import { withBatch } from './with-batch.js';
 import { createState } from './create-state.js';
 
@@ -118,4 +118,22 @@ describe('withBatch', () => {
         unsubscribe1();
         unsubscribe2();
     });
+
+    it('should not drop a batched undefined value', async () => {
+        const [source, setSource] = createState<number | undefined>(1);
+        const batched = withBatch(source);
+
+        const values: (number | undefined)[] = [];
+        const unsubscribe = batched((value) => values.push(value));
+
+        expect(values).toEqual([1]);
+
+        setSource(undefined);
+
+        await new Promise(resolve => setTimeout(resolve, 0));
+
+        expect(values).toEqual([1, undefined]);
+
+        unsubscribe();
+    });
 }); 
\ No newline at end of file
diff --git a/packages/data/src/observe/with-batch.ts b/packages/data/src/observe/with-batch.ts
index 512fd46c..45f12498 100644
--- a/packages/data/src/observe/with-batch.ts
+++ b/packages/data/src/observe/with-batch.ts
@@ -8,7 +8,8 @@ import { Observe } from "./index.js";
  */
 export function withBatch<T>(observable: Observe<T>): Observe<T> {
     return (observer) => {
-        let pendingValue: T | undefined;
+        let pendingValue: T;
+        let hasPendingValue = false;
         let isScheduled = false;
         let hasInitialValue = false;
 
@@ -16,9 +17,10 @@ export function withBatch<T>(observable: Observe<T>): Observe<T> {
             if (!isScheduled) {
                 isScheduled = true;
                 queueMicrotask(() => {
-                    if (pendingValue !== undefined) {
-                        observer(pendingValue);
-                        pendingValue = undefined;
+                    if (hasPendingValue) {
+                        const value = pendingValue;
+                        hasPendingValue = false;
+                        observer(value);
                     }
                     isScheduled = false;
                 });
@@ -27,19 +29,18 @@ export function withBatch<T>(observable: Observe<T>): Observe<T> {
 
         const unobserve = observable((value) => {
             if (!hasInitialValue) {
-                // Emit initial value immediately
                 observer(value);
                 hasInitialValue = true;
             } else {
-                // Batch subsequent values
                 pendingValue = value;
+                hasPendingValue = true;
                 scheduleNotification();
             }
         });
 
         return () => {
             unobserve();
-            pendingValue = undefined;
+            hasPendingValue = false;
             isScheduled = false;
             hasInitialValue = false;
         };
diff --git a/packages/data/src/observe/with-deduplicate-data.test.ts b/packages/data/src/observe/with-deduplicate-data.test.ts
new file mode 100644
index 00000000..dfa4fe66
--- /dev/null
+++ b/packages/data/src/observe/with-deduplicate-data.test.ts
@@ -0,0 +1,43 @@
+// © 2026 Adobe. MIT License. See /LICENSE for details.
+import { describe, it, expect } from 'vitest';
+import { withDeduplicateData } from './with-deduplicate-data.js';
+import { Observe } from './index.js';
+
+describe('withDeduplicateData', () => {
+    it('should emit first value', () => {
+        const source: Observe<number> = (observer) => {
+            observer(1);
+            return () => {};
+        };
+        const values: number[] = [];
+        withDeduplicateData(source)((v) => values.push(v));
+        expect(values).toEqual([1]);
+    });
+
+    it('should deduplicate consecutive equal values', () => {
+        const source: Observe<number> = (observer) => {
+            observer(1);
+            observer(1);
+            observer(2);
+            observer(2);
+            return () => {};
+        };
+        const values: number[] = [];
+        withDeduplicateData(source)((v) => values.push(v));
+        expect(values).toEqual([1, 2]);
+    });
+
+    // Defensive: T extends Data excludes undefined at compile time, but runtime
+    // guards should hold even if undefined arrives via any/generics.
+    it('should deduplicate consecutive undefined values (defensive)', () => {
+        const source = ((observer: (v: null) => void) => {
+            (observer as (v: unknown) => void)(undefined);
+            (observer as (v: unknown) => void)(undefined);
+            return () => {};
+        }) satisfies Observe<null>;
+
+        const values: (null | undefined)[] = [];
+        withDeduplicateData(source)((v: any) => values.push(v));
+        expect(values).toEqual([undefined]);
+    });
+});
diff --git a/packages/data/src/observe/with-deduplicate-data.ts b/packages/data/src/observe/with-deduplicate-data.ts
index f360c0ca..2449daf3 100644
--- a/packages/data/src/observe/with-deduplicate-data.ts
+++ b/packages/data/src/observe/with-deduplicate-data.ts
@@ -11,10 +11,12 @@ export function withDeduplicateData<T extends Data>(
   observable: Observe<T>
 ): Observe<T> {
   return (observer) => {
-    let lastValue: T | undefined = undefined;
+    let notified = false;
+    let lastValue: T;
     return observable((value) => {
-      const notify = lastValue === undefined || !equals(lastValue, value);
+      const notify = !notified || !equals(lastValue, value);
       if (notify) {
+        notified = true;
         lastValue = value;
         observer(value);
       }
diff --git a/packages/data/src/observe/with-filter.ts b/packages/data/src/observe/with-filter.ts
index 23747dbf..1e237619 100644
--- a/packages/data/src/observe/with-filter.ts
+++ b/packages/data/src/observe/with-filter.ts
@@ -2,10 +2,11 @@
 import { Observe } from "./index.js";
 
 /**
- * Creates a new Observe function that converts the original observe functions notify values into a new value at each notification,
- * optionally returning undefined to filter out the value.
+ * Creates a new Observe function that converts values, using `undefined` (or `void`) as the skip signal.
+ * U must not include `undefined` — if the filter can legitimately produce `undefined` as a value,
+ * use `withMap` instead and handle absent values downstream.
  */
-export function withFilter<T, U>(
+export function withFilter<T, U extends {} | null>(
   observable: Observe<T>,
   filter: (value: T) => U | undefined | void
 ): Observe<U> {
diff --git a/packages/data/src/observe/with-filter.type-test.ts b/packages/data/src/observe/with-filter.type-test.ts
new file mode 100644
index 00000000..372c1c44
--- /dev/null
+++ b/packages/data/src/observe/with-filter.type-test.ts
@@ -0,0 +1,16 @@
+// © 2026 Adobe. MIT License. See /LICENSE for details.
+
+import { fromConstant } from "./from-constant.js";
+import { withFilter } from "./with-filter.js";
+
+// Valid uses: U is non-undefined
+function _testValidUses() {
+    withFilter(fromConstant(1), (v) => v > 0 ? v : null);
+    withFilter(fromConstant("a"), (v) => v.length > 0 ? v : undefined);
+    withFilter(fromConstant(1), (v) => v > 0 ? v : undefined);
+}
+
+// Invalid: undefined is the skip sentinel; U must not include undefined.
+// Explicit annotation with U = number | undefined must be rejected.
+// @ts-expect-error — U explicitly includes undefined, which is disallowed
+withFilter<number, number | undefined>(fromConstant(1), (v) => v > 0 ? v : undefined);