diff --git a/packages/framework/presence/api-report/presence.alpha.api.md b/packages/framework/presence/api-report/presence.alpha.api.md
index 2ed0ce115573..d4936c351d82 100644
--- a/packages/framework/presence/api-report/presence.alpha.api.md
+++ b/packages/framework/presence/api-report/presence.alpha.api.md
@@ -86,7 +86,7 @@ export namespace InternalTypes {
     // @system (undocumented)
     export interface NotificationType {
         // (undocumented)
-        args: (JsonSerializable<unknown> & JsonDeserialized<unknown>)[];
+        args: unknown[];
         // (undocumented)
         name: string;
     }
@@ -109,15 +109,15 @@ export namespace InternalTypes {
     }
     // @system (undocumented)
     export type ValueDirectoryOrState<T> = ValueRequiredState<T> | ValueDirectory<T>;
-    // @system (undocumented)
+    // @system
     export interface ValueOptionalState<TValue> extends ValueStateMetadata {
         // (undocumented)
-        value?: JsonDeserialized<TValue>;
+        value?: OpaqueJsonDeserialized<TValue>;
     }
-    // @system (undocumented)
+    // @system
     export interface ValueRequiredState<TValue> extends ValueStateMetadata {
         // (undocumented)
-        value: JsonDeserialized<TValue>;
+        value: OpaqueJsonDeserialized<TValue>;
     }
     // @system (undocumented)
     export interface ValueStateMetadata {
@@ -131,23 +131,23 @@ export namespace InternalTypes {
 // @alpha @system
 export namespace InternalUtilityTypes {
     // @system
-    export type IsNotificationListener<Event> = Event extends (...args: infer P) => void ? InternalUtilityTypes_2.IfSameType<P, JsonSerializable<P> & JsonDeserialized<P>, true, false> : false;
+    export type IfNotificationListener<Event, IfListener, Else> = Event extends (...args: infer P) => void ? InternalUtilityTypes_2.IfSameType<P, JsonSerializable<P>, IfListener, Else> : Else;
     // @system
-    export type JsonDeserializedParameters<T extends (...args: any) => any> = T extends (...args: infer P) => any ? JsonDeserialized<P> : never;
+    export type JsonDeserializedParameters<T extends (...args: any[]) => any> = T extends (...args: infer P) => any ? JsonDeserialized<P> : never;
     // @system
-    export type JsonSerializableParameters<T extends (...args: any) => any> = T extends (...args: infer P) => any ? JsonSerializable<P> : never;
+    export type JsonSerializableParameters<T extends (...args: any[]) => any> = T extends (...args: infer P) => any ? JsonSerializable<P> : never;
     // @system
     export type NotificationListeners<E> = {
-        [P in string & keyof E as IsNotificationListener<E[P]> extends true ? P : never]: E[P];
+        [P in keyof E as IfNotificationListener<E[P], P, never>]: E[P];
     };
 }
 
 // @beta
 export function latest<T extends object | null, Key extends string = string>(args: LatestArguments<T>): InternalTypes.ManagerFactory<Key, InternalTypes.ValueRequiredState<T>, LatestRaw<T>>;
 
-// @beta
+// @beta @input
 export interface LatestArguments<T extends object | null> {
-    local: JsonSerializable<T> & JsonDeserialized<T> & (object | null);
+    local: JsonSerializable<T>;
     settings?: BroadcastControlSettings | undefined;
 }
 
@@ -165,10 +165,10 @@ export interface LatestData<T> {
 // @beta
 export function latestMap<T, Keys extends string | number = string | number, RegistrationKey extends string = string>(args?: LatestMapArguments<T, Keys>): InternalTypes.ManagerFactory<RegistrationKey, InternalTypes.MapValueState<T, Keys>, LatestMapRaw<T, Keys>>;
 
-// @beta
+// @beta @input
 export interface LatestMapArguments<T, Keys extends string | number = string | number> {
     local?: {
-        [K in Keys]: JsonSerializable<T> & JsonDeserialized<T>;
+        [K in Keys]: JsonSerializable<T>;
     };
     settings?: BroadcastControlSettings | undefined;
 }
@@ -210,7 +210,7 @@ export interface LatestMapRawEvents<T, K extends string | number> {
     }) => void;
     // @eventProperty
     localItemUpdated: (updatedItem: {
-        value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+        value: DeepReadonly<JsonSerializable<T>>;
         key: K;
     }) => void;
     // @eventProperty
@@ -235,7 +235,7 @@ export interface LatestRaw<T> {
     getRemotes(): IterableIterator<LatestClientData<T>>;
     getStateAttendees(): Attendee[];
     get local(): DeepReadonly<JsonDeserialized<T>>;
-    set local(value: JsonSerializable<T> & JsonDeserialized<T>);
+    set local(value: JsonSerializable<T>);
     readonly presence: Presence;
 }
 
@@ -243,7 +243,7 @@ export interface LatestRaw<T> {
 export interface LatestRawEvents<T> {
     // @eventProperty
     localUpdated: (update: {
-        value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+        value: DeepReadonly<JsonSerializable<T>>;
     }) => void;
     // @eventProperty
     remoteUpdated: (update: LatestClientData<T>) => void;
@@ -251,8 +251,8 @@ export interface LatestRawEvents<T> {
 
 // @alpha @sealed
 export interface NotificationEmitter<E extends InternalUtilityTypes.NotificationListeners<E>> {
-    broadcast<K extends string & keyof InternalUtilityTypes.NotificationListeners<E>>(notificationName: K, ...args: Parameters<E[K]>): void;
-    unicast<K extends string & keyof InternalUtilityTypes.NotificationListeners<E>>(notificationName: K, targetAttendee: Attendee, ...args: Parameters<E[K]>): void;
+    broadcast<K extends keyof InternalUtilityTypes.NotificationListeners<E>>(notificationName: K, ...args: Parameters<E[K]>): void;
+    unicast<K extends keyof InternalUtilityTypes.NotificationListeners<E>>(notificationName: K, targetAttendee: Attendee, ...args: Parameters<E[K]>): void;
 }
 
 // @alpha @sealed
@@ -339,7 +339,7 @@ export interface StateMap<K extends string | number, V> {
     get(key: K): DeepReadonly<JsonDeserialized<V>> | undefined;
     has(key: K): boolean;
     keys(): IterableIterator<K>;
-    set(key: K, value: JsonSerializable<V> & JsonDeserialized<V>): this;
+    set(key: K, value: JsonSerializable<V>): this;
     readonly size: number;
 }
 
diff --git a/packages/framework/presence/api-report/presence.beta.api.md b/packages/framework/presence/api-report/presence.beta.api.md
index 240e944302dd..65c89257634d 100644
--- a/packages/framework/presence/api-report/presence.beta.api.md
+++ b/packages/framework/presence/api-report/presence.beta.api.md
@@ -73,7 +73,7 @@ export namespace InternalTypes {
     // @system (undocumented)
     export interface NotificationType {
         // (undocumented)
-        args: (JsonSerializable<unknown> & JsonDeserialized<unknown>)[];
+        args: unknown[];
         // (undocumented)
         name: string;
     }
@@ -96,15 +96,15 @@ export namespace InternalTypes {
     }
     // @system (undocumented)
     export type ValueDirectoryOrState<T> = ValueRequiredState<T> | ValueDirectory<T>;
-    // @system (undocumented)
+    // @system
     export interface ValueOptionalState<TValue> extends ValueStateMetadata {
         // (undocumented)
-        value?: JsonDeserialized<TValue>;
+        value?: OpaqueJsonDeserialized<TValue>;
     }
-    // @system (undocumented)
+    // @system
     export interface ValueRequiredState<TValue> extends ValueStateMetadata {
         // (undocumented)
-        value: JsonDeserialized<TValue>;
+        value: OpaqueJsonDeserialized<TValue>;
     }
     // @system (undocumented)
     export interface ValueStateMetadata {
@@ -118,9 +118,9 @@ export namespace InternalTypes {
 // @beta
 export function latest<T extends object | null, Key extends string = string>(args: LatestArguments<T>): InternalTypes.ManagerFactory<Key, InternalTypes.ValueRequiredState<T>, LatestRaw<T>>;
 
-// @beta
+// @beta @input
 export interface LatestArguments<T extends object | null> {
-    local: JsonSerializable<T> & JsonDeserialized<T> & (object | null);
+    local: JsonSerializable<T>;
     settings?: BroadcastControlSettings | undefined;
 }
 
@@ -138,10 +138,10 @@ export interface LatestData<T> {
 // @beta
 export function latestMap<T, Keys extends string | number = string | number, RegistrationKey extends string = string>(args?: LatestMapArguments<T, Keys>): InternalTypes.ManagerFactory<RegistrationKey, InternalTypes.MapValueState<T, Keys>, LatestMapRaw<T, Keys>>;
 
-// @beta
+// @beta @input
 export interface LatestMapArguments<T, Keys extends string | number = string | number> {
     local?: {
-        [K in Keys]: JsonSerializable<T> & JsonDeserialized<T>;
+        [K in Keys]: JsonSerializable<T>;
     };
     settings?: BroadcastControlSettings | undefined;
 }
@@ -183,7 +183,7 @@ export interface LatestMapRawEvents<T, K extends string | number> {
     }) => void;
     // @eventProperty
     localItemUpdated: (updatedItem: {
-        value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+        value: DeepReadonly<JsonSerializable<T>>;
         key: K;
     }) => void;
     // @eventProperty
@@ -208,7 +208,7 @@ export interface LatestRaw<T> {
     getRemotes(): IterableIterator<LatestClientData<T>>;
     getStateAttendees(): Attendee[];
     get local(): DeepReadonly<JsonDeserialized<T>>;
-    set local(value: JsonSerializable<T> & JsonDeserialized<T>);
+    set local(value: JsonSerializable<T>);
     readonly presence: Presence;
 }
 
@@ -216,7 +216,7 @@ export interface LatestRaw<T> {
 export interface LatestRawEvents<T> {
     // @eventProperty
     localUpdated: (update: {
-        value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+        value: DeepReadonly<JsonSerializable<T>>;
     }) => void;
     // @eventProperty
     remoteUpdated: (update: LatestClientData<T>) => void;
@@ -257,7 +257,7 @@ export interface StateMap<K extends string | number, V> {
     get(key: K): DeepReadonly<JsonDeserialized<V>> | undefined;
     has(key: K): boolean;
     keys(): IterableIterator<K>;
-    set(key: K, value: JsonSerializable<V> & JsonDeserialized<V>): this;
+    set(key: K, value: JsonSerializable<V>): this;
     readonly size: number;
 }
 
diff --git a/packages/framework/presence/src/exposedInternalTypes.ts b/packages/framework/presence/src/exposedInternalTypes.ts
index 46e457098129..ff746b10cbe9 100644
--- a/packages/framework/presence/src/exposedInternalTypes.ts
+++ b/packages/framework/presence/src/exposedInternalTypes.ts
@@ -3,10 +3,7 @@
  * Licensed under the MIT License.
  */
 
-import type {
-	JsonDeserialized,
-	JsonSerializable,
-} from "@fluidframework/core-interfaces/internal/exposedUtilityTypes";
+import type { OpaqueJsonDeserialized } from "@fluidframework/core-interfaces/internal/exposedUtilityTypes";
 
 /**
  * Collection of value types that are not intended to be used/imported
@@ -26,17 +23,35 @@ export namespace InternalTypes {
 	}
 
 	/**
+	 * Represents a state that may have a value.
+	 * And it includes standard metadata.
+	 *
+	 * @remarks
+	 * See {@link InternalTypes.ValueRequiredState}.
+	 *
 	 * @system
 	 */
 	export interface ValueOptionalState<TValue> extends ValueStateMetadata {
-		value?: JsonDeserialized<TValue>;
+		value?: OpaqueJsonDeserialized<TValue>;
 	}
 
 	/**
+	 * Represents a state that must have a value.
+	 * And it includes standard metadata.
+	 *
+	 * @remarks
+	 * The value is wrapped in `OpaqueJsonDeserialized` as uses are expected
+	 * to involve generic or unknown types that will be filtered. It is here
+	 * mostly as a convenience to the many such uses that would otherwise
+	 * need to specify some wrapper themselves.
+	 *
+	 * For known cases, construct a custom interface that extends
+	 * {@link InternalTypes.ValueStateMetadata}.
+	 *
 	 * @system
 	 */
 	export interface ValueRequiredState<TValue> extends ValueStateMetadata {
-		value: JsonDeserialized<TValue>;
+		value: OpaqueJsonDeserialized<TValue>;
 	}
 
 	/**
@@ -121,6 +136,6 @@ export namespace InternalTypes {
 	 */
 	export interface NotificationType {
 		name: string;
-		args: (JsonSerializable<unknown> & JsonDeserialized<unknown>)[];
+		args: unknown[];
 	}
 }
diff --git a/packages/framework/presence/src/exposedUtilityTypes.ts b/packages/framework/presence/src/exposedUtilityTypes.ts
index a6df51d9f084..dec9994efa2f 100644
--- a/packages/framework/presence/src/exposedUtilityTypes.ts
+++ b/packages/framework/presence/src/exposedUtilityTypes.ts
@@ -19,18 +19,16 @@ import type {
 // eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace InternalUtilityTypes {
 	/**
-	 * `true` iff the given type is an acceptable shape for a notification.
+	 * Yields `IfListener` when the given type is an acceptable shape for a notification.
+	 * `Else` otherwise.
 	 *
 	 * @system
 	 */
-	export type IsNotificationListener<Event> = Event extends (...args: infer P) => void
-		? CoreInternalUtilityTypes.IfSameType<
-				P,
-				JsonSerializable<P> & JsonDeserialized<P>,
-				true,
-				false
-			>
-		: false;
+	export type IfNotificationListener<Event, IfListener, Else> = Event extends (
+		...args: infer P
+	) => void
+		? CoreInternalUtilityTypes.IfSameType<P, JsonSerializable<P>, IfListener, Else>
+		: Else;
 
 	/**
 	 * Used to specify the kinds of notifications emitted by a {@link NotificationListenable}.
@@ -52,7 +50,7 @@ export namespace InternalUtilityTypes {
 	 * @system
 	 */
 	export type NotificationListeners<E> = {
-		[P in string & keyof E as IsNotificationListener<E[P]> extends true ? P : never]: E[P];
+		[P in keyof E as IfNotificationListener<E[P], P, never>]: E[P];
 	};
 
 	/**
@@ -60,7 +58,7 @@ export namespace InternalUtilityTypes {
 	 *
 	 * @system
 	 */
-	export type JsonDeserializedParameters<T extends (...args: any) => any> = T extends (
+	export type JsonDeserializedParameters<T extends (...args: any[]) => any> = T extends (
 		...args: infer P
 	) => any
 		? JsonDeserialized<P>
@@ -71,7 +69,7 @@ export namespace InternalUtilityTypes {
 	 *
 	 * @system
 	 */
-	export type JsonSerializableParameters<T extends (...args: any) => any> = T extends (
+	export type JsonSerializableParameters<T extends (...args: any[]) => any> = T extends (
 		...args: infer P
 	) => any
 		? JsonSerializable<P>
diff --git a/packages/framework/presence/src/internalUtils.ts b/packages/framework/presence/src/internalUtils.ts
index eb741cbe8e46..3f2730f67298 100644
--- a/packages/framework/presence/src/internalUtils.ts
+++ b/packages/framework/presence/src/internalUtils.ts
@@ -3,7 +3,13 @@
  * Licensed under the MIT License.
  */
 
-import type { DeepReadonly } from "@fluidframework/core-interfaces/internal";
+import type {
+	DeepReadonly,
+	JsonDeserialized,
+	JsonSerializable,
+	OpaqueJsonDeserialized,
+	OpaqueJsonSerializable,
+} from "@fluidframework/core-interfaces/internal";
 
 /**
  * Returns union of types of values in a record.
@@ -75,8 +81,55 @@ export function getOrCreateRecord<const K extends string | number | symbol, cons
 }
 
 /**
- * Do nothing helper to apply deep immutability to a value's type.
+ * No-runtime-effect helper to apply deep immutability to a value's type.
  */
 export function asDeeplyReadonly<T>(value: T): DeepReadonly<T> {
 	return value as DeepReadonly<T>;
 }
+
+export function asDeeplyReadonlyDeserializedJson<T>(
+	value: OpaqueJsonDeserialized<T>,
+): DeepReadonly<JsonDeserialized<T>>;
+export function asDeeplyReadonlyDeserializedJson<T>(
+	value: OpaqueJsonDeserialized<T> | undefined,
+): DeepReadonly<JsonDeserialized<T>> | undefined;
+/**
+ * No-runtime-effect helper to apply deep immutability to a value's opaque JSON
+ * type, revealing the JSON type.
+ */
+export function asDeeplyReadonlyDeserializedJson<T>(
+	value: OpaqueJsonDeserialized<T> | undefined,
+): DeepReadonly<JsonDeserialized<T>> | undefined {
+	return value as DeepReadonly<JsonDeserialized<T>> | undefined;
+}
+
+type RevealOpaqueJsonDeserialized<T> = T extends OpaqueJsonDeserialized<infer U>
+	? JsonDeserialized<U>
+	: { [Key in keyof T]: RevealOpaqueJsonDeserialized<T[Key]> };
+
+/**
+ * No-runtime-effect helper to reveal the JSON type from a value's opaque JSON
+ * types throughout a structure.
+ *
+ * @remarks
+ * {@link OpaqueJsonDeserialized} instances will be replaced shallowly such
+ * that nested instances are retained.
+ */
+export function revealOpaqueJson<T>(value: T): RevealOpaqueJsonDeserialized<T> {
+	return value as RevealOpaqueJsonDeserialized<T>;
+}
+
+/**
+ * No-runtime-effect helper to automatically cast JSON type to Opaque JSON type
+ * at outermost scope.
+ *
+ * @remarks
+ * Types that satisfy {@link JsonSerializable} may also be deserialized. Thus,
+ * the return type is both {@link OpaqueJsonSerializable} and
+ * {@link OpaqueJsonDeserialized}.
+ */
+export function toOpaqueJson<const T>(
+	value: JsonSerializable<T>,
+): OpaqueJsonSerializable<T> & OpaqueJsonDeserialized<T> {
+	return value as OpaqueJsonSerializable<T> & OpaqueJsonDeserialized<T>;
+}
diff --git a/packages/framework/presence/src/latestMapValueManager.ts b/packages/framework/presence/src/latestMapValueManager.ts
index 44e1adff0f22..51c8ab613426 100644
--- a/packages/framework/presence/src/latestMapValueManager.ts
+++ b/packages/framework/presence/src/latestMapValueManager.ts
@@ -16,7 +16,13 @@ import type { BroadcastControls, BroadcastControlSettings } from "./broadcastCon
 import { OptionalBroadcastControl } from "./broadcastControls.js";
 import type { InternalTypes } from "./exposedInternalTypes.js";
 import type { PostUpdateAction, ValueManager } from "./internalTypes.js";
-import { asDeeplyReadonly, objectEntries, objectKeys } from "./internalUtils.js";
+import {
+	asDeeplyReadonly,
+	asDeeplyReadonlyDeserializedJson,
+	objectEntries,
+	objectKeys,
+	toOpaqueJson,
+} from "./internalUtils.js";
 import type { LatestClientData, LatestData, LatestMetadata } from "./latestValueTypes.js";
 import type { AttendeeId, Attendee, Presence, SpecificAttendee } from "./presence.js";
 import { datastoreFromHandle, type StateDatastore } from "./stateDatastore.js";
@@ -122,7 +128,7 @@ export interface LatestMapRawEvents<T, K extends string | number> {
 	 * @eventProperty
 	 */
 	localItemUpdated: (updatedItem: {
-		value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+		value: DeepReadonly<JsonSerializable<T>>;
 		key: K;
 	}) => void;
 
@@ -196,7 +202,7 @@ export interface StateMap<K extends string | number, V> {
 	 * Make a deep clone before setting, if needed. No comparison is done to detect changes; all
 	 * sets are transmitted.
 	 */
-	set(key: K, value: JsonSerializable<V> & JsonDeserialized<V>): this;
+	set(key: K, value: JsonSerializable<V>): this;
 
 	/**
 	 * The number of elements in the StateMap.
@@ -286,23 +292,24 @@ class ValueMapImpl<T, K extends string | number> implements StateMap<K, T> {
 	): void {
 		for (const [key, item] of objectEntries(this.value.items)) {
 			if (item.value !== undefined) {
-				callbackfn(asDeeplyReadonly(item.value), key, this);
+				callbackfn(asDeeplyReadonlyDeserializedJson(item.value), key, this);
 			}
 		}
 	}
 	public get(key: K): DeepReadonly<JsonDeserialized<T>> | undefined {
-		return asDeeplyReadonly(this.value.items[key]?.value);
+		return asDeeplyReadonlyDeserializedJson(this.value.items[key]?.value);
 	}
 	public has(key: K): boolean {
 		return this.value.items[key]?.value !== undefined;
 	}
-	public set(key: K, value: JsonSerializable<T> & JsonDeserialized<T>): this {
+	public set(key: K, inValue: JsonSerializable<T>): this {
+		const value = toOpaqueJson<T>(inValue);
 		if (!(key in this.value.items)) {
 			this.countDefined += 1;
 			this.value.items[key] = { rev: 0, timestamp: 0, value };
 		}
 		this.updateItem(key, value);
-		this.emitter.emit("localItemUpdated", { key, value: asDeeplyReadonly(value) });
+		this.emitter.emit("localItemUpdated", { key, value: asDeeplyReadonly(inValue) });
 		return this;
 	}
 	public get size(): number {
@@ -433,7 +440,7 @@ class LatestMapRawValueManagerImpl<
 			const value = item.value;
 			if (value !== undefined) {
 				items.set(key, {
-					value: asDeeplyReadonly(value),
+					value: asDeeplyReadonlyDeserializedJson(value),
 					metadata: { revision: item.rev, timestamp: item.timestamp },
 				});
 			}
@@ -484,7 +491,7 @@ class LatestMapRawValueManagerImpl<
 			currentState.items[key] = item;
 			const metadata = { revision: item.rev, timestamp: item.timestamp };
 			if (item.value !== undefined) {
-				const itemValue = asDeeplyReadonly(item.value);
+				const itemValue = asDeeplyReadonlyDeserializedJson(item.value);
 				const updatedItem = {
 					attendee,
 					key,
@@ -512,6 +519,7 @@ class LatestMapRawValueManagerImpl<
 /**
  * Arguments that are passed to the {@link StateFactory.latestMap} function.
  *
+ * @input
  * @beta
  */
 export interface LatestMapArguments<T, Keys extends string | number = string | number> {
@@ -519,7 +527,7 @@ export interface LatestMapArguments<T, Keys extends string | number = string | n
 	 * The initial value of the local state.
 	 */
 	local?: {
-		[K in Keys]: JsonSerializable<T> & JsonDeserialized<T>;
+		[K in Keys]: JsonSerializable<T>;
 	};
 
 	/**
@@ -559,7 +567,7 @@ export function latestMap<
 			value.items[key] = {
 				rev: 0,
 				timestamp,
-				value: initialValues[key],
+				value: toOpaqueJson(initialValues[key]),
 			};
 		}
 	}
diff --git a/packages/framework/presence/src/latestValueManager.ts b/packages/framework/presence/src/latestValueManager.ts
index 08d0fc16732c..bed1839d8cdb 100644
--- a/packages/framework/presence/src/latestValueManager.ts
+++ b/packages/framework/presence/src/latestValueManager.ts
@@ -16,7 +16,12 @@ import type { BroadcastControls, BroadcastControlSettings } from "./broadcastCon
 import { OptionalBroadcastControl } from "./broadcastControls.js";
 import type { InternalTypes } from "./exposedInternalTypes.js";
 import type { PostUpdateAction, ValueManager } from "./internalTypes.js";
-import { asDeeplyReadonly, objectEntries } from "./internalUtils.js";
+import {
+	asDeeplyReadonly,
+	asDeeplyReadonlyDeserializedJson,
+	objectEntries,
+	toOpaqueJson,
+} from "./internalUtils.js";
 import type { LatestClientData, LatestData } from "./latestValueTypes.js";
 import type { Attendee, Presence } from "./presence.js";
 import { datastoreFromHandle, type StateDatastore } from "./stateDatastore.js";
@@ -42,7 +47,7 @@ export interface LatestRawEvents<T> {
 	 * @eventProperty
 	 */
 	localUpdated: (update: {
-		value: DeepReadonly<JsonSerializable<T> & JsonDeserialized<T>>;
+		value: DeepReadonly<JsonSerializable<T>>;
 	}) => void;
 }
 
@@ -78,7 +83,7 @@ export interface LatestRaw<T> {
 	 * setting, if needed. No comparison is done to detect changes; all sets are transmitted.
 	 */
 	get local(): DeepReadonly<JsonDeserialized<T>>;
-	set local(value: JsonSerializable<T> & JsonDeserialized<T>);
+	set local(value: JsonSerializable<T>);
 
 	/**
 	 * Iterable access to remote clients' values.
@@ -114,13 +119,13 @@ class LatestValueManagerImpl<T, Key extends string>
 	}
 
 	public get local(): DeepReadonly<JsonDeserialized<T>> {
-		return asDeeplyReadonly(this.value.value);
+		return asDeeplyReadonlyDeserializedJson(this.value.value);
 	}
 
-	public set local(value: JsonSerializable<T> & JsonDeserialized<T>) {
+	public set local(value: JsonSerializable<T>) {
 		this.value.rev += 1;
 		this.value.timestamp = Date.now();
-		this.value.value = value;
+		this.value.value = toOpaqueJson<T>(value);
 		this.datastore.localUpdate(this.key, this.value, {
 			allowableUpdateLatencyMs: this.controls.allowableUpdateLatencyMs,
 		});
@@ -134,7 +139,7 @@ class LatestValueManagerImpl<T, Key extends string>
 			if (attendeeId !== allKnownStates.self) {
 				yield {
 					attendee: this.datastore.presence.attendees.getAttendee(attendeeId),
-					value: asDeeplyReadonly(value.value),
+					value: asDeeplyReadonlyDeserializedJson(value.value),
 					metadata: { revision: value.rev, timestamp: value.timestamp },
 				};
 			}
@@ -155,7 +160,7 @@ class LatestValueManagerImpl<T, Key extends string>
 			throw new Error("No entry for clientId");
 		}
 		return {
-			value: asDeeplyReadonly(clientState.value),
+			value: asDeeplyReadonlyDeserializedJson(clientState.value),
 			metadata: { revision: clientState.rev, timestamp: Date.now() },
 		};
 	}
@@ -176,24 +181,38 @@ class LatestValueManagerImpl<T, Key extends string>
 			() =>
 				this.events.emit("remoteUpdated", {
 					attendee,
-					value: asDeeplyReadonly(value.value),
+					value: asDeeplyReadonlyDeserializedJson(value.value),
 					metadata: { revision: value.rev, timestamp: value.timestamp },
 				}),
 		];
 	}
 }
 
+/**
+ * Shallow clone an object that might be null.
+ *
+ * @param value - The object to clone
+ * @returns A shallow clone of the input value
+ */
+export function shallowCloneNullableObject<T extends object | null>(value: T): T {
+	return value === null ? value : shallowCloneObject(value);
+}
+
 /**
  * Arguments that are passed to the {@link StateFactory.latest} function.
  *
+ * @input
  * @beta
  */
 export interface LatestArguments<T extends object | null> {
 	/**
 	 * The initial value of the local state.
+	 *
+	 * @remarks
+	 * `latest` assumes ownership of the value and its references.
+	 * Make a deep clone before passing, if needed.
 	 */
-	// eslint-disable-next-line @rushstack/no-new-null
-	local: JsonSerializable<T> & JsonDeserialized<T> & (object | null);
+	local: JsonSerializable<T>;
 
 	/**
 	 * See {@link BroadcastControlSettings}.
@@ -213,10 +232,11 @@ export function latest<T extends object | null, Key extends string = string>(
 
 	// Latest takes ownership of the initial local value but makes a shallow
 	// copy for basic protection.
+	const opaqueLocal = toOpaqueJson<T>(local);
 	const value: InternalTypes.ValueRequiredState<T> = {
 		rev: 0,
 		timestamp: Date.now(),
-		value: local === null ? local : shallowCloneObject(local),
+		value: shallowCloneNullableObject(opaqueLocal),
 	};
 	const factory = (
 		key: Key,
diff --git a/packages/framework/presence/src/notificationsManager.ts b/packages/framework/presence/src/notificationsManager.ts
index 12857b260599..dfd6c9d8cda0 100644
--- a/packages/framework/presence/src/notificationsManager.ts
+++ b/packages/framework/presence/src/notificationsManager.ts
@@ -10,6 +10,7 @@ import type { JsonTypeWith } from "@fluidframework/core-interfaces/internal";
 import type { InternalTypes } from "./exposedInternalTypes.js";
 import type { InternalUtilityTypes } from "./exposedUtilityTypes.js";
 import type { PostUpdateAction, ValueManager } from "./internalTypes.js";
+import { revealOpaqueJson, toOpaqueJson } from "./internalUtils.js";
 import type { Attendee, PresenceWithNotifications as Presence } from "./presence.js";
 import { datastoreFromHandle, type StateDatastore } from "./stateDatastore.js";
 import { brandIVM } from "./valueManager.js";
@@ -100,7 +101,7 @@ export interface NotificationEmitter<E extends InternalUtilityTypes.Notification
 	 * @param notificationName - the name of the notification to fire
 	 * @param args - the arguments sent with the notification
 	 */
-	broadcast<K extends string & keyof InternalUtilityTypes.NotificationListeners<E>>(
+	broadcast<K extends keyof InternalUtilityTypes.NotificationListeners<E>>(
 		notificationName: K,
 		...args: Parameters<E[K]>
 	): void;
@@ -111,7 +112,7 @@ export interface NotificationEmitter<E extends InternalUtilityTypes.Notification
 	 * @param targetAttendee - the single attendee to notify
 	 * @param args - the arguments sent with the notification
 	 */
-	unicast<K extends string & keyof InternalUtilityTypes.NotificationListeners<E>>(
+	unicast<K extends keyof InternalUtilityTypes.NotificationListeners<E>>(
 		notificationName: K,
 		targetAttendee: Attendee,
 		...args: Parameters<E[K]>
@@ -171,26 +172,32 @@ class NotificationsManagerImpl<
 	public readonly events = createEmitter<NotificationsManagerEvents>();
 
 	public readonly emit: NotificationEmitter<T> = {
-		broadcast: (name, ...args) => {
+		broadcast: (name: string, ...args) => {
 			this.datastore.localUpdate(
 				this.key,
 				{
 					rev: 0,
 					timestamp: 0,
-					value: { name, args: [...(args as JsonTypeWith<never>[])] },
+					value: toOpaqueJson({
+						name,
+						args: [...(args as JsonTypeWith<never>[])],
+					}),
 					ignoreUnmonitored: true,
 				},
 				// This is a notification, so we want to send it immediately.
 				{ allowableUpdateLatencyMs: 0 },
 			);
 		},
-		unicast: (name, targetAttendee, ...args) => {
+		unicast: (name: string, targetAttendee, ...args) => {
 			this.datastore.localUpdate(
 				this.key,
 				{
 					rev: 0,
 					timestamp: 0,
-					value: { name, args: [...(args as JsonTypeWith<never>[])] },
+					value: toOpaqueJson({
+						name,
+						args: [...(args as JsonTypeWith<never>[])],
+					}),
 					ignoreUnmonitored: true,
 				},
 				// This is a notification, so we want to send it immediately.
@@ -202,7 +209,6 @@ class NotificationsManagerImpl<
 	// Workaround for types
 	private readonly notificationsInternal = createEmitter<NotificationSubscriptions<T>>();
 
-	// @ts-expect-error TODO
 	public readonly notifications: NotificationListenable<T> = this.notificationsInternal;
 
 	public constructor(
@@ -235,25 +241,21 @@ class NotificationsManagerImpl<
 	public update(
 		attendee: Attendee,
 		_received: number,
-		value: InternalTypes.ValueRequiredState<InternalTypes.NotificationType>,
+		updateValue: InternalTypes.ValueRequiredState<InternalTypes.NotificationType>,
 	): PostUpdateAction[] {
 		const postUpdateActions: PostUpdateAction[] = [];
-		const eventName = value.value.name as keyof Listeners<NotificationSubscriptions<T>>;
+		const value = revealOpaqueJson(updateValue.value);
+		const eventName = value.name as keyof Listeners<NotificationSubscriptions<T>>;
 		if (this.notificationsInternal.hasListeners(eventName)) {
 			// Without schema validation, we don't know that the args are the correct type.
 			// For now we assume the user is sending the correct types and there is no corruption along the way.
-			const args = [attendee, ...value.value.args] as Parameters<
+			const args = [attendee, ...value.args] as Parameters<
 				NotificationSubscriptions<T>[typeof eventName]
 			>;
 			postUpdateActions.push(() => this.notificationsInternal.emit(eventName, ...args));
 		} else {
 			postUpdateActions.push(() =>
-				this.events.emit(
-					"unattendedNotification",
-					value.value.name,
-					attendee,
-					...value.value.args,
-				),
+				this.events.emit("unattendedNotification", value.name, attendee, ...value.args),
 			);
 		}
 		return postUpdateActions;
diff --git a/packages/framework/presence/src/systemWorkspace.ts b/packages/framework/presence/src/systemWorkspace.ts
index 342de7818f5e..9d7a8907ecb2 100644
--- a/packages/framework/presence/src/systemWorkspace.ts
+++ b/packages/framework/presence/src/systemWorkspace.ts
@@ -10,18 +10,29 @@ import { assert } from "@fluidframework/core-utils/internal";
 import type { ClientConnectionId } from "./baseTypes.js";
 import type { InternalTypes } from "./exposedInternalTypes.js";
 import type { PostUpdateAction } from "./internalTypes.js";
+import { revealOpaqueJson } from "./internalUtils.js";
 import type { Attendee, AttendeesEvents, AttendeeId, Presence } from "./presence.js";
 import { AttendeeStatus } from "./presence.js";
 import type { PresenceStatesInternal } from "./presenceStates.js";
 import { TimerManager } from "./timerManager.js";
 import type { AnyWorkspace, StatesWorkspaceSchema } from "./types.js";
 
+/**
+ * `ConnectionValueState` is known value state for `clientToSessionId` data.
+ *
+ * @remarks
+ * It is {@link InternalTypes.ValueRequiredState} with a known value type.
+ */
+interface ConnectionValueState extends InternalTypes.ValueStateMetadata {
+	value: AttendeeId;
+}
+
 /**
  * The system workspace's datastore structure.
  */
 export interface SystemWorkspaceDatastore {
 	clientToSessionId: {
-		[ConnectionId: ClientConnectionId]: InternalTypes.ValueRequiredState<AttendeeId>;
+		[ConnectionId: ClientConnectionId]: ConnectionValueState;
 	};
 }
 
@@ -117,11 +128,21 @@ class SystemWorkspaceImpl implements PresenceStatesInternal, SystemWorkspace {
 	public processUpdate(
 		_received: number,
 		_timeModifier: number,
+		/**
+		 * Remote datastore typed to match {@link PresenceStatesInternal.processUpdate}'s
+		 * `ValueUpdateRecord` type that uses {@link InternalTypes.ValueRequiredState}
+		 * and expects an Opaque JSON type. (We get away with a non-`unknown` value type
+		 * per TypeScript's method parameter bivariance.) Proper type would be
+		 * {@link ConnectionValueState} directly.
+		 * {@link ClientConnectionId} use for index is also a deviation, but conveniently
+		 * the accurate {@link AttendeeId} type is just a branded string, and
+		 * {@link ClientConnectionId} is just `string`.
+		 */
 		remoteDatastore: {
 			clientToSessionId: {
-				[ConnectionId: ClientConnectionId]: InternalTypes.ValueRequiredState<AttendeeId> & {
-					ignoreUnmonitored?: true;
-				};
+				[ConnectionId: ClientConnectionId]: InternalTypes.ValueRequiredState<
+					ConnectionValueState["value"]
+				>;
 			};
 		},
 		senderConnectionId: ClientConnectionId,
@@ -129,7 +150,7 @@ class SystemWorkspaceImpl implements PresenceStatesInternal, SystemWorkspace {
 		const audienceMembers = this.audience.getMembers();
 		const postUpdateActions: PostUpdateAction[] = [];
 		for (const [clientConnectionId, value] of Object.entries(
-			remoteDatastore.clientToSessionId,
+			revealOpaqueJson(remoteDatastore.clientToSessionId),
 		)) {
 			const attendeeId = value.value;
 			const { attendee, isJoining } = this.ensureAttendee(
@@ -146,8 +167,7 @@ class SystemWorkspaceImpl implements PresenceStatesInternal, SystemWorkspace {
 				postUpdateActions.push(() => this.events.emit("attendeeConnected", attendee));
 			}
 
-			const knownSessionId: InternalTypes.ValueRequiredState<AttendeeId> | undefined =
-				this.datastore.clientToSessionId[clientConnectionId];
+			const knownSessionId = this.datastore.clientToSessionId[clientConnectionId];
 			if (knownSessionId === undefined) {
 				this.datastore.clientToSessionId[clientConnectionId] = value;
 			} else {
diff --git a/packages/framework/presence/src/test/batching.spec.ts b/packages/framework/presence/src/test/batching.spec.ts
index fa74fefc29c5..ce450824fcec 100644
--- a/packages/framework/presence/src/test/batching.spec.ts
+++ b/packages/framework/presence/src/test/batching.spec.ts
@@ -9,6 +9,7 @@ import { useFakeTimers, type SinonFakeTimers } from "sinon";
 
 import type { NotificationsWorkspace } from "../index.js";
 import { Notifications, StateFactory } from "../index.js";
+import { toOpaqueJson } from "../internalUtils.js";
 import type { createPresenceManager } from "../presenceManager.js";
 
 import { MockEphemeralRuntime } from "./mockEphemeralRuntime.js";
@@ -66,11 +67,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -78,9 +75,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 1010,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 0,
-												},
+												}),
 											},
 										},
 									},
@@ -97,11 +94,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -109,9 +102,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 1,
 												"timestamp": 1020,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 42,
-												},
+												}),
 											},
 										},
 									},
@@ -128,11 +121,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -140,9 +129,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 2,
 												"timestamp": 1020,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 84,
-												},
+												}),
 											},
 										},
 									},
@@ -196,9 +185,9 @@ describe("Presence", () => {
 										[attendeeId2]: {
 											"rev": 0,
 											"timestamp": 1010,
-											"value": {
+											"value": toOpaqueJson({
 												"num": 0,
-											},
+											}),
 										},
 									},
 								},
@@ -232,11 +221,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -244,9 +229,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 3,
 												"timestamp": 1060,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 22,
-												},
+												}),
 											},
 										},
 									},
@@ -263,11 +248,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -275,9 +256,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 6,
 												"timestamp": 1140,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 90,
-												},
+												}),
 											},
 										},
 									},
@@ -340,11 +321,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -352,9 +329,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 2,
 												"timestamp": 1100,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 34,
-												},
+												}),
 											},
 										},
 									},
@@ -371,11 +348,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -383,9 +356,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 5,
 												"timestamp": 1220,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 90,
-												},
+												}),
 											},
 										},
 									},
@@ -446,11 +419,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -458,18 +427,18 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 1010,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 0,
-												},
+												}),
 											},
 										},
 										"immediateUpdate": {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 1010,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 0,
-												},
+												}),
 											},
 										},
 									},
@@ -486,11 +455,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -498,18 +463,18 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 2,
 												"timestamp": 1100,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 34,
-												},
+												}),
 											},
 										},
 										"immediateUpdate": {
 											[attendeeId2]: {
 												"rev": 1,
 												"timestamp": 1110,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 56,
-												},
+												}),
 											},
 										},
 									},
@@ -560,11 +525,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -572,18 +533,18 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 2,
 												"timestamp": 1050,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 34,
-												},
+												}),
 											},
 										},
 										"note": {
 											[attendeeId2]: {
 												"rev": 1,
 												"timestamp": 1020,
-												"value": {
+												"value": toOpaqueJson({
 													"message": "will be queued",
-												},
+												}),
 											},
 										},
 									},
@@ -608,7 +569,7 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 2,
 												"timestamp": 1060,
-												"value": { "message": "final message" },
+												"value": toOpaqueJson({ "message": "final message" }),
 											},
 										},
 									},
@@ -676,9 +637,9 @@ describe("Presence", () => {
 										[attendeeId2]: {
 											"rev": 2,
 											"timestamp": 1050,
-											"value": {
+											"value": toOpaqueJson({
 												"num": 34,
-											},
+											}),
 										},
 									},
 								},
@@ -687,9 +648,9 @@ describe("Presence", () => {
 										[attendeeId2]: {
 											"rev": 2,
 											"timestamp": 1060,
-											"value": {
+											"value": toOpaqueJson({
 												"message": "final message",
-											},
+											}),
 										},
 									},
 								},
@@ -755,7 +716,7 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 0,
-												"value": { "name": "newId", "args": [77] },
+												"value": toOpaqueJson({ "name": "newId", "args": [77] }),
 												"ignoreUnmonitored": true,
 											},
 										},
@@ -781,7 +742,7 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 0,
-												"value": { "name": "newId", "args": [88] },
+												"value": toOpaqueJson({ "name": "newId", "args": [88] }),
 												"ignoreUnmonitored": true,
 											},
 										},
@@ -835,11 +796,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"s:name:testStateWorkspace": {
@@ -847,9 +804,9 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 3,
 												"timestamp": 1040,
-												"value": {
+												"value": toOpaqueJson({
 													"num": 56,
-												},
+												}),
 											},
 										},
 									},
@@ -858,10 +815,10 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 0,
-												"value": {
+												"value": toOpaqueJson({
 													"name": "newId",
 													"args": [99],
-												},
+												}),
 												"ignoreUnmonitored": true,
 											},
 										},
@@ -879,11 +836,7 @@ describe("Presence", () => {
 								"data": {
 									"system:presence": {
 										"clientToSessionId": {
-											[connectionId2]: {
-												"rev": 0,
-												"timestamp": 1000,
-												"value": attendeeId2,
-											},
+											[connectionId2]: { "rev": 0, "timestamp": 1000, "value": attendeeId2 },
 										},
 									},
 									"n:name:testNotificationWorkspace": {
@@ -891,10 +844,10 @@ describe("Presence", () => {
 											[attendeeId2]: {
 												"rev": 0,
 												"timestamp": 0,
-												"value": {
+												"value": toOpaqueJson({
 													"name": "newId",
 													"args": [111],
-												},
+												}),
 												"ignoreUnmonitored": true,
 											},
 										},
diff --git a/packages/framework/presence/src/test/latestMapValueManager.spec.ts b/packages/framework/presence/src/test/latestMapValueManager.spec.ts
index ab70e4fb44dd..a1601d8815cc 100644
--- a/packages/framework/presence/src/test/latestMapValueManager.spec.ts
+++ b/packages/framework/presence/src/test/latestMapValueManager.spec.ts
@@ -201,7 +201,7 @@ export function checkCompiles(): void {
 				null: null,
 				string: "string",
 				number: 0,
-				true: true,
+				boolean: true,
 			},
 		}),
 	);
@@ -210,19 +210,20 @@ export function checkCompiles(): void {
 
 	// map value types are not matched to specific key
 	localPrimitiveMap.set("string", 1);
-	localPrimitiveMap.set("number", true);
+	// latestMap should infer that `true` or `false` is a valid value
+	// without use of `true as const` or explicit specification.
+	// That happened under PR #24752 unexpectedly. Presumably from some
+	// additional inference complication where `& JsonDeserialized<T>`
+	// was used in `LatestMapArguments` that was relaxed in PR #247??. !!! <- to fill in
+	// Caller can always use explicit generic specification to be
+	// completely clear about the types.
+	localPrimitiveMap.set("number", false);
 	// eslint-disable-next-line unicorn/no-null
-	localPrimitiveMap.set("true", null);
+	localPrimitiveMap.set("boolean", null);
 	localPrimitiveMap.set("null", "null");
 
 	// @ts-expect-error with inferred keys only those named in init are accessible
 	localPrimitiveMap.set("key3", "value");
 	// @ts-expect-error value of type value is not assignable
 	localPrimitiveMap.set("null", { value: "value" });
-	// latestMap infers that only `true` is a valid value without use of `false` or explicit specification.
-	// This happened under PR #24752 unexpectedly. Presumably from some additional inference complication.
-	// This is a better inferred result; so it can stand, but would not be terrible if the behavior changes.
-	// Caller can always use explicit generic specification to be completely clear about the types.
-	// @ts-expect-error Argument of type 'false' is not assignable to parameter of type 'string | number | true | null'.
-	localPrimitiveMap.set("true", false);
 }
diff --git a/packages/framework/presence/src/test/latestValueManager.spec.ts b/packages/framework/presence/src/test/latestValueManager.spec.ts
index 7afc32adf988..f1cabca79eb2 100644
--- a/packages/framework/presence/src/test/latestValueManager.spec.ts
+++ b/packages/framework/presence/src/test/latestValueManager.spec.ts
@@ -84,6 +84,22 @@ describe("Presence", () => {
 				assert.deepStrictEqual(workspace.states.nullable.local, null);
 			});
 
+			it("can set and get inferred nullable type as initial value", () => {
+				// Setup
+				// Use a function to generate the initial value so that TypeScript
+				// can't statically infer the type as exactly null.
+				function generateInitialValue(): { x: number; y: number } | null {
+					return { x: 0, y: 0 };
+				}
+				const initialValue = generateInitialValue();
+				// Act
+				const workspace = presence.states.getWorkspace(testWorkspaceName, {
+					nullable: StateFactory.latest({ local: initialValue }),
+				});
+				// Verify
+				assert.deepStrictEqual(workspace.states.nullable.local, initialValue);
+			});
+
 			it(".presence provides Presence it was created under", () => {
 				const workspace = presence.states.getWorkspace(testWorkspaceName, {
 					camera: StateFactory.latest({ local: { x: 0, y: 0, z: 0 } }),
diff --git a/packages/framework/presence/src/test/notificationsManager.spec.ts b/packages/framework/presence/src/test/notificationsManager.spec.ts
index c7d3555888c5..8dfe971b0afb 100644
--- a/packages/framework/presence/src/test/notificationsManager.spec.ts
+++ b/packages/framework/presence/src/test/notificationsManager.spec.ts
@@ -15,6 +15,7 @@ import type {
 	NotificationsWorkspace,
 } from "../index.js";
 import { Notifications } from "../index.js";
+import { toOpaqueJson } from "../internalUtils.js";
 import type { createPresenceManager } from "../presenceManager.js";
 
 import { MockEphemeralRuntime } from "./mockEphemeralRuntime.js";
@@ -84,7 +85,8 @@ describe("Presence", () => {
 			notificationsWorkspace.add(
 				"testEvents",
 				Notifications<
-					// Below explicit generic specification should not be required.
+					// Below explicit generic specification should not be required
+					// when default handler is specified.
 					{
 						newId: (id: number) => void;
 					},
@@ -139,7 +141,7 @@ describe("Presence", () => {
 									[attendeeId2]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "newId", "args": [42] },
+										"value": toOpaqueJson({ "name": "newId", "args": [42] }),
 										"ignoreUnmonitored": true,
 									},
 								},
@@ -192,7 +194,7 @@ describe("Presence", () => {
 									[attendeeId2]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "newId", "args": [42] },
+										"value": toOpaqueJson({ "name": "newId", "args": [42] }),
 										"ignoreUnmonitored": true,
 									},
 								},
@@ -271,7 +273,7 @@ describe("Presence", () => {
 									[attendeeId3]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "newId", "args": [42] },
+										"value": toOpaqueJson({ "name": "newId", "args": [42] }),
 										"ignoreUnmonitored": true,
 									},
 								},
@@ -349,7 +351,7 @@ describe("Presence", () => {
 									[attendeeId3]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "oldId", "args": [41] },
+										"value": toOpaqueJson({ "name": "oldId", "args": [41] }),
 										"ignoreUnmonitored": true,
 									},
 								},
@@ -415,7 +417,7 @@ describe("Presence", () => {
 									[attendeeId3]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "newId", "args": [43] },
+										"value": toOpaqueJson({ "name": "newId", "args": [43] }),
 										"ignoreUnmonitored": true,
 									},
 								},
@@ -487,7 +489,7 @@ describe("Presence", () => {
 									[attendeeId3]: {
 										"rev": 0,
 										"timestamp": 0,
-										"value": { "name": "newId", "args": [44] },
+										"value": toOpaqueJson({ "name": "newId", "args": [44] }),
 										"ignoreUnmonitored": true,
 									},
 								},
diff --git a/packages/framework/presence/src/test/presenceDatastoreManager.spec.ts b/packages/framework/presence/src/test/presenceDatastoreManager.spec.ts
index aa8e9ff051d9..a8c03795ccb4 100644
--- a/packages/framework/presence/src/test/presenceDatastoreManager.spec.ts
+++ b/packages/framework/presence/src/test/presenceDatastoreManager.spec.ts
@@ -9,6 +9,7 @@ import { EventAndErrorTrackingLogger } from "@fluidframework/test-utils/internal
 import type { SinonFakeTimers } from "sinon";
 import { useFakeTimers, spy } from "sinon";
 
+import { toOpaqueJson } from "../internalUtils.js";
 import type { AttendeeId } from "../presence.js";
 import { createPresenceManager } from "../presenceManager.js";
 import type { InternalWorkspaceAddress } from "../protocol.js";
@@ -221,7 +222,7 @@ describe("Presence", () => {
 					[attendeeId1]: {
 						"rev": 1,
 						"timestamp": 0,
-						"value": {},
+						"value": toOpaqueJson({}),
 					},
 				},
 			};
@@ -231,7 +232,7 @@ describe("Presence", () => {
 					[attendeeId1]: {
 						"rev": 0,
 						"timestamp": 0,
-						"value": {},
+						"value": toOpaqueJson({}),
 						"ignoreUnmonitored": true,
 					},
 				},
@@ -329,7 +330,7 @@ describe("Presence", () => {
 										[attendeeId1]: {
 											"rev": 1,
 											"timestamp": 0,
-											"value": { x: 1, y: 1, z: 1 },
+											"value": toOpaqueJson({ x: 1, y: 1, z: 1 }),
 										},
 									},
 								},
diff --git a/packages/framework/presence/src/test/presenceStates.spec.ts b/packages/framework/presence/src/test/presenceStates.spec.ts
index 1aa11dd87885..4268aed0be6e 100644
--- a/packages/framework/presence/src/test/presenceStates.spec.ts
+++ b/packages/framework/presence/src/test/presenceStates.spec.ts
@@ -43,7 +43,7 @@ describe("Presence", () => {
 });
 
 declare function createValueManager<T, Key extends string>(
-	initial: JsonSerializable<T> & JsonDeserialized<T>,
+	initial: JsonSerializable<T>,
 ): { instanceBase: new () => unknown } & ((
 	key: Key,
 	datastoreHandle: InternalTypes.StateDatastoreHandle<