diff --git a/packages/effect-fc-next/src/Mutation.ts b/packages/effect-fc-next/src/Mutation.ts
index 0d873eb..5ae14d4 100644
--- a/packages/effect-fc-next/src/Mutation.ts
+++ b/packages/effect-fc-next/src/Mutation.ts
@@ -1,146 +1,157 @@
-import { type Context, Effect, Equal, type Fiber, Option, Pipeable, Predicate, type Scope, Stream, SubscriptionRef } from "effect"
-import { Subscribable } from "effect-lens"
-import * as Result from "./Result.js"
+import { type Context, Effect, Equal, Exit, type Fiber, Option, Pipeable, Predicate, type Scope, Stream, SubscriptionRef } from "effect"
+import { AsyncResult } from "effect/unstable/reactivity"
+import * as Lens from "./Lens.js"
+import type * as Subscribable from "./Subscribable.js"
 
 
 export const MutationTypeId: unique symbol = Symbol.for("@effect-fc/Mutation/Mutation")
 export type MutationTypeId = typeof MutationTypeId
 
-export interface Mutation<in out K extends Mutation.AnyKey, in out A, in out E = never, in out R = never, in out P = never>
+export interface Mutation<in out K extends Mutation.AnyKey, in out A, in out E = never, in out R = never>
 extends Pipeable.Pipeable {
     readonly [MutationTypeId]: MutationTypeId
 
     readonly context: Context.Context<Scope.Scope | R>
     readonly f: (key: K) => Effect.Effect<A, E, R>
-    readonly initialProgress: P
 
     readonly latestKey: Subscribable.Subscribable<Option.Option<K>>
     readonly fiber: Subscribable.Subscribable<Option.Option<Fiber.Fiber<A, E>>>
-    readonly result: Subscribable.Subscribable<Result.Result<A, E, P>>
-    readonly latestFinalResult: Subscribable.Subscribable<Option.Option<Result.Final<A, E, P>>>
+    readonly result: Subscribable.Subscribable<AsyncResult.AsyncResult<A, E>>
+    readonly latestFinalResult: Subscribable.Subscribable<Option.Option<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>>>
 
-    mutate(key: K): Effect.Effect<Result.Final<A, E, P>>
-    mutateSubscribable(key: K): Effect.Effect<Subscribable.Subscribable<Result.Result<A, E, P>>>
+    mutate(key: K): Effect.Effect<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>>
+    mutateSubscribable(key: K): Effect.Effect<Subscribable.Subscribable<AsyncResult.AsyncResult<A, E>>>
 }
 
 export declare namespace Mutation {
     export type AnyKey = readonly any[]
 }
 
-export class MutationImpl<in out K extends Mutation.AnyKey, in out A, in out E = never, in out R = never, in out P = never>
-extends Pipeable.Class implements Mutation<K, A, E, R, P> {
+export class MutationImpl<in out K extends Mutation.AnyKey, in out A, in out E = never, in out R = never>
+extends Pipeable.Class implements Mutation<K, A, E, R> {
     readonly [MutationTypeId]: MutationTypeId = MutationTypeId
-    readonly latestKey: Subscribable.Subscribable<Option.Option<K>>
-    readonly fiber: Subscribable.Subscribable<Option.Option<Fiber.Fiber<A, E>>>
-    readonly result: Subscribable.Subscribable<Result.Result<A, E, P>>
-    readonly latestFinalResult: Subscribable.Subscribable<Option.Option<Result.Final<A, E, P>>>
 
     constructor(
         readonly context: Context.Context<Scope.Scope | R>,
         readonly f: (key: K) => Effect.Effect<A, E, R>,
-        readonly initialProgress: P,
 
-        readonly latestKeyRef: SubscriptionRef.SubscriptionRef<Option.Option<K>>,
-        readonly fiberRef: SubscriptionRef.SubscriptionRef<Option.Option<Fiber.Fiber<A, E>>>,
-        readonly resultRef: SubscriptionRef.SubscriptionRef<Result.Result<A, E, P>>,
-        readonly latestFinalResultRef: SubscriptionRef.SubscriptionRef<Option.Option<Result.Final<A, E, P>>>,
+        readonly latestKey: Lens.Lens<Option.Option<K>>,
+        readonly fiber: Lens.Lens<Option.Option<Fiber.Fiber<A, E>>>,
+        readonly result: Lens.Lens<AsyncResult.AsyncResult<A, E>>,
+        readonly latestFinalResult: Lens.Lens<Option.Option<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>>>,
     ) {
         super()
-        this.latestKey = fromSubscriptionRef(latestKeyRef)
-        this.fiber = fromSubscriptionRef(fiberRef)
-        this.result = fromSubscriptionRef(resultRef)
-        this.latestFinalResult = fromSubscriptionRef(latestFinalResultRef)
     }
 
-    mutate(key: K): Effect.Effect<Result.Final<A, E, P>> {
-        return SubscriptionRef.set(this.latestKeyRef, Option.some(key)).pipe(
+    mutate(key: K): Effect.Effect<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>> {
+        return Lens.set(this.latestKey, Option.some(key)).pipe(
             Effect.andThen(this.start(key)),
-            Effect.andThen(sub => this.watch(sub)),
+            Effect.flatMap(state => this.watch(state)),
             Effect.provide(this.context),
         )
     }
-    mutateSubscribable(key: K): Effect.Effect<Subscribable.Subscribable<Result.Result<A, E, P>>> {
-        return SubscriptionRef.set(this.latestKeyRef, Option.some(key)).pipe(
+    mutateSubscribable(key: K): Effect.Effect<Subscribable.Subscribable<AsyncResult.AsyncResult<A, E>>> {
+        return Lens.set(this.latestKey, Option.some(key)).pipe(
             Effect.andThen(this.start(key)),
-            Effect.tap(sub => Effect.forkScoped(this.watch(sub))),
+            Effect.tap(state => Effect.forkScoped(this.watch(state))),
             Effect.provide(this.context),
         )
     }
 
     start(key: K): Effect.Effect<
-        Subscribable.Subscribable<Result.Result<A, E, P>>,
+        Subscribable.Subscribable<AsyncResult.AsyncResult<A, E>>,
         never,
         Scope.Scope | R
     > {
-        const self = this
-        return Effect.gen(function*() {
-            const initial = yield* SubscriptionRef.get(self.latestFinalResultRef)
-            const [sub, fiber] = yield* Result.unsafeForkEffect<A, E, R, P>(
-                Effect.onExit(self.f(key), () => Effect.andThen(
-                    Effect.all([Effect.fiberId, SubscriptionRef.get(self.fiberRef)]),
-                    ([currentFiberId, fiber]) => Option.match(fiber, {
-                        onSome: v => Equal.equals(currentFiberId, v.id)
-                            ? SubscriptionRef.set(self.fiberRef, Option.none())
-                            : Effect.succeed(undefined),
-                        onNone: () => Effect.succeed(undefined),
-                    }),
-                )),
+        return Effect.gen({ self: this }, function*() {
+            const previous = yield* Lens.get(this.latestFinalResult)
+            const state = Lens.fromSubscriptionRef(yield* SubscriptionRef.make<AsyncResult.AsyncResult<A, E>>(
+                Option.getOrElse(previous, () => AsyncResult.initial(false))
+            ))
 
-                {
-                    initial: Option.isSome(initial) ? Result.willFetch(initial.value) : Result.initial(),
-                    initialProgress: self.initialProgress,
-                } as Result.unsafeForkEffect.Options<A, E, P>,
-            )
-            yield* SubscriptionRef.set(self.fiberRef, Option.some(fiber))
-            return sub
+            const fiber = yield* Effect.forkScoped(Effect.andThen(
+                Lens.update(state, AsyncResult.match({
+                    onInitial: () => AsyncResult.initial(true),
+                    onSuccess: v => AsyncResult.success(v.value, {
+                        waiting: true,
+                    }),
+                    onFailure: v => AsyncResult.failure(v.cause, {
+                        waiting: true,
+                        previousSuccess: v.previousSuccess,
+                    })
+                })),
+
+                Effect.onExit(this.f(key), exit => Lens.update(
+                    state,
+                    previous => Exit.match(exit, {
+                        onSuccess: v => AsyncResult.success(v),
+                        onFailure: c => AsyncResult.match(previous, {
+                            onInitial: () => AsyncResult.failure(c),
+                            onSuccess: v => AsyncResult.failure(c, {
+                                previousSuccess: Option.some(v),
+                            }),
+                            onFailure: v => AsyncResult.failure(c, {
+                                previousSuccess: v.previousSuccess,
+                            })
+                        }),
+                    }),
+                ).pipe(
+                    Effect.andThen(Effect.all([
+                        Effect.fiberId,
+                        Lens.get(this.fiber),
+                    ])),
+                    Effect.flatMap(([fiberId, fiber]) => Option.match(fiber, {
+                        onSome: v => Equal.equals(fiberId, v.id)
+                            ? Lens.set(this.fiber, Option.none())
+                            : Effect.void,
+                        onNone: () => Effect.void,
+                    })),
+                )),
+            ))
+
+            yield* Lens.set(this.fiber, Option.some(fiber))
+            return state
         })
     }
 
     watch(
-        sub: Subscribable.Subscribable<Result.Result<A, E, P>>
-    ): Effect.Effect<Result.Final<A, E, P>> {
-        return sub.get.pipe(
+        state: Subscribable.Subscribable<AsyncResult.AsyncResult<A, E>>
+    ): Effect.Effect<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>> {
+        return state.get.pipe(
             Effect.andThen(initial => Stream.runFoldEffect(
-                Stream.takeUntil(sub.changes, result => Result.isFinal(result) && !Result.hasFlag(result)),
+                state.changes,
                 () => initial,
-                (_, result) => Effect.as(SubscriptionRef.set(this.resultRef, result), result),
-            ) as Effect.Effect<Result.Final<A, E, P>>),
-            Effect.tap(result => SubscriptionRef.set(this.latestFinalResultRef, Option.some(result))),
+                (_, result) => Effect.as(Lens.set(this.result, result), result),
+            ) as Effect.Effect<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>>),
+            Effect.tap(result => Lens.set(this.latestFinalResult, Option.some(result))),
         )
     }
 }
 
 
-export const isMutation = (u: unknown): u is Mutation<readonly unknown[], unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, MutationTypeId)
+export const isMutation = (u: unknown): u is Mutation<readonly unknown[], unknown, unknown, unknown> => Predicate.hasProperty(u, MutationTypeId)
 
 
 export declare namespace make {
-    export interface Options<K extends Mutation.AnyKey = never, A = void, E = never, R = never, P = never> {
-        readonly f: (key: K) => Effect.Effect<A, E, Result.forkEffect.InputContext<R, NoInfer<P>>>
-        readonly initialProgress?: P
+    export interface Options<K extends Mutation.AnyKey = never, A = void, E = never, R = never> {
+        readonly f: (key: K) => Effect.Effect<A, E, R>
     }
 }
 
-export const make = Effect.fnUntraced(function* <const K extends Mutation.AnyKey = never, A = void, E = never, R = never, P = never>(
-    options: make.Options<K, A, E, R, P>
+export const make = Effect.fnUntraced(function* <const K extends Mutation.AnyKey = never, A = void, E = never, R = never>(
+    options: make.Options<K, A, E, R>
 ): Effect.fn.Return<
-    Mutation<K, A, E, Result.forkEffect.OutputContext<R, P>, P>,
+    Mutation<K, A, E, R>,
     never,
-    Scope.Scope | Result.forkEffect.OutputContext<R, P>
+    Scope.Scope | R
 > {
     return new MutationImpl(
-        yield* Effect.context<Scope.Scope | Result.forkEffect.OutputContext<R, P>>(),
-        options.f as any,
-        options.initialProgress as P,
+        yield* Effect.context<Scope.Scope | R>(),
+        options.f,
 
-        yield* SubscriptionRef.make(Option.none<K>()),
-        yield* SubscriptionRef.make(Option.none<Fiber.Fiber<A, E>>()),
-        yield* SubscriptionRef.make(Result.initial<A, E, P>()),
-        yield* SubscriptionRef.make(Option.none<Result.Final<A, E, P>>()),
+        Lens.fromSubscriptionRef(yield* SubscriptionRef.make(Option.none<K>())),
+        Lens.fromSubscriptionRef(yield* SubscriptionRef.make(Option.none<Fiber.Fiber<A, E>>())),
+        Lens.fromSubscriptionRef(yield* SubscriptionRef.make<AsyncResult.AsyncResult<A, E>>(AsyncResult.initial())),
+        Lens.fromSubscriptionRef(yield* SubscriptionRef.make(Option.none<AsyncResult.Success<A, E> | AsyncResult.Failure<A, E>>())),
     )
 })
-
-const fromSubscriptionRef = <A>(ref: SubscriptionRef.SubscriptionRef<A>): Subscribable.Subscribable<A> => Subscribable.make({
-    get: SubscriptionRef.get(ref),
-    changes: SubscriptionRef.changes(ref),
-})
diff --git a/packages/effect-fc-next/src/Query.ts b/packages/effect-fc-next/src/Query.ts
index 670f15d..27a6531 100644
--- a/packages/effect-fc-next/src/Query.ts
+++ b/packages/effect-fc-next/src/Query.ts
@@ -286,7 +286,7 @@ extends Pipeable.Class implements Query<K, A, KE, KR, E, R> {
 }
 
 
-export const isQuery = (u: unknown): u is Query<readonly unknown[], unknown> => Predicate.hasProperty(u, QueryTypeId)
+export const isQuery = (u: unknown): u is Query<readonly unknown[], unknown, unknown, unknown, unknown, unknown> => Predicate.hasProperty(u, QueryTypeId)
 
 
 export declare namespace make {