Change build system

2026-07-25 23:47:16 +02:00
parent 3533fa0c84
commit 65e90325d0
26 changed files with 78 additions and 48 deletions
@@ -0,0 +1,63 @@
+import { act, fireEvent, render, screen } from "@testing-library/react"
+import { Effect, Layer } from "effect"
+import * as React from "react"
+import { describe, expect, it, vi } from "vitest"
+import * as Async from "./Async.js"
+import * as Component from "./Component.js"
+import * as Memoized from "./Memoized.js"
+import * as ReactRuntime from "./ReactRuntime.js"
+
+describe("Async", () => {
+    it("does not rerun for an unrelated parent state update", async () => {
+        const load = vi.fn((_id: number) => Effect.never)
+        const renderPost = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const context = await runtime.runtime.context()
+
+        const Post = Component.make("Post")(function*(props: { readonly id: number }) {
+            renderPost()
+            const value = yield* Component.useOnChange(() => load(props.id), [props.id])
+            return <div>{value}</div>
+        }).pipe(
+            Async.async,
+            Memoized.memoized,
+        )
+
+        const Parent = Component.make("Parent")(function*() {
+            const [text, setText] = React.useState("")
+            const AsyncPost = yield* Post.use
+
+            return <>
+                <input
+                    aria-label="text"
+                    value={text}
+                    onChange={event => setText(event.currentTarget.value)}
+                />
+                <AsyncPost id={1} fallback={<div>loading</div>} />
+            </>
+        }).pipe(Component.withContext(runtime.context))
+
+        let view!: ReturnType<typeof render>
+        await act(async () => {
+            view = render(
+                <runtime.context.Provider value={context}>
+                    <Parent />
+                </runtime.context.Provider>,
+            )
+        })
+
+        expect(screen.getByText("loading")).toBeTruthy()
+        expect(load).toHaveBeenCalledTimes(2)
+        const callsAfterLoad = load.mock.calls.length
+        const rendersAfterLoad = renderPost.mock.calls.length
+
+        await act(async () => {
+            fireEvent.change(screen.getByLabelText("text"), { target: { value: "a" } })
+        })
+        expect(load).toHaveBeenCalledTimes(callsAfterLoad)
+        expect(renderPost).toHaveBeenCalledTimes(rendersAfterLoad)
+
+        view.unmount()
+        await runtime.runtime.dispose()
+    })
+})
@@ -0,0 +1,571 @@
+import { act, fireEvent, render, screen, waitFor } from "@testing-library/react"
+import { Context, Effect, HashMap, Layer, SubscriptionRef } from "effect"
+import * as React from "react"
+import { afterEach, describe, expect, it, vi } from "vitest"
+import * as Component from "./Component.js"
+import * as ReactRuntime from "./ReactRuntime.js"
+import * as Refreshable from "./Refreshable.js"
+import * as ScopeRegistry from "./ScopeRegistry.js"
+
+
+class ValueService extends Context.Service<ValueService, { readonly value: string }>()("ValueService") {}
+
+afterEach(() => {
+    vi.useRealTimers()
+})
+
+describe("Component", () => {
+    it("does not rerun useOnMount across rerenders after Strict Mode initialization", async () => {
+        const onMount = vi.fn(() => Effect.succeed("mounted"))
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const Probe = Component.makeUntraced("UseOnMountProbe")(function*() {
+            const value = yield* Component.useOnMount(onMount)
+            return <div>{value}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("mounted")
+        expect(onMount).toHaveBeenCalledTimes(2)
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+        expect(await screen.findByText("mounted")).toBeTruthy()
+        expect(onMount).toHaveBeenCalledTimes(2)
+
+        view.unmount()
+        await runtime.runtime.dispose()
+    })
+
+    it("recomputes useOnChange only when dependencies change", async () => {
+        const onChange = vi.fn((value: number) => Effect.succeed(`value:${value}`))
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const Probe = Component.makeUntraced("UseOnChangeProbe")(function*(props: { readonly value: number }) {
+            const result = yield* Component.useOnChange(() => onChange(props.value), [props.value], {
+                finalizerExecutionDebounce: 0,
+            })
+
+            return <div>{result}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value={1} />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("value:1")
+        expect(onChange).toHaveBeenCalledTimes(2)
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value={1} />
+            </runtime.context.Provider>
+        )
+
+        expect(await screen.findByText("value:1")).toBeTruthy()
+        expect(onChange).toHaveBeenCalledTimes(2)
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value={2} />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("value:2")
+        expect(onChange).toHaveBeenCalledTimes(4)
+
+        view.unmount()
+        await runtime.runtime.dispose()
+    })
+
+    it("closes the previous scope on dependency changes and unmount", async () => {
+        const cleanup = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const Probe = Component.makeUntraced("ScopeCleanupProbe")(function*(props: { readonly value: string }) {
+            const result = yield* Component.useOnChange(
+                () => Effect.gen(function*() {
+                    yield* Effect.addFinalizer(() => Effect.sync(() => cleanup(props.value)))
+                    return props.value
+                }),
+                [props.value],
+                { finalizerExecutionDebounce: 0 },
+            )
+
+            return <div>{result}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="first" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+        expect(cleanup).not.toHaveBeenCalled()
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="second" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("second")
+        await waitFor(() => expect(cleanup).toHaveBeenCalledWith("first"))
+        expect(cleanup).toHaveBeenCalledTimes(1)
+
+        view.unmount()
+
+        await waitFor(() => expect(cleanup).toHaveBeenCalledWith("second"))
+        expect(cleanup).toHaveBeenCalledTimes(2)
+        await runtime.runtime.dispose()
+    })
+
+    it("runs useReactEffect setup and cleanup when dependencies change", async () => {
+        const lifecycle = vi.fn<(message: string) => void>()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const Probe = Component.makeUntraced("UseReactEffectProbe")(function*(props: { readonly value: string }) {
+            yield* Component.useReactEffect(() =>
+                Effect.gen(function*() {
+                    yield* Effect.sync(() => lifecycle(`mount:${props.value}`))
+                    yield* Effect.addFinalizer(() => Effect.sync(() => lifecycle(`cleanup:${props.value}`)))
+                }),
+            [props.value])
+
+            return <div>{props.value}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="first" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+        await waitFor(() => expect(lifecycle).toHaveBeenCalledWith("mount:first"))
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="second" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("second")
+        await waitFor(() => expect(lifecycle).toHaveBeenCalledWith("cleanup:first"))
+        await waitFor(() => expect(lifecycle).toHaveBeenCalledWith("mount:second"))
+
+        view.unmount()
+
+        await waitFor(() => expect(lifecycle).toHaveBeenCalledWith("cleanup:second"))
+        expect(lifecycle.mock.calls.map(([message]) => message)).toEqual([
+            "mount:first",
+            "cleanup:first",
+            "mount:first",
+            "cleanup:first",
+            "mount:second",
+            "cleanup:second",
+        ])
+        await runtime.runtime.dispose()
+    })
+
+    it("keeps useCallbackSync stable until dependencies change", async () => {
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+        const seenCallbacks: Array<(value: number) => string> = []
+
+        const Probe = Component.makeUntraced("UseCallbackSyncProbe")(function*(props: { readonly prefix: string }) {
+            const callback = yield* Component.useCallbackSync(
+                (value: number) => Effect.succeed(`${props.prefix}:${value}`),
+                [props.prefix],
+            )
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                seenCallbacks.push(callback)
+            }))
+
+            React.useEffect(() => {
+                seenCallbacks.push(callback)
+            }, [callback])
+
+            return <div>{callback(1)}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe prefix="a" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("a:1")
+        const initialLength = seenCallbacks.length
+        const initialCallback = seenCallbacks.at(-1)
+        expect(initialCallback?.(2)).toBe("a:2")
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe prefix="a" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("a:1")
+        expect(seenCallbacks).toHaveLength(initialLength)
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe prefix="b" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("b:1")
+        await waitFor(() => expect(seenCallbacks.length).toBeGreaterThan(initialLength))
+        expect(seenCallbacks.at(-1)).not.toBe(initialCallback)
+        expect(seenCallbacks.at(-1)?.(2)).toBe("b:2")
+
+        view.unmount()
+        await runtime.runtime.dispose()
+    })
+
+    it("delays cleanup according to finalizerExecutionDebounce", async () => {
+        const cleanup = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const Probe = Component.makeUntraced("DebouncedCleanupProbe")(function*(props: { readonly value: string }) {
+            const result = yield* Component.useOnChange(
+                () => Effect.gen(function*() {
+                    yield* Effect.addFinalizer(() => Effect.sync(() => cleanup(props.value)))
+                    return props.value
+                }),
+                [props.value],
+                { finalizerExecutionDebounce: "20 millis" },
+            )
+
+            return <div>{result}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="first" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe value="second" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("second")
+        expect(cleanup).not.toHaveBeenCalled()
+
+        await new Promise(resolve => setTimeout(resolve, 5))
+        expect(cleanup).not.toHaveBeenCalled()
+
+        await waitFor(() => expect(cleanup).toHaveBeenCalledWith("first"), { timeout: 100 })
+
+        view.unmount()
+        await waitFor(() => expect(cleanup).toHaveBeenCalledWith("second"), { timeout: 100 })
+        await runtime.runtime.dispose()
+    })
+
+    it("does not remount a component when only nonReactiveTags change", async () => {
+        const mounts = vi.fn()
+        const unmounts = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const SubComponent = Component.makeUntraced("NonReactiveSubComponent")(function*() {
+            const service = yield* ValueService
+            const [count, setCount] = React.useState(0)
+
+            yield* Component.useOnMount(() => Effect.gen(function*() {
+                yield* Effect.sync(() => mounts())
+                yield* Effect.addFinalizer(() => Effect.sync(() => unmounts()))
+            }))
+
+            return <button onClick={() => setCount(value => value + 1)}>{`${service.value}:${count}`}</button>
+        }).pipe(
+            Component.withOptions({
+                nonReactiveTags: [...Component.defaultOptions.nonReactiveTags, ValueService],
+            })
+        )
+
+        const Parent = Component.makeUntraced("NonReactiveParent")(function*(props: { readonly value: string }) {
+            const serviceLayer = React.useMemo(
+                () => Layer.succeed(ValueService, { value: props.value }),
+                [props.value],
+            )
+            const context = yield* Component.useLayer(serviceLayer, {
+                finalizerExecutionDebounce: 0,
+            })
+            const Child = yield* Effect.provide(SubComponent.use, context)
+
+            return <Child />
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Parent value="first" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first:0")
+        const initialMounts = mounts.mock.calls.length
+        expect(initialMounts).toBeGreaterThan(0)
+        expect(unmounts).not.toHaveBeenCalled()
+
+        fireEvent.click(screen.getByRole("button", { name: "first:0" }))
+        await screen.findByText("first:1")
+
+        view.rerender(
+            <runtime.context.Provider value={effectRuntime}>
+                <Parent value="second" />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("second:1")
+        expect(mounts).toHaveBeenCalledTimes(initialMounts)
+        expect(unmounts).not.toHaveBeenCalled()
+
+        view.unmount()
+        await waitFor(() => expect(unmounts).toHaveBeenCalledTimes(1))
+        await runtime.runtime.dispose()
+    })
+
+    it("does not commit effects or retain registered scopes for a discarded Suspense render", async () => {
+        const setup = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+        const scopeRegistry = Context.get(effectRuntime, ScopeRegistry.ScopeRegistry)
+        const pending = new Promise<void>(() => {})
+
+        const Probe = Component.makeUntraced("DiscardedSuspenseProbe")(function*() {
+            yield* Component.useReactEffect(() => Effect.sync(setup), [])
+            React.use(pending)
+            return <div>committed</div>
+        }).pipe(
+            Component.withOptions({ scopeCommitTimeout: "10 millis" }),
+            Component.withContext(runtime.context)
+        )
+
+        let view!: ReturnType<typeof render>
+        await act(async () => {
+            view = render(
+                <React.Suspense fallback={<div>fallback</div>}>
+                    <runtime.context.Provider value={effectRuntime}>
+                        <Probe />
+                    </runtime.context.Provider>
+                </React.Suspense>
+            )
+        })
+
+        try {
+            await screen.findByText("fallback")
+            expect(setup).not.toHaveBeenCalled()
+            await waitFor(() => expect(HashMap.size(Effect.runSync(SubscriptionRef.get(scopeRegistry.ref)))).toBe(0))
+        }
+        finally {
+            view.unmount()
+            await runtime.runtime.dispose()
+        }
+    })
+
+    it("keeps committed scopes alive without heartbeats", async () => {
+        const acquisitions = vi.fn()
+        const releases = vi.fn()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+        const scopeRegistry = Context.get(effectRuntime, ScopeRegistry.ScopeRegistry)
+
+        const Probe = Component.makeUntraced("CommittedScopeProbe")(function*() {
+            yield* Component.useOnMount(() => Effect.gen(function*() {
+                yield* Effect.sync(acquisitions)
+                yield* Effect.addFinalizer(() => Effect.sync(releases))
+            }))
+
+            return <div>committed</div>
+        }).pipe(
+            Component.withOptions({
+                finalizerExecutionDebounce: "10 millis",
+                scopeCommitTimeout: "10 millis",
+            }),
+            Component.withContext(runtime.context),
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("committed")
+        await waitFor(() => expect(releases).toHaveBeenCalledTimes(acquisitions.mock.calls.length - 1))
+        await new Promise(resolve => setTimeout(resolve, 30))
+
+        expect(HashMap.size(Effect.runSync(SubscriptionRef.get(scopeRegistry.ref)))).toBe(1)
+        expect(releases).toHaveBeenCalledTimes(acquisitions.mock.calls.length - 1)
+
+        view.unmount()
+        await waitFor(() => expect(releases).toHaveBeenCalledTimes(acquisitions.mock.calls.length))
+        await waitFor(() => expect(HashMap.size(Effect.runSync(SubscriptionRef.get(scopeRegistry.ref)))).toBe(0))
+        await runtime.runtime.dispose()
+    })
+
+    it("does not expire a scope while a descendant is suspended past the finalizer debounce", async () => {
+        const runtime = ReactRuntime.make(Layer.empty)
+        let resolve!: () => void
+        const pending = new Promise<void>(complete => {
+            resolve = complete
+        })
+
+        const Suspended = () => {
+            React.use(pending)
+            return <div>committed</div>
+        }
+
+        let view!: ReturnType<typeof render>
+        await act(async () => {
+            view = render(
+                <ReactRuntime.Provider runtime={runtime} fallback={<div>fallback</div>}>
+                    <Suspended />
+                </ReactRuntime.Provider>
+            )
+        })
+
+        try {
+            await screen.findByText("fallback")
+            await new Promise(resolve => setTimeout(resolve, 150))
+            await act(async () => {
+                resolve()
+                await pending
+            })
+            await screen.findByText("committed")
+        }
+        finally {
+            view.unmount()
+            await runtime.runtime.dispose()
+        }
+    })
+
+    it("clears ScopeRegistry after a suspended render retries, commits, and unmounts", async () => {
+        const lifecycle = vi.fn<(message: string) => void>()
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+        const scopeRegistry = Context.get(effectRuntime, ScopeRegistry.ScopeRegistry)
+        let resolve!: () => void
+        const pending = new Promise<void>(complete => {
+            resolve = complete
+        })
+
+        const Probe = Component.makeUntraced("RetriedSuspenseProbe")(function*() {
+            React.use(pending)
+            yield* Component.useReactEffect(() => Effect.gen(function*() {
+                yield* Effect.sync(() => lifecycle("mount"))
+                yield* Effect.addFinalizer(() => Effect.sync(() => lifecycle("cleanup")))
+            }), [])
+            return <div>committed</div>
+        }).pipe(
+            Component.withOptions({ scopeCommitTimeout: "10 millis" }),
+            Component.withContext(runtime.context)
+        )
+
+        let view!: ReturnType<typeof render>
+        await act(async () => {
+            view = render(
+                <React.Suspense fallback={<div>fallback</div>}>
+                    <runtime.context.Provider value={effectRuntime}>
+                        <Probe />
+                    </runtime.context.Provider>
+                </React.Suspense>
+            )
+        })
+
+        try {
+            await screen.findByText("fallback")
+            await act(async () => {
+                resolve()
+                await pending
+            })
+            await screen.findByText("committed")
+            await waitFor(() => expect(lifecycle).toHaveBeenCalledWith("mount"))
+
+            view.unmount()
+            await waitFor(() => expect(HashMap.size(Effect.runSync(SubscriptionRef.get(scopeRegistry.ref)))).toBe(0))
+            expect(lifecycle.mock.calls.filter(([message]) => message === "mount")).toHaveLength(2)
+            expect(lifecycle.mock.calls.filter(([message]) => message === "cleanup")).toHaveLength(2)
+        }
+        finally {
+            view.unmount()
+            await runtime.runtime.dispose()
+        }
+    })
+
+    it("refreshes a registered body while preserving or resetting local state", async () => {
+        const runtime = ReactRuntime.make(Layer.empty)
+        const effectRuntime = await runtime.runtime.context()
+
+        const makeProbe = (label: string) => Component.makeUntraced("RefreshProbe")(function*() {
+            const [count, setCount] = React.useState(0)
+            return <button type="button" onClick={() => setCount(value => value + 1)}>{label}:{count}</button>
+        })
+        const original = makeProbe("old")
+        const cell = Refreshable.makeCell(original, "hooks", false)
+        Refreshable.attach(original, cell)
+
+        const Probe = Component.withContext(original, runtime.context)
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        fireEvent.click(await screen.findByRole("button"))
+        expect(screen.getByRole("button").textContent).toBe("old:1")
+
+        await act(async () => {
+            cell.update(makeProbe("compatible"), "hooks", false)
+            await Promise.resolve()
+        })
+        expect(screen.getByRole("button").textContent).toBe("compatible:1")
+
+        await act(async () => {
+            cell.update(makeProbe("reset"), "changed-hooks", false)
+            await Promise.resolve()
+        })
+        expect(screen.getByRole("button").textContent).toBe("reset:0")
+
+        view.unmount()
+        await runtime.runtime.dispose()
+    })
+})
@@ -0,0 +1,165 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react"
+import { Effect, Layer, SubscriptionRef } from "effect"
+import * as React from "react"
+import { describe, expect, it } from "vitest"
+import * as Component from "./Component.js"
+import * as Lens from "./Lens.js"
+import * as ReactRuntime from "./ReactRuntime.js"
+
+
+const makeRuntime = async () => {
+    const runtime = ReactRuntime.make(Layer.empty)
+    const effectRuntime = await runtime.runtime.context()
+
+    return {
+        runtime,
+        effectRuntime,
+        dispose: () => runtime.runtime.dispose(),
+    }
+}
+
+describe("Lens", () => {
+    it("useState stays in sync with lens updates in both directions", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const ref = await Effect.runPromise(SubscriptionRef.make(0))
+        const lens = Lens.fromSubscriptionRef(ref)
+
+        const Probe = Component.makeUntraced("LensUseStateProbe")(function*() {
+            const [value, setValue] = yield* Lens.useState(lens)
+
+            return (
+                <>
+                    <div>{value}</div>
+                    <button onClick={() => setValue(previous => previous + 1)}>increment</button>
+                </>
+            )
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("0")
+
+        await Effect.runPromise(Lens.set(lens, 5))
+        await screen.findByText("5")
+
+        fireEvent.click(screen.getByRole("button", { name: "increment" }))
+        await screen.findByText("6")
+        expect(await Effect.runPromise(Lens.get(lens))).toBe(6)
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useState respects the provided equivalence when subscribing to lens changes", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const ref = await Effect.runPromise(SubscriptionRef.make({ id: 1, label: "first" }))
+        const lens = Lens.fromSubscriptionRef(ref)
+
+        const Probe = Component.makeUntraced("LensUseStateEquivalenceProbe")(function*() {
+            const [value] = yield* Lens.useState(lens, {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+
+        await Effect.runPromise(Lens.set(lens, { id: 1, label: "ignored" }))
+        await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
+        expect(screen.queryByText("ignored")).toBeNull()
+
+        await Effect.runPromise(Lens.set(lens, { id: 2, label: "updated" }))
+        await screen.findByText("updated")
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useFromReactState writes React state changes into the returned lens", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        let lens: Lens.Lens<string, never, never, never, never> | undefined
+
+        const Probe = Component.makeUntraced("LensUseFromReactStateProbe")(function*() {
+            const [value, setValue] = React.useState("hello")
+            const reactLens = yield* Lens.useFromReactState([value, setValue])
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <button onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("hello")
+        await waitFor(() => expect(lens).toBeDefined())
+
+        fireEvent.click(screen.getByRole("button", { name: "hello" }))
+        await screen.findByText("hello!")
+        await waitFor(async () => expect(await Effect.runPromise(Lens.get(lens!))).toBe("hello!"))
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useFromReactState respects equivalence when lens updates flow back into React state", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        let lens: Lens.Lens<{ readonly id: number; readonly label: string }, never, never, never, never> | undefined
+
+        const Probe = Component.makeUntraced("LensUseFromReactStateEquivalenceProbe")(function*() {
+            const [value, setValue] = React.useState({ id: 1, label: "first" })
+            const reactLens = yield* Lens.useFromReactState([value, setValue], {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+        await waitFor(() => expect(lens).toBeDefined())
+
+        await Effect.runPromise(Lens.set(lens!, { id: 1, label: "ignored" }))
+        await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
+        expect(screen.queryByText("ignored")).toBeNull()
+
+        await Effect.runPromise(Lens.set(lens!, { id: 2, label: "updated" }))
+        await screen.findByText("updated")
+
+        view.unmount()
+        await dispose()
+    })
+})
@@ -0,0 +1,167 @@
+import { Effect, type Scope, Stream } from "effect"
+import { AsyncResult } from "effect/unstable/reactivity"
+import { describe, expect, it } from "vitest"
+import * as Query from "./Query.js"
+import * as QueryClient from "./QueryClient.js"
+import * as View from "./View.js"
+
+
+const runQueryTest = <A, E>(effect: Effect.Effect<A, E, QueryClient.QueryClient | Scope.Scope>) =>
+    Effect.runPromise(Effect.scoped(effect.pipe(
+        Effect.provide(QueryClient.layer()),
+    )))
+
+const staticKey = <K>(key: K): View.View<K> => View.make({
+    get: Effect.succeed(key),
+    changes: Stream.make(key),
+})
+
+const expectSuccessValue = <A, E>(
+    state: Query.FinalQueryState<unknown, A, E>,
+): A => {
+    expect(AsyncResult.isSuccess(state.result)).toBe(true)
+
+    if (!AsyncResult.isSuccess(state.result))
+        throw new Error(`Expected Success result, received ${state.result._tag}`)
+
+    return state.result.value
+}
+
+describe("Query", () => {
+    it("fetch caches successful results until they are invalidated or stale", async () => {
+        let calls = 0
+        const key = staticKey<readonly [number]>([1])
+
+        const result = await runQueryTest(Effect.gen(function*() {
+            const query = yield* Query.make({
+                key,
+                f: ([id]: readonly [number]) => Effect.sync(() => {
+                    calls += 1
+                    return `value:${id}:${calls}`
+                }),
+                staleTime: "1 minute",
+            })
+
+            const first = yield* query.fetch([1])
+            const second = yield* query.fetch([1])
+
+            return [first, second] as const
+        }))
+
+        expect(calls).toBe(1)
+        expect(expectSuccessValue(result[0])).toBe("value:1:1")
+        expect(expectSuccessValue(result[1])).toBe("value:1:1")
+    })
+
+    it("refresh reruns the latest query key", async () => {
+        let calls = 0
+        const key = staticKey<readonly [number]>([1])
+
+        const result = await runQueryTest(Effect.gen(function*() {
+            const query = yield* Query.make({
+                key,
+                f: ([id]: readonly [number]) => Effect.sync(() => {
+                    calls += 1
+                    return `value:${id}:${calls}`
+                }),
+                staleTime: "0 millis",
+            })
+
+            const first = yield* query.fetch([1])
+            yield* Effect.sleep("1 millis")
+            const refreshed = yield* query.refresh
+
+            return [first, refreshed] as const
+        }))
+
+        expect(calls).toBe(2)
+        expect(expectSuccessValue(result[0])).toBe("value:1:1")
+        expect(expectSuccessValue(result[1])).toBe("value:1:2")
+    })
+
+    it("invalidateCacheEntry forces the next fetch for that key to rerun", async () => {
+        let calls = 0
+        const key = staticKey<readonly [number]>([1])
+
+        const result = await runQueryTest(Effect.gen(function*() {
+            const query = yield* Query.make({
+                key,
+                f: ([id]: readonly [number]) => Effect.sync(() => {
+                    calls += 1
+                    return `value:${id}:${calls}`
+                }),
+                staleTime: "1 minute",
+            })
+
+            const first = yield* query.fetch([1])
+            yield* query.invalidateCacheEntry([1])
+            const second = yield* query.fetch([1])
+
+            return [first, second] as const
+        }))
+
+        expect(calls).toBe(2)
+        expect(expectSuccessValue(result[0])).toBe("value:1:1")
+        expect(expectSuccessValue(result[1])).toBe("value:1:2")
+    })
+
+    it("invalidateCache clears cached entries for the query function", async () => {
+        let calls = 0
+        const key = staticKey<readonly [number]>([1])
+
+        const result = await runQueryTest(Effect.gen(function*() {
+            const query = yield* Query.make({
+                key,
+                f: ([id]: readonly [number]) => Effect.sync(() => {
+                    calls += 1
+                    return `value:${id}:${calls}`
+                }),
+                staleTime: "1 minute",
+            })
+
+            const first = yield* query.fetch([1])
+            yield* query.invalidateCache
+            const second = yield* query.fetch([1])
+
+            return [first, second] as const
+        }))
+
+        expect(calls).toBe(2)
+        expect(expectSuccessValue(result[0])).toBe("value:1:1")
+        expect(expectSuccessValue(result[1])).toBe("value:1:2")
+    })
+
+    it("service starts the key view automatically and records its latest final state", async () => {
+        let calls = 0
+        const key = staticKey<readonly [number]>([1])
+
+        const effect = Effect.gen(function*() {
+            const query = yield* Query.service({
+                key,
+                f: ([id]: readonly [number]) => Effect.sync(() => {
+                    calls += 1
+                    return `value:${id}:${calls}`
+                }),
+                staleTime: "1 minute",
+            })
+
+            const latestFinalState = yield* Effect.sleep("1 millis").pipe(
+                Effect.andThen(View.get(query.latestFinalState)),
+                Effect.flatMap(Effect.fromOption),
+                Effect.eventually,
+                Effect.timeout("1 second"),
+            )
+
+            return {
+                state: yield* View.get(query.state),
+                latestFinalState,
+            }
+        })
+
+        const result = await runQueryTest(effect)
+
+        expect(calls).toBe(1)
+        expect(result.state.key).toEqual([1])
+        expect(expectSuccessValue(result.latestFinalState)).toBe("value:1:1")
+    })
+})
@@ -0,0 +1,60 @@
+import { describe, expect, it, vi } from "vitest"
+import type * as Component from "./Component.js"
+import * as Refreshable from "./Refreshable.js"
+
+
+describe("Refreshable", () => {
+    it("attaches a cell and notifies subscribers after a compatible update", async () => {
+        const first = {} as Component.Component.Any
+        const cell = Refreshable.makeCell(first, "hooks", false)
+        const listener = vi.fn()
+
+        expect(Refreshable.isRefreshable(first)).toBe(false)
+        const attached = Refreshable.attach(first, cell)
+        expect(attached).toBe(first)
+        expect(Refreshable.isRefreshable(first)).toBe(true)
+        expect(attached[Refreshable.RefreshableTypeId]).toBe(cell)
+        expect(Object.getPrototypeOf(attached).asFunctionComponent)
+            .toBe(Refreshable.RefreshablePrototype.asFunctionComponent)
+
+        cell.subscribe(listener)
+        const second = {} as Component.Component.Any
+        cell.update(second, "hooks", false)
+
+        expect(cell.current).toBe(second)
+        expect(cell.snapshot).toEqual({
+            revision: 1,
+            resetRevision: 0,
+        })
+
+        await Promise.resolve()
+        expect(listener).toHaveBeenCalledTimes(1)
+    })
+
+    it("requests a remount when a signature changes or reset is forced", () => {
+        const component = {} as Component.Component.Any
+        const cell = Refreshable.makeCell(component, "one", false)
+
+        cell.update({} as Component.Component.Any, "two", false)
+        expect(cell.snapshot.resetRevision).toBe(1)
+
+        cell.update({} as Component.Component.Any, "two", true)
+        expect(cell.snapshot.resetRevision).toBe(2)
+    })
+
+    it("builds the refresh shell from the current descriptor implementation", () => {
+        const implementation = () => null
+        const makeFunctionComponent = vi.fn(() => implementation)
+        const component = {
+            makeFunctionComponent,
+        } as unknown as Component.ComponentImpl.Any
+        const contextRef = {
+            current: {},
+        } as never
+        const cell = Refreshable.makeCell(component, "hooks", false)
+        const attached = Refreshable.attach(component, cell)
+
+        expect(attached.asFunctionComponent(contextRef)).not.toBe(implementation)
+        expect(makeFunctionComponent).toHaveBeenCalledWith(contextRef)
+    })
+})
@@ -0,0 +1,94 @@
+import { render, screen, waitFor } from "@testing-library/react"
+import { Effect, Layer, SubscriptionRef } from "effect"
+import { Lens } from "effect-lens"
+import { describe, expect, it } from "vitest"
+import * as Component from "./Component.js"
+import * as ReactRuntime from "./ReactRuntime.js"
+import * as View from "./View.js"
+
+
+const makeRuntime = async () => {
+    const runtime = ReactRuntime.make(Layer.empty)
+    const effectRuntime = await runtime.runtime.context()
+
+    return {
+        runtime,
+        effectRuntime,
+        dispose: () => runtime.runtime.dispose(),
+    }
+}
+
+describe("View", () => {
+    it("useAll returns the latest values and rerenders when any input changes", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const countRef = await Effect.runPromise(SubscriptionRef.make(1))
+        const labelRef = await Effect.runPromise(SubscriptionRef.make("a"))
+        const count = Lens.fromSubscriptionRef(countRef)
+        const label = Lens.fromSubscriptionRef(labelRef)
+
+        const Probe = Component.makeUntraced("ViewUseAllProbe")(function*() {
+            const [currentCount, currentLabel] = yield* View.useAll([count, label])
+
+            return <div>{`${currentCount}:${currentLabel}`}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("1:a")
+
+        await Effect.runPromise(Lens.set(count, 2))
+        await screen.findByText("2:a")
+
+        await Effect.runPromise(Lens.set(label, "b"))
+        await screen.findByText("2:b")
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useAll respects the provided equivalence when processing updates", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const itemRef = await Effect.runPromise(SubscriptionRef.make({ id: 1, label: "first" }))
+        const flagRef = await Effect.runPromise(SubscriptionRef.make(true))
+        const item = Lens.fromSubscriptionRef(itemRef)
+        const flag = Lens.fromSubscriptionRef(flagRef)
+
+        const Probe = Component.makeUntraced("ViewUseAllEquivalenceProbe")(function*() {
+            const [currentItem, currentFlag] = yield* View.useAll([item, flag], {
+                equivalence: ([selfItem, selfFlag], [thatItem, thatFlag]) =>
+                    selfItem.id === thatItem.id && selfFlag === thatFlag,
+            })
+
+            return <div>{`${currentItem.label}:${currentFlag ? "on" : "off"}`}</div>
+        }).pipe(
+            Component.withContext(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first:on")
+
+        await Effect.runPromise(Lens.set(item, { id: 1, label: "ignored" }))
+        await waitFor(() => expect(screen.getByText("first:on")).toBeTruthy())
+        expect(screen.queryByText("ignored:on")).toBeNull()
+
+        await Effect.runPromise(Lens.set(flag, false))
+        await screen.findByText("ignored:off")
+
+        await Effect.runPromise(Lens.set(item, { id: 2, label: "updated" }))
+        await screen.findByText("updated:off")
+
+        view.unmount()
+        await dispose()
+    })
+})
@@ -0,0 +1,4 @@
+import { configure } from "@testing-library/react"
+
+
+configure({ reactStrictMode: true })