diff --git a/packages/effect-fc/test/Lens.test.tsx b/packages/effect-fc/test/Lens.test.tsx
new file mode 100644
index 0000000..4728bfc
--- /dev/null
+++ b/packages/effect-fc/test/Lens.test.tsx
@@ -0,0 +1,166 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react"
+import { Effect, Layer, SubscriptionRef } from "effect"
+import { Lens } from "effect-lens"
+import * as React from "react"
+import { describe, expect, it } from "vitest"
+import * as Component from "../src/Component.js"
+import * as LensModule from "../src/Lens.js"
+import * as ReactRuntime from "../src/ReactRuntime.js"
+
+
+const makeRuntime = async () => {
+    const runtime = ReactRuntime.make(Layer.empty)
+    const effectRuntime = await Effect.runPromise(runtime.runtime.runtimeEffect)
+
+    return {
+        runtime,
+        effectRuntime,
+        dispose: () => Effect.runPromise(runtime.runtime.disposeEffect),
+    }
+}
+
+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* LensModule.useState(lens)
+
+            return (
+                <>
+                    <div>{value}</div>
+                    <button onClick={() => setValue(previous => previous + 1)}>increment</button>
+                </>
+            )
+        }).pipe(
+            Component.withRuntime(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* LensModule.useState(lens, {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withRuntime(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* LensModule.useFromReactState([value, setValue])
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <button onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
+        }).pipe(
+            Component.withRuntime(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* LensModule.useFromReactState([value, setValue], {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withRuntime(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()
+    })
+})
diff --git a/packages/effect-fc/test/Subscribable.test.tsx b/packages/effect-fc/test/Subscribable.test.tsx
new file mode 100644
index 0000000..eec6289
--- /dev/null
+++ b/packages/effect-fc/test/Subscribable.test.tsx
@@ -0,0 +1,130 @@
+import { render, screen, waitFor } from "@testing-library/react"
+import { Effect, Fiber, Layer, Stream, SubscriptionRef } from "effect"
+import { Lens } from "effect-lens"
+import * as React from "react"
+import { describe, expect, it } from "vitest"
+import * as Component from "../src/Component.js"
+import * as ReactRuntime from "../src/ReactRuntime.js"
+import * as SubscribableModule from "../src/Subscribable.js"
+
+
+const makeRuntime = async () => {
+    const runtime = ReactRuntime.make(Layer.empty)
+    const effectRuntime = await Effect.runPromise(runtime.runtime.runtimeEffect)
+
+    return {
+        runtime,
+        effectRuntime,
+        dispose: () => Effect.runPromise(runtime.runtime.disposeEffect),
+    }
+}
+
+describe("Subscribable", () => {
+    it("zipLatestAll reads current values from all inputs", async () => {
+        const leftRef = await Effect.runPromise(SubscriptionRef.make(1))
+        const rightRef = await Effect.runPromise(SubscriptionRef.make("a"))
+        const left = Lens.fromSubscriptionRef(leftRef)
+        const right = Lens.fromSubscriptionRef(rightRef)
+
+        const zipped = SubscribableModule.zipLatestAll(left, right)
+
+        expect(await Effect.runPromise(zipped.get)).toEqual([1, "a"])
+    })
+
+    it("zipLatestAll emits updates when any input changes", async () => {
+        const leftRef = await Effect.runPromise(SubscriptionRef.make(1))
+        const rightRef = await Effect.runPromise(SubscriptionRef.make("a"))
+        const left = Lens.fromSubscriptionRef(leftRef)
+        const right = Lens.fromSubscriptionRef(rightRef)
+
+        const zipped = SubscribableModule.zipLatestAll(left, right)
+        const values: Array<readonly [number, string]> = []
+
+        const collector = Effect.runFork(Effect.scoped(zipped.changes.pipe(
+            Stream.runForEach(value => Effect.sync(() => {
+                values.push(value as readonly [number, string])
+            })),
+        )))
+
+        await Effect.runPromise(Lens.set(left, 2))
+        await waitFor(() => expect(values).toContainEqual([2, "a"]))
+
+        await Effect.runPromise(Lens.set(right, "b"))
+        await waitFor(() => expect(values).toContainEqual([2, "b"]))
+
+        Fiber.interruptFork(collector)
+    })
+
+    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("SubscribableUseAllProbe")(function*() {
+            const [currentCount, currentLabel] = yield* SubscribableModule.useAll([count, label])
+
+            return <div>{`${currentCount}:${currentLabel}`}</div>
+        }).pipe(
+            Component.withRuntime(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("1:a")
+
+        await Effect.runPromise(Lens.set(count, 2))
+        await screen.findByText("2:a")
+
+        await Effect.runPromise(Lens.set(label, "b"))
+        await screen.findByText("2:b")
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useAll respects the provided equivalence when processing updates", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const itemRef = await Effect.runPromise(SubscriptionRef.make({ id: 1, label: "first" }))
+        const flagRef = await Effect.runPromise(SubscriptionRef.make(true))
+        const item = Lens.fromSubscriptionRef(itemRef)
+        const flag = Lens.fromSubscriptionRef(flagRef)
+
+        const Probe = Component.makeUntraced("SubscribableUseAllEquivalenceProbe")(function*() {
+            const [currentItem, currentFlag] = yield* SubscribableModule.useAll([item, flag], {
+                equivalence: ([selfItem, selfFlag], [thatItem, thatFlag]) =>
+                    selfItem.id === thatItem.id && selfFlag === thatFlag,
+            })
+
+            return <div>{`${currentItem.label}:${currentFlag ? "on" : "off"}`}</div>
+        }).pipe(
+            Component.withRuntime(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()
+    })
+})