diff --git a/packages/opencode/test/effect/managed-runtime.test.ts b/packages/opencode/test/effect/managed-runtime.test.ts
new file mode 100644
index 0000000000..35ca382cc1
--- /dev/null
+++ b/packages/opencode/test/effect/managed-runtime.test.ts
@@ -0,0 +1,78 @@
+import { describe, expect, test } from "bun:test"
+import { Context, Effect, Layer } from "effect"
+import { makeManagedRuntime } from "@/effect/managed-runtime"
+import { lazy } from "@/util/lazy"
+
+class Counter extends Context.Service<Counter, { readonly value: number }>()("@test/Counter") {}
+
+const layerWith = (value: number) => Layer.succeed(Counter, { value })
+
+describe("makeManagedRuntime", () => {
+  test("disposing an unbuilt runtime is a no-op", async () => {
+    const rt = makeManagedRuntime(layerWith(0))
+    expect(rt.peek()).toBeUndefined()
+    await rt.dispose()
+    expect(rt.peek()).toBeUndefined()
+  })
+
+  test("disposing rebuilds on next access", async () => {
+    const rt = makeManagedRuntime(layerWith(7))
+    const first = rt()
+    const value = await first.runPromise(
+      Effect.gen(function* () {
+        return (yield* Counter).value
+      }),
+    )
+    expect(value).toBe(7)
+
+    await rt.dispose()
+    expect(rt.peek()).toBeUndefined()
+
+    const second = rt()
+    expect(second).not.toBe(first)
+    expect(rt.peek()).toBe(second)
+    await rt.dispose()
+  })
+
+  test("dispose() does not clobber a runtime that was rebuilt mid-dispose", async () => {
+    // Simulates a race where dispose() ran on instance A, then someone
+    // invoked the lazy and got a fresh instance B before dispose() returned.
+    // The resetIf guard must leave instance B intact.
+    const rt = makeManagedRuntime(layerWith(1))
+    const first = rt()
+    rt.reset() // force-eject the lazy
+    const second = rt() // build a new instance, distinct from first
+    expect(second).not.toBe(first)
+
+    // Calling dispose() now should tear down `second` (the current value),
+    // not the orphaned `first`.
+    await rt.dispose()
+    expect(rt.peek()).toBeUndefined()
+  })
+})
+
+describe("lazy.resetIf", () => {
+  test("resets when the value matches", () => {
+    const factory = lazy(() => ({}))
+    const value = factory()
+    expect(factory.peek()).toBe(value)
+    factory.resetIf(value)
+    expect(factory.peek()).toBeUndefined()
+  })
+
+  test("leaves the lazy intact when the value does not match", () => {
+    const factory = lazy(() => ({}))
+    const captured = factory()
+    factory.reset()
+    const fresh = factory()
+    expect(fresh).not.toBe(captured)
+    factory.resetIf(captured)
+    expect(factory.peek()).toBe(fresh)
+  })
+
+  test("is a no-op on an unloaded lazy", () => {
+    const factory = lazy(() => ({}))
+    factory.resetIf({} as never)
+    expect(factory.peek()).toBeUndefined()
+  })
+})
diff --git a/packages/opencode/test/storage/db-effect.test.ts b/packages/opencode/test/storage/db-effect.test.ts
new file mode 100644
index 0000000000..648eaaae9a
--- /dev/null
+++ b/packages/opencode/test/storage/db-effect.test.ts
@@ -0,0 +1,119 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { Effect, ManagedRuntime } from "effect"
+import { memoMap } from "@opencode-ai/core/effect/memo-map"
+import { Database } from "@/storage/db"
+import { DatabaseEffect } from "@/storage/db-effect"
+import { resetDatabase } from "../fixture/db"
+
+afterEach(async () => {
+  await resetDatabase()
+})
+
+describe("DatabaseEffect.layer", () => {
+  test("yields a working Service that round-trips a query", async () => {
+    const rt = ManagedRuntime.make(DatabaseEffect.layer)
+    try {
+      const value = await rt.runPromise(
+        Effect.gen(function* () {
+          const db = yield* DatabaseEffect.Service
+          return db.$client.prepare("SELECT 42 as n").get() as { n: number }
+        }),
+      )
+      expect(value).toEqual({ n: 42 })
+    } finally {
+      await rt.dispose()
+    }
+  })
+
+  test("rebuilds a fresh handle after Database.close + runtime dispose", async () => {
+    const rt1 = ManagedRuntime.make(DatabaseEffect.layer)
+    const first = await rt1.runPromise(Effect.sync(() => Database.Client().$client))
+    expect(first.prepare("SELECT 1 as n").get()).toEqual({ n: 1 })
+
+    await rt1.dispose()
+    Database.close()
+
+    const rt2 = ManagedRuntime.make(DatabaseEffect.layer)
+    try {
+      const second = await rt2.runPromise(
+        Effect.gen(function* () {
+          const db = yield* DatabaseEffect.Service
+          return db.$client
+        }),
+      )
+      expect(second).not.toBe(first)
+      expect(second.prepare("SELECT 1 as n").get()).toEqual({ n: 1 })
+    } finally {
+      await rt2.dispose()
+    }
+  })
+})
+
+// Regression for the memoMap lifecycle bug. The shared layer memoMap caches
+// every `DatabaseEffect.layer` build across every runtime built with
+// `makeManagedRuntime`. If a runtime that consumed the layer is NOT disposed
+// before `Database.close()`, the cached Service value (a Drizzle wrapper
+// over a now-closed `bun:sqlite` handle) persists in the memoMap and any
+// subsequent runtime that consumes the layer reuses it and operates on a
+// closed handle.
+//
+// `test/fixture/db.ts:resetDatabase` disposes every module-scoped runtime
+// before closing the DB to release the memoMap entries. The two tests below
+// pin both halves of the invariant.
+describe("DatabaseEffect.layer + shared memoMap lifecycle", () => {
+  test("disposing a runtime releases its memoMap entry so the next build sees a fresh DB handle", async () => {
+    const rt1 = ManagedRuntime.make(DatabaseEffect.layer, { memoMap })
+    const captured = await rt1.runPromise(Effect.sync(() => Database.Client().$client))
+    expect(captured.prepare("SELECT 1 as n").get()).toEqual({ n: 1 })
+
+    await rt1.dispose()
+    Database.close()
+
+    const rt2 = ManagedRuntime.make(DatabaseEffect.layer, { memoMap })
+    try {
+      const fresh = await rt2.runPromise(
+        Effect.gen(function* () {
+          const db = yield* DatabaseEffect.Service
+          return db.$client
+        }),
+      )
+      expect(fresh).not.toBe(captured)
+      expect(fresh.prepare("SELECT 1 as n").get()).toEqual({ n: 1 })
+    } finally {
+      await rt2.dispose()
+    }
+  })
+
+  test("a stale runtime kept alive over Database.close poisons later memoMap consumers", async () => {
+    const stale = ManagedRuntime.make(DatabaseEffect.layer, { memoMap })
+    const captured = await stale.runPromise(
+      Effect.gen(function* () {
+        const db = yield* DatabaseEffect.Service
+        return db.$client
+      }),
+    )
+    expect(captured.prepare("SELECT 1 as n").get()).toEqual({ n: 1 })
+
+    // Intentionally do NOT dispose `stale` before closing the DB. This is
+    // the shape of the bug `resetDatabase` guards against.
+    Database.close()
+
+    const next = ManagedRuntime.make(DatabaseEffect.layer, { memoMap })
+    try {
+      const seen = await next.runPromise(
+        Effect.gen(function* () {
+          const db = yield* DatabaseEffect.Service
+          return db.$client
+        }),
+      )
+      // The memoMap returned the same stale handle because `stale` was
+      // never disposed. The underlying connection is closed, so any query
+      // on the handle throws.
+      expect(seen).toBe(captured)
+      expect(() => seen.prepare("SELECT 1 as n").get()).toThrow()
+    } finally {
+      await next.dispose()
+      await stale.dispose()
+    }
+  })
+})