diff --git a/packages/opencode/test/server/session-messages.test.ts b/packages/opencode/test/server/session-messages.test.ts
index f5ee5bdcb0..e603accbbe 100644
--- a/packages/opencode/test/server/session-messages.test.ts
+++ b/packages/opencode/test/server/session-messages.test.ts
@@ -1,191 +1,179 @@
-import { afterEach, describe, expect, test } from "bun:test"
+import { afterEach, describe, expect } from "bun:test"
 import { Effect } from "effect"
-import { WithInstance } from "../../src/project/with-instance"
 import { Server } from "../../src/server/server"
 import { Session as SessionNs } from "@/session/session"
 import { MessageV2 } from "../../src/session/message-v2"
+import { ModelID, ProviderID } from "../../src/provider/schema"
 import { MessageID, PartID, type SessionID } from "../../src/session/schema"
 import * as Log from "@opencode-ai/core/util/log"
-import { disposeAllInstances, tmpdir } from "../fixture/fixture"
+import { disposeAllInstances, TestInstance } from "../fixture/fixture"
+import { testEffect } from "../lib/effect"
 
 void Log.init({ print: false })
 
-function run<A, E>(fx: Effect.Effect<A, E, SessionNs.Service>) {
-  return Effect.runPromise(fx.pipe(Effect.provide(SessionNs.defaultLayer)))
-}
+const it = testEffect(SessionNs.defaultLayer)
 
-const svc = {
-  ...SessionNs,
-  create(input?: SessionNs.CreateInput) {
-    return run(SessionNs.Service.use((svc) => svc.create(input)))
-  },
-  remove(id: SessionID) {
-    return run(SessionNs.Service.use((svc) => svc.remove(id)))
-  },
-  updateMessage<T extends MessageV2.Info>(msg: T) {
-    return run(SessionNs.Service.use((svc) => svc.updateMessage(msg)))
-  },
-  updatePart<T extends MessageV2.Part>(part: T) {
-    return run(SessionNs.Service.use((svc) => svc.updatePart(part)))
-  },
+const model = {
+  providerID: ProviderID.make("test"),
+  modelID: ModelID.make("test"),
 }
 
 afterEach(async () => {
   await disposeAllInstances()
 })
 
-async function withoutWatcher<T>(fn: () => Promise<T>) {
-  if (process.platform !== "win32") return fn()
-  const prev = process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER
-  process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = "true"
-  try {
-    return await fn()
-  } finally {
-    if (prev === undefined) delete process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER
-    else process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = prev
-  }
+const withoutWatcher = <A, E, R>(effect: Effect.Effect<A, E, R>) => {
+  if (process.platform !== "win32") return effect
+  return Effect.acquireUseRelease(
+    Effect.sync(() => {
+      const previous = process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER
+      process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = "true"
+      return previous
+    }),
+    () => effect,
+    (previous) =>
+      Effect.sync(() => {
+        if (previous === undefined) delete process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER
+        else process.env.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = previous
+      }),
+  )
 }
 
-async function fill(sessionID: SessionID, count: number, time = (i: number) => Date.now() + i) {
-  const ids = [] as MessageID[]
-  for (let i = 0; i < count; i++) {
-    const id = MessageID.ascending()
-    ids.push(id)
-    await svc.updateMessage({
-      id,
-      sessionID,
-      role: "user",
-      time: { created: time(i) },
-      agent: "test",
-      model: { providerID: "test", modelID: "test" },
-      tools: {},
-      mode: "",
-    } as unknown as MessageV2.Info)
-    await svc.updatePart({
-      id: PartID.ascending(),
-      sessionID,
-      messageID: id,
-      type: "text",
-      text: `m${i}`,
-    })
-  }
-  return ids
+const sessionScoped = Effect.acquireRelease(
+  SessionNs.Service.use((svc) => svc.create({})),
+  (session) => SessionNs.Service.use((svc) => svc.remove(session.id)).pipe(Effect.ignore),
+)
+
+const fill = Effect.fn("SessionMessagesTest.fill")(function* (
+  sessionID: SessionID,
+  count: number,
+  time = (i: number) => Date.now() + i,
+) {
+  const session = yield* SessionNs.Service
+  return yield* Effect.forEach(
+    Array.from({ length: count }, (_, i) => i),
+    (i) =>
+      Effect.gen(function* () {
+        const id = MessageID.ascending()
+        yield* session.updateMessage({
+          id,
+          sessionID,
+          role: "user",
+          time: { created: time(i) },
+          agent: "test",
+          model,
+          tools: {},
+        } satisfies MessageV2.User)
+        yield* session.updatePart({
+          id: PartID.ascending(),
+          sessionID,
+          messageID: id,
+          type: "text",
+          text: `m${i}`,
+        } satisfies MessageV2.TextPart)
+        return id
+      }),
+  )
+})
+
+function request(path: string) {
+  return Effect.promise(() => Promise.resolve(Server.Default().app.request(path)))
+}
+
+function json<T>(response: Response) {
+  return Effect.promise(() => response.json() as Promise<T>)
 }
 
 describe("session messages endpoint", () => {
-  test("returns cursor headers for older pages", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await withoutWatcher(() =>
-      WithInstance.provide({
-        directory: tmp.path,
-        fn: async () => {
-          const session = await svc.create({})
-          const ids = await fill(session.id, 5)
-          const app = Server.Default().app
+  it.instance(
+    "returns cursor headers for older pages",
+    withoutWatcher(
+      Effect.gen(function* () {
+        const session = yield* sessionScoped
+        const ids = yield* fill(session.id, 5)
 
-          const a = await app.request(`/session/${session.id}/message?limit=2`)
-          expect(a.status).toBe(200)
-          const aBody = (await a.json()) as MessageV2.WithParts[]
-          expect(aBody.map((item) => item.info.id)).toEqual(ids.slice(-2))
-          const cursor = a.headers.get("x-next-cursor")
-          expect(cursor).toBeTruthy()
-          expect(a.headers.get("link")).toContain('rel="next"')
+        const a = yield* request(`/session/${session.id}/message?limit=2`)
+        expect(a.status).toBe(200)
+        const aBody = yield* json<MessageV2.WithParts[]>(a)
+        expect(aBody.map((item) => item.info.id)).toEqual(ids.slice(-2))
+        const cursor = a.headers.get("x-next-cursor")
+        expect(cursor).toBeTruthy()
+        expect(a.headers.get("link")).toContain('rel="next"')
 
-          const b = await app.request(`/session/${session.id}/message?limit=2&before=${encodeURIComponent(cursor!)}`)
-          expect(b.status).toBe(200)
-          const bBody = (await b.json()) as MessageV2.WithParts[]
-          expect(bBody.map((item) => item.info.id)).toEqual(ids.slice(-4, -2))
-
-          await svc.remove(session.id)
-        },
+        const b = yield* request(`/session/${session.id}/message?limit=2&before=${encodeURIComponent(cursor!)}`)
+        expect(b.status).toBe(200)
+        const bBody = yield* json<MessageV2.WithParts[]>(b)
+        expect(bBody.map((item) => item.info.id)).toEqual(ids.slice(-4, -2))
       }),
-    )
-  })
+    ),
+    { git: true },
+  )
 
-  test("keeps full-history responses when limit is omitted", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await withoutWatcher(() =>
-      WithInstance.provide({
-        directory: tmp.path,
-        fn: async () => {
-          const session = await svc.create({})
-          const ids = await fill(session.id, 3)
-          const app = Server.Default().app
+  it.instance(
+    "keeps full-history responses when limit is omitted",
+    withoutWatcher(
+      Effect.gen(function* () {
+        const session = yield* sessionScoped
+        const ids = yield* fill(session.id, 3)
 
-          const res = await app.request(`/session/${session.id}/message`)
-          expect(res.status).toBe(200)
-          const body = (await res.json()) as MessageV2.WithParts[]
-          expect(body.map((item) => item.info.id)).toEqual(ids)
-
-          await svc.remove(session.id)
-        },
+        const res = yield* request(`/session/${session.id}/message`)
+        expect(res.status).toBe(200)
+        const body = yield* json<MessageV2.WithParts[]>(res)
+        expect(body.map((item) => item.info.id)).toEqual(ids)
       }),
-    )
-  })
+    ),
+    { git: true },
+  )
 
-  test("rejects invalid cursors and missing sessions", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await withoutWatcher(() =>
-      WithInstance.provide({
-        directory: tmp.path,
-        fn: async () => {
-          const session = await svc.create({})
-          const app = Server.Default().app
+  it.instance(
+    "rejects invalid cursors and missing sessions",
+    withoutWatcher(
+      Effect.gen(function* () {
+        const session = yield* sessionScoped
 
-          const bad = await app.request(`/session/${session.id}/message?limit=2&before=bad`)
-          expect(bad.status).toBe(400)
+        const bad = yield* request(`/session/${session.id}/message?limit=2&before=bad`)
+        expect(bad.status).toBe(400)
 
-          const miss = await app.request(`/session/ses_missing/message?limit=2`)
-          expect(miss.status).toBe(404)
-
-          await svc.remove(session.id)
-        },
+        const miss = yield* request(`/session/ses_missing/message?limit=2`)
+        expect(miss.status).toBe(404)
       }),
-    )
-  })
+    ),
+    { git: true },
+  )
 
-  test("does not truncate large legacy limit requests", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await withoutWatcher(() =>
-      WithInstance.provide({
-        directory: tmp.path,
-        fn: async () => {
-          const session = await svc.create({})
-          await fill(session.id, 520)
-          const app = Server.Default().app
+  it.instance(
+    "does not truncate large legacy limit requests",
+    withoutWatcher(
+      Effect.gen(function* () {
+        const session = yield* sessionScoped
+        yield* fill(session.id, 520)
 
-          const res = await app.request(`/session/${session.id}/message?limit=510`)
-          expect(res.status).toBe(200)
-          const body = (await res.json()) as MessageV2.WithParts[]
-          expect(body).toHaveLength(510)
-
-          await svc.remove(session.id)
-        },
+        const res = yield* request(`/session/${session.id}/message?limit=510`)
+        expect(res.status).toBe(200)
+        const body = yield* json<MessageV2.WithParts[]>(res)
+        expect(body).toHaveLength(510)
       }),
-    )
-  })
+    ),
+    { git: true },
+  )
 
-  test("accepts directory query used by workspace routing", async () => {
-    await using tmp = await tmpdir({ git: true })
-    await withoutWatcher(() =>
-      WithInstance.provide({
-        directory: tmp.path,
-        fn: async () => {
-          const session = await svc.create({})
-          await fill(session.id, 1)
-          const app = Server.Default().app
+  it.instance(
+    "accepts directory query used by workspace routing",
+    withoutWatcher(
+      Effect.gen(function* () {
+        const tmp = yield* TestInstance
+        const session = yield* sessionScoped
+        yield* fill(session.id, 1)
 
-          const res = await app.request(
-            `/session/${session.id}/message?limit=80&directory=${encodeURIComponent(tmp.path)}`,
-          )
-          expect(res.status).toBe(200)
-          const body = await res.json()
-          expect(Array.isArray(body)).toBe(true)
-          expect(body).toHaveLength(1)
-
-          await svc.remove(session.id)
-        },
+        const res = yield* request(
+          `/session/${session.id}/message?limit=80&directory=${encodeURIComponent(tmp.directory)}`,
+        )
+        expect(res.status).toBe(200)
+        const body = yield* json<unknown[]>(res)
+        expect(Array.isArray(body)).toBe(true)
+        expect(body).toHaveLength(1)
       }),
-    )
-  })
+    ),
+    { git: true },
+  )
 })