diff --git a/packages/opencode/test/agent/agent.test.ts b/packages/opencode/test/agent/agent.test.ts
index df68fdfdc6..7fd489150b 100644
--- a/packages/opencode/test/agent/agent.test.ts
+++ b/packages/opencode/test/agent/agent.test.ts
@@ -1,12 +1,15 @@
-import { afterEach, test, expect } from "bun:test"
-import { Effect } from "effect"
+import { afterEach, expect } from "bun:test"
+import { Cause, Effect, Exit } from "effect"
 import path from "path"
-import { disposeAllInstances, provideInstance, tmpdir } from "../fixture/fixture"
-import { WithInstance } from "../../src/project/with-instance"
+import { disposeAllInstances, TestInstance } from "../fixture/fixture"
+import { testEffect } from "../lib/effect"
 import { Agent } from "../../src/agent/agent"
 import { Global } from "@opencode-ai/core/global"
 import { Flag } from "@opencode-ai/core/flag/flag"
 import { Permission } from "../../src/permission"
+import { Truncate } from "../../src/tool/truncate"
+
+const it = testEffect(Agent.defaultLayer)
 
 // Helper to evaluate permission for a tool with wildcard pattern
 function evalPerm(agent: Agent.Info | undefined, permission: string): Permission.Action | undefined {
@@ -14,196 +17,189 @@ function evalPerm(agent: Agent.Info | undefined, permission: string): Permission
   return Permission.evaluate(permission, "*", agent.permission).action
 }
 
-function load<A>(dir: string, fn: (svc: Agent.Interface) => Effect.Effect<A>) {
-  return Effect.runPromise(provideInstance(dir)(Agent.Service.use(fn)).pipe(Effect.provide(Agent.defaultLayer)))
+function load<A>(fn: (svc: Agent.Interface) => Effect.Effect<A>) {
+  return Agent.Service.use(fn)
 }
 
-async function withExperimentalScout(enabled: boolean, fn: () => Promise<void>) {
-  const original = Flag.OPENCODE_EXPERIMENTAL_SCOUT
-  Flag.OPENCODE_EXPERIMENTAL_SCOUT = enabled
-  try {
-    await fn()
-  } finally {
-    Flag.OPENCODE_EXPERIMENTAL_SCOUT = original
-  }
+function withExperimentalScout<A, E, R>(enabled: boolean, self: Effect.Effect<A, E, R>) {
+  return Effect.acquireUseRelease(
+    Effect.sync(() => {
+      const original = Flag.OPENCODE_EXPERIMENTAL_SCOUT
+      Flag.OPENCODE_EXPERIMENTAL_SCOUT = enabled
+      return original
+    }),
+    () => self,
+    (original) =>
+      Effect.sync(() => {
+        Flag.OPENCODE_EXPERIMENTAL_SCOUT = original
+      }),
+  )
 }
 
+const expectDefaultAgentError = Effect.fn("AgentTest.expectDefaultAgentError")(function* (message: string) {
+  const exit = yield* load((svc) => svc.defaultAgent()).pipe(Effect.exit)
+  expect(Exit.isFailure(exit)).toBe(true)
+  if (Exit.isFailure(exit)) expect(Cause.pretty(exit.cause)).toContain(message)
+})
+
 afterEach(async () => {
   await disposeAllInstances()
 })
 
-test("returns default native agents when no config", async () => {
-  await withExperimentalScout(false, async () => {
-    await using tmp = await tmpdir()
-    await WithInstance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const agents = await load(tmp.path, (svc) => svc.list())
-        const names = agents.map((a) => a.name)
-        expect(names).toContain("build")
-        expect(names).toContain("plan")
-        expect(names).toContain("general")
-        expect(names).toContain("explore")
-        expect(names).not.toContain("scout")
-        expect(names).toContain("compaction")
-        expect(names).toContain("title")
-        expect(names).toContain("summary")
-      },
-    })
-  })
-})
+it.instance("returns default native agents when no config", () =>
+  withExperimentalScout(
+    false,
+    Effect.gen(function* () {
+      const agents = yield* load((svc) => svc.list())
+      const names = agents.map((a) => a.name)
+      expect(names).toContain("build")
+      expect(names).toContain("plan")
+      expect(names).toContain("general")
+      expect(names).toContain("explore")
+      expect(names).not.toContain("scout")
+      expect(names).toContain("compaction")
+      expect(names).toContain("title")
+      expect(names).toContain("summary")
+    }),
+  ),
+)
 
-test("build agent has correct default properties", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build).toBeDefined()
-      expect(build?.mode).toBe("primary")
-      expect(build?.native).toBe(true)
-      expect(evalPerm(build, "edit")).toBe("allow")
-      expect(evalPerm(build, "bash")).toBe("allow")
-      expect(evalPerm(build, "repo_clone")).toBe("deny")
-      expect(evalPerm(build, "repo_overview")).toBe("deny")
-    },
-  })
-})
+it.instance("build agent has correct default properties", () =>
+  Effect.gen(function* () {
+    const build = yield* load((svc) => svc.get("build"))
+    expect(build).toBeDefined()
+    expect(build?.mode).toBe("primary")
+    expect(build?.native).toBe(true)
+    expect(evalPerm(build, "edit")).toBe("allow")
+    expect(evalPerm(build, "bash")).toBe("allow")
+    expect(evalPerm(build, "repo_clone")).toBe("deny")
+    expect(evalPerm(build, "repo_overview")).toBe("deny")
+  }),
+)
 
-test("plan agent denies edits except .opencode/plans/*", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const plan = await load(tmp.path, (svc) => svc.get("plan"))
-      expect(plan).toBeDefined()
-      // Wildcard is denied
-      expect(evalPerm(plan, "edit")).toBe("deny")
-      // But specific path is allowed
-      expect(Permission.evaluate("edit", ".opencode/plans/foo.md", plan!.permission).action).toBe("allow")
-    },
-  })
-})
+it.instance("plan agent denies edits except .opencode/plans/*", () =>
+  Effect.gen(function* () {
+    const plan = yield* load((svc) => svc.get("plan"))
+    expect(plan).toBeDefined()
+    // Wildcard is denied
+    expect(evalPerm(plan, "edit")).toBe("deny")
+    // But specific path is allowed
+    expect(Permission.evaluate("edit", ".opencode/plans/foo.md", plan!.permission).action).toBe("allow")
+  }),
+)
 
-test("explore agent denies edit and write", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const explore = await load(tmp.path, (svc) => svc.get("explore"))
-      expect(explore).toBeDefined()
-      expect(explore?.mode).toBe("subagent")
-      expect(evalPerm(explore, "edit")).toBe("deny")
-      expect(evalPerm(explore, "write")).toBe("deny")
-      expect(evalPerm(explore, "todowrite")).toBe("deny")
-    },
-  })
-})
+it.instance("explore agent denies edit and write", () =>
+  Effect.gen(function* () {
+    const explore = yield* load((svc) => svc.get("explore"))
+    expect(explore).toBeDefined()
+    expect(explore?.mode).toBe("subagent")
+    expect(evalPerm(explore, "edit")).toBe("deny")
+    expect(evalPerm(explore, "write")).toBe("deny")
+    expect(evalPerm(explore, "todowrite")).toBe("deny")
+  }),
+)
 
-test("explore agent asks for external directories and allows whitelisted external paths", async () => {
-  const { Truncate } = await import("../../src/tool/truncate")
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const explore = await load(tmp.path, (svc) => svc.get("explore"))
-      expect(explore).toBeDefined()
-      expect(Permission.evaluate("external_directory", "/some/other/path", explore!.permission).action).toBe("ask")
-      expect(Permission.evaluate("external_directory", Truncate.GLOB, explore!.permission).action).toBe("allow")
+it.instance("explore agent asks for external directories and allows whitelisted external paths", () =>
+  Effect.gen(function* () {
+    const explore = yield* load((svc) => svc.get("explore"))
+    expect(explore).toBeDefined()
+    expect(Permission.evaluate("external_directory", "/some/other/path", explore!.permission).action).toBe("ask")
+    expect(Permission.evaluate("external_directory", Truncate.GLOB, explore!.permission).action).toBe("allow")
+    expect(Permission.evaluate("external_directory", path.join(Global.Path.tmp, "agent-work"), explore!.permission).action).toBe(
+      "allow",
+    )
+  }),
+)
+
+it.instance("scout agent allows repo cloning and repo cache reads", () =>
+  withExperimentalScout(
+    true,
+    Effect.gen(function* () {
+      const scout = yield* load((svc) => svc.get("scout"))
+      expect(scout).toBeDefined()
+      expect(scout?.mode).toBe("subagent")
+      expect(evalPerm(scout, "repo_clone")).toBe("allow")
+      expect(evalPerm(scout, "repo_overview")).toBe("allow")
+      expect(evalPerm(scout, "edit")).toBe("deny")
       expect(
-        Permission.evaluate("external_directory", path.join(Global.Path.tmp, "agent-work"), explore!.permission).action,
+        Permission.evaluate(
+          "external_directory",
+          path.join(Global.Path.repos, "github.com", "owner", "repo", "README.md"),
+          scout!.permission,
+        ).action,
       ).toBe("allow")
-    },
-  })
-})
+    }),
+  ),
+)
 
-test("scout agent allows repo cloning and repo cache reads", async () => {
-  await withExperimentalScout(true, async () => {
-    await using tmp = await tmpdir()
-    await WithInstance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const scout = await load(tmp.path, (svc) => svc.get("scout"))
-        expect(scout).toBeDefined()
-        expect(scout?.mode).toBe("subagent")
-        expect(evalPerm(scout, "repo_clone")).toBe("allow")
-        expect(evalPerm(scout, "repo_overview")).toBe("allow")
-        expect(evalPerm(scout, "edit")).toBe("deny")
-        expect(
-          Permission.evaluate(
-            "external_directory",
-            path.join(Global.Path.repos, "github.com", "owner", "repo", "README.md"),
-            scout!.permission,
-          ).action,
-        ).toBe("allow")
-      },
-    })
-  })
-})
-
-test("reference config does not create subagents", async () => {
-  await withExperimentalScout(true, async () => {
-    await using tmp = await tmpdir({
-      config: {
-        reference: {
-          effect: "github.com/effect/effect-smol",
-          effectFull: {
-            repository: "Effect-TS/effect",
-            branch: "main",
-          },
-          localdocs: "../docs",
-          localdocsFull: {
-            path: "../local-docs",
-          },
-        },
-      },
-    })
-    await WithInstance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const agents = await load(tmp.path, (svc) => svc.list())
+it.instance(
+  "reference config does not create subagents",
+  () =>
+    withExperimentalScout(
+      true,
+      Effect.gen(function* () {
+        const agents = yield* load((svc) => svc.list())
         const names = agents.map((agent) => agent.name)
         expect(names).toContain("scout")
         expect(names).not.toContain("effect")
         expect(names).not.toContain("effectFull")
         expect(names).not.toContain("localdocs")
         expect(names).not.toContain("localdocsFull")
+      }),
+    ),
+  {
+    config: {
+      reference: {
+        effect: "github.com/effect/effect-smol",
+        effectFull: {
+          repository: "Effect-TS/effect",
+          branch: "main",
+        },
+        localdocs: "../docs",
+        localdocsFull: {
+          path: "../local-docs",
+        },
       },
-    })
-  })
-})
-
-test("general agent denies todo tools", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const general = await load(tmp.path, (svc) => svc.get("general"))
-      expect(general).toBeDefined()
-      expect(general?.mode).toBe("subagent")
-      expect(general?.hidden).toBeUndefined()
-      expect(evalPerm(general, "todowrite")).toBe("deny")
     },
-  })
-})
+  },
+)
 
-test("compaction agent denies all permissions", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const compaction = await load(tmp.path, (svc) => svc.get("compaction"))
-      expect(compaction).toBeDefined()
-      expect(compaction?.hidden).toBe(true)
-      expect(evalPerm(compaction, "bash")).toBe("deny")
-      expect(evalPerm(compaction, "edit")).toBe("deny")
-      expect(evalPerm(compaction, "read")).toBe("deny")
-    },
-  })
-})
+it.instance("general agent denies todo tools", () =>
+  Effect.gen(function* () {
+    const general = yield* load((svc) => svc.get("general"))
+    expect(general).toBeDefined()
+    expect(general?.mode).toBe("subagent")
+    expect(general?.hidden).toBeUndefined()
+    expect(evalPerm(general, "todowrite")).toBe("deny")
+  }),
+)
 
-test("custom agent from config creates new agent", async () => {
-  await using tmp = await tmpdir({
+it.instance("compaction agent denies all permissions", () =>
+  Effect.gen(function* () {
+    const compaction = yield* load((svc) => svc.get("compaction"))
+    expect(compaction).toBeDefined()
+    expect(compaction?.hidden).toBe(true)
+    expect(evalPerm(compaction, "bash")).toBe("deny")
+    expect(evalPerm(compaction, "edit")).toBe("deny")
+    expect(evalPerm(compaction, "read")).toBe("deny")
+  }),
+)
+
+it.instance(
+  "custom agent from config creates new agent",
+  () =>
+    Effect.gen(function* () {
+      const custom = yield* load((svc) => svc.get("my_custom_agent"))
+      expect(custom).toBeDefined()
+      expect(String(custom?.model?.providerID)).toBe("openai")
+      expect(String(custom?.model?.modelID)).toBe("gpt-4")
+      expect(custom?.description).toBe("My custom agent")
+      expect(custom?.temperature).toBe(0.5)
+      expect(custom?.topP).toBe(0.9)
+      expect(custom?.native).toBe(false)
+      expect(custom?.mode).toBe("all")
+    }),
+  {
     config: {
       agent: {
         my_custom_agent: {
@@ -214,25 +210,23 @@ test("custom agent from config creates new agent", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const custom = await load(tmp.path, (svc) => svc.get("my_custom_agent"))
-      expect(custom).toBeDefined()
-      expect(String(custom?.model?.providerID)).toBe("openai")
-      expect(String(custom?.model?.modelID)).toBe("gpt-4")
-      expect(custom?.description).toBe("My custom agent")
-      expect(custom?.temperature).toBe(0.5)
-      expect(custom?.topP).toBe(0.9)
-      expect(custom?.native).toBe(false)
-      expect(custom?.mode).toBe("all")
-    },
-  })
-})
+  },
+)
 
-test("custom agent config overrides native agent properties", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "custom agent config overrides native agent properties",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build).toBeDefined()
+      expect(String(build?.model?.providerID)).toBe("anthropic")
+      expect(String(build?.model?.modelID)).toBe("claude-3")
+      expect(build?.description).toBe("Custom build agent")
+      expect(build?.temperature).toBe(0.7)
+      expect(build?.color).toBe("#FF0000")
+      expect(build?.native).toBe(true)
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -243,44 +237,40 @@ test("custom agent config overrides native agent properties", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build).toBeDefined()
-      expect(String(build?.model?.providerID)).toBe("anthropic")
-      expect(String(build?.model?.modelID)).toBe("claude-3")
-      expect(build?.description).toBe("Custom build agent")
-      expect(build?.temperature).toBe(0.7)
-      expect(build?.color).toBe("#FF0000")
-      expect(build?.native).toBe(true)
-    },
-  })
-})
+  },
+)
 
-test("agent disable removes agent from list", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent disable removes agent from list",
+  () =>
+    Effect.gen(function* () {
+      const explore = yield* load((svc) => svc.get("explore"))
+      expect(explore).toBeUndefined()
+      const agents = yield* load((svc) => svc.list())
+      const names = agents.map((a) => a.name)
+      expect(names).not.toContain("explore")
+    }),
+  {
     config: {
       agent: {
         explore: { disable: true },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const explore = await load(tmp.path, (svc) => svc.get("explore"))
-      expect(explore).toBeUndefined()
-      const agents = await load(tmp.path, (svc) => svc.list())
-      const names = agents.map((a) => a.name)
-      expect(names).not.toContain("explore")
-    },
-  })
-})
+  },
+)
 
-test("agent permission config merges with defaults", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent permission config merges with defaults",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build).toBeDefined()
+      // Specific pattern is denied
+      expect(Permission.evaluate("bash", "rm -rf *", build!.permission).action).toBe("deny")
+      // Edit still allowed
+      expect(evalPerm(build, "edit")).toBe("allow")
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -292,111 +282,102 @@ test("agent permission config merges with defaults", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build).toBeDefined()
-      // Specific pattern is denied
-      expect(Permission.evaluate("bash", "rm -rf *", build!.permission).action).toBe("deny")
-      // Edit still allowed
-      expect(evalPerm(build, "edit")).toBe("allow")
-    },
-  })
-})
+  },
+)
 
-test("global permission config applies to all agents", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "global permission config applies to all agents",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build).toBeDefined()
+      expect(evalPerm(build, "bash")).toBe("deny")
+    }),
+  {
     config: {
       permission: {
         bash: "deny",
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build).toBeDefined()
-      expect(evalPerm(build, "bash")).toBe("deny")
-    },
-  })
-})
+  },
+)
 
-test("agent steps/maxSteps config sets steps property", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent steps/maxSteps config sets steps property",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      const plan = yield* load((svc) => svc.get("plan"))
+      expect(build?.steps).toBe(50)
+      expect(plan?.steps).toBe(100)
+    }),
+  {
     config: {
       agent: {
         build: { steps: 50 },
         plan: { maxSteps: 100 },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      const plan = await load(tmp.path, (svc) => svc.get("plan"))
-      expect(build?.steps).toBe(50)
-      expect(plan?.steps).toBe(100)
-    },
-  })
-})
+  },
+)
 
-test("agent mode can be overridden", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent mode can be overridden",
+  () =>
+    Effect.gen(function* () {
+      const explore = yield* load((svc) => svc.get("explore"))
+      expect(explore?.mode).toBe("primary")
+    }),
+  {
     config: {
       agent: {
         explore: { mode: "primary" },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const explore = await load(tmp.path, (svc) => svc.get("explore"))
-      expect(explore?.mode).toBe("primary")
-    },
-  })
-})
+  },
+)
 
-test("agent name can be overridden", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent name can be overridden",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build?.name).toBe("Builder")
+    }),
+  {
     config: {
       agent: {
         build: { name: "Builder" },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build?.name).toBe("Builder")
-    },
-  })
-})
+  },
+)
 
-test("agent prompt can be set from config", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent prompt can be set from config",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build?.prompt).toBe("Custom system prompt")
+    }),
+  {
     config: {
       agent: {
         build: { prompt: "Custom system prompt" },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build?.prompt).toBe("Custom system prompt")
-    },
-  })
-})
+  },
+)
 
-test("unknown agent properties are placed into options", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "unknown agent properties are placed into options",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build?.options.random_property).toBe("hello")
+      expect(build?.options.another_random).toBe(123)
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -405,19 +386,18 @@ test("unknown agent properties are placed into options", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build?.options.random_property).toBe("hello")
-      expect(build?.options.another_random).toBe(123)
-    },
-  })
-})
+  },
+)
 
-test("agent options merge correctly", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "agent options merge correctly",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(build?.options.custom_option).toBe(true)
+      expect(build?.options.another_option).toBe("value")
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -428,19 +408,21 @@ test("agent options merge correctly", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(build?.options.custom_option).toBe(true)
-      expect(build?.options.another_option).toBe("value")
-    },
-  })
-})
+  },
+)
 
-test("multiple custom agents can be defined", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "multiple custom agents can be defined",
+  () =>
+    Effect.gen(function* () {
+      const agentA = yield* load((svc) => svc.get("agent_a"))
+      const agentB = yield* load((svc) => svc.get("agent_b"))
+      expect(agentA?.description).toBe("Agent A")
+      expect(agentA?.mode).toBe("subagent")
+      expect(agentB?.description).toBe("Agent B")
+      expect(agentB?.mode).toBe("primary")
+    }),
+  {
     config: {
       agent: {
         agent_a: {
@@ -453,22 +435,18 @@ test("multiple custom agents can be defined", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const agentA = await load(tmp.path, (svc) => svc.get("agent_a"))
-      const agentB = await load(tmp.path, (svc) => svc.get("agent_b"))
-      expect(agentA?.description).toBe("Agent A")
-      expect(agentA?.mode).toBe("subagent")
-      expect(agentB?.description).toBe("Agent B")
-      expect(agentB?.mode).toBe("primary")
-    },
-  })
-})
+  },
+)
 
-test("Agent.list keeps the default agent first and sorts the rest by name", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "Agent.list keeps the default agent first and sorts the rest by name",
+  () =>
+    Effect.gen(function* () {
+      const names = (yield* load((svc) => svc.list())).map((a) => a.name)
+      expect(names[0]).toBe("plan")
+      expect(names.slice(1)).toEqual(names.slice(1).toSorted((a, b) => a.localeCompare(b)))
+    }),
+  {
     config: {
       default_agent: "plan",
       agent: {
@@ -482,53 +460,40 @@ test("Agent.list keeps the default agent first and sorts the rest by name", asyn
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const names = (await load(tmp.path, (svc) => svc.list())).map((a) => a.name)
-      expect(names[0]).toBe("plan")
-      expect(names.slice(1)).toEqual(names.slice(1).toSorted((a, b) => a.localeCompare(b)))
-    },
-  })
-})
+  },
+)
 
-test("Agent.get returns undefined for non-existent agent", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const nonExistent = await load(tmp.path, (svc) => svc.get("does_not_exist"))
-      expect(nonExistent).toBeUndefined()
-    },
-  })
-})
+it.instance("Agent.get returns undefined for non-existent agent", () =>
+  Effect.gen(function* () {
+    const nonExistent = yield* load((svc) => svc.get("does_not_exist"))
+    expect(nonExistent).toBeUndefined()
+  }),
+)
 
-test("default permission includes doom_loop and external_directory as ask", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(evalPerm(build, "doom_loop")).toBe("ask")
-      expect(evalPerm(build, "external_directory")).toBe("ask")
-    },
-  })
-})
+it.instance("default permission includes doom_loop and external_directory as ask", () =>
+  Effect.gen(function* () {
+    const build = yield* load((svc) => svc.get("build"))
+    expect(evalPerm(build, "doom_loop")).toBe("ask")
+    expect(evalPerm(build, "external_directory")).toBe("ask")
+  }),
+)
 
-test("webfetch is allowed by default", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(evalPerm(build, "webfetch")).toBe("allow")
-    },
-  })
-})
+it.instance("webfetch is allowed by default", () =>
+  Effect.gen(function* () {
+    const build = yield* load((svc) => svc.get("build"))
+    expect(evalPerm(build, "webfetch")).toBe("allow")
+  }),
+)
 
-test("legacy tools config converts to permissions", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "legacy tools config converts to permissions",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(evalPerm(build, "bash")).toBe("deny")
+      expect(evalPerm(build, "read")).toBe("deny")
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -539,19 +504,17 @@ test("legacy tools config converts to permissions", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(evalPerm(build, "bash")).toBe("deny")
-      expect(evalPerm(build, "read")).toBe("deny")
-    },
-  })
-})
+  },
+)
 
-test("legacy tools config maps write/edit/patch to edit permission", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "legacy tools config maps write/edit/patch to edit permission",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(evalPerm(build, "edit")).toBe("deny")
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -561,53 +524,47 @@ test("legacy tools config maps write/edit/patch to edit permission", async () =>
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(evalPerm(build, "edit")).toBe("deny")
-    },
-  })
-})
+  },
+)
 
-test("Truncate.GLOB is allowed even when user denies external_directory globally", async () => {
-  const { Truncate } = await import("../../src/tool/truncate")
-  await using tmp = await tmpdir({
+it.instance(
+  "Truncate.GLOB is allowed even when user denies external_directory globally",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(Permission.evaluate("external_directory", Truncate.GLOB, build!.permission).action).toBe("allow")
+      expect(Permission.evaluate("external_directory", Truncate.DIR, build!.permission).action).toBe("deny")
+      expect(Permission.evaluate("external_directory", "/some/other/path", build!.permission).action).toBe("deny")
+    }),
+  {
     config: {
       permission: {
         external_directory: "deny",
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
+  },
+)
+
+it.instance("global tmp directory children are allowed for external_directory", () =>
+  Effect.gen(function* () {
+    const build = yield* load((svc) => svc.get("build"))
+    expect(Permission.evaluate("external_directory", path.join(Global.Path.tmp, "scratch"), build!.permission).action).toBe(
+      "allow",
+    )
+    expect(Permission.evaluate("external_directory", "/some/other/path", build!.permission).action).toBe("ask")
+  }),
+)
+
+it.instance(
+  "Truncate.GLOB is allowed even when user denies external_directory per-agent",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
       expect(Permission.evaluate("external_directory", Truncate.GLOB, build!.permission).action).toBe("allow")
       expect(Permission.evaluate("external_directory", Truncate.DIR, build!.permission).action).toBe("deny")
       expect(Permission.evaluate("external_directory", "/some/other/path", build!.permission).action).toBe("deny")
-    },
-  })
-})
-
-test("global tmp directory children are allowed for external_directory", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(
-        Permission.evaluate("external_directory", path.join(Global.Path.tmp, "scratch"), build!.permission).action,
-      ).toBe("allow")
-      expect(Permission.evaluate("external_directory", "/some/other/path", build!.permission).action).toBe("ask")
-    },
-  })
-})
-
-test("Truncate.GLOB is allowed even when user denies external_directory per-agent", async () => {
-  const { Truncate } = await import("../../src/tool/truncate")
-  await using tmp = await tmpdir({
+    }),
+  {
     config: {
       agent: {
         build: {
@@ -617,21 +574,18 @@ test("Truncate.GLOB is allowed even when user denies external_directory per-agen
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(Permission.evaluate("external_directory", Truncate.GLOB, build!.permission).action).toBe("allow")
-      expect(Permission.evaluate("external_directory", Truncate.DIR, build!.permission).action).toBe("deny")
-      expect(Permission.evaluate("external_directory", "/some/other/path", build!.permission).action).toBe("deny")
-    },
-  })
-})
+  },
+)
 
-test("explicit Truncate.GLOB deny is respected", async () => {
-  const { Truncate } = await import("../../src/tool/truncate")
-  await using tmp = await tmpdir({
+it.instance(
+  "explicit Truncate.GLOB deny is respected",
+  () =>
+    Effect.gen(function* () {
+      const build = yield* load((svc) => svc.get("build"))
+      expect(Permission.evaluate("external_directory", Truncate.GLOB, build!.permission).action).toBe("deny")
+      expect(Permission.evaluate("external_directory", Truncate.DIR, build!.permission).action).toBe("deny")
+    }),
+  {
     config: {
       permission: {
         external_directory: {
@@ -640,81 +594,72 @@ test("explicit Truncate.GLOB deny is respected", async () => {
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const build = await load(tmp.path, (svc) => svc.get("build"))
-      expect(Permission.evaluate("external_directory", Truncate.GLOB, build!.permission).action).toBe("deny")
-      expect(Permission.evaluate("external_directory", Truncate.DIR, build!.permission).action).toBe("deny")
-    },
-  })
-})
+  },
+)
 
-test("skill directories are allowed for external_directory", async () => {
-  await using tmp = await tmpdir({
-    git: true,
-    init: async (dir) => {
-      const skillDir = path.join(dir, ".opencode", "skill", "perm-skill")
-      await Bun.write(
-        path.join(skillDir, "SKILL.md"),
-        `---
+it.instance(
+  "skill directories are allowed for external_directory",
+  () =>
+    Effect.gen(function* () {
+      const test = yield* TestInstance
+      const skillDir = path.join(test.directory, ".opencode", "skill", "perm-skill")
+      yield* Effect.promise(() =>
+        Bun.write(
+          path.join(skillDir, "SKILL.md"),
+          `---
 name: perm-skill
 description: Permission skill.
 ---
 
 # Permission Skill
 `,
+        ),
       )
-    },
-  })
 
-  const home = process.env.OPENCODE_TEST_HOME
-  process.env.OPENCODE_TEST_HOME = tmp.path
+      const home = process.env.OPENCODE_TEST_HOME
+      process.env.OPENCODE_TEST_HOME = test.directory
+      yield* Effect.addFinalizer(() =>
+        Effect.sync(() => {
+          process.env.OPENCODE_TEST_HOME = home
+        }),
+      )
 
-  try {
-    await WithInstance.provide({
-      directory: tmp.path,
-      fn: async () => {
-        const build = await load(tmp.path, (svc) => svc.get("build"))
-        const skillDir = path.join(tmp.path, ".opencode", "skill", "perm-skill")
-        const target = path.join(skillDir, "reference", "notes.md")
-        expect(Permission.evaluate("external_directory", target, build!.permission).action).toBe("allow")
-      },
-    })
-  } finally {
-    process.env.OPENCODE_TEST_HOME = home
-  }
-})
+      const build = yield* load((svc) => svc.get("build"))
+      const target = path.join(skillDir, "reference", "notes.md")
+      expect(Permission.evaluate("external_directory", target, build!.permission).action).toBe("allow")
+    }),
+  { git: true },
+)
 
-test("defaultAgent returns build when no default_agent config", async () => {
-  await using tmp = await tmpdir()
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const agent = await load(tmp.path, (svc) => svc.defaultAgent())
-      expect(agent).toBe("build")
-    },
-  })
-})
+it.instance("defaultAgent returns build when no default_agent config", () =>
+  Effect.gen(function* () {
+    const agent = yield* load((svc) => svc.defaultAgent())
+    expect(agent).toBe("build")
+  }),
+)
 
-test("defaultAgent respects default_agent config set to plan", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent respects default_agent config set to plan",
+  () =>
+    Effect.gen(function* () {
+      const agent = yield* load((svc) => svc.defaultAgent())
+      expect(agent).toBe("plan")
+    }),
+  {
     config: {
       default_agent: "plan",
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const agent = await load(tmp.path, (svc) => svc.defaultAgent())
-      expect(agent).toBe("plan")
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent respects default_agent config set to custom agent with mode all", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent respects default_agent config set to custom agent with mode all",
+  () =>
+    Effect.gen(function* () {
+      const agent = yield* load((svc) => svc.defaultAgent())
+      expect(agent).toBe("my_custom")
+    }),
+  {
     config: {
       default_agent: "my_custom",
       agent: {
@@ -723,92 +668,65 @@ test("defaultAgent respects default_agent config set to custom agent with mode a
         },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const agent = await load(tmp.path, (svc) => svc.defaultAgent())
-      expect(agent).toBe("my_custom")
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent throws when default_agent points to subagent", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent throws when default_agent points to subagent",
+  () => expectDefaultAgentError('default agent "explore" is a subagent'),
+  {
     config: {
       default_agent: "explore",
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      await expect(load(tmp.path, (svc) => svc.defaultAgent())).rejects.toThrow('default agent "explore" is a subagent')
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent throws when default_agent points to hidden agent", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent throws when default_agent points to hidden agent",
+  () => expectDefaultAgentError('default agent "compaction" is hidden'),
+  {
     config: {
       default_agent: "compaction",
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      await expect(load(tmp.path, (svc) => svc.defaultAgent())).rejects.toThrow('default agent "compaction" is hidden')
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent throws when default_agent points to non-existent agent", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent throws when default_agent points to non-existent agent",
+  () => expectDefaultAgentError('default agent "does_not_exist" not found'),
+  {
     config: {
       default_agent: "does_not_exist",
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      await expect(load(tmp.path, (svc) => svc.defaultAgent())).rejects.toThrow(
-        'default agent "does_not_exist" not found',
-      )
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent returns plan when build is disabled and default_agent not set", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent returns plan when build is disabled and default_agent not set",
+  () =>
+    Effect.gen(function* () {
+      const agent = yield* load((svc) => svc.defaultAgent())
+      // build is disabled, so it should return plan (next primary agent)
+      expect(agent).toBe("plan")
+    }),
+  {
     config: {
       agent: {
         build: { disable: true },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      const agent = await load(tmp.path, (svc) => svc.defaultAgent())
-      // build is disabled, so it should return plan (next primary agent)
-      expect(agent).toBe("plan")
-    },
-  })
-})
+  },
+)
 
-test("defaultAgent throws when all primary agents are disabled", async () => {
-  await using tmp = await tmpdir({
+it.instance(
+  "defaultAgent throws when all primary agents are disabled",
+  () => expectDefaultAgentError("no primary visible agent found"),
+  {
     config: {
       agent: {
         build: { disable: true },
         plan: { disable: true },
       },
     },
-  })
-  await WithInstance.provide({
-    directory: tmp.path,
-    fn: async () => {
-      // build and plan are disabled, no primary-capable agents remain
-      await expect(load(tmp.path, (svc) => svc.defaultAgent())).rejects.toThrow("no primary visible agent found")
-    },
-  })
-})
+  },
+)