diff --git a/packages/opencode/specs/effect-migration.md b/packages/opencode/specs/effect-migration.md
index 4f195917fd..0f9f5d6050 100644
--- a/packages/opencode/specs/effect-migration.md
+++ b/packages/opencode/specs/effect-migration.md
@@ -127,7 +127,7 @@ Done now:
 Still open and likely worth migrating:
 
 - [ ] `Plugin`
-- [ ] `ToolRegistry`
+- [x] `ToolRegistry`
 - [ ] `Pty`
 - [ ] `Worktree`
 - [ ] `Installation`
diff --git a/packages/opencode/src/bus/bus-event.ts b/packages/opencode/src/bus/bus-event.ts
index 7fe13833c8..1d9a31d4a2 100644
--- a/packages/opencode/src/bus/bus-event.ts
+++ b/packages/opencode/src/bus/bus-event.ts
@@ -1,5 +1,5 @@
 import z from "zod"
-import type { ZodType } from "zod"
+import type { ZodObject, ZodRawShape } from "zod"
 import { Log } from "../util/log"
 
 export namespace BusEvent {
@@ -9,7 +9,7 @@ export namespace BusEvent {
 
   const registry = new Map<string, Definition>()
 
-  export function define<Type extends string, Properties extends ZodType>(type: Type, properties: Properties) {
+  export function define<Type extends string, Properties extends ZodObject<ZodRawShape>>(type: Type, properties: Properties) {
     const result = {
       type,
       properties,
diff --git a/packages/opencode/src/bus/global.ts b/packages/opencode/src/bus/global.ts
index 43386dd6b2..dcc7664007 100644
--- a/packages/opencode/src/bus/global.ts
+++ b/packages/opencode/src/bus/global.ts
@@ -4,7 +4,7 @@ export const GlobalBus = new EventEmitter<{
   event: [
     {
       directory?: string
-      payload: any
+      payload: { type: string; properties: Record<string, unknown> }
     },
   ]
 }>()
diff --git a/packages/opencode/src/control-plane/workspace.ts b/packages/opencode/src/control-plane/workspace.ts
index e5294844b1..b519895b2f 100644
--- a/packages/opencode/src/control-plane/workspace.ts
+++ b/packages/opencode/src/control-plane/workspace.ts
@@ -124,7 +124,7 @@ export namespace Workspace {
       await parseSSE(res.body, stop, (event) => {
         GlobalBus.emit("event", {
           directory: space.id,
-          payload: event,
+          payload: event as { type: string; properties: Record<string, unknown> },
         })
       })
       // Wait 250ms and retry if SSE connection fails
diff --git a/packages/opencode/src/effect/instances.ts b/packages/opencode/src/effect/instances.ts
index 6fcfddb24f..327691a9e9 100644
--- a/packages/opencode/src/effect/instances.ts
+++ b/packages/opencode/src/effect/instances.ts
@@ -10,6 +10,7 @@ import { ProviderAuth } from "@/provider/auth-service"
 import { Question } from "@/question/service"
 import { Skill } from "@/skill/service"
 import { Snapshot } from "@/snapshot/service"
+import { ToolRegistry } from "@/tool/registry"
 import { InstanceContext } from "./instance-context"
 import { registerDisposer } from "./instance-registry"
 
@@ -26,6 +27,7 @@ export type InstanceServices =
   | File.Service
   | Skill.Service
   | Snapshot.Service
+  | ToolRegistry.Service
 
 // NOTE: LayerMap only passes the key (directory string) to lookup, but we need
 // the full instance context (directory, worktree, project). We read from the
@@ -46,6 +48,7 @@ function lookup(_key: string) {
     File.layer,
     Skill.defaultLayer,
     Snapshot.defaultLayer,
+    ToolRegistry.layer,
   ).pipe(Layer.provide(ctx))
 }
 
diff --git a/packages/opencode/src/tool/registry.ts b/packages/opencode/src/tool/registry.ts
index 6d648a097a..dc57d14961 100644
--- a/packages/opencode/src/tool/registry.ts
+++ b/packages/opencode/src/tool/registry.ts
@@ -1,132 +1,240 @@
-import { PlanExitTool } from "./plan"
-import { QuestionTool } from "./question"
-import { BashTool } from "./bash"
-import { EditTool } from "./edit"
-import { GlobTool } from "./glob"
-import { GrepTool } from "./grep"
-import { BatchTool } from "./batch"
-import { ReadTool } from "./read"
-import { TaskTool } from "./task"
-import { TodoWriteTool, TodoReadTool } from "./todo"
-import { WebFetchTool } from "./webfetch"
-import { WriteTool } from "./write"
-import { InvalidTool } from "./invalid"
-import { SkillTool } from "./skill"
 import type { Agent } from "../agent/agent"
 import { Tool } from "./tool"
-import { Instance } from "../project/instance"
-import { Config } from "../config/config"
 import path from "path"
 import { type ToolContext as PluginToolContext, type ToolDefinition } from "@opencode-ai/plugin"
 import z from "zod"
-import { Plugin } from "../plugin"
 import { ProviderID, type ModelID } from "../provider/schema"
-import { WebSearchTool } from "./websearch"
-import { CodeSearchTool } from "./codesearch"
 import { Flag } from "@/flag/flag"
 import { Log } from "@/util/log"
-import { LspTool } from "./lsp"
 import { Truncate } from "./truncate"
-
-import { ApplyPatchTool } from "./apply_patch"
 import { Glob } from "../util/glob"
 import { pathToFileURL } from "url"
+import { Effect, Layer, ServiceMap } from "effect"
+import { InstanceContext } from "@/effect/instance-context"
 
 export namespace ToolRegistry {
   const log = Log.create({ service: "tool.registry" })
 
-  export const state = Instance.state(async () => {
-    const custom = [] as Tool.Info[]
+  export interface Interface {
+    readonly register: (tool: Tool.Info) => Effect.Effect<void>
+    readonly ids: () => Effect.Effect<string[]>
+    readonly tools: (
+      model: { providerID: ProviderID; modelID: ModelID },
+      agent?: Agent.Info,
+    ) => Effect.Effect<(Awaited<ReturnType<Tool.Info["init"]>> & { id: string })[]>
+  }
 
-    const matches = await Config.directories().then((dirs) =>
-      dirs.flatMap((dir) =>
-        Glob.scanSync("{tool,tools}/*.{js,ts}", { cwd: dir, absolute: true, dot: true, symlink: true }),
-      ),
-    )
-    if (matches.length) await Config.waitForDependencies()
-    for (const match of matches) {
-      const namespace = path.basename(match, path.extname(match))
-      const mod = await import(process.platform === "win32" ? match : pathToFileURL(match).href)
-      for (const [id, def] of Object.entries<ToolDefinition>(mod)) {
-        custom.push(fromPlugin(id === "default" ? namespace : `${namespace}_${id}`, def))
-      }
-    }
+  export class Service extends ServiceMap.Service<Service, Interface>()("@opencode/ToolRegistry") {}
 
-    const plugins = await Plugin.list()
-    for (const plugin of plugins) {
-      for (const [id, def] of Object.entries(plugin.tool ?? {})) {
-        custom.push(fromPlugin(id, def))
-      }
-    }
+  export const layer = Layer.effect(
+    Service,
+    Effect.gen(function* () {
+      const instance = yield* InstanceContext
 
-    return { custom }
-  })
+      const custom: Tool.Info[] = []
+      let task: Promise<void> | undefined
 
-  function fromPlugin(id: string, def: ToolDefinition): Tool.Info {
-    return {
-      id,
-      init: async (initCtx) => ({
-        parameters: z.object(def.args),
-        description: def.description,
-        execute: async (args, ctx) => {
-          const pluginCtx = {
-            ...ctx,
-            directory: Instance.directory,
-            worktree: Instance.worktree,
-          } as unknown as PluginToolContext
-          const result = await def.execute(args as any, pluginCtx)
-          const out = await Truncate.output(result, {}, initCtx?.agent)
-          return {
-            title: "",
-            output: out.truncated ? out.content : result,
-            metadata: { truncated: out.truncated, outputPath: out.truncated ? out.outputPath : undefined },
+      const load = Effect.fn("ToolRegistry.load")(function* () {
+        yield* Effect.promise(async () => {
+          const [{ Config }, { Plugin }] = await Promise.all([import("../config/config"), import("../plugin")])
+          const matches = await Config.directories().then((dirs) =>
+            dirs.flatMap((dir) =>
+              Glob.scanSync("{tool,tools}/*.{js,ts}", { cwd: dir, absolute: true, dot: true, symlink: true }),
+            ),
+          )
+          if (matches.length) await Config.waitForDependencies()
+          for (const match of matches) {
+            const namespace = path.basename(match, path.extname(match))
+            const mod = await import(process.platform === "win32" ? match : pathToFileURL(match).href)
+            for (const [id, def] of Object.entries<ToolDefinition>(mod)) {
+              custom.push(fromPlugin(id === "default" ? namespace : `${namespace}_${id}`, def))
+            }
           }
-        },
-      }),
-    }
+
+          const plugins = await Plugin.list()
+          for (const plugin of plugins) {
+            for (const [id, def] of Object.entries(plugin.tool ?? {})) {
+              custom.push(fromPlugin(id, def))
+            }
+          }
+        })
+      })
+
+      const ensure = Effect.fn("ToolRegistry.ensure")(function* () {
+        yield* Effect.promise(() => {
+          task ??= Effect.runPromise(
+            load().pipe(Effect.catchCause((cause) => Effect.sync(() => log.error("init failed", { cause })))),
+          )
+          return task
+        })
+      })
+
+      function fromPlugin(id: string, def: ToolDefinition): Tool.Info {
+        return {
+          id,
+          init: async (initCtx) => ({
+            parameters: z.object(def.args),
+            description: def.description,
+            execute: async (args, ctx) => {
+              const pluginCtx = {
+                ...ctx,
+                directory: instance.directory,
+                worktree: instance.worktree,
+              } as unknown as PluginToolContext
+              const result = await def.execute(args as any, pluginCtx)
+              const out = await Truncate.output(result, {}, initCtx?.agent)
+              return {
+                title: "",
+                output: out.truncated ? out.content : result,
+                metadata: { truncated: out.truncated, outputPath: out.truncated ? out.outputPath : undefined },
+              }
+            },
+          }),
+        }
+      }
+
+      async function all(): Promise<Tool.Info[]> {
+        const { Config } = await import("../config/config")
+        const config = await Config.get()
+        const question = ["app", "cli", "desktop"].includes(Flag.OPENCODE_CLIENT) || Flag.OPENCODE_ENABLE_QUESTION_TOOL
+        const [
+          invalid,
+          questionMod,
+          bash,
+          read,
+          glob,
+          grep,
+          edit,
+          write,
+          task,
+          webfetch,
+          todo,
+          websearch,
+          codesearch,
+          skill,
+          applyPatch,
+          lsp,
+          batch,
+          plan,
+        ] = await Promise.all([
+          import("./invalid"),
+          import("./question"),
+          import("./bash"),
+          import("./read"),
+          import("./glob"),
+          import("./grep"),
+          import("./edit"),
+          import("./write"),
+          import("./task"),
+          import("./webfetch"),
+          import("./todo"),
+          import("./websearch"),
+          import("./codesearch"),
+          import("./skill"),
+          import("./apply_patch"),
+          import("./lsp"),
+          import("./batch"),
+          import("./plan"),
+        ])
+
+        return [
+          invalid.InvalidTool,
+          ...(question ? [questionMod.QuestionTool] : []),
+          bash.BashTool,
+          read.ReadTool,
+          glob.GlobTool,
+          grep.GrepTool,
+          edit.EditTool,
+          write.WriteTool,
+          task.TaskTool,
+          webfetch.WebFetchTool,
+          todo.TodoWriteTool,
+          // TodoReadTool,
+          websearch.WebSearchTool,
+          codesearch.CodeSearchTool,
+          skill.SkillTool,
+          applyPatch.ApplyPatchTool,
+          ...(Flag.OPENCODE_EXPERIMENTAL_LSP_TOOL ? [lsp.LspTool] : []),
+          ...(config.experimental?.batch_tool === true ? [batch.BatchTool] : []),
+          ...(Flag.OPENCODE_EXPERIMENTAL_PLAN_MODE && Flag.OPENCODE_CLIENT === "cli" ? [plan.PlanExitTool] : []),
+          ...custom,
+        ]
+      }
+
+      const register = Effect.fn("ToolRegistry.register")(function* (tool: Tool.Info) {
+        yield* ensure()
+        const idx = custom.findIndex((t) => t.id === tool.id)
+        if (idx >= 0) {
+          custom.splice(idx, 1, tool)
+          return
+        }
+        custom.push(tool)
+      })
+
+      const ids = Effect.fn("ToolRegistry.ids")(function* () {
+        yield* ensure()
+        const tools = yield* Effect.promise(() => all())
+        return tools.map((t) => t.id)
+      })
+
+      const tools = Effect.fn("ToolRegistry.tools")(function* (
+        model: { providerID: ProviderID; modelID: ModelID },
+        agent?: Agent.Info,
+      ) {
+        yield* ensure()
+        const allTools = yield* Effect.promise(() => all())
+        return yield* Effect.promise(() =>
+          Promise.all(
+            allTools
+              .filter((t) => {
+                // Enable websearch/codesearch for zen users OR via enable flag
+                if (t.id === "codesearch" || t.id === "websearch") {
+                  return model.providerID === ProviderID.opencode || Flag.OPENCODE_ENABLE_EXA
+                }
+
+                // use apply tool in same format as codex
+                const usePatch =
+                  model.modelID.includes("gpt-") && !model.modelID.includes("oss") && !model.modelID.includes("gpt-4")
+                if (t.id === "apply_patch") return usePatch
+                if (t.id === "edit" || t.id === "write") return !usePatch
+
+                return true
+              })
+              .map(async (t) => {
+                using _ = log.time(t.id)
+                const tool = await t.init({ agent })
+                const output = {
+                  description: tool.description,
+                  parameters: tool.parameters,
+                }
+                const { Plugin } = await import("../plugin")
+                await Plugin.trigger("tool.definition", { toolID: t.id }, output)
+                return {
+                  id: t.id,
+                  ...tool,
+                  description: output.description,
+                  parameters: output.parameters,
+                }
+              }),
+          ),
+        )
+      })
+
+      return Service.of({ register, ids, tools })
+    }),
+  ).pipe(Layer.fresh)
+
+  async function run<A, E>(effect: Effect.Effect<A, E, Service>) {
+    const { runPromiseInstance } = await import("@/effect/runtime")
+    return runPromiseInstance(effect)
   }
 
   export async function register(tool: Tool.Info) {
-    const { custom } = await state()
-    const idx = custom.findIndex((t) => t.id === tool.id)
-    if (idx >= 0) {
-      custom.splice(idx, 1, tool)
-      return
-    }
-    custom.push(tool)
-  }
-
-  async function all(): Promise<Tool.Info[]> {
-    const custom = await state().then((x) => x.custom)
-    const config = await Config.get()
-    const question = ["app", "cli", "desktop"].includes(Flag.OPENCODE_CLIENT) || Flag.OPENCODE_ENABLE_QUESTION_TOOL
-
-    return [
-      InvalidTool,
-      ...(question ? [QuestionTool] : []),
-      BashTool,
-      ReadTool,
-      GlobTool,
-      GrepTool,
-      EditTool,
-      WriteTool,
-      TaskTool,
-      WebFetchTool,
-      TodoWriteTool,
-      // TodoReadTool,
-      WebSearchTool,
-      CodeSearchTool,
-      SkillTool,
-      ApplyPatchTool,
-      ...(Flag.OPENCODE_EXPERIMENTAL_LSP_TOOL ? [LspTool] : []),
-      ...(config.experimental?.batch_tool === true ? [BatchTool] : []),
-      ...(Flag.OPENCODE_EXPERIMENTAL_PLAN_MODE && Flag.OPENCODE_CLIENT === "cli" ? [PlanExitTool] : []),
-      ...custom,
-    ]
+    return run(Service.use((svc) => svc.register(tool)))
   }
 
   export async function ids() {
-    return all().then((x) => x.map((t) => t.id))
+    return run(Service.use((svc) => svc.ids()))
   }
 
   export async function tools(
@@ -136,39 +244,6 @@ export namespace ToolRegistry {
     },
     agent?: Agent.Info,
   ) {
-    const tools = await all()
-    const result = await Promise.all(
-      tools
-        .filter((t) => {
-          // Enable websearch/codesearch for zen users OR via enable flag
-          if (t.id === "codesearch" || t.id === "websearch") {
-            return model.providerID === ProviderID.opencode || Flag.OPENCODE_ENABLE_EXA
-          }
-
-          // use apply tool in same format as codex
-          const usePatch =
-            model.modelID.includes("gpt-") && !model.modelID.includes("oss") && !model.modelID.includes("gpt-4")
-          if (t.id === "apply_patch") return usePatch
-          if (t.id === "edit" || t.id === "write") return !usePatch
-
-          return true
-        })
-        .map(async (t) => {
-          using _ = log.time(t.id)
-          const tool = await t.init({ agent })
-          const output = {
-            description: tool.description,
-            parameters: tool.parameters,
-          }
-          await Plugin.trigger("tool.definition", { toolID: t.id }, output)
-          return {
-            id: t.id,
-            ...tool,
-            description: output.description,
-            parameters: output.parameters,
-          }
-        }),
-    )
-    return result
+    return run(Service.use((svc) => svc.tools(model, agent)))
   }
 }
diff --git a/packages/opencode/test/file/watcher.test.ts b/packages/opencode/test/file/watcher.test.ts
index 2cd27643e8..d4893e963e 100644
--- a/packages/opencode/test/file/watcher.test.ts
+++ b/packages/opencode/test/file/watcher.test.ts
@@ -16,7 +16,7 @@ const describeWatcher = FileWatcher.hasNativeBinding() && !process.env.CI ? desc
 // Helpers
 // ---------------------------------------------------------------------------
 
-type BusUpdate = { directory?: string; payload: { type: string; properties: WatcherEvent } }
+type BusUpdate = { directory?: string; payload: { type: string; properties: Record<string, unknown> } }
 type WatcherEvent = { file: string; event: "add" | "change" | "unlink" }
 
 /** Run `body` with a live FileWatcher service. */
@@ -40,18 +40,18 @@ function listen(directory: string, check: (evt: WatcherEvent) => boolean, hit: (
     if (done) return
     if (evt.directory !== directory) return
     if (evt.payload.type !== FileWatcher.Event.Updated.type) return
-    if (!check(evt.payload.properties)) return
-    hit(evt.payload.properties)
+    const props = evt.payload.properties as WatcherEvent
+    if (!check(props)) return
+    hit(props)
   }
 
-  function cleanup() {
+  GlobalBus.on("event", on)
+
+  return () => {
     if (done) return
     done = true
     GlobalBus.off("event", on)
   }
-
-  GlobalBus.on("event", on)
-  return cleanup
 }
 
 function wait(directory: string, check: (evt: WatcherEvent) => boolean) {