refactor(core): make Code Mode a service

packages/core/test/plugin/fixture.ts

@@ -1,6 +1,7 @@
 import { AgentV2 } from "@opencode-ai/core/agent"
 import { AISDK } from "@opencode-ai/core/aisdk"
 import { Catalog } from "@opencode-ai/core/catalog"
+import { CodeModeV2 } from "@opencode-ai/core/code-mode"
 import { CommandV2 } from "@opencode-ai/core/command"
 import { Credential } from "@opencode-ai/core/credential"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
@@ -43,6 +44,7 @@ export const PluginTestLayer = AppNodeBuilder.build(
     AgentV2.node,
     AISDK.node,
     Catalog.node,
+    CodeModeV2.node,
     CommandV2.node,
     Integration.node,
     PluginRuntime.node,

packages/core/test/plugin/host.ts

@@ -39,6 +39,9 @@ export function host(overrides: Overrides = {}): PluginContext {
       transform: () => Effect.die("unused command.transform"),
       reload: () => Effect.die("unused command.reload"),
     },
+    codemode: overrides.codemode ?? {
+      register: () => Effect.die("unused codemode.register"),
+    },
     event: overrides.event ?? {
       subscribe: () => Stream.empty,
     },