refactor(core): resolve default agent info (#27125)

packages/opencode/test/agent/agent.test.ts

@@ -638,6 +638,14 @@ it.instance("defaultAgent returns build when no default_agent config", () =>
   }),
 )
 
+it.instance("defaultInfo returns resolved build agent when no default_agent config", () =>
+  Effect.gen(function* () {
+    const agent = yield* load((svc) => svc.defaultInfo())
+    expect(agent.name).toBe("build")
+    expect(agent.mode).toBe("primary")
+  }),
+)
+
 it.instance(
   "defaultAgent respects default_agent config set to plan",
   () =>

packages/opencode/test/tool/registry.test.ts

@@ -180,7 +180,7 @@ describe("tool.registry", () => {
       const promptTools = yield* registry.tools({
         providerID: ProviderID.opencode,
         modelID: ModelID.make("test"),
-        agent: yield* agents.get(yield* agents.defaultAgent()),
+        agent: yield* agents.defaultInfo(),
       })
       const promptTool = promptTools.find((tool) => tool.id === "sql")
       if (!promptTool) throw new Error("custom sql tool was not returned for prompts")