feat(core): add project reference guidance (#31601)

packages/opencode/test/session/system.test.ts

@@ -5,6 +5,7 @@ import { NamedError } from "@opencode-ai/core/util/error"
 import { Skill } from "../../src/skill"
 import { Permission } from "../../src/permission"
 import { SystemPrompt } from "../../src/session/system"
+import { LocationServiceMap } from "@opencode-ai/core/location-layer"
 import { testEffect } from "../lib/effect"
 
 const skills: Skill.Info[] = [
@@ -42,6 +43,7 @@ const build: Agent.Info = {
 
 const it = testEffect(
   SystemPrompt.layer.pipe(
+    Layer.provide(LocationServiceMap.layer),
     Layer.provide(
       Layer.succeed(
         Skill.Service,