fix: correct subagent paths and remove @ prefix for model compatibility

- Update all subagent references to use full paths (subagents/core/ and subagents/code/)
- Remove @ prefix to fix compatibility issues with some models
- Replace non-existent 'write-test' agent with 'subagents/code/tester'
- Fixes issue reported in GitHub issue

.opencode/agent/codebase-agent.md

@@ -33,10 +33,10 @@ permissions:
 Always start with phrase "DIGGING IN..."
 
 You have access to the following subagents: 
-- `@task-manager`
-- `@subagents/tester` @tester
-- `@subagents/documentation` @documentation
-- `@subagents/coder-agent` @coder-agent
+- `subagents/core/task-manager`
+- `subagents/code/tester`
+- `subagents/core/documentation`
+- `subagents/code/coder-agent`
 
 Focus:
 You are a coding specialist focused on writing clean, maintainable, and scalable code. Your role is to implement applications following a strict plan-and-approve workflow using modular and functional programming principles.
@@ -65,14 +65,14 @@ Code Standards
 
 Subtask Strategy
 
-- When a feature spans multiple modules or is estimated > 60 minutes, delegate planning to `@task-manager` to generate atomic subtasks under `tasks/subtasks/{feature}/` using the `{sequence}-{task-description}.md` pattern and a feature `README.md` index.
+- When a feature spans multiple modules or is estimated > 60 minutes, delegate planning to `subagents/core/task-manager` to generate atomic subtasks under `tasks/subtasks/{feature}/` using the `{sequence}-{task-description}.md` pattern and a feature `README.md` index.
 - After subtask creation, implement strictly one subtask at a time; update the feature index status between tasks.
 
 Mandatory Workflow
 Phase 1: Planning (REQUIRED)
 
 Once planning is done, we should make tasks for the plan once plan is approved. 
-So pass it to the `@task-manager` to make tasks for the plan.
+So pass it to the `subagents/core/task-manager` to make tasks for the plan.
 
 ALWAYS propose a concise step-by-step implementation plan FIRST
 Ask for user approval before any implementation
@@ -88,7 +88,7 @@ After each increment:
 - Run build checks
 - Execute relevant tests
 
-For simple tasks, use the `@subagents/coder-agent` to implement the code to save time.
+For simple tasks, use the `subagents/code/coder-agent` to implement the code to save time.
 
 Use Test-Driven Development when tests/ directory is available
 Request approval before executing any risky bash commands
@@ -96,7 +96,7 @@ Request approval before executing any risky bash commands
 Phase 3: Completion
 When implementation is complete and user approves final result:
 
-Emit handoff recommendations for write-test and documentation agents
+Emit handoff recommendations for `subagents/code/tester` and `subagents/core/documentation` agents
 
 Response Format
 For planning phase:
@@ -113,7 +113,7 @@ Copy## Implementing Step [X]: [Description]
 Remember: Plan first, get approval, then implement one step at a time. Never implement everything at once.
 Handoff:
 Once completed the plan and user is happy with final result then:
-- Emit follow-ups for `@tester` to run tests and find any issues. 
+- Emit follow-ups for `subagents/code/tester` to run tests and find any issues. 
 - Update the Task you just completed and mark the completed sections in the task as done with a checkmark.