Built-in agent overrides don't fully apply #3895

Description

When trying to override the default agents with custom configurations, not all configs and metadata are applied and propagated in the TUI.

Nothing is majorly blocking, but it seems like the preamble of the .md files aren't fully applied.
The prompt itself is applied as expected and a workaround is to simply give another name to the file.

Workaround for now is to rename an agent file to not collide with the built-in.

OpenCode version

1.0.20

Steps to reproduce

1. Create an agent with the same name as a built-in agent, e.g., plan.md
2. Add in a preamble, such as the blow (not the mode: all and description:

<!-- agent/plan.md -->
---
description: Strategic analysis and development planning specialist. Provides comprehensive analysis and actionable implementation roadmaps without making code changes.
model: opencode/qwen3-coder
mode: all
tools:
  read: true
  grep: true
  glob: true
  list: true
  todoread: true
  webfetch: true
  context7: true
  write: false
  edit: false
  bash: false
  patch: false
  todowrite: false
---
<!-- Agent prompt -->

3. Start up OpenCode in a new session
4. Try to ping plan as a subagent

• Notice that it won't show up

5. Open up the agent picker and see that the description for the agent is still native

Screenshot and/or share link

plan.md file

Subagent ping for @plan

Agent picker showing "native" description

Operating System

macOS Sequoia 15.6.1

Terminal

Ghostty