agent-md

YAML frontmatter for agent persona files requires specific schema fields and a structured Markdown body to prevent scope confusion across GitHub Copilot, OpenCode, and Claude Code. Establishing correct frontmatter ensures platforms parse permissions and persona definitions accurately.

Agents, Skills, and Instructions separate persona responsibilities in agent files: Agents define "Who" the AI is, Skills define "How" it executes tasks, and Instructions define the domain "Rules" it follows. Separating these boundaries reduces context drift and duplication.

GitHub Copilot supports custom agent persona files like *.agent.md, but requires respecting platform-specific constraints for tool permissions and size limits. Validating schema correctness and boundary patterns ensures portability across Copilot, OpenCode, and Claude Code.

Validating CLAUDE.md and opencode.json for platform compatibility involves checking schema correctness, YAML frontmatter fields, boundary patterns, and relative-link portability. Correct validation prevents misconfigured tool permissions and size-limit violations across different coding platforms.

Relative links in agent persona Markdown files face portability limitations across GitHub Copilot, OpenCode, and Claude Code due to differing platform constraints and size limits. Enforcing relative-link portability and negative-scope boundaries prevents broken references and scope confusion.