Skills Are Replacing Commands, Rules, and Subagents

This might be obvious to many, but it just clicked for me while building agent-resources.

When Anthropic released the Agent Skills open standard on December 18, 2025, GitHub announced support the same day. OpenAI Codex followed shortly after. The consolidation is happening fast.

The evidence

• Commands: OpenAI Codex has deprecated custom prompts in favor of skills. Claude Code's /slash-commands documentation now redirects to the skills page — skills are invoked as slash commands with /skill-name.
• Rules: Cursor includes a built-in /migrate-to-skills command that converts dynamic rules and slash commands into skills.
• Subagents: There's an open proposal to add context: fork to skills, allowing them to run in isolated context. Cursor's subagents docs recommend: "If you find yourself creating a subagent for a simple, single-purpose task... consider using a skill instead."

What skills don't replace

Instruction files. Skills are task-specific capabilities. Instruction files (CLAUDE.md, AGENTS.md) are persistent environment context — project structure, conventions, workflows. You need both.

Why I pivoted agent-resources

agent-resources originally supported skills, commands, rules, and subagents. I've now removed everything except skills. The other primitives are being absorbed — no point maintaining them.

Next up: instruction file templates. That's the gap that remains.