1. What Agent Skills Is Agent Skills is a production-grade engineering skill pack for AI coding assistants. It encodes the way senior engineers work — their working methods, quality gates, and best practices across the full Define → Plan → Build → Verify → Review → Ship lifecycle — into Markdown workflows (Skills) that an agent can execute.

1. What Headroom Is Headroom is a context compression layer for AI agents. Before the LLM receives a request, it performs content-aware compression on tool output, logs, RAG chunks, file contents, and conversation history, cutting token usage to 5%–40% of the original while keeping answer quality as unchanged as possible.

References: Claude Code Configuration, Environment Variables, Connecting to an LLM Gateway Claude Code talks to the Anthropic Messages API. When connecting to a custom gateway, use the env block of settings.json to override the endpoint and the model. 1. Where the Configuration File Lives The user configuration is at ~/.

References: Codex Configuration Basics, Codex Advanced Configuration Codex uses the OpenAI Responses API. When connecting to a custom gateway, define the endpoint with [model_providers.<id>], and the top-level model and model_provider determine the actual call. 1. Where the Configuration File Lives The user configuration is at ~/.codex/config.toml by default (on Windows,

References: OpenCode Config, Providers OpenCode uses the OpenAI Chat Completions API. When connecting to a custom gateway, declare the endpoint and the model list in the provider block of opencode.jsonc. 1. Installation and Configuration File 1 npm install -g opencode-ai The user configuration is at ~/.config/opencode/opencode.jsonc by default (opencode.json also