Chapter 16. Building Skills and Plugins with Coding Agents
In this section
- Chapter 16. Building Skills and Plugins with Coding AgentsPackage professional work as skills, written with the person who owns the rules, and ship them as an installable plugin. Taught through the open standards for skills, plugins and telemetry, then built with Claude Code and ported with Codex and OpenCode to six places where people use AI.
- 16.1 From a prompt you repeat to a skillWork you keep explaining becomes a skill: a folder with a SKILL.md and supporting files, taught through the Agent Skills specification and its three stages of loading.
- 16.2 Choosing the right pieceA built-in tool, your own code, a skill, a connector, a helper agent, or a hook or setting: what each is for, what it costs, and why a skill guides while a hook or setting enforces.
- 16.3 Writing a skill with the expertThe co-build split: the expert writes the rules, cases and what must never happen, the builder writes the skill, its script and its tests. A description that loads for the right requests, and testing that a skill loads and behaves.
- 16.4 Commands and who may start themA command is a skill a person starts by name, with arguments. Work that acts should run only when asked. Running a skill in a separate context. No shared standard says who may start a skill yet.
- 16.5 What a plugin bundlesA plugin is one installable unit, taught through the Agent Plugins 1.0.0 specification: a plugin.json manifest, skills and connectors as the two portable parts, and extensions for everything else. Adding a ready-made connector with no code, and when you need no plugin.
- 16.6 Shipping a versionWhat a version number promises, what a changed rule must move, how a change reaches each installed copy, how anyone knows which version ran, and the checks and catalogs around a release.
- 16.7 One skill, three bundlesThe agent that builds a plugin is not the host that loads it. Skills and remote connectors travel through open standards, the bundle travels only where the bundle standard is implemented, and one bundle behaves differently on each surface. Design the core to the standard and test on every surface.
- 16.8 Watching it run: telemetryTaught through OpenTelemetry: traces, spans, metrics and log events, what each part of a plugin can report, trace context into a connector, and two limits. Telemetry does not reach inside code that is not instrumented, and it shows that work ran, never that it was right.
- 16.9 Installing is a trust decisionA plugin runs as you. Hooks, code modules and connector processes run with your rights and no sandbox, and every enabled plugin costs context. Read a plugin before you install it, as you read a pull request.
- 16.10 How today's tools realize itHow to practice each lesson of this chapter in your own tools, and how Claude, OpenAI's products and OpenCode carry out the standards, as of November 2, 2026: one table, what each product adds or leaves out, and the differences that change a decision.
- Lab 16: the Brightline AP plugin v0.1Chapter 16's lab: turn the AP analyst's triage rules into tests, a tested engine and a skill, package three skills and a read-only connector as a plugin, ship it through a reviewed pull request, read a stranger's plugin before installing it, rehearse a changed limit, then package the same skills for OpenAI with Codex and for OpenCode with OpenCode.
- Check yourselfRecall and practice for the whole chapter: the flashcards, and a final quiz round from all ten concepts.