skill-management

Self-Documentation

You (Claude Code) are the primary consumer of .agents/skills/. These files are your persistent knowledge base for working on this codebase. They survive across sessions and make you effective from the first turn.

Core principle: whenever you learn something useful that doesn't belong in CLAUDE.md, capture it in a skill so your future self doesn't have to rediscover it.

When to Create or Update a Skill

After implementing a complex feature

If the feature has conventions, multi-file coordination, or non-obvious rules — write them down. Examples of things that warranted a skill:

• Testing harness (/testing) — helpers, mock types, readability rules
• Tracing (/tracing) — span naming, OTel conventions, #[instrument] patterns
• Lua scripting (/lua-scripting) — host globals, ctx bindings, sandbox rules
• E2e tests (/e2e-testing) — fixture layout, step chaining, iteration workflow

After making structural changes

If you moved files, renamed types, changed module boundaries, or altered a subsystem's public API — check if an existing skill references the old names and update it.

After debugging a non-obvious issue

If you spent significant effort diagnosing something (e.g., "reqwest 0.13 renamed rustls-tls to rustls"), that's worth capturing. Future sessions shouldn't repeat the investigation.

After discovering a pattern the codebase relies on

If you notice the codebase consistently follows a convention that isn't documented anywhere (e.g., "all provider errors use retry-after headers"), write it down.

What Goes Where

Content	Destination	Why
Project-wide rules everyone must follow	CLAUDE.md	Always loaded, high visibility
Subsystem-specific conventions & API reference	.agents/skills/<name>/SKILL.md	Loaded on demand via /skill-name
Session-specific context, task state	Auto-memory (memory/MEMORY.md)	Lightweight, auto-managed
Operator-facing workflows for the GHOST	prompts/skills/<name>.md	Embedded in binary, for runtime

Rule of thumb: if the information is needed every session, it goes in CLAUDE.md. If it's needed when working on a specific subsystem, it goes in a skill. If it's ephemeral or speculative, it goes in auto-memory (or nowhere).

Skill File Format

Developer skills live in .agents/skills/<name>/SKILL.md:

---
name: skill-name
description: >-
  One paragraph. Start with what it covers. Then say WHEN to read it (triggers). The
  description is shown in the skill list — make it specific enough that you know when to
  load the full file. Under 1024 chars.
---

# Title

## Section — concrete rules, tables, code examples

Description triggers

The description field is what you see in the skill list. Write it so you'll know to load the skill at the right time. Good triggers:

• "MUST READ before modifying anything in src/scripting/"
• "MUST READ before writing or modifying any test"
• "MUST READ after implementing complex features or making structural changes"

Content guidelines

• File paths — which files to read/modify for this subsystem
• Contracts — data formats, type shapes, naming conventions
• Do/Don't rules — concrete, actionable, with rationale
• Patterns — recurring code shapes with short examples
• Gotchas — non-obvious behaviors, known failure modes, migration notes
• Keep skills under 500 lines. Split if needed (testing + e2e-testing).
• Use lowercase kebab-case names: lua-scripting, e2e-testing

Runtime Skills (for the GHOST, not for you)

The GHOST runtime also has skills in prompts/skills/. These teach the GHOST how to perform operator tasks. Some are symlinked into .agents/skills/ so you can read them too (e.g., agent-creator).

Directory	Audience	Loaded by
prompts/skills/	GHOST runtime	Embedded in binary, installed to $WORKSPACE/skills/
.agents/skills/	Claude Code (you)	Read via /skill-name in sessions

When modifying a runtime skill, remember it gets compiled into the binary via include_str!() in src/skills.rs.

Maintenance Checklist

Run this mentally before finishing any significant PR:

1. Did I change a subsystem that has a skill? Grep: rg "file_or_type_I_changed" .agents/skills/. Update any stale references.
2. Did I learn something non-obvious? If yes, does it belong in an existing skill or a new one?
3. Are the description triggers still accurate? Would you find the right skill when working on this feature next time?
4. Remove stale content — delete sections about removed features, don't comment them out.