darkmatter-skills

darkmatter/skills

Team-wide LLM preset infrastructure for the darkmatter umbrella. OpenCode is the preferred client, but this repo stays source-oriented: shared assets live here and are synced into OpenCode, Claude-compatible, Codex, and generic agent locations as needed.

This repo ships four things:

1. OpenCode-first presets (presets/) — installable source packs for LLM clients.
2. A catalog of shared skills (skills/) — installed across all darkmatter projects via Nix Home Manager, or as a Claude Code plugin (see Claude Code plugin marketplace).
3. A project template (template/) — .agent/, config, and shims to stamp into a new project repo.
4. Tooling (scripts/) — generators, installers, sync scripts, and validation helpers.

It is provider-agnostic. Skills and .agent/ content target any agent tool (Claude Code, Codex, OpenCode, Cursor, Aider, etc.) by following the cross-vendor AGENTS.md convention plus the per-vendor shims (CLAUDE.md, .cursorrules).

Layout

darkmatter/skills/
├── .claude-plugin/          ← Claude Code marketplace + plugin manifests
├── README.md                ← this file
├── flake.nix                ← Nix entry; exports the Home Manager module
├── home-manager.nix         ← HM module that wires skills/ into agent CLIs
├── presets/                 ← installable source packs, especially OpenCode
├── skills/                  ← team-wide shareable skills (the catalog)
├── template/                ← the per-project bootstrap (stamped by new-project.sh)
├── scripts/
│   ├── new-project.sh       ← stamp template/ into a target dir
│   └── validate-skill.sh    ← sanity-check skills/ catalog
├── evals/
│   ├── skills/              ← Promptfoo behavior evals (LLM decision checks, CI)
│   └── prompt-tests/        ← real-repo opencode evals (local/manual only)
└── docs/
    ├── catalog.md           ← what's in skills/
    └── new-project-guide.md ← walkthrough for bootstrapping a project

Claude Code plugin marketplace

The skills catalog is also installable as a Claude Code plugin — no Nix required. Inside Claude Code:

/plugin marketplace add darkmatter/skills
/plugin install darkmatter-skills@darkmatter

.claude-plugin/marketplace.json defines the marketplace and lists the repo root (./) as a single plugin; .claude-plugin/plugin.json is that plugin's manifest. Claude Code auto-discovers every skills/<name>/SKILL.md, so adding a skill to the catalog adds it to the plugin with no extra registration. Validate changes with claude plugin validate ..

The Nix Home Manager module remains the primary distribution path on darkmatter machines; the marketplace is for Claude Code users outside that setup (or for trying the catalog before wiring up Nix).

OpenCode presets

OpenCode-native assets live in presets/opencode/. Shared cross-client instructions live in presets/base/, and shared skills remain in skills/.

See docs/opencode-layout.md for the source-to-install mapping.

Where to put what

Use this table before adding a new instruction, skill, command, hook, or tool. The goal is to keep always-on context small while still making reusable behavior discoverable.