Skill

lythoskill-deck: Declarative Skill Deck Governance

What matters is not how many skills you have, but which ones the agent sees at the same time.

Core Model

skill-deck.toml declares desired state. deck link makes the working set (default .claude/skills/) match — creates symlinks for declared skills, removes everything else. Deny-by-default: undeclared skills do not exist in the agent's view.

Cold Pool (~/.agents/skill-repos/)  →  deck add  →  skill-deck.toml  →  deck link  →  .claude/skills/
     (all downloaded skills)              (declare)      (desired state)    (reconcile)    (working set — what agent sees)

Multi-File Phase Decks (BEST PRACTICE)

When a task spans different skill sets, use separate deck files per phase instead of editing a single toml:

# Phase 1 — brand design
deck link --deck phase1-brand.toml --cold-pool ~/.agents/skill-repos

# Phase 2 — content creation (atomic switch, Phase 1 skills gone)
deck link --deck phase2-content.toml --cold-pool ~/.agents/skill-repos

# Done — restore parent deck
deck link --deck ./skill-deck.toml

Each phase deck is independently auditable. Never add/remove entries in-place when switching contexts — a wrong edit silently breaks the previous phase's composition. The reconciler handles the transition: old symlinks removed, new ones created, no state leaks.

Seed Bootstrap

Start with a minimal deck (only lythoskill-deck as innate). The agent reads deck SKILL.md → learns schema → uses curator name LIKE '%keyword%' to discover skills → deck add + deck link → self-expands. Governance skill is the only irreducible dependency.

[deck]
max_cards = 8
cold_pool = "~/.agents/skill-repos"
working_set = ".claude/skills"

[innate.skills.lythoskill-deck]
path = "github.com/lythos-labs/lythoskill/skills/lythoskill-deck"

Commands

# ── Core (use these every time) ──

# Reconcile working set to match declaration
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} link
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} link --deck ./phase1-brand.toml

# Add skill from cold pool or download URL
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} add github.com/owner/repo/skill-name
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} add github.com/owner/repo/skill-name --alias my-skill --type tool

# ── Maintenance ──

bunx @lythos/skill-deck@{{PACKAGE_VERSION}} refresh              # plan-only scan for updates
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} refresh --exec       # actually git pull (self-heals dirty cold pool; non-zero exit + trailing ⚠️ on failure)
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} remove <alias>       # remove from deck + working set
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} validate                   # check current deck
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} validate --deck <path>     # check specific deck
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} validate --remote          # probe locators against GitHub
# Cold-pool-missing skills warn (not error) — they may exist on GitHub.
# HATEOAS output: each warning suggests curator add <locator> as next step.

# ── Advanced ──

bunx @lythos/skill-deck@{{PACKAGE_VERSION}} to-symlink <alias>   # snapshot → symlink
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} to-snapshot <alias>  # symlink → snapshot (pin HEAD)
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} reconcile            # drift report vs cold pool
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} reconcile --apply    # converge
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} migrate-schema       # old string-array → alias-as-key

link is a reconciler: undeclared symlinks → removed; broken symlinks → recreated; non-symlink entities → backed up then removed; missing declared skills → linked from cold pool. It also prints best-effort ⚠️ warnings when a cold-pool repo is behind origin, dirty, or on a non-default branch — drift is surfaced at the step every boot already runs.

refresh defaults to plan-only (no git pull). Use --exec to apply, or let an agent read the plan and execute per target — the agent can probe remotes, switch mirrors, handle divergence.

deck update is deprecated. Use refresh.

Format Detection (agent duty)

Before running any deck command, check the toml format. If you see skills = [...] (string array), it's the deprecated format. Ask before migrating:

⚠️  This deck uses the deprecated string-array format. Run migrate?
   bunx @lythos/skill-deck@{{PACKAGE_VERSION}} migrate-schema
   bunx @lythos/skill-deck@{{PACKAGE_VERSION}} migrate-schema --dry-run  # preview first

Do NOT silently migrate.

Key Concepts

Concept	One-liner
Cold Pool	All downloaded skills (~/.agents/skill-repos/). Agent cannot see here.
skill-deck.toml	Declares desired state. Alias-as-key dict format.
deck link	Reconciler. Makes the working set match the declaration.
Working Set	Symlinks only. What the agent actually scans. Default: .claude/skills/ (configurable per platform).
skill-deck.lock	Machine-generated snapshot: resolved paths, hashes, constraints.

Constraints

• deny-by-default — undeclared skills are physically absent from working set
• max_cards — exceeding the budget causes link to refuse
• link backs up real directories — non-symlink entries archived to .claude/skills.bak.*.tar.gz
• transient expires — past-due transients trigger warnings
• managed_dirs overlap — two skills claiming same directory triggers warning
• Never manually create subdirectories in the working set directory — use deck link
• deck does not run post-install steps — API keys, env vars are the skill's own responsibility

Locators — Always Fully-Qualified

Style	Example	Reliability
Fully-qualified	github.com/lythos-labs/lythoskill/skills/lythoskill-deck	Reliable — deterministic path
Bare name	lythoskill-deck	Fragile — non-deterministic readdir order

The deck does NOT auto-insert a skills/ prefix. Verify repo structure before writing locators.

Gotchas

deck link uses lstatSync, not existsSync — existsSync returns false for broken symlinks, causing EEXIST errors.

SKILL.md type field: Only standard or flow are valid. innate/tool/transient are deck toml section names, not SKILL.md types. deck_skill_type (custom field) for fork/transient declarations.

Network restrictions: If deck add or validate --remote fails with "Cannot reach github.com", use one of these env vars:

Variable	When to use	Example
LYTHOS_GH_MIRROR	You have a GitHub mirror/proxy	export LYTHOS_GH_MIRROR="https://mirror.example.com"
LYTHOS_SOCKS_PROXY	You have a SOCKS5 proxy	export LYTHOS_SOCKS_PROXY="127.0.0.1:1080"
LYTHOS_GIT_PROTOCOL	You need SSH instead of HTTPS	export LYTHOS_GIT_PROTOCOL="ssh"

export LYTHOS_SOCKS_PROXY="127.0.0.1:1080"
bunx @lythos/skill-deck@{{PACKAGE_VERSION}} add github.com/owner/repo/skill

Innate priority: After compaction, read innate skills' full SKILL.md first. tool skills are lazy — read on trigger. Agent-side convention.

Never guess locators — web-search the repo structure before writing paths for unfamiliar repos.

Deck as Orchestrator — Task → Deck Mapping

lythos has no standalone orchestrator. The deck IS the orchestrator entry point. You (the agent) select the right pre-built deck for the user's task, link it in an isolated environment, and execute. The three-layer distribution: light orchestration in combo prompt, medium in SKILL.md, heavy mechanical in CLI.

When you encounter a deck with [combo.<name>] sections, READ the combo prompts. They are the orchestration playbook — step-by-step instructions for multi-skill pipelines. The combo section is not optional metadata; it IS the orchestrator. Skipping it means executing skills in isolation without the coordination logic.

Intent → Deck mapping

User says	Deck to use	Command
调研 / 研究 / 查一下 / research	deep-research.toml	arena single --deck examples/decks/deep-research.toml --brief "..."
扫一下 / 审计 / 找问题 / audit / sweep	qa-sweep.toml	arena single --deck examples/decks/qa-sweep.toml --brief "..."
设计 / 架构 / 画图 / architecture	architecture-explainer.toml	arena single --deck examples/decks/architecture-explainer.toml --brief "..."
写文档 / 科普 / docs	documents.toml	arena single --deck examples/decks/documents.toml --brief "..."
治理 / task / epic / governance	governance.toml	arena single --deck examples/decks/governance.toml --brief "..."
体验 / 测试 UX / scout	scout.toml	arena single --deck examples/decks/scout.toml --brief "..."
改bug / 诊断 / diagnose	Use diagnose skill directly	—
写测试 / TDD	Use tdd skill directly	—
发布 / release / ship	Use lythoskill-red-green-release skill directly	—

Rule: deck first, don't ask. User says "调研" → reach for deep-research.toml. User says "扫一下" → qa-sweep.toml. Do NOT ask "should I use X or do it manually?" — just dispatch. The subagent works in parallel.

Full catalogue: examples/decks/INDEX.md.

Isolation discipline

Experiments run in /tmp, never in committed directories. Arena's prepare-workdir creates an isolated temp dir, links the deck there, and archives only outputs. No pollution of the project working set.

# Golden rule: never run experiments in the project root
arena single --deck examples/decks/deep-research.toml --brief "..."  # auto-isolates in /tmp

Orchestration weight — where does the logic go?

Your orchestration logic is…	Put it in…	Example
Light + conditional ("if X then Y")	[combo.<name>] prompt in skill-deck.toml	"If git status shows conflicts, call merge-conflict"
Medium + reusable across projects	Standalone SKILL.md in cold pool	A complex workflow with branching logic
Heavy + mechanical (filesystem, backup)	CLI npm package	deck link, arena single

The agent is the orchestrator. Tools execute. You reason about conditions, pass state between calls, handle errors. Combo prompt gives you the playbook; CLI gives you the mechanical layer.

Supporting References

When you need to…	Read
Understand cold pool → deck → working set pipeline	references/architecture.md
Look up a lythoskill term	references/glossary.md
Write or edit skill-deck.toml	references/toml-format.md
Set up a cold pool	references/cold-pool-setup.md
Build or organize a deck	references/deck-building.md
Run arena benchmarks with deck isolation	references/arena-integration.md
Understand SKILL.md types or skill thickness	references/skill-types.md
Add custom frontmatter fields	references/custom-fields.md