Lex

Lex — Claude Code plugin

A Claude Code plugin that teaches Claude to drive the Lex toolchain and, optionally, a hosted lex-hub gateway.

It bundles three things:

• A skill (skills/lex/) — when/how to run the lex CLI plus the effect-discipline idiom rules and syntax pitfalls. Auto-loads when you're working with .lex files or lex.toml.
• Slash commands — one-key wrappers over the agent-code loop:
  • /lex:lex-check — type-check and surface structured errors.
  • /lex:lex-repair — the repair-not-regenerate loop (lex repair --apply).
  • /lex:lex-publish — fmt + check + publish to the store.
  • /lex:lex-run — check + run a function under a narrow policy.
• An MCP server (lex-hub) — first-class tools (lex_check, lex_publish, lex_run, lex_patch, lex_stage_attestations, lex_health) against a remote lex-hub gateway.

Install

/plugin marketplace add alpibrusl/lex-lang
/plugin install lex@lex

That installs the skill and slash commands immediately. The two integration points below are only needed for the workflows that use them.

Local lex CLI (for the skill + slash commands)

The skill and commands shell out to the lex binary. Install a release from https://github.com/alpibrusl/lex-lang/releases (or cargo build --release in a checkout) and make sure lex is on your PATH:

lex --version

Remote lex-hub (for the MCP tools)

The lex-hub MCP server runs the lex-hub-mcp binary, which lives in the lex-hub repo. Put it on your PATH:

cargo install --git https://github.com/alpibrusl/lex-hub lex-hub-mcp

Then set the gateway URL and credentials in your environment (the plugin's .mcp.json passes these through). Provide either a pre-minted token or a secret + tenant to mint one:

export LEXHUB_URL="https://api.example.com"

# Option A — a pre-minted bearer JWT:
export LEXHUB_TOKEN="eyJhbGciOi..."

# Option B — mint a short-lived HS256 token (sub = tenant):
export LEXHUB_JWT_SECRET="your-secret"
export LEXHUB_TENANT="my-tenant"

If LEXHUB_URL and credentials aren't set, the MCP server won't start — the skill and slash commands (local CLI) still work without it.

Layout

integrations/claude-plugin/
├── .claude-plugin/plugin.json   # manifest
├── .mcp.json                    # lex-hub MCP server (runs lex-hub-mcp)
├── commands/                    # /lex:lex-check, lex-repair, lex-publish, lex-run
├── skills/lex/SKILL.md          # the lex CLI skill + idiom rules
└── README.md

The marketplace manifest is at the repo root: .claude-plugin/marketplace.json.

Why this split

The local lex CLI is already agent-discoverable (it implements the ACLI contract: lex introspect / lex skill / lex agent-guidelines), so the skill + commands are thin orchestration over a self-describing tool. The hosted gateway isn't MCP-native — it speaks JWT'd HTTP/JSON — so the lex-hub-mcp bridge (shipped in the lex-hub repo) turns it into first-class MCP tools.