Lema MCP server

lema-mcp

Your coding agent can read the code. It can't read the argument behind it. lema-mcp gives your agent the recorded why — and the alternatives a project already ruled out — cited to the source. For React, Kubernetes, and Rust out of the box, and for your own repo with one command.

A local MCP server. No account, no database, no network for your own repo — install it in 30 seconds and ask why a project decided something, or whether the approach you're about to take was already rejected.

❌ Without lema

wrongly. The rationale lives in RFC / KEP / PR threads; it was never in the code.

• The agent invents the why from training recall — fluently, and sometimes

because a rejected alternative leaves no trace in the source.

• It re-proposes the approach the maintainers already rejected two years ago —

a real ruling from a hallucinated one.

• Ask "was this ever ruled out?" and you get a confident guess, with no way to tell

✅ With lema

links to the RFC / PR where the call was made.

• One cited answer from the project's actual recorded deliberation — every [n]

with the recorded reason and a pointer to where the docs say to do it instead.

• A typed ruledout** verdict when a project already rejected your approach,

recorded choice — the governing decision cited, with a docs pointer for the how.

• A typed settled verdict when your approach is the project's in-force

unknown, not approved. lema never fills the gap with a guess.

• An honest "no recorded ruling" when the record is silent — which means

lema holds reasoning — why a decision was made, what was rejected — not API

syntax or code samples. For those, reach for a docs tool. lema is the right place

for why.

Try it in 30 seconds — no account

npx lema-mcp try react        # or: kubernetes · rust

That writes a read-only public server to your project's .mcp.json. Reload your agent's MCP servers (in Claude Code: /mcp) and try the flagship tool, checkapproach** — name a direction, get the recorded verdict:

> "Let's add a delayMs prop to Suspense to debounce the fallback."   (repo: react)

  ⛔ ruled_out — the React team considered and rejected this.
     "<the recorded rationale, summarized — not a quote>"  [1]
     Where to look instead →  https://react.dev/reference/react
     [1] reactjs/rfcs#212

> "I'll add a global event bus for cross-component communication."   (repo: react)

  ◦ no_recorded_ruling — React's public record doesn't settle this.
     (Unknown — not approved.)

Or just ask in plain language — "why did React adopt Hooks over mixins?" — and get one cited answer, with an honest abstain when the record is silent.

Covered today: React · Kubernetes · Rust, served from lema's public API (api.lema.sh). Tokenless. It's a curated three-project demo corpus — not analytics over a graph you own.

Install

No-account public demo (React's recorded decisions, zero setup):

Shortened. The full README is on GitHub.