LiveDocs MCP (che-livedocs-mcp)

A primary-source-first, always-latest documentation engine for AI agents.

Where context7 is a pre-built, periodically-recrawled, lossy vector index, LiveDocs auto-discovers each library's canonical machine-readable source on demand and reads it live. It can reach raw primary content and the exact latest version, which a lossy index structurally cannot.

Why this exists

The ecosystem is moving toward machine-discoverable primary sources (llms.txt, package registries, OpenAPI). Live probing of 25 popular docs hosts (2026-06-30) found ~88% already ship llms.txt, and the rest resolve deterministically via package registries. That tailwind makes a pre-built index increasingly redundant for the head of the distribution — and it's a source LiveDocs can read verbatim.

Discovery chain (primary-source-first)

1. llms.txt / llms-full.txt — the LLM-designed index/full dump, probed across root, /docs/, and full-variant paths, with a soft-404 guard (a real hit is 200 + text/plain + non-trivial size; many hosts answer 200/404 with an HTML shell).
2. Package registry — npm (registry.npmjs.org/<pkg>/latest) / PyPI (pypi.org/pypi/<pkg>/json): the exact latest version + changelog/repo/docs URLs, deterministically, no scraping.
3. Repo — GitHub README / CHANGELOG / releases (raw).
4. Introspection (introspect) — the highest-fidelity "can I actually use it" source, read directly from the machine/installed artifact: OpenAPI / GraphQL schema, an installed CLI's --help/--version, or a locally installed R package's version (kind:"r-pkg", read-only). This is the "local" half of a version check — for targets with both a web-latest and an installed version, the docs-router skill reconciles them and always defers to the installed version (web only gates the upgrade).
5. Fallback — context7 / web, always labeled low-fidelity.

Results are ranked fidelity-first, then freshness.

Tools

Tool	Purpose
resolve_source	Discover ranked primary sources for a library (library+ecosystem and/or docs_url).
fetch_docs	Fetch the raw text of a source URL — verbatim, no lossy layer.
latest_version	Deterministic "latest released version right now" + changelog/repo, from the registry.

Architecture

• LiveDocsCore — dependency-free discovery logic (candidate generation, soft-404 classification, registry parsing, ranking). Network is injected via the HTTPClient protocol, so the whole engine is unit-tested without a server or the network.
• CheLiveDocsMCP — a thin MCP stdio shell over the engine.

The fuzzy "which library is this?" decision belongs to the calling agent (a router skill); these tools take concrete inputs and do deterministic work.

Develop

swift test     # 20 unit tests (pure logic + engine orchestration via fakes)
swift build    # builds the MCP executable

Status: MVP — llms.txt + registry + repo legs working end-to-end and verified live. Shipped: 9-ecosystem registry resolution, version pinning, OpenAPI/GraphQL/CLI + installed-R introspection, docs-router skill (incl. per-question has-local/web-only classification + version reconciliation), signed+notarized release, marketplace distribution.

Design boundary (what LiveDocs is and isn't for): docs/design/primary-source-spectrum.md.