scarlet sovereign systems products · crimson codex
Local code intelligence over MCP

Give your agent a repo it actually understands.

One small Rust binary that gives your AI coding agent three ways to understand a codebase — fast keyword search, a whole-repo symbol map, and semantic ranking — entirely on your own machine. No cloud, no upload, no telemetry, no token bill. Built for the moment you want an agent that knows your repo but won't send proprietary source to someone else's API to get it.

Three tools, one binarysearch, print_repo, graph over plain MCP stdio JSON-RPC
The coordinate joinA search hit's line range is the edit handle — find it, then edit exactly those lines
Sovereign by defaultSearch, analysis and ranking all run locally. No telemetry to turn off — there's none
Drives any agentPlugs into the MCP client you already use. Not an editor lock-in
Three tools over one local binary, joined on shared coordinates An AI agent talks to one sovereign binary over MCP. The binary exposes three tools — search, print_repo, and graph. A search hit returns a file and a line range; that exact range is the handle print_repo edits against. Search and edits join on identical coordinates. Everything stays on the local machine. // your machine · nothing leaves disk agent MCP client stdio JSON-RPC crimson codex search BM25 · returns line range + hash print_repo symbols · imports · languages graph semantic + recency ranking same coords a search hit's {file, start, end} is the exact handle print_repo edits against
one binary, three tools, joined on shared coordinates — find it, then edit precisely the lines you found

What it does

Crimson Codex is a single MCP server (stdio JSON-RPC 2.0). Point any MCP-speaking agent at it and the agent gets three code-understanding tools:

  • search — BM25 keyword retrieval over your source, chunked by line. Each hit comes back as {file, start, end, score, blake3} — a precise line range, plus a content hash that acts as a staleness lock for safe, surgical edits.
  • print_repo — walks a repository and extracts its structure: symbols, imports, per-file line and byte counts, and a language breakdown. The map an agent needs before it touches anything.
  • graph — ingests code chunks into our semantic engine's gravity manifold and ranks results by a blend of meaning, recency, importance, and novelty — not just literal keyword match.

The edge is how they join. A search hit returns a line range. That same range is the handle print_repo works against — identical coordinates, with the blake3 hash confirming nothing changed underneath. Find it, confirm it's fresh, edit exactly those lines. No re-reading the whole file, no guessing offsets.

crimson-codex · one Rust binary · MCP stdio JSON-RPC 2.0 · search / print_repo / graph · 4/4 unit tests · local-only · zero telemetry

What we verified

Run against a real 31-file repository, end to end. No synthetic benchmarks, no rounding in our favour:

  • full MCP handshake — initialize, tools/list, and all three tool calls returned correct results
  • 4 / 4 unit tests pass
  • cold search ≈ 40 ms at roughly 7 MB resident on that 31-file repo — small, fast, frugal

These are the numbers from our own runs on one repo. We don't publish benchmarks we haven't measured.

How it compares

Tools like Sourcegraph Cody and Continue.dev are good at what they do, and for many teams a cloud-backed assistant is exactly right. Crimson Codex is built for a different constraint: keeping the whole loop on your own machine.

  • Sovereign by default — search, repo analysis, and ranking all run in one local binary. Your source isn't uploaded to a model provider or an indexing service. There's no telemetry to turn off, because there's none to begin with.
  • One tool surface, not a platform — three focused MCP tools any agent can drive, rather than an editor extension or a hosted service. It plugs into the agent you already use.
  • The coordinate join — because a search hit's line range is also the edit handle (locked by a content hash), an agent can go from "find" to "edit exactly these lines" without re-reading files or losing its place. That tight loop is the genuine edge.
  • Bought once — a perpetual local tool at a flat $99, not a per-seat monthly bill.

Get it

One-time purchase: the cross-platform Codex binary and a license key. No subscription, no seat metering, no telemetry.

Crimson Codex · MCP server binary + license key $99USD · one-time

License Crimson Codex →
  • Team — site license for a team / CI. Per-contract — talk to us.

Checkout and tax handled by Polar as merchant of record. Download link + license key by email the moment payment clears. If it doesn't do what this page says it does, we refund — that's the whole point of keeping the claims honest.

Who this is for

  • Developers running local coding agents who want them to actually understand the repo — search it, map it, rank it — over MCP
  • Regulated, air-gapped, and IP-sensitive shops that structurally cannot send source to a cloud agent or indexing service
  • Teams who want agent code-access tooling priced once, not a per-seat subscription that scales with headcount

Contact

crimson-codex · one sovereign Rust binary · search / print_repo / graph over MCP · local-only · one-time license