Weavatrix — native MCP repository intelligence

Give your coding agent repository evidence before it starts guessing.

Weavatrix is the native MCP product for repository intelligence. It gives Codex, Claude Code, and other coding agents 43 read-only operations over one revision-bound evidence graph: impact, architecture, APIs, Git history, duplicates, dead code, search, semantic links, and temporal memory.

It does not answer from a larger grep or an invented confidence score. Every bounded result can carry the repository revision, file, line, extractor, evidence kind, and confidence that produced it.

Ecosystem place (UNDERSTAND)

Weavatrix (this) — code facts
        │
        ▼
Weavatrix Loom — semantic composition (capabilities, registry, compile → Rust)
        │
        ▼
Realforge — artifact construction (scaffold / package / deploy)

Loom consumes Weavatrix facts for semantic classification (e.g. “this fn is a candidate for data.json.parse@1”). Loom must not grow a second product code indexer. Normative Loom side: ADR-0012.

The same source is distributed in two forms:

The npm package exists for convenience; it does not contain a different JavaScript engine. Both distributions run the same native adapter and the same weavatrix-rust analysis engine. The separately versioned weavatrix-js package is the legacy JavaScript implementation used for compatibility and historical baselines; it is not bundled into weavatrix.

Install in 30 seconds

Run the convenient prebuilt npm distribution:

npx -y weavatrix mcp .

Or install the same MCP product through Cargo:

cargo install weavatrix
weavatrix mcp .

Codex

# ~/.codex/config.toml
[mcp_servers.weavatrix]
command = "npx"
args = ["-y", "weavatrix", "mcp", "."]

Claude Code

claude mcp add weavatrix -- npx -y weavatrix mcp .

Grok

grok mcp add weavatrix -- npx -y weavatrix mcp .

Everything after -- is the server command, so -y reaches npx instead of Grok. The equivalent hand-written entry:

# ~/.grok/config.toml
[mcp_servers.weavatrix]
command = "npx"
args = ["-y", "weavatrix", "mcp", "."]
startup_timeout_sec = 120

The package unpacks to roughly 40 MB, so the first npx launch can spend longer fetching it than Grok's 30-second default startup timeout allows. startup_timeout_sec covers that once; npm i -g weavatrix or cargo install weavatrix removes the cold start for every later session.

Use --scope project to write .grok/config.toml inside a repository instead, so a clone carries the server with it.

Cursor

// ~/.cursor/mcp.json
{
  "mcpServers": {
    "weavatrix": {
      "command": "npx",
      "args": ["-y", "weavatrix", "mcp", "."]
    }
  }
}

Profiles expose bounded views of the same engine:

npx -y weavatrix mcp . --profile=all
npx -y weavatrix mcp . --profile=code
npx -y weavatrix mcp . --profile=seo

The npm package contains native binaries for Windows x64/arm64, macOS x64/arm64, and glibc Linux x64/arm64. It has no install script and performs no runtime download.

Halve every answer on a client that reads structured output

An MCP result carries the payload twice: once as structuredContent, and once mirrored into a text block for clients that read only content. The mirror is the pretty-printed copy, so it is the larger of the two.

npx -y weavatrix mcp . --output-format=structured

Measured on run_audit over a real repository, the response falls from 8931 to 3589 bytes, 59.8% smaller. Whether a client reads structured output does not change between calls, so it is chosen once at startup rather than restated as an argument on every call; WEAVATRIX_OUTPUT_FORMAT=structured does the same where a flag is awkward, and a call that names its own output_format still wins.

json is the default and keeps the mirror, because a client that ignores structuredContent would otherwise see an empty result. text returns the concise text block alone.

What an agent can ask

What breaks if I change src/auth/middleware.ts?
Trace POST /api/orders through this backend and its clients.
Which production symbols are dead, and what evidence proves it?
Show duplicate implementations but suppress router boilerplate.
Which dependency violates .weavatrix/architecture.json?
Find every GraphQL, gRPC, Kafka, RabbitMQ, NATS, JMS, SQS, or SNS
contract affected by this branch.
Build the smallest source bundle needed to edit this symbol safely.
Suggest internal links without mixing inferred SEO relationships into
the deterministic code graph.

The graph is built once per revision. Impact, API traces, health findings, architecture checks, clone families, and context bundles therefore agree about repository identity instead of recomputing incompatible partial views.

The 43 read-only operations

Every operation is read-only with respect to the analyzed repository. Pagination and explicit limits bound large neighborhoods, histories, searches, and contract inventories.

Languages and repository surfaces

The engine recognizes 24 named surfaces across 65 registered extensions. Support is evidence-specific: lossless tokenization is not presented as typed semantic resolution.

Cross-surface passes connect HTTP routes and calls, GraphQL operations and schema types, gRPC services and streaming modes, and Kafka, RabbitMQ/AMQP, JMS, NATS, SQS, and SNS producers and consumers. Package manifests, lockfiles, coverage artifacts, and architecture contracts become evidence too.

Dynamic dispatch that cannot be proved stays unresolved. Static reachability is not called measured coverage, and absent optional evidence remains explicitly absent.

Product boundary

Weavatrix is deliberately split into a protocol-independent engine and a thin product adapter:

coding agent
    |
    | MCP over stdio
    v
weavatrix 1.9.0
    profile catalog · session refresh · filesystem watcher · MCP framing
    |
    v
weavatrix-rust 2.7.1
    typed graph · analysis pipeline · 43 read-only operations
    |
    +-- weavatrix-scan      repository discovery and selection
    +-- weavatrix-parse     lossless tokenization and structural facts
    +-- weavatrix-graph     graph model and algorithms
    +-- weavatrix-git       direct Git-object evidence
    +-- weavatrix-search    bounded content and index search
    +-- vector / clone / semantic / memory components

This repository owns the MCP transport, watcher, native npm packaging, and client-facing identity weavatrix. The weavatrix-rust crate owns the reusable engine and standalone diagnostic CLI; it is not an MCP server. Its separate binary therefore reports weavatrix-rust <engine-version> from --version, while this product reports both the weavatrix product version and its embedded engine version.

The 2.0.2 engine also closes an integrity gap in duplicate results. After test/classified/low-signal filtering and after top_n truncation, Weavatrix rebuilds clone families from the pairs that remain. Every returned member and pair now belongs to the same deterministic connected component; filtered members and dangling pair identifiers cannot leak into find_duplicates.

Rust applications that want to embed the engine should depend on the crate:

[dependencies]
weavatrix-rust = "2"

use weavatrix_rust::{Weavatrix, operations};

let mut engine = Weavatrix::open(".")?;
let result = operations::call(
    &mut engine,
    "change_impact",
    blazingly_json::json!({"target": "src/auth.rs"}),
)?;
# Ok::<(), weavatrix_rust::Error>(())

Release evidence

The release gate measures the installed npm boundary, not an in-process microbenchmark. Each side is packed, installed into an isolated npm root, and started with empty HOME, XDG, AppData, and graph caches. The harness validates package/native/initialize identity, advertised operations, successful MCP results, and process cleanup.

The packaged 1.2.0 product, backed by weavatrix-rust 2.1.1, was measured on 2026-08-03 against installed weavatrix-js 0.3.15 on the same real JavaScript service repository (2,165 nodes / 5,712 edges), three paired fresh processes per tool with alternating start order:

Both release thresholds (24x cold, 30x warm) passed, and the paired cold median sits slightly above the 30.34x recorded for the 1.0.0 baseline, so the three new tools, token budgets, and dependency-injection evidence did not regress the installed boundary. Raw evidence and methodology live in benchmark-results and docs/benchmarks.md.

Safety and determinism

• read-only MCP surface;
• no source-writing operation;
• no execution of repository code;
• no spawned git, rg, language server, Node, or Python from the native engine;
• no network path in repository analysis;
• no npm install script or post-install binary download;
• bounded files, bytes, results, histories, and pagination;
• stable ordering and revision provenance;
• unsafe Rust forbidden in first-party engine crates;
• MIT license for the product, engine, and maintained first-party components.

Filesystem watching only invalidates derived state. The next operation performs a bounded refresh; it never edits the repository. Watching costs constant memory: every event is classified as it arrives and collapses into one pending change flag, so build output churning under target/ or node_modules/ never accumulates in a server that is sitting idle between tool calls.

Architecture and development

The product adapter follows ports and adapters:

inbound MCP server
        |
application session
        |
repository + change-monitor ports
        |
weavatrix-rust adapter · notify adapter

mcport is isolated to the inbound server. The application layer sees neither MCP frames nor notify events, and the engine sees neither dependency.

Local gates:

cargo fmt --all -- --check
cargo clippy --all-targets -- -D warnings
cargo test --all-targets

Native npm artifacts are built by scripts/build-npm-packages.mjs; publication is performed by the protected GitHub Actions workflow after all platform binaries, identity checks, package checks, and installed-boundary gates pass.

Documentation

• Getting started
• Tool reference
• Evidence model
• Language support
• MCP product architecture
• npm distribution
• Dependencies
• Benchmarks
• Engine API and architecture

License

MIT. See LICENSE.