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Hythe MCP Server

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HYTHE — coordination bus + shared truth for AI agent fleets — self-hosted MCP server + stdio bridge.

About

HYTHE — coordination bus + shared truth for AI agent fleets — self-hosted MCP server + stdio bridge.

Security Report

3.3
Use Caution3.3High Risk

HYTHE is a sophisticated MCP server with thoughtful security architecture (audit logging, authorization framework, tenant isolation), but several medium-severity vulnerabilities warrant attention: missing input validation on critical paths, unsafe SQL error logging that risks exposing sensitive data, potential information disclosure via error messages, and overly broad error handling that masks failures. The codebase demonstrates architectural maturity but needs hardening in data sanitization and error boundary management. Supply chain analysis found 6 known vulnerabilities in dependencies (0 critical, 1 high severity). Package verification found 1 issue.

3 files analyzed · 17 issues found

Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.

Permissions Required

This plugin requests these system permissions. Most are normal for its category.

File System Read

Reads files on your machine. Normal for tools that analyze or process local data.

File System Write

Writes or modifies files on your machine. Check that this is expected for the tool.

env_vars

Check that this permission is expected for this type of plugin.

HTTP Network Access

Connects to external APIs or services over the internet.

database

Check that this permission is expected for this type of plugin.

What You'll Need

Set these up before or after installing:

Shared API key authenticating the bridge to your self-hosted HYTHE server (generate with: npx -y @hythe/mcp init)Required

Environment variable: API_KEY

HYTHE server host (default 127.0.0.1)Optional

Environment variable: MCP_HOST

HYTHE server port (default 6174)Optional

Environment variable: MCP_PORT

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "dev-hythe-hythe": {
      "env": {
        "API_KEY": "your-api-key-here",
        "MCP_HOST": "your-mcp-host-here",
        "MCP_PORT": "your-mcp-port-here"
      },
      "args": [
        "-y",
        "@hythe/mcp"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub README.

HYTHE

A coordination bus + shared truth for your agent fleet. Self-hosted, two-component setup: a dockerized server plus a thin stdio bridge for your MCP clients.

HYTHE is an MCP server that lets multiple AI coding agents — Claude Code, Codex, Cursor, custom harnesses — share state, preserve context across sessions, and coordinate with each other. It is not another memory store. Its differentiators:

  • Supersession + current-state resolution: observations supersede each other (replace-current), and get_current_observation resolves the chain server-side — so readers get the newest non-superseded state. Conflict handling is implemented: checkpoint is branch-preserving CAS — concurrent writers branch rather than overwrite, and conflicts surface as heads, never silently resolved (contract-tested; see the evidence ledger).
  • Agent messaging with a tracked delivery lifecycle: direct and capability-based sends, message supersession, read-state as a shared signal, atomic ack+archive. (Described as tracked lifecycle, not guaranteed delivery — the states are honest about what the server knows.)
  • The Adaptive Coordination Protocol (ACP): the ETA-driven coordination discipline that co-evolved with the server — published as docs/SPEC.md with a real two-harness worked tutorial.

Documentation

DocWhat it covers
QuickstartClean machine → two coordinating agents in ~15 minutes
ConceptsOne current truth, messaging lifecycle, resume/checkpoint, honest security model
ACP SPECThe coordination protocol, versioned (1.0.0)
TutorialAnnotated transcript of a real Claude Code ↔ Codex review loop from the original Engram deployment
Tool compatibility mapThe 19-tool v1 surface; every retired tool and its exact replacement
Backup & restoreTested SQLite backup/restore/compaction runbook

Status

Published. @hythe/mcp@0.1.2 is the additive HYTHE distribution, with source at github.com/hythe-dev/hythe. New installs use npx -y @hythe/mcp. The predecessor @tomcat65/engram-mcp and io.github.tomcat65/engram remain available as compatibility history and point forward to HYTHE; they are never unpublished.

House rule: every claim in these docs must trace to a test or a measurement (see the evidence ledger below). Claims that don't are bugs.

Evidence ledger

ClaimEvidenceSourceDate
Tree green, full gateslock-verify (manifest-bound pin matched), clean npm ci, script-integrity, typecheck, build, tests (33 files, 408 passed | 2 skipped | 6 todo), schema-docs, final-tree smoke, docker build — all PASS, exit 0this repository, internal/run-staged-proof.sh2026-07-16
Documented env boots the runtimeFinal-tree smoke gate: server starts from .env.example variables with a generated key, authenticated MCP request succeeds, DB lands at the documented path, bridge round-trips on the same contract, compose ports are loopback-bound, and the untouched placeholder key fails startupthis repository, internal/final-tree-smoke.mjs2026-07-16
resume/checkpoint + conflict handling implementedENG-4 P0 contract suite (120 executable tests: CAS branching, conflict heads, idempotent replay, budget coverage closedness, scope-bound handles)tests/contract-eng4-p0.test.ts2026-07-16
Install path worksCLI contract suite (9 tests: bin mapping, wizard key-gen + parseable configs, .env write-once, live demo round-trip verified server-side, bridge delegation)tests/contract-cli.test.ts2026-07-16
Closed-safe defaultsPlaceholder key fails startup; compose ports loopback-bound; CORS grants no cross-origin access unless CORS_ORIGINS is set (tested)internal/final-tree-smoke.mjs, tests/contract-cli.test.ts2026-07-16
Discovery is truthfultools/list advertises the exact frozen schemas the handlers implement; retired legacy shapes are schema-rejected (regressions added after an adversarial review caught drift)tests/contract-eng4-p0.test.ts2026-07-16
Published + installable from the registrynpm publish succeeded under 2FA (auth-and-writes, security key); npm view @tomcat65/engram-mcp version0.1.0; clean-machine smoke: fresh npx cache, npx -y @tomcat65/engram-mcp --help and … init ran from the registry installnpm registry, post-publish smoke2026-07-16

v1 surface (short)

  • Install (two-component setup): server via docker compose up, then the @hythe/mcp stdio bridge per MCP client; first-run wizard generates the API key and prints ready-to-paste config for Claude Code / Codex / Cursor / Claude Desktop; optional namespaced (demo-*) demo seed on an otherwise empty DB.
  • Knowledge graph: entities, observations, relations, supersession, current-state resolution, conflict surfacing.
  • Agent messaging: direct, capability-based, superseding; tracked delivery lifecycle.
  • resume / checkpoint: budgeted one-call session rehydration with closed coverage accounting, and CAS-protected, branch-preserving structured state capture.
  • ACP: the coordination protocol as a versioned spec + real worked example.

License

Apache-2.0

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