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other (replace-current), and get_current_observation resolves the chain server-side — so readers get the newest non-superseded state.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

Doc	What it covers
Quickstart	Clean machine → two coordinating agents in ~15 minutes
Concepts	One current truth, messaging lifecycle, resume/checkpoint, honest security model
ACP SPEC	The coordination protocol, versioned (1.0.0)
Tutorial	Annotated transcript of a real Claude Code ↔ Codex review loop from the original Engram deployment
Tool compatibility map	The 19-tool v1 surface; every retired tool and its exact replacement
Backup & restore	Tested 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and io.github.tomcat65/engram remain available as compatibility history and point forward to HYTHE; they are never unpublished.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

Claim	Evidence	Source	Date
Tree green, full gates	lock-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 0	this repository, `internal/run-staged-proof.sh`	2026-07-16
Documented env boots the runtime	Final-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 startup	this repository, `internal/final-tree-smoke.mjs`	2026-07-16
resume/checkpoint + conflict handling implemented	ENG-4 P0 contract suite (120 executable tests: CAS branching, conflict heads, idempotent replay, budget coverage closedness, scope-bound handles)	`tests/contract-eng4-p0.test.ts`	2026-07-16
Install path works	CLI 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.ts`	2026-07-16
Closed-safe defaults	Placeholder 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.ts`	2026-07-16
Discovery is truthful	tools/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.ts`	2026-07-16
Published + installable from the registry	`npm publish` succeeded under 2FA (auth-and-writes, security key); `npm view @tomcat65/engram-mcp version` → `0.1.0`; clean-machine smoke: fresh npx cache, `npx -y @tomcat65/engram-mcp --help` and `… init` ran from the registry install	npm registry, post-publish smoke	2026-07-16

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.