Agent Coherence — Stale Write Guard (FS) MCP server

agent-coherence

agent-coherence stops one agent from silently clobbering another's work on a shared plan.md, store key, or memory.json — a vendor-neutral MESI + optimistic-concurrency coordinator for agent state on a single host, with the safety invariants machine-checked in TLA+.

Two agents share an artifact — a plan.md, a store key, a memory.json. One reads it and works; meanwhile a peer commits a newer version; the first writes back anyway. Last write wins, the peer's work is silently gone, nothing errors, and every downstream decision builds on the wrong version.

Why it goes unnoticed. An agent system keeps two records of what happened: the one your infrastructure can verify — which version each agent held, what actually committed, what was refused — and the one the model narrates, "task complete", "the plan is updated". They agree until an agent acts on a version that moved underneath it, and the narrated record is the one you read. That is why a lost update looks like a clean run and gets debugged as a model problem. agent-coherence is the verified record for the state your agents share. (It does not verify what an agent did in the outside world — a sent email, a fired webhook — that stays your outbox and idempotency layer's job.) agent-coherence turns that silent clobber into a loud, typed refusal: MESI-style ownership and invalidation over shared artifacts, optimistic commit-CAS for concurrent writers, and a read-generation fence for crash-reclaimed ones — a stale write is denied or returned as a retryable conflict, never silently applied. Same library, same protocol, across LangGraph, CrewAI, AutoGen, the OpenAI Agents SDK, plain files shared across processes (CoherentVolume), any MCP client (the stale-write-guard-fs server, via the mcp extra), and any custom orchestrator. Same behavior regardless of which model provider (Anthropic, OpenAI, Google, Mistral, open-source) the agents talk to.

<!-- MCP Registry — PyPI ownership tag for the stale-write-guard-fs server --> mcp-name: io.github.Cohexa-ai/stale-write-guard-fs

# Requires Python 3.11+
pip install "agent-coherence[langgraph]"        # LangGraph drop-in
pip install "agent-coherence[crewai]"           # CrewAI adapter
pip install "agent-coherence[openai-agents]"    # OpenAI Agents SDK adapter (experimental)
pip install "agent-coherence[diagnose]"         # ccs-diagnose CLI
pip install "agent-coherence[mcp]"              # stale-write-guard-fs MCP server
pip install "agent-coherence[conformance]"      # substrate conformance corpus (for foreign implementations)
pip install "agent-coherence[all]"              # everything

# Before
from langgraph.store.memory import InMemoryStore
store = InMemoryStore()

# After — one import change, no node code changes
from ccs.adapters import CCSStore
store = CCSStore(strategy="lazy")

store.get(), store.put(), store.search() keep working unchanged. CCSStore adds read-side coherence: a peer's commit invalidates your cached view, so your next read is a fresh miss. It does not deny a stale write-back — put is not version-CAS; for write-side lost-update prevention, route writes through CoherentVolume or write_cas (below).

Shortened. The full README is on GitHub.