Reference

Use this section when you need the exact contract, not a walkthrough of how to use it.

Every page here describes a promise: a wire format, a tool signature, a permission rule, a file location. If a detail here changes, it changes as a breaking change to the protocol, not as an internal refactor.

Topics

MCP Protocol

Transport, version negotiation, and the error shapes returned by NEXUS's local MCP server.

MCP Tools

Every tool exposed through tools/list: what it does, how it is scoped, and what it returns.

Canvas Roles

The role ladder, the write-outcome contract, and the concurrency model for the shared canvas.

Agent Hooks

How a hook post is attributed to an agent, and the refusals that apply when it isn't.

Entitlements

The cloud entitlements endpoint: keys, limits, and propagation timing.

Paths & Credentials

Where NEXUS's configuration and credential files live, and why their naming is load-bearing.

Looking for the reasoning?

These pages state contracts without justifying them. For the reasoning behind a design — why writes are optimistic, why the mesh has no synchronous reply, why two independent gates exist for autonomous chains — see Explanation.