Implements the walking skeleton from the roadmap: agents connect to one HTTP
endpoint and Nexus aggregates upstream MCP servers behind it with namespaced
tools. Written in Go (single static binary), no external services required.
What works end-to-end (verified live + hermetic e2e tests):
- MCP protocol layer: JSON-RPC 2.0 + initialize/tools.list/tools.call
(internal/mcp), with stdio (subprocess) and Streamable HTTP client
transports, and a reusable stream transport for in-process wiring.
- Router + Dynamic Tool Registry: connects/initializes upstreams in parallel,
loads tools, namespaces them as {namespace}.{tool}, dispatches tools/call to
the owning upstream; refreshes on list_changed. A failed upstream stays
not-ready without taking down the gateway (data plane stays up).
- Gateway: single MCP endpoint (POST /mcp) that is an MCP server to agents,
plus /healthz and a minimal /metrics exposition.
- CLI (cmd/nexus): `serve`, `connect` (stdio<->HTTP bridge for local agents),
`demo-mcp` (built-in zero-dep demo server: echo/add/now), `version`.
- Config: declarative YAML with env expansion + validation.
- Store: persistence interfaces + in-memory impl (SQLite lands later).
Foundations for later phases: domain types (ARCHITECTURE §7), two-plane
split, event-driven refresh seam.
Tooling: Makefile (build/test/vet/fmt with version ldflags), config.example
.yaml. GOPATH moved to /go so it doesn't collide with the module root at /root;
.gitignore whitelist extended to track Go sources while ignoring build output.
Tests: unit (registry/namespacing) + full e2e (client -> demo server over
pipes -> router -> HTTP gateway: initialize, aggregated tools/list, tool-call
routing, unknown-tool error). go vet + gofmt clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
MCP Nexus is a self-hosted control plane for MCP servers — "Kubernetes for
MCP." Agents connect to one endpoint; Nexus discovers services, installs the
right MCP servers, aggregates them behind a namespaced router, secures access
with auth/RBAC, and heals/updates them via a reconcile loop.
This first commit is design-phase only (no runnable code yet):
- README.md project front door + module map
- docs/ARCHITECTURE.md target design: tenets, two-plane split, reconcile
loop, domain types, storage, security, deployment
- docs/ROADMAP.md phased delivery (foundations -> walking skeleton ->
discover+install -> secure -> operate -> extend/scale)
- docs/modules/01-20 one design doc per module, all cross-linked
Backend stack decision: Go (single static binary, embedded SQLite + embedded
React dashboard). Repo initialized in /root with a whitelist .gitignore so
only project files are tracked.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
