MCP server hosting architecture

Location: enterprise/apps/gateway/internal/mcphost/ — protocol, registry, backend, transport.

MCP server hosting architecture

Location: enterprise/apps/gateway/internal/mcphost/ — protocol, registry, backend, transport.

It shares the LLM process and middleware chain (auth → policy stage mcp_tool → quota → audit) with a separate handler branch. Off by default. See gateway/mcp-hosting-overview.md.

Diagram: /mcp/{server}/* enters Host, then splits into Registry, Backend, and Transport.

Components

Part	Job	Code
Router	Mounts `GET /mcp/registry` and three transports	`internal/server/mcp_handlers.go`
Host	Resolve server, EffectiveScopes, call backend	`mcphost/host.go`
Registry	Read `mcp_servers` + `mcp_tools`; builtin `demo`	`mcphost/registry.go`
Entitlement	A capability pack can revoke access	`mcphost/entitlement.go`
Backend	`echo` / `openapi`; `custom-go` is a stub	`mcphost` backends
Transport	Streamable HTTP or SSE + messages	Endpoint map from Host

Data model

mcp_servers — metadata + backend_config (openapi_json / gzip openapi_blob)
mcp_tools — enabled tools + JSON Schema
gateway_audit_events.mcp_* — tool-call audit (nullable, Blake2b-compatible)

OpenAPI → MCP

Each allowlisted operationId becomes one MCP tool. Parameters + requestBody merge into inputSchema. oneOf / anyOf degrade to object + description.

Not shipped

custom-go backend
apps/edge-agent as an MCP host (that binary is still a skeleton)

Operations: runbooks/mcp-hosting.md.

Made-with: Damon Li