Entity engine, adapters, and facades

Pulse Entities separates governed operation semantics from the protocol that selects an operation and from any facade that presents those operations to an external ecosystem.

The three layers

Layer	Owns	Does not own
Entity engine	Static operation names, schema declarations, handler identity, governed execution, deterministic catalog	HTTP/JSON-RPC syntax, MCP lifecycle, provider SDKs
JSON-RPC adapter	Bounded envelope parsing, request/notification selection, named params, stable JSON-RPC result/error framing	Handler semantics, schema registry authority, direct provider access
Tools or MCP facade	Catalog projection, external tool naming/annotations, transport-facing invocation policy	Direct handler calls, runtime registry mutation, hidden Pulse authority

The entity engine is therefore not a server. EntityRouter records a static registry and binds it to one governed request. jsonRpc() is the only current adapter. A facade may read the emitted entities-catalog.json and construct a request for that adapter, but it cannot enumerate live handler functions or call them outside a Pulse request context.

Why the catalog is protocol-neutral

The catalog contains operation names, schema IDs, static metadata, and target eligibility. It excludes handlers, raw requests, request IDs, provider objects, secrets, and runtime values. That makes it suitable for build-time discovery without making discovery a new ambient runtime authority.

The inspection artifact is richer and maintainer-facing: it adds redacted handler-effect summaries and measured target evidence. Neither artifact is a mutable service registry.

Authority flow

1. Project configuration owns declared schemas and provider selection.
2. The trusted first-party lowerer extracts entity declarations without evaluating application code.
3. The selected adapter owns bounded protocol decoding and operation selection.
4. The selected schema codecs decode only the chosen input and encode only the chosen output.
5. The handler receives the normal request-owned PulseContext; every fetch, config, secret, KV, log, or package effect remains governed by that context.
6. The adapter frames completion. A facade sees only the framed boundary.

No layer may silently choose another target. Native ineligibility fails closed; it never authorizes JavaScript fallback.

MCP/tools boundary

@pulse-compute/mcp provides two explicit ways to expose governed tools. Both keep protocol framing outside the entity engine.

Binding	How a tool is invoked	Where it runs
Static @pulse-compute/mcp/pulse facade	Admits the MCP request and dispatches the selected Entities operation inside the same invocation.	Node Native, Fastly Native or explicit Node JavaScript.
Host @pulse-compute/mcp or /node adapter	Projects an emitted catalog and sends one request to a fixed governed Entities HTTP endpoint.	Ordinary JavaScript host code.

The static facade is the path used by the compiled Pulse context server. It dispatches a statically declared set of tools without an internal HTTP hop. Entities owns input/output validation and operation invocation; MCP owns admission, discovery and result framing. Reusable computation runs through the same ctx.call boundary available to admitted HTTP handlers, with shared request budgets and no extra host authority.

The separate host adapter retains optional external OAuth admission and backend credentials. Those options do not apply to the static facade. Its fixed endpoint, matching catalog/schema artifacts and deployment protection are application responsibilities. See the MCP package guide for exact imports, limits and authorization boundaries.

The Entities tools example remains a small JSON-RPC/tool-projection example. Use the context server for a complete bounded MCP application. Neither binding introduces a mutable runtime registry or provider authority through tool metadata.

Adapter scope

jsonRpc() is the supported Entities adapter. Queue, scheduled-event and other adapter shapes require separately defined selection, completion and lifecycle contracts; there is no third-party adapter registration surface. Pulse's static event handlers are a separate application entry plane, not an Entities adapter.

See the Entities package guide for current behavior and Entities lowering for the trusted maintainer boundary.