Feat/implemented by

[BelfordZ]

Summary

Add support for the OpenRPC x-implemented-by extension to server-js, enabling basic bidirectional APIs.

The server will no longer require handlers for methods declared as client-implemented and can optionally call those methods over WebSocket connections.

This introduces a minimal ownership model:

• server implements server methods
• connected peers implement client methods

No transport semantics or lifecycle rules are introduced — this strictly enables ownership-aware routing and outbound calls.

---

What this changes

Routing behavior

• Methods marked x-implemented-by: ["client"] are excluded from server handler registration
• Inbound calls to those methods are rejected (Method not found)
• Existing OpenRPC documents continue to work (default = server)

WebSocket outbound support

When using the WebSocket transport:

• Each connection is treated as a callable peer
• The server can call client-implemented methods on connected peers
• Handler context now exposes a client interface for calling peer methods

New usage patterns enabled

Inside a handler:

async sendMessage(params, { client }) {
  await client.chatMessage({ text: "hello back" });
}

Server-level outbound usage:

setInterval(() => {
  for (const client of server.clients()) {
    client.foo({ time: Date.now() });
  }
}, 1000);

---

Examples added

• Bidirectional WebSocket example
• Outbound server → client example

These demonstrate callback-style JSON-RPC usage without introducing pubsub semantics.

---

Motivation

OpenRPC historically models a server-handled API surface, but real JSON-RPC systems are commonly bidirectional:

• callbacks
• notifications in both directions
• peer-style APIs

Without an ownership signal, tooling cannot deterministically:

• decide which handlers to require
• expose callable peer methods
• implement realistic mocks

x-implemented-by enables this while remaining transport-agnostic and minimal.

---

Scope

This PR intentionally does not introduce:

• subscription semantics
• routing policies
• lifecycle modeling
• transport negotiation

It only adds ownership-aware dispatch and optional outbound peer calls for WebSocket connections.

---

Backwards compatibility

Existing APIs continue to behave exactly the same:

• Missing x-implemented-by ⇒ treated as server-implemented
• No changes required for current users

[codecov]

Codecov Report

❌ Patch coverage is 90.24390% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.32%. Comparing base (8531407) to head (cb82590).

Files with missing lines	Patch %	Lines
src/router.ts	83.33%	10 Missing ⚠️
src/plugins.ts	83.33%	4 Missing ⚠️
src/transports/websocket.ts	97.26%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #871      +/-   ##
==========================================
- Coverage   98.96%   95.32%   -3.64%     
==========================================
  Files           9       10       +1     
  Lines         289      428     +139     
  Branches       43       79      +36     
==========================================
+ Hits          286      408     +122     
- Misses          3       20      +17     

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