The host-agnostic bridge client for the Plannotator agent dispatch protocol. It is the shared core under every adapter that connects a coding agent to an Artifact Server (or any server implementing the protocol): review comments dispatched from the web UI arrive in the agent's session as follow-up work, and the agent's replies close the loop.

The protocol itself is documented in PROTOCOL.md.

• Connect — resolves credentials (environment or the local server's discovery record), registers a self-named agent with a stable identity that survives restarts, declares capabilities, and reads the protocol version handshake.
• Claim — long-polls the dispatch mailbox; the poll is the heartbeat that makes presence honest.
• Render — turns a claimed bundle of comment threads into one readable message, stripping bidirectional-override and invisible Unicode from all untrusted text before it enters an agent's context.
• Deliver — hands the message to the host through a three-method port, follow-up only (never interrupting), held while the host compacts, and reports delivered only after the host accepted it.
• Close the loop — comment reply/resolve operations for the host's artifact_comments tool.
• Presence — a fire-and-forget activity beacon (thinking / replying / idle) at natural work boundaries.
• Fail open — no configuration means one notice then dormancy; a dead server means bounded backoff; no failure ever reaches the host.

An adapter supplies a HostPort — three functions — and gets everything above:

import {startBridge, resolveBridgeCredentials} from "@plannotator/agent-bridge";

const credentials = await resolveBridgeCredentials(environment, homedir());
const bridge = startBridge({
  agentSessionId: null,
  credentials,
  displayName: "my-project",
  fetchImplementation: fetch,
  host: {
    isCompacting: () => false,
    notify: (message, kind) => { /* surface a notice in your host */ },
    sendUserMessage: async (text) => { /* await host admission */ },
  },
  hostname: hostname(),
  kind: "my-harness",
  workingDirectory: process.cwd(),
});

Reference adapters live in the Artifact Server repository under integrations/: the Pi extension, the OpenCode plugin, and the Claude Code channel — each ~250 lines over this core.

sendUserMessage may return void for a synchronous host or a promise for an asynchronous host. Resolve that promise only after the host admits the message. Rejecting it fails that dispatch and leaves the bridge available for later work. Reserve a synchronous throw for an invalid host handle that requires the claim loop to stop.

renderBundleMessage(bundle) defaults to the native/channel instruction that names artifact_comments. Pass "mailbox" as its second argument when the receiving agent instead has the MCP comment_reply and comment_resolve tools. Both profiles use the same sanitization and message structure.

The package exports index.ts directly. Every current host loads TypeScript natively (Pi via jiti, OpenCode via Bun, channel processes via tsx); a compiled distribution can be added when a consumer needs one.

The protocol's conformance suite (BRP/PRS requirement IDs) runs in the Artifact Server repository against a real server, with this package as the client under test.

MIT