Race observed on first turn: ClaudePlugin emits notifications/claude/channel before Claude Code finishes registering the channel handler internally. Claude logs "MCP server synthesis: Channel notifications registered" ~25ms AFTER hello_ack arrives. Notifications that arrive earlier are silently dropped — observed empty session, no turn, curl hangs until timeout. Fix: on first `inbound` frame after WS hello, wait 800ms before emitting the MCP notification. Subsequent inbounds skip the wait. End-to-end verified twice on laptop. Cold-start ~10s, hot path 2-3s.
SynthesisAgent.ClaudePlugin
Stdio MCP server registered as a Claude Code --channels server:<name> source. Lives inside every long-lived Claude process spawned by SynthesisAgent.OpenclawPlugin.
What it does
- Connects out (WebSocket) to OpenclawPlugin's bridge on startup, sends
hello - Listens for
inboundframes → emitsnotifications/claude/channelso Claude opens a new turn - Exposes a single
reply(text, final?)MCP tool — the model calls it to send its answer back to the OpenClaw side
Capability declaration (important detail)
new Server({...}, {
capabilities: {
tools: {},
experimental: {
'claude/channel': {},
},
},
})
Top-level placement of 'claude/channel' is silently ignored — Claude Code logs "server did not declare claude/channel capability". Verified 2026-05-14 against the official Anthropic discord plugin source.
Required env vars
Set by OpenclawPlugin's process-manager when spawning claude:
| Var | Example |
|---|---|
SYNTHESIS_WS_URL |
ws://127.0.0.1:18901/bridge |
SYNTHESIS_OPENCLAW_SESSION |
developer::discord:channel:123 |
SYNTHESIS_CLAUDE_SESSION |
<uuid> |
Manual registration (laptop smoke test)
To use this MCP server with claude --channels server:synthesis, register it once globally:
claude mcp add --scope user synthesis -- bun run /absolute/path/to/server.ts
Then OpenclawPlugin can spawn:
claude --channels server:synthesis \
--dangerously-load-development-channels server:synthesis \
--resume <uuid> \
--permission-mode bypassPermissions
(The --dangerously-load-development-channels flag triggers a one-time interactive dev-mode confirmation. OpenclawPlugin's process-manager pipes "1\n" to stdin shortly after spawn to dismiss it automatically.)
Tool surface (v1)
Just reply. The model uses Claude Code's built-in tools (Read, Edit, Bash, etc.) for any actual work; reply is purely the output channel.
reply(text, final=true) sends a complete answer.
reply(text, final=false) queues a progress chunk; OpenclawPlugin buffers chunks until a final call arrives.
License
Apache-2.0 (modeled after Anthropic's official discord@claude-plugins-official plugin).