Discord plugin: notifications/claude/channel not delivered to Claude Code

Summary

The Discord MCP plugin (v0.0.1) successfully receives inbound DMs via messageCreate, but mcp.notification({ method: 'notifications/claude/channel', ... }) never reaches Claude Code. Outbound tools (reply, fetch_messages, react, edit_message) all work correctly.

Reproduction steps

1. Install the Discord plugin (discord@claude-plugins-official)
2. Configure bot token and add a user to the allowlist in access.json
3. Start Claude Code with --channels plugin:discord
4. Send a DM to the bot from Discord

Expected behavior

The message should appear in the Claude Code session as an inbound channel notification.

Actual behavior

• Discord shows "typing..." indicator (meaning handleInbound → sendTyping() succeeds)
• The typing indicator disappears after ~10 seconds
• No message appears in Claude Code
• No error is visible to the user

Diagnosis

| Step | Status |
|---|---|
| Discord → bot (messageCreate) | ✅ OK |
| gate() → deliver (user in allowlist) | ✅ OK |
| sendTyping() | ✅ OK (typing indicator visible) |
| mcp.notification() → Claude Code | ❌ Not delivered |
| Outbound reply tool | ✅ OK |
| fetch_messages tool | ✅ OK |

The MCP server declares experimental: { 'claude/channel': {} } in capabilities (server.ts:429). Standard request/response tool calls work perfectly. Only the server→client notification path (notifications/claude/channel at server.ts:716-731) fails silently.

Environment

• macOS (Darwin 25.3.0, Apple Silicon)
• Claude Code CLI (latest as of 2025-03-21)
• Discord plugin v0.0.1 (claude-plugins-official)
• MCP server runtime: Bun 1.3.11
• discord.js ^14.14.0
• @modelcontextprotocol/sdk ^1.0.0

Additional context

• Restarting Claude Code does not fix the issue
• Multiple sessions tested with the same result
• The .catch() on mcp.notification() (server.ts:729) does not appear to fire (no stderr output observed)
• The MCP server process is correctly parented to the Claude process