Discord plugin MCP server silently crashes on startup (Gateway WebSocket rejected)

Bug description

The Discord plugin MCP server (plugin:discord:discord) frequently fails to start or crashes shortly after startup when used with --channels plugin:discord@claude-plugins-official. Claude Code shows "Listening for channel messages" but the bot never comes online on Discord.

Steps to reproduce

1. Run claude --channels plugin:discord@claude-plugins-official
2. Check /mcp — plugin:discord:discord shows ✘ failed
3. No bun child process exists for the Discord MCP server
4. Other MCP servers (gmail, zotero) start fine

Observed behavior

• Claude Code displays "Listening for channel messages" even when the Discord plugin MCP server has failed — no visible error
• The bun process either never spawns or crashes within seconds
• /mcp shows plugin:discord:discord · ✘ failed
• Manual /mcp → Reconnect sometimes works briefly but the bun process dies again
• stderr from manual testing: discord channel: login failed: Error: WebSocket connection to 'wss://gateway.discord.gg/?v=10&encoding=json' failed: Connection ended
• The bot token is valid (confirmed via curl to Discord REST API)
• Running the MCP server manually with stdio works correctly (returns valid MCP initialize response)

Root cause hypothesis

When a healthcheck script or user restarts Claude Code multiple times, each restart attempts a new Discord Gateway WebSocket connection. After ~10+ restarts, Discord rate-limits the bot token's Gateway connections. The bun process then fails to connect and exits, but Claude Code doesn't surface this error clearly — it still shows "Listening for channel messages."

Key issues

1. Silent failure: Claude Code shows "Listening" even when the Discord plugin MCP is failed. There should be a visible warning on the main screen.
2. No retry with backoff: The plugin MCP server doesn't implement reconnection backoff, so rapid restarts trigger Discord rate limits.
3. Startup race condition: The plugin MCP server frequently fails on initial startup but succeeds on manual /mcp Reconnect, suggesting a timing issue during Claude Code's MCP initialization.

Environment

• Claude Code v2.1.88 and v2.1.89 (both affected)
• macOS Darwin 25.4.0 (Apple Silicon)
• bun 1.3.11
• Discord plugin v0.0.4 (from claude-plugins-official)
• Plugin path: ~/.claude/plugins/marketplaces/claude-plugins-official/external_plugins/discord/

Related issues

• #37026 (--channels ignored)
• #36837 (Discord plugin connected but no gateway messages on Linux)
• #38104 (notifications/claude/channel not waking up REPL)

Workaround

• Stop all Claude Code instances and wait 15-20 minutes for Discord rate limit to cool down
• Restart and use /mcp → Reconnect if initial startup fails
• Add exponential backoff to external healthcheck scripts to prevent rapid restarts