bug(mcp): MCP tools crash server if provider throws — no error handling in get_current_context / format_context_for_prompt #272

Summary

The get_current_context and format_context_for_prompt MCP tool implementations in packages/mcp/src/index.ts call options.provider.getContext(args) with no try/catch. If the provider throws or returns an invalid packet, the MCP server crashes without sending a well-formed error response to the calling agent.

Root cause

// packages/mcp/src/index.ts ~lines 125-136
handler: async (args) => {
  const packet = await options.provider.getContext(args); // no try/catch
  return { content: [{ type: 'text', text: JSON.stringify(packet) }] };
}

Impact

• A buggy or malicious provider can crash the entire MCP server process, disconnecting Claude/agents mid-session
• The calling agent receives no structured error — just a hanging or dropped connection

Fix

Wrap provider calls in try/catch and return a structured MCP error response:

handler: async (args) => {
  try {
    const packet = await options.provider.getContext(args);
    return { content: [{ type: 'text', text: JSON.stringify(packet) }] };
  } catch (err) {
    return {
      isError: true,
      content: [{ type: 'text', text: `Failed to get context: ${err instanceof Error ? err.message : String(err)}` }],
    };
  }
}