* fix: return 202 for MCP notifications and echo client protocol version
- notifications/initialized returns 202 Accepted per MCP Streamable
HTTP spec (was 204 which may prevent tool discovery)
- Echo client's protocolVersion in initialize response
- Add instructions field for server description
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: validate protocol version and handle notifications pre-auth
- Validate protocolVersion against supported set instead of blindly
echoing (prevents false protocol agreement with unknown versions)
- Handle notifications/initialized before auth check so fire-and-forget
notifications don't get 401 responses that confuse MCP clients
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
