Implements the HTTP+SSE transport for the MCP server per bead pdftract-g0ro2.
All acceptance criteria PASS.
Routes:
- POST /: JSON-RPC requests (single or batch)
- GET /sse: Server-Sent Events for notifications
- GET /health: Health check (auth-exempt)
Key features:
- Reuses axum/tokio/tower-http from Phase 6.4 (no new deps)
- Bearer token auth (from sibling bead 6.7.7)
- Request body limit (256 MB default, configurable via --max-upload-mb)
- SSE keepalive every 30 seconds
- Broadcast channel for fan-out notifications
- Backpressure handling (drops lagged clients with WARN log)
- 100-client SSE limit (MAX_SSE_CLIENTS)
- Custom 413 Payload Too Large JSON response
- Batch request support per JSON-RPC 2.0 spec
All 10 integration tests pass:
- test_post_tools_list: POST / returns tool catalog
- test_get_sse_stream: GET /sse opens SSE stream with keepalive
- test_50_concurrent_clients: 50 concurrent clients succeed
- test_health_during_load: GET /health returns 200 under load
- test_post_batch_request: Batch requests return batch responses
- test_post_payload_too_large: POST / over limit returns 413 with JSON body
- test_auth_required_for_non_loopback: Bearer auth returns 401 with WWW-Authenticate
- test_post_single_request_returns_single_response: Single request returns single response
- test_unknown_method: Unknown method returns method_not_found error
- test_get_health: GET /health returns 200 with version info
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
