[metalagman]

Summary

• decouple MCP cancellation-tail slot reuse from a second cold HTTP handshake
• isolate processor parity from discovery timing while retaining real SDK tool behavior
• drive paginated discovery to a blocked third request and verify the production setup timeout drains it

Validation

• go test ./...
• go test -race ./...
• go tool golangci-lint run ./...
• affected race tests with -count=100
• git diff --check