Module backpressure 

Backpressure handling for graceful degradation under load.

The sync engine uses a six-tier backpressure cascade to handle memory pressure gracefully without dropping data.

Example

use sync_engine::BackpressureLevel;

// Normal operation
let level = BackpressureLevel::from_pressure(0.5);
assert_eq!(level, BackpressureLevel::Normal);
assert!(level.should_accept_writes());

// Under pressure - throttle writes
let level = BackpressureLevel::from_pressure(0.85);
assert_eq!(level, BackpressureLevel::Throttle);
assert!(level.should_accept_writes()); // Still accepts, but slower

// Critical - reject new writes
let level = BackpressureLevel::from_pressure(0.92);
assert_eq!(level, BackpressureLevel::Critical);
assert!(!level.should_accept_writes());

Enums

BackpressureLevel

Backpressure level based on memory/queue pressure.