# Scoring Engine

Вычисляет score (0..100) для каждой ноды. Ноды со score = -100 исключаются из роутинга.

## Lethal Conditions (score → -100)

Если хотя бы одно условие истинно — нода исключается:
If at least one is true — node is excluded from routing.

| Condition | Threshold |
|-----------|-----------|
| `status != "ok"` | Any status other than `ok` |
| Stale | > `stale_threshold_sec` (default 20s) |
| `active_calls >= max_calls` | 100% capacity used |
| `idle_cpu < idle_cpu_min` | < 5% |
| `call_failure_rate > call_failure_rate_lethal` | > 15% |
| `disabled == true` | Manual admin disable |

## Weighted Score (0..100)

```
call_score = clamp(100 - (active_calls / max_calls * 100), 0, 100)
load_score = clamp(100 - (load_avg * 50), 0, 100)
idle_score = clamp(idle_cpu, 0, 100)
fail_score = clamp(100 - call_failure_rate, 0, 100)

score = call_score × 0.40 +
        load_score × 0.30 +
        idle_score × 0.20 +
        fail_score × 0.10
```

Weight defaults (configurable in `config.json`): call 40%, load 30%, idle 20%, fail 10%.

## Example

Node `pbx-01`: `active_calls=42`, `max_calls=250`, `load_avg=0.85`, `idle_cpu=35`, `fail_rate=0.5`

```
call_score = clamp(100 - (42/250)*100, 0, 100) = 83.2
load_score = clamp(100 - 0.85*50, 0, 100)      = 57.5
idle_score = clamp(35, 0, 100)                   = 35.0
fail_score = clamp(100 - 0.5, 0, 100)            = 99.5

score = 83.2×0.40 + 57.5×0.30 + 35.0×0.20 + 99.5×0.10 = 70.1
```

## Caching

`best_node_id`, `best_score`, and `fallback_active` are recalculated on every metric update.
`/api/route` reads them under RLock — O(1) constant time.

## Configuration

```json
{
  "stale_threshold_sec": 20,
  "scoring": {
    "idle_cpu_min": 5,
    "call_failure_rate_lethal": 15.0,
    "weights": {
      "call_score": 0.40,
      "load_score": 0.30,
      "idle_score": 0.20,
      "fail_score": 0.10
    }
  }
}
```

Weights must sum to 1.0. All thresholds configurable in `config.json`.