Health conditions (ground truth)

Source: src/sim/herd.ts (CONDITION_EFFECTS, setCondition). The sidebar's Inject anomaly controls apply a hidden condition to a cow — the ground truth the detection layer has to find. Injected cows are deliberately not marked on the paddock; the only place ground truth appears is the sidebar's Ground truth list.

Each condition reshapes pace, behaviour-state weights, body temperature, and the cow's position within the herd:

Lame

Painful to walk. Modelled as:

• pace drops to 35% of normal — she lags visibly when the herd moves,
• walking bouts become rare, lying/resting bouts nearly double,
• slight temperature rise (+0.2 °C), mild drift towards the herd edge.

Detectable signature: sustained low speed relative to the herd, especially during herd moves.

Ill

A general sickness/fever profile (think early mastitis or metabolic disease):

• fever: +1.4 °C target offset, developing over ~1.5 h,
• rumination collapses: rumination and grazing weights drop to a third or less,
• social withdrawal: her home offset from the herd centre is scaled ×2.6 — she settles at the edge of the herd and her social graph edges decay.

Detectable signature: high temperature + low rumination + distance from herd centre. The combination matters — heat stress alone raises everyone's temperature, and a naturally aloof cow is far from centre but ruminating normally.

Oestrus

Not an illness — but commercially critical to catch (missed heats cost real money):

• restlessness: walking weight ×3.5, resting weight down to a third,
• pace up ~35%, rumination mildly suppressed,
• moves towards the herd rather than away (isolation ×0.8).

Detectable signature: walking fraction and speed well above herd norms without the illness markers.

Recovery

Cure returns the cow to healthy. Effects unwind at their natural time constants — temperature relaxes over a couple of hours, rumination rebuilds, and the detector's score decays below the resolve threshold, closing the alert automatically.