# Parked extraction helicopter: verified landing-gear support

The parent's native `logs_2026-09-19_07-20-14` showed ten seconds of an intact, upright, motionless authored Mi8 with a valid controller/simulation/physics and `HasAnyGroundContact()==false`. The caller/helper were alive and correctly positioned. Native helicopter simulation exposes this aggregate contact flag and terrain altitude, but no per-wheel query equivalent to wheeled simulation. The installed vanilla available-action condition also simply reads the aggregate flag; it provides no alternative initialization mechanism. No physics wake, engine start, teleport or simulation mutation is added to production.

`ERR_CasualtyGroundSupport` supplies a conservative fallback only for the known Mi8 family when its physics body is asleep and its engine is off. The ordinary native contact path is retained. Existing speed (0.5m/s), angular velocity (0.1rad/s) and upright (up.y >= 0.85) limits still apply to both routes. Powered hovering cannot use the fallback.

The installed Mi8_base.et defines three landing-gear bones: `v_wheel_F` with radius 0.30m and `v_wheel_bL`/`v_wheel_bR` with radius 0.45m. Native PointInfo resolves their actual world pivots. All three pivots must exist and remain separated by at least one metre, guarding against failed/collapsed resolution. At each tire bottom, a short vertical trace spans 0.10m above to 0.12m below. Every trace must hit upward-facing collision (normal.y >= 0.85). Hits on the aircraft or its children, dynamic entities and entities without physical support are rejected. Terrain/static collision can support the aircraft; altitude alone cannot. The small tolerance covers collision/placement precision and does not claim exact zero-distance tire contact. Active aircraft without a native contact flag fail closed; unsupported dynamic platforms are outside this fallback.

Native PointInfo bone resolution, actual tire-to-ground gaps, awake state and trace normal/entity behavior are still **unverified in the engine for this patch**. The opt-in fixture prints all of them. If the untouched aircraft is awake or its authored geometry lies outside the tight support tolerance, the test will fail explicitly; do not silently widen it or activate physics simply to get a pass.

## Files and integration

New files:

- `addons/core/Scripts/Game/ERR/00_Core/ERR_CasualtyGroundSupport.c`
- `addons/core/Scripts/Game/ERR/00_Core/ERR_NativeCasualtyGroundProbe.c`
- `tests/test_casualty_ground_policy.py`

Apply `ground-support-integration.patch` only to the indicated AircraftReady/Nearby and native casualty-fixture hunks. Its latest central-service baseline preserves the separately reviewed committed-lifecycle changes. Add `test_casualty_ground_policy.py` to the parent's `tools/check.py` test list. No new outcome or BaseSmoke steps are required: the existing `casualty-service` readiness stage runs the bounded ground probe before causing unconsciousness.

The positive native check reads the untouched actual mission helicopter. It then spawns a separate empty aircraft twenty metres higher, protects that disposable entity from damage, and verifies airborne rejection. On that clone only, it sets a 90-degree tilt and reads the resulting native up vector, then assigns and immediately reads a nonzero native velocity. The production motion policy is checked independently with those actual values, while full AircraftReady must also reject the clone. This is not a travelled-distance/flight-control test. The clone is deleted on completion or failure. The mission aircraft's transform, velocity, activation, engine and health handling are never changed.

The focused support policy test passed. Native compilation, positive wheel support and the negative physics checks remain pending. `source-sha256.json` identifies the exact installed Mi8 configuration inspected.