AI exterior lighting not actualized at prolonged stops and running engine

[unorthodox-paradox]

Symptoms

At prolonged stops, if the AI decides not to turn off, or subsequently re-ignite, the engine, due to environmental adversity, it will beyond that point in time fail to actualize its exterior lighting any further -- both due to improving and due to worsening conditions alike --, until either a) conditions allow the engine to once again be turned off, or b) departure time arrives.

Identified causes and resolution progress

The cause lies here (lights_ai.osc:lights_ai_engine_dependent_lighting_context_evaluate_and_translate):

(L.L.lights_ai_sun_alt) l1 >= l2 || (L.L.Envir_Brightness) l3 >= &&
    (L.L.lights_ai_precip_type) 0 =
    (L.L.lights_ai_precip_type) 1 = l4 -1 = (L.L.lights_ai_env_wetness) l4 <= || && ||
    (L.L.lights_ai_precip_type) 2 = l5 -1 = (L.L.lights_ai_env_wetness) l5 <= || && || &&
    l1 91 = ! &&
{if}
    -1 (S.L.lights_ai_ext_lighting_env_perception_target)
    0 (S.L.lights_ai_ext_lighting_target)
{else}
    (L.L.ai_pre_cockpit_engine_target) (L.L.ai_pre_cockpit_transmission_target) ! &&
    {if}
        -1 (S.L.lights_ai_ext_lighting_env_perception_target)
        (L.L.lights_ai_ext_lighting_env_perception) 4 =
        {if}
            2
        {else}
            1
        {endif}
        (L.L.lights_ai_ext_lighting) min (S.L.lights_ai_ext_lighting_target)
    {endif}
{endif}

Specifically, when the first if (temporarily-off context) doesn't hold, then we only query the current state of exterior lights and bound it (to prevent headlight usage while stopped), effectively disregarding target state. That else-if should be corrected to evaluate exterior lighting target perception and preferences instead.

Some further things to take into account:

• Currently head fog lights are left activated whenever the preference set includes them (standstill + head fog lights; standstill + head + tail fog lights; headlights + head fog lights; headlights + head + tail fog lights). Given that it is for the most part just tail fog lights that count for safety, when stopped under adverse conditions, we should only leave head fog lights activated in those cases where the actual goal is to leave tail fog lights activated as a consequence (because of circuit-level activation constraints) as well. In practice this means that a) the target perception must be 4 (adverse-seeing), and b) the target exterior lighting must be 6 (headlights + head + tail fog lights).
• When at the time of arrival an exterior lighting preference set including use of headlights used to be in effect, and the conditions for engine re-ignition only became effective later on, then consequent exterior lighting reduction is to occur fast, as it would have had it been known in advance (i.e. at arrival time) that the engine was going to be left running (see #42 for the general case).
• Care should be taken to not mistake such provisional / faster-than-normal exterior lighting reduction as a hint of environmental condition improvement, that can be relied upon by apposite interior lighting reduction timing/adjustment logic as a shortcut as well. This is merely about the exterior lighting perception-to-preference translation yielding a different result given additional context (stop arrival plus the decision to leave the engine running), and should therefore not affect the interior lighting adjustment delay.
• For added realism, after exterior lighting has been reduced to below headlights, yet is still active, do not increase back to headlights or above anew before departure, even if engine subsequently turned (back) off.

User-level workarounds

None available.