Currently, labor allocated to a unit type that subsequently becomes unbuildable is wasted until the player manually reallocates it. Yards, academies and citadels should automatically redirect labor to simple units that do not require components- explorers, gunships or basic infantry- if a previously supplied component type is unavailable (due to trade routes getting severed or an autofac losing TLs).
If a needed component is supplied but not in sufficient quantity, surplus labor should again overflow into simple units rather than being wasted.
The player specified labor %s should not be reallocated; instead, wasted labor should get dumped into the basic unit type without modifying allocations.
Big picture: unit-producing structures should respect player labor % allocations only to the point that it doesn't cripple the player. The military-industrial complex needs to be resilient enough to keep building simple armed units during component shortages, which are inevitable for new players and players who don't have time to micromanage.
I don't think this should apply to mineral shortages; it's fine for high-TL yards to be totally inoperable without chronimium/chtholon, and for all yards to be inoperable without hexacarbide (e.g. a yards built on a primordial world with no working trade route or a ramjet autofac built on a world with no aetherium & no working trade route). A yards or autofac experiencing mineral nonsupply should display a pop-up alert or warning if it is unable to build any unit or component. Ideally, labor would not be entirely wasted and instead could get dumped into another structure to build up stockpiles that improve resiliency when supply is reestablished- consumer goods autofac, trillum extractor, militia barracks, etc. There could be a social order penalty for yard worlds forced to allocate labor into non-yards structures via this mechanism though.
Player labor % allocations should be remembered so that the player doesn't have to retype them if they fix their economy to supply enough components. Contrast with the current situation with defenses, where resources can be auto-allocated away but never get auto-allocated back.