-- Close-range geometric corroboration, NOT an engine-reported parent link.
-- MountComponent + zero-offset AttachableComponent, fixed FileDiver data snapshot.
-- Names independently matched to unique hashes in the installed base model.
-- No serialized node index is used. Runtime must query has_node/node each sample.
local M={radius=.35,margin=.5,max_mechs=8,max_arms=16}
local profiles={
 ['79e4b3d2da5e45e3']={L={resource='824b7e0c4c879eb5',name='attach_turret_l_socket'},R={resource='08f6089289c83d22',name='attach_turret_r_socket'}},
 ['c2d449ecf7facab1']={L={resource='e5f64dcc3bfe9dd1',name='attach_turret_l'},R={resource='ff9878576a4c543b',name='attach_turret_r'}},
 ['7b2326f6fd9c8069']={L={resource='0736bee2d6328726',name='attach_turret_l'},R={resource='17c5d12d8d5dee2c',name='attach_turret_r'}},
 ['35dbf54f016f3624']={L={resource='65489809a8181b96',name='attach_turret_l_socket'},R={resource='df51fe8d62f294be',name='attach_turret_r_socket'}},
}
function M.specs(d)return d and profiles[d.resource]end
local function valid(p)
 if type(p)~='table'then return false end
 for i=1,3 do local n=p[i];if type(n)~='number'or n~=n or math.abs(n)>1000000 then return false end end
 return true
end
function M.select(current,bodies,arms,key,distance)
 local meta={heuristic=true,method='MOUNT_POINT_TEST',radius=M.radius,margin=M.margin,slots={},native_parent_proven=false}
 local function no(why)return nil,why,meta end
 if #bodies<1 or #bodies>M.max_mechs or #arms<1 or #arms>M.max_arms then return no('MOUNT_COUNT_BOUND')end
 local all,here,seen={},{},{}
 for _,body in ipairs(bodies)do
  local d=body.descriptor;local specs=M.specs(d)
  if not specs or seen[d.entity]then return no('MOUNT_BODY_INVALID')end;seen[d.entity]=true
  for _,side in ipairs({'L','R'})do
   local slot=body.mounts and body.mounts[side];local spec=specs[side]
   if not slot or slot.name~=spec.name or slot.resource~=spec.resource or not valid(slot.position)then return no('MOUNT_SLOT_INVALID')end
   local entry={descriptor=d,side=side,resource=spec.resource,position=slot.position};all[#all+1]=entry
   if key(d)==key(current)then here[side]=entry end
  end
 end
 if not here.L or not here.R then return no('MOUNT_CURRENT_NOT_FOUND')end
 for _,arm in ipairs(arms)do
  if not valid(arm.position)or seen[arm.descriptor.entity]then return no('MOUNT_ARM_INVALID')end;seen[arm.descriptor.entity]=true
 end
 local selected,used={},{}
 for _,side in ipairs({'L','R'})do
  local slot=here[side];local best,second,pick=math.huge,math.huge,nil
  for _,arm in ipairs(arms)do
   if arm.descriptor.resource==slot.resource then
    local residual=distance(slot.position,arm.position)
    if residual<best then second=best;best=residual;pick=arm elseif residual<second then second=residual end
   end
  end
  local row={side=side,resource=slot.resource,decision='UNFILLED'};meta.slots[#meta.slots+1]=row
  if best<math.huge then row.best_residual=best;row.candidate_entity=pick.descriptor.entity end
  if second<math.huge then row.other_arm_residual=second;row.other_arm_gap=second-best end
  if pick and best<=M.radius then
   if second-best<M.margin then row.decision='COMPETING_ARM';return no('MOUNT_COMPETING_ARM')end
   local competitor=math.huge
   for _,other in ipairs(all)do
    if other~=slot and other.resource==slot.resource then
     local residual=distance(other.position,pick.position)
     if residual<competitor then competitor=residual;row.other_mech_entity=other.descriptor.entity end
    end
   end
   if competitor<math.huge then row.other_mount_residual=competitor;row.other_mount_gap=competitor-best end
   if competitor-best<M.margin then row.decision='COMPETING_SLOT';return no('MOUNT_COMPETING_SLOT')end
   if used[pick.descriptor.entity]then return no('MOUNT_ARM_ALIAS')end
   used[pick.descriptor.entity]=true;selected[#selected+1]=pick.descriptor;row.decision='SELECTED'
  end
 end
 if #selected==0 then return no('MOUNT_NO_MATCH')end
 local sig={key(current)};for _,d in ipairs(selected)do sig[#sig+1]=key(d)end
 meta.signature=table.concat(sig,'|');meta.selected=#selected
 return selected,'SPATIAL_HEURISTIC',meta
end
return M