A field's default is one expression, walked at every 'new' of its record: marked LOCAL by a frame's
temporary, it stayed marked when a record a pool keeps was made from it, and that record's list came
from the frame's scratch. The marks are now taken off any node one walk found kept.
examples/lang/arena_defaults.ludic is the case (a pool's record made in frame 3, a temporary of the
same type every frame): foundations 1315baf crashes on it poisoned; this prints '497 124747', as the
heap does. In ludic-dev test.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
