One runtime level of shared-seed block condensation #
Read fixed-width input blocks from one flat word, apply the scheduled condenser to each with the same seed, and concatenate the outputs in order. The count word's length specifies the number of blocks. Its bit values are irrelevant; extra input bits are ignored and short slices remain valid inputs to the total underlying program. Width zero and count zero are allowed.
This is one block-processing level, not a variable-depth recursive evaluator.