The smallest-fitting-variant fallback now groups split GGUF shards
by their variant prefix and sums all shard sizes per variant.
For example, DeepSeek-V3.2 UD-Q4_K_XL has 9 shards totaling
379.8 GB. The previous code treated each shard as a separate
"variant" and would have incorrectly selected a single 50 GB shard
as fitting, ignoring the other 8 shards needed.
Tested with unsloth/DeepSeek-V3.2-GGUF (237 GGUF files, 27
variants from 150 GB to 1.25 TB). Correctly groups and sorts
all variants by total size.
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