Problem

Centipede distillation aborts when a corpus shard and its feature file are both empty. The estimated memory requirement is zero, resulting in a zero-sized lease request that the resource pool rejects.

Acceptance Criteria

• All-empty shards produce an empty distilled result without aborting.
• Mixed empty and populated shards preserve the expected inputs and features, including filtering and deduplication.
• Existing resource-pool validation, corpus updates, and crash retention are preserved.
• Add regression tests with actual zero-byte shard files and validate the fix in Mongo.
• Before landing in Mongo, verify that a session which times out without completing any input still fails.