A hostile manifest of empty chunks no longer becomes a request flood: fetch_content
refuses a zero-size chunk beside other chunks, and settles the content hash and every
chunk hash (normalised, non-empty) before the first request.
Every bad chunk request is now answered found:false in the reference handler's
validation order, never refused at decode. validate_message no longer refuses content
chunk requests or responses, so a blank message id or hash, a prefix-only hash and a
negative size reach answer_content_chunk_request. The answer follows the reference's
double normalisation (handler, then CreateRecordKey), which fixes the prefix-only
hash spelling to ArgumentException on 'chunkHash'. The cs vectors gain nine
reference-server answers (blank and whitespace id, blank, whitespace and prefix-only
hash, negative size, record-key case, blank record key, double prefix) and a
metadata-order manifest; Rust answers all of them byte-identically.
Manifest metadata is Vec<(String, String)> in wire order and refuses a duplicate key,
replacing the BTreeMap that re-sorted keys.
Tests pin the surviving mutants: unusable chunk sizes, the payload-length and
claimed-size halves of the chunk check, stable sort at equal offsets, the normalised
hash and canonical key actually sent, and the kind/mime defaults never trimming.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>