sym-adv-encoding

sym-adv-encoding provides byte and UTF-8 encoders that map payloads into sym_adv_ring::RingElement values over Z_m.

The crate currently ships two encoding strategies:

• fixed-width bit packing for compact canonical residue streams
• length-delimited base-m transduction for self-delimiting payload recovery

The repository also contains a companion Lean 4 formalization for the length-delimited base-m construction in lean/encoding-dr-1.

That formalization proves:

• fixed-width base-m prefix encoding and decoding are inverse on u64 values
• whole-stream recovery for the deployed length || state || payload format
• trailing residue padding does not change the decoded byte string
• every emitted symbol is a valid residue < modulus

It does not prove Rust implementation equivalence, allocator behavior, or the bit-packing encoder/decoder path.