Re-ran the full cross-stack matrix after patching two bench-driver bugs (C/TS token-decode fallback, vllm REPS=1 noise). All three engines × six client languages now produce byte-identical Codec frames per cell, including vllm, which previously read as 0/24 unanimous in the post-mortem.

The 2026-05-08 cross-stack run had a §7 post-mortem flagging three sources of variance; vllm reading as 0/24 unanimous on Codec cells was the loudest. Ran it down to three issues:

1. C and TS demos were emitting 'tokens_emitted=0' for compressed cells (the 'tokens' field was only populated on 'identity' decode), which threw off the unanimity check.

2. vllm at 2 K tokens has ~10-20 % wire-byte variance from non-deterministic batching even at temperature=0; needs ≥2 reps to land a stable median.

3. JSON-SSE rows have 10-16 B per-client framing-accounting drift that's structural, not noise.

Patches shipped (commits '7c12286' (https://github.com/wdunn001/Codec/commit/7c12286), 'eb574b6' (https://github.com/wdunn001/Codec/commit/eb574b6)) and the bench re-ran on the same lab box (vinez@192.168.1.88, 2× RTX 3090).

┌───────────┬───────────────────────┬──────────────────────────────────────────┐

│ Engine │ Codec cells unanimous │ Notes │

├───────────┼───────────────────────┼──────────────────────────────────────────┤

│ sglang │ 24/24 │ clean │

│ vllm │ 24/24 │ was 0/24 in earlier run │

│ llama.cpp │ 24/24 │ only ≤5 B drift remains on JSON-SSE rows │

└───────────┴───────────────────────┴──────────────────────────────────────────┘

┌───────────┬──────────┬──────────────────────┬───────────┐

│ Engine │ JSON-SSE │ Codec msgpack + gzip │ Reduction │

├───────────┼──────────┼──────────────────────┼───────────┤

│ sglang │ 485.2 KB │ 354 B │ 1,404× │

│ vllm │ 517.8 KB │ 3,874 B │ 137× │

│ llama.cpp │ 529.2 KB │ 16.1 KB │ 33× │

└───────────┴──────────┴──────────────────────┴───────────┘

The 'Benchmarks' panel on the front page now points at the new run and the engineRows numbers are refreshed accordingly.