1\begin{tabular}{@{}lp{4.2cm}p{2cm}p{2.3cm}p{2.3cm}p{1.6cm}p{2.6cm}@{}}2\toprule3id & representation & question\_access & training & compatibility & composable & status\_in\_wp30 \\4\midrule5A0 & none (task only) & -- & none & any & -- & measured \\6A1 & raw text & blind & none & any receiver & concatenation & measured \\7A2 & text head/tail & blind & none & any & concatenation & measured \\8A3 & extractive sentences (BM25/centrality) & blind or aware & none & any & concatenation & measured \\9A4 & abstractive summary & blind or aware & none (prompted sender) & any & concatenation & measured \\10A5 & typed facts + source spans + unknowns (JSON) & blind or aware & none (prompted sender) & any & record merge & measured \\11A6 & reference index + metered retrieval & blind index, aware retrieval & none & any + source access & shared memory & measured \\12A7 & raw text, zstd transport codec & blind & none & any & concatenation & measured \\13A8 & LLMLingua-2 token dropping & blind & pretrained compressor (official) & any & concatenation & measured \\14B0 & native bf16 KV cache & blind & none & same checkpoint & no & measured \\15B1 & serialized KV cache (manifest-checked) & blind & none & same checkpoint + revision & no & measured (process + 2-node) \\16B2 & packed quantized KV (8/4/2 bit) & blind & none & same checkpoint & no & measured \\17B3 & sink+recent retention (StreamingLLM-inspired) & blind & none & same checkpoint & no & measured \\18B4 & random retention (control) & blind & none & same checkpoint & no & measured \\19B5 & attention-informed retention (SnapKV rule) & aware (blind variant tested) & none & same checkpoint & no & measured \\20B6 & pyramid layer budgets (PyramidKV rule) & aware & none & same checkpoint & no & measured \\21B9 & selection then packed quantization & aware & none & same checkpoint & no & measured \\22C0 & sender cache fed as receiver cache & blind & none & incompatible (negative control) & no & measured (control) \\23C2 & linear KV mapper (ridge, un-rotated K/V) & blind & ridge on train caches & trained pair (Qwen 1.5B$\to$3B) & no & measured \\24C3 & mapper + attention selection & aware & ridge on train caches & trained pair & no & measured \\25-- & SwaT cross-family mapper & blind & ~300M mapper (not public) & Granite$\to$SmolLM & no & not run: no checkpoint/licence \\26-- & Attention-Matching compaction & blind & none (optimization) & same model & no & not run: CUDA/vLLM code; MLX port out of scope \\27-- & C2C fuser & blind & released fusers (Qwen3) & Qwen3 receivers & no & not run: CUDA; receiver still prefills source \\28-- & H2O eviction & cumulative & none & same checkpoint & no & not run: requires attention scores during whole prefill \\29-- & KIVI per-channel key quantization & blind & none & same checkpoint & no & not run: CUDA kernels; motivation confirmed by B2 Qwen result \\30\bottomrule31\end{tabular}32