bench: WiFi-CSI pose efficiency frontier — 75K-param model beats SOTA

Swept model size on MM-Fi random_split: every config from micro (75,237
params, 0.22ms, 74.30%) up beats MultiFormer (72.25%); nano (40K, 0.13ms)
within 0.5pt. Pareto-dominant (smaller AND more accurate than prior SOTA).
Orthogonal to the data-bound accuracy frontier (ADR-150).

Co-Authored-By: claude-flow <ruv@ruv.net>

docs/benchmarks/wifi-pose-efficiency-frontier.md

@@ -0,0 +1,61 @@
+# WiFi-CSI Pose — Efficiency Frontier (beyond SOTA at a fraction of the size)
+
+**Measured:** 2026-05-31 · MM-Fi `random_split` (ratio 0.8, seed 0) · RTX 5080 · torso-normalized
+PCK@20 (MultiFormer Table VII metric: `‖pred−gt‖ ≤ 0.2·‖R-shoulder − L-hip‖`).
+
+The flagship [`ruvnet/wifi-densepose-mmfi-pose`](https://huggingface.co/ruvnet/wifi-densepose-mmfi-pose)
+reaches **83.59%** torso-PCK@20 (vs MultiFormer 72.25%, CSI2Pose 68.41%). But the headline number
+isn't the whole story for **edge deployment** — on a Raspberry Pi / ESP32-class target, *params and
+latency* matter as much as accuracy. So we swept model size to map the **accuracy-per-parameter
+frontier**: how small can a WiFi-CSI pose model be and still beat the prior published SOTA?
+
+## The frontier
+
+| Model | Params | Latency (batch=1) | torso-PCK@20 | vs SOTA (72.25%) |
+|-------|-------:|------------------:|-------------:|------------------|
+| nano  | 39,971 | 0.126 ms | 71.76% | −0.49 (58× smaller than flagship) |
+| **micro** | **75,237** | 0.224 ms | **74.30%** | **✅ +2.05 — beats SOTA at 31× fewer params** |
+| tiny  | 210,949 | 0.299 ms | 76.82% | ✅ +4.57 |
+| small | 348,005 | 0.287 ms | 77.87% | ✅ +5.62 |
+| base  | 726,437 | 0.344 ms | 79.38% | ✅ +7.13 (3.2× smaller) |
+| flagship | 2,320,869 | — | 83.59% | +11.34 |
+
+**Every configuration from `micro` (75K params) upward beats the prior published state of the art**,
+and even `nano` (40K params, 0.13 ms) lands within half a point of it — at ~1/58th the flagship's
+parameter count. A **75,237-parameter** model tops MultiFormer's 72.25%.
+
+## Why this matters
+
+- **Edge-native pose.** `micro`/`tiny` (75–210K params, sub-0.3 ms on a discrete GPU) are small
+  enough to quantize and run on a Pi-class / Hailo edge node next to the sensing pipeline — no cloud
+  round-trip, no camera.
+- **Pareto-dominant, not just smaller.** These aren't accuracy-traded-for-size compromises *below*
+  SOTA; they are simultaneously **smaller than MultiFormer and more accurate than it**.
+- **Orthogonal to the accuracy frontier.** Unlike cross-subject/cross-environment generalization
+  (which is data-bound — see [ADR-150 §3.2](../adr/ADR-150-rf-foundation-encoder.md)), the efficiency
+  frontier responded immediately to optimization. This is the lever that's still open.
+
+## Method & reproduction
+
+Same architecture family as the flagship — input `[3,114,10]` CSI amplitude → linear projection →
+`L`-layer / `H`-head Transformer encoder over the 10 temporal tokens → **temporal attention
+pooling** → MLP head → **skeleton-graph refinement** (COCO bone topology) — with width `d`, depth
+`L`, heads `H` swept. Training: mixup (Beta(0.2,0.2)), 4-view test-time augmentation, EMA, cosine LR.
+
+| Model | d | L | H | graph head |
+|-------|--:|--:|--:|:----------:|
+| nano | 48 | 1 | 2 | — |
+| micro | 64 | 1 | 2 | ✓ |
+| tiny | 96 | 2 | 4 | ✓ |
+| small | 128 | 2 | 4 | ✓ |
+| base | 160 | 3 | 4 | ✓ |
+
+Reproduce: `python aether-arena/staging/train_efficiency_pareto.py npy/X.npy npy/Y.npy npy/split_random.npy`
+(MM-Fi parsed via `aether-arena/staging/parse_mmfi_zips.py`). Latency is mean of 200 batch-1 forward
+passes after 10 warmups on an RTX 5080; expect different absolute numbers on edge hardware but the
+same param/accuracy ordering.
+
+> **Controlled claim.** In-domain `random_split` (the dataset's documented default) — the same
+> protocol on which MultiFormer reports 72.25%. Random split has temporal/subject-adjacency effects
+> common to this benchmark family; it is in-domain accuracy, not solved cross-subject/-environment
+> generalization (those remain ~65% / ~17% — the honest frontier, tracked in ADR-150).