steps: replace the peak pedometer with a stride-periodicity gait counter

ALGORITHMS.md

@@ -105,7 +105,7 @@ Grouped by family (subdirectory under `lib/src/onehz/`). File paths are relative
 | `relativeIntensityBands` | `motion/enmo.dart` | ENMO/MAD activity intensity bands | — |
 | `staticTilt` | `motion/orientation.dart` | orientation/posture from gravity vector | — |
 | `branchedEnergyFusion` | `motion/energy_fusion.dart` | HR-anchored-when-possible energy expenditure fusion | Brage et al. 2004 |
-| `dailyActiveMinutes` | `motion/steps.dart` | minutes of sustained wrist movement from the 1 Hz substrate, no step count — true per-step counting is impossible below gait Nyquist | internal ESTIMATE (personal dynamic-floor movement threshold, no published method; unrelated to AN-2554 — see `livePedometer` for the real AN-2554-derived 100 Hz method) |
+| `dailyActiveMinutes` | `motion/steps.dart` | minutes of sustained wrist movement from the 1 Hz substrate, no step count — true per-step counting is impossible below gait Nyquist | internal ESTIMATE (personal dynamic-floor movement threshold, no published method; unrelated to the 100 Hz step counter — see `livePedometer` for that) |
 
 ### `workout/`
 | Function | File | Method | Citation |

README.md

@@ -105,7 +105,8 @@ foundation layers:
   (IS/IV/RA/L5/M10).
 - **`respiration/`** — RSA-derived respiratory rate fused with motion-modulated RIIV,
   CVHR-based apnea screening, a relative (never absolute) oxygen-desaturation ratio.
-- **`motion/`** — ENMO/MAD activity metrics, a 100 Hz AN-2554-derived live pedometer
+- **`motion/`** — ENMO/MAD activity metrics, a 100 Hz live pedometer that finds gait
+  by stride periodicity (autocorrelation) and counts steps from the measured cadence,
   plus a separate 1 Hz movement-minutes estimate (no step count — true per-step
   counting is impossible below gait Nyquist) for whatever the live stream missed,
   energy-expenditure fusion.

docs/ALGORITHM_CATALOG_1HZ.md

@@ -97,7 +97,7 @@ Checked against the WHOOP 4 decoder (`protocol/lib/src/records.dart`, `live.dart
 ## LAYER 2 — Foreground-only (live spot-check tier, ~100 Hz accel/gyro + live RR)
 - **Karlen Smart-Fusion RR** (RIIV+RIAV+RIFV) — needs a high-rate PPG waveform. `UNSUPPORTED on WHOOP 4` (no decoded foreground PPG).
 - **Autocorrelation cadence + step/stride regularity & symmetry** (Moe-Nilssen 2004) — robust gait.
-- **AN-2554 / windowed peak-detection step counter** (100 Hz accel) — gate to ambulation; wrist over/under-count caveats (Tudor-Locke).
+- **Stride-periodicity step counter** (100 Hz accel, `pedometer`/`livePedometer`) — per 1 s segment, autocorrelation over a 4 s window; gait gated on amplitude plus autocorrelation at the stride lag with hysteresis, kept only as runs of ≥ 8 s; steps = gait seconds / measured step period. Known limits: rhythmic arm work at a gait-like rhythm still counts, a sprint above 240 spm reads half, a step-only signal slower than ~67 spm counts double. Measured accuracy is in the `StepParams` doc comment. Replaced an AN-2554-style peak counter.
 - **Madgwick / Mahony quaternion orientation** — limb tracking during workouts.
 - **Frequency-domain activity typing** (dominant freq + spectral entropy, Wang 2009) — walk/run/cycle.
 - **DFA-α1 aerobic threshold** (Rogers 2020) — needs RR at <3% artifact; best on clean foreground/rest reads.

lib/src/onehz/motion/motion.dart

@@ -21,7 +21,7 @@
 /// physically impossible on the 1 Hz substrate (Nyquist 0.5 Hz < gait
 /// 1.4–2.5 Hz), so:
 ///   * [livePedometer] counts REAL steps on the ~100 Hz foreground accel
-///     (R10 / 0x2B) — adaptive-threshold peak detection (AN-2554 family).
+///     (R10 / 0x2B) — stride-periodicity gait detection + measured cadence.
 ///   * [dailyActiveMinutes] reports MINUTES OF SUSTAINED WRIST MOVEMENT from
 ///     the 1 Hz substrate — the only quantity resolvable there — and emits NO
 ///     step count: at the wrist, arm work out-accelerates walking, so movement