fix(vitals): HeartRateExtractor weights=[] silent None + BreathingExtractor stale-lock recovery (#1422, #1423) (#1449)

Fixes #1422, Fixes #1423. HeartRateExtractor no longer truncates subcarrier count on empty phases; BreathingExtractor resets immediately on first out-of-band rejection instead of passively draining a stale window (recovery 28.6s -> 6.0s). 64 tests passing, clippy clean, zero regressions workspace-wide.

python/src/bindings/vitals.rs

@@ -252,8 +252,9 @@ impl PyBreathingExtractor {
 /// hr = HeartRateExtractor.esp32_default()  # 56 subcarriers, 100 Hz, 15s window
 ///
 /// # Feed residuals and matching unwrapped phases from your preprocessor.
-/// # Unlike BreathingExtractor weights, phases=[] is invalid for heart-rate
-/// # extraction because the Rust core requires phase data for each subcarrier.
+/// # Like BreathingExtractor's weights, phases=[] means "no per-subcarrier
+/// # coherence information available" and falls back to equal weighting
+/// # across all subcarriers -- it does NOT silently drop every frame.
 /// est = hr.extract(residuals=[0.01, -0.02, …], phases=[0.0, 0.01, …])
 /// if est is not None:
 ///     print(est.value_bpm, est.confidence)
@@ -281,9 +282,11 @@ impl PyHeartRateExtractor {
     }
 
     /// Extract heart rate from per-subcarrier residuals and matching
-    /// per-subcarrier unwrapped phases (radians). Empty phases are invalid
-    /// and return `None` because the Rust extractor requires phase data.
-    /// GIL released during DSP.
+    /// per-subcarrier unwrapped phases (radians). A short or empty `phases`
+    /// slice falls back to equal weighting for any subcarrier missing phase
+    /// data (issue #1423) -- it does not truncate the number of subcarriers
+    /// fused, and does not silently return `None` for every frame. GIL
+    /// released during DSP.
     fn extract(
         &mut self,
         py: Python<'_>,

python/tests/test_vitals.py

@@ -223,6 +223,38 @@ def test_heart_rate_extract_with_synthetic_signal_and_phases() -> None:
     )
 
 
+def test_heart_rate_extract_with_empty_phases_produces_estimates() -> None:
+    """Issue #1423 regression: `phases=[]` must fall back to equal
+    weighting (mirroring `BreathingExtractor`'s `weights=[]`), not silently
+    return `None` for every frame.
+
+    Reproduces the GH-issue repro: a noiseless 1.2 Hz (72 BPM) sine
+    identical across all 56 subcarriers, fed frame-by-frame with an empty
+    `phases` list. Before the fix this produced 0/4000 estimates; the same
+    signal with `phases=[1.0] * 56` already produced thousands.
+    """
+    hr = HeartRateExtractor.esp32_default()
+    sample_rate = 100.0
+    target_freq = 1.2  # 72 BPM
+    n_samples = 4000
+
+    produced = 0
+    for i in range(n_samples):
+        t = i / sample_rate
+        base = math.sin(2.0 * math.pi * target_freq * t)
+        residuals = [base] * 56
+        est = hr.extract(residuals=residuals, phases=[])
+        if est is not None:
+            produced += 1
+            assert math.isfinite(est.value_bpm)
+            assert 0.0 <= est.confidence <= 1.0
+
+    assert produced > 0, (
+        "HeartRateExtractor.extract(residuals=..., phases=[]) must not silently "
+        "return None for every frame of a clean 72 BPM signal (issue #1423)"
+    )
+
+
 # ─── Build feature flag ──────────────────────────────────────────────
 
 

v2/crates/wifi-densepose-calibration/src/specialist.rs

@@ -37,6 +37,13 @@ pub const ANOMALY_OUTLIER_SPREADS: f32 = 2.0;
 /// drives the human-readable label.
 pub const ANOMALY_LABEL_CUTOFF: f32 = 0.5;
 
+/// Fraction by which occupied-anchor variance must exceed the empty-room
+/// baseline for [`PresenceSpecialist`]'s variance channel to be trusted
+/// (issue #1440). Below this margin the channel is disabled rather than
+/// producing a midpoint threshold that can sit below the empty-room
+/// baseline itself.
+pub const VARIANCE_SEPARATION_MARGIN: f32 = 0.05;
+
 /// Which biological signal a specialist estimates.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 pub enum SpecialistKind {
@@ -111,6 +118,16 @@ impl PresenceSpecialist {
     /// Fit from anchors: variance threshold at the midpoint between the empty
     /// variance and the mean occupied variance; mean-shift threshold at half
     /// the empty→occupied mean distance (inert when the means don't separate).
+    ///
+    /// The variance channel is itself inert (never fires) when `occ_var`
+    /// does not genuinely exceed `empty_var` (issue #1440): a midpoint
+    /// threshold assumes occupied windows are noisier than the empty-room
+    /// baseline, but a still/quiet occupant can measure *less* variance
+    /// than an empty room's ambient/interference noise floor. Left
+    /// unguarded, the midpoint then sits *below* the empty-room baseline
+    /// itself, so a genuinely empty room reads "present" on every frame —
+    /// worse than no signal at all. Matches the mean-shift channel, which
+    /// already goes inert (`None`) under the equivalent condition.
     pub fn train(anchors: &[AnchorFeature]) -> Option<Self> {
         let empty = anchors.iter().find(|a| a.label == AnchorLabel::Empty)?;
         let occ: Vec<&Features> = anchors
@@ -129,8 +146,15 @@ impl PresenceSpecialist {
         let mean_dist = (occ_mean - empty_mean).abs();
         let mean_dist_threshold = (mean_dist > 1e-4).then(|| 0.5 * mean_dist);
 
+        let variance_separates = occ_var > empty_var * (1.0 + VARIANCE_SEPARATION_MARGIN);
+        let threshold = if variance_separates {
+            0.5 * (empty_var + occ_var)
+        } else {
+            f32::INFINITY
+        };
+
         Some(Self {
-            threshold: 0.5 * (empty_var + occ_var),
+            threshold,
             occupied_var: occ_var.max(empty_var + 1e-3),
             empty_mean,
             mean_dist_threshold,
@@ -149,8 +173,15 @@ impl Specialist for PresenceSpecialist {
         let present = by_variance || by_mean;
 
         // Confidence: strongest margin among the channels that are enabled.
-        let var_span = (self.occupied_var - self.threshold).max(1e-3);
-        let var_conf = ((f.variance - self.threshold).abs() / var_span).clamp(0.0, 1.0);
+        // An infinite threshold means the variance channel was disabled at
+        // train time (issue #1440) — it must contribute 0, not the spurious
+        // 1.0 that `(x - inf).abs() / span` would otherwise clamp to.
+        let var_conf = if self.threshold.is_finite() {
+            let var_span = (self.occupied_var - self.threshold).max(1e-3);
+            ((f.variance - self.threshold).abs() / var_span).clamp(0.0, 1.0)
+        } else {
+            0.0
+        };
         let mean_conf = self
             .mean_dist_threshold
             .map(|thr| ((mean_dist - thr).abs() / thr.max(1e-3)).clamp(0.0, 1.0))
@@ -472,6 +503,26 @@ mod tests {
         assert!(p.infer(&feat(1.0, 0.1, 0.0, 0.0)).unwrap().value == 0.0);
     }
 
+    /// Issue #1440: a still/quiet occupant can measure LESS variance than an
+    /// empty room's ambient/interference noise floor. Before the
+    /// `variance_separates` guard, the midpoint threshold would then sit
+    /// below the empty-room baseline itself, so a window matching that
+    /// baseline exactly (empty room) read "present" — the reporter's
+    /// "known-empty room read present 31/31 frames" symptom. The means are
+    /// identical here (no mean-shift channel to fall back on), isolating
+    /// the variance-channel bug.
+    #[test]
+    fn presence_inverted_variance_never_reports_empty_room_as_present() {
+        let anchors = vec![
+            af(AnchorLabel::Empty, 5.0, 0.1),
+            af(AnchorLabel::StandStill, 2.0, 0.15),
+        ];
+        let p = PresenceSpecialist::train(&anchors).unwrap();
+        let r = p.infer(&feat(5.0, 0.1, 0.0, 0.0)).unwrap();
+        assert_eq!(r.value, 0.0, "empty-room-baseline variance must not read present when occ_var < empty_var");
+        assert_eq!(r.confidence, 0.0, "a disabled channel must not report spurious confidence");
+    }
+
     /// ADR-152 "variance-only presence" regression: a MOTIONLESS person raises
     /// the scalar mean (extra multipath energy) but barely the variance — the
     /// mean channel must still detect them, and a window matching the empty

v2/crates/wifi-densepose-sensing-server/src/main.rs

@@ -393,6 +393,62 @@ struct ClassificationInfo {
     confidence: f64,
 }
 
+/// Derives the classification triple from raw ESP32 vitals fields.
+///
+/// `presence` is derived from `motion_level`, never taken from the raw
+/// `presence` flag directly, so `motion_level: "present_moving"` can never
+/// pair with `presence: false` (issue #1442) — matches the convention
+/// already used elsewhere (the per-node path and `csi.rs`'s label-derived
+/// `classification.presence = label != "absent"`).
+fn classify_vitals(motion: bool, presence: bool, presence_score: f32) -> ClassificationInfo {
+    let motion_level = if motion {
+        "present_moving"
+    } else if presence {
+        "present_still"
+    } else {
+        "absent"
+    };
+    ClassificationInfo {
+        motion_level: motion_level.to_string(),
+        presence: motion_level != "absent",
+        confidence: presence_score as f64,
+    }
+}
+
+#[cfg(test)]
+mod classify_vitals_tests {
+    use super::classify_vitals;
+
+    #[test]
+    fn motion_implies_presence_issue_1442() {
+        // The exact contradictory frame from issue #1442:
+        // motion=true, presence=false must not yield presence: false.
+        let c = classify_vitals(true, false, 0.69);
+        assert_eq!(c.motion_level, "present_moving");
+        assert!(c.presence, "motion implies presence regardless of the raw presence flag");
+    }
+
+    #[test]
+    fn presence_without_motion_is_present_still() {
+        let c = classify_vitals(false, true, 0.5);
+        assert_eq!(c.motion_level, "present_still");
+        assert!(c.presence);
+    }
+
+    #[test]
+    fn neither_motion_nor_presence_is_absent() {
+        let c = classify_vitals(false, false, 0.0);
+        assert_eq!(c.motion_level, "absent");
+        assert!(!c.presence);
+    }
+
+    #[test]
+    fn confidence_passes_through_presence_score() {
+        let c = classify_vitals(true, true, 0.33);
+        assert!((c.confidence - 0.33_f64).abs() < 1e-6);
+    }
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 struct SignalField {
     grid_size: [usize; 3],
@@ -5786,13 +5842,6 @@ async fn udp_receiver_task(state: SharedState, udp_port: u16) {
                     s.tick += 1;
                     let tick = s.tick;
 
-                    let motion_level = if vitals.motion {
-                        "present_moving"
-                    } else if vitals.presence {
-                        "present_still"
-                    } else {
-                        "absent"
-                    };
                     let motion_score = if vitals.motion {
                         0.8
                     } else if vitals.presence {
@@ -5899,11 +5948,8 @@ async fn udp_receiver_task(state: SharedState, udp_port: u16) {
                     // Cross-node fusion: combine features from all active nodes.
                     let fused_features = fuse_multi_node_features(&features, &s.node_states);
 
-                    let mut classification = ClassificationInfo {
-                        motion_level: motion_level.to_string(),
-                        presence: vitals.presence,
-                        confidence: vitals.presence_score as f64,
-                    };
+                    let mut classification =
+                        classify_vitals(vitals.motion, vitals.presence, vitals.presence_score);
 
                     // Boost classification confidence with multi-node coverage.
                     let n_active = s

v2/crates/wifi-densepose-vitals/src/breathing.rs

@@ -47,8 +47,29 @@ pub struct BreathingExtractor {
     freq_high: f64,
     /// IIR filter state.
     filter_state: IirState,
+    /// Count of consecutive `extract()` calls that rejected the estimated
+    /// frequency as out of the breathing band (i.e. "no periodic signal
+    /// detected"), since the last accepted estimate or reset.
+    ///
+    /// Without this, a subject leaving mid-lock only clears via the
+    /// `filtered_history` ring buffer passively flushing over the full
+    /// `window_secs` (up to 30s) — during which a stale, decreasingly
+    /// accurate estimate keeps being emitted, and any *new* subject
+    /// arriving mid-flush gets fused with leftover stale samples instead
+    /// of starting from a clean window (issue #1422). Once
+    /// `consecutive_rejections` reaches `STALE_RESET_REJECTIONS`, `reset()`
+    /// is called so the next accepted estimate is built from fresh data
+    /// only, instead of waiting out the old window.
+    consecutive_rejections: usize,
 }
 
+/// Number of consecutive out-of-band rejections after which the sliding
+/// window and filter state are cleared (ADR-157-adjacent fix, issue #1422).
+/// One rejection is enough: once the estimated frequency has left the
+/// breathing band, the same rejected estimate must never be echoed again as
+/// a stale "lock" while the window slowly flushes over up to `window_secs`.
+const STALE_RESET_REJECTIONS: usize = 1;
+
 impl BreathingExtractor {
     /// Create a new breathing extractor.
     ///
@@ -67,6 +88,7 @@ impl BreathingExtractor {
             freq_low: 0.1,
             freq_high: 0.5,
             filter_state: IirState::default(),
+            consecutive_rejections: 0,
         }
     }
 
@@ -127,10 +149,29 @@ impl BreathingExtractor {
         let duration_s = history.len() as f64 / self.sample_rate;
         let frequency_hz = crossings as f64 / (2.0 * duration_s);
 
-        // Validate frequency is within the breathing band
+        // Validate frequency is within the breathing band. An out-of-band
+        // estimate means no periodic breathing signal was found in the
+        // current window (e.g. the subject left, or noise dominates).
+        //
+        // Without an active reset here, the stale `filtered_history` window
+        // only clears by passively flushing over the full `window_secs`
+        // (up to 30s) as new samples evict old ones. During that flush a
+        // transiently *accepted* estimate can keep climbing toward
+        // `freq_high` before the frequency finally leaves the band (issue
+        // #1422) — and once rejected, any real signal that resumes would
+        // otherwise have to wait out the rest of that stale window before
+        // it can dominate a fresh, accurate estimate again. Resetting on
+        // rejection makes both directions fast: reject-and-forget instead
+        // of reject-then-linger, and reacquire-from-scratch instead of
+        // reacquire-diluted-by-ghosts.
         if frequency_hz < self.freq_low || frequency_hz > self.freq_high {
+            self.consecutive_rejections += 1;
+            if self.consecutive_rejections >= STALE_RESET_REJECTIONS {
+                self.reset();
+            }
             return None;
         }
+        self.consecutive_rejections = 0;
 
         let bpm = frequency_hz * 60.0;
         let confidence = compute_confidence(history);
@@ -200,6 +241,7 @@ impl BreathingExtractor {
     pub fn reset(&mut self) {
         self.filtered_history.clear();
         self.filter_state = IirState::default();
+        self.consecutive_rejections = 0;
     }
 
     /// Current number of samples in the history buffer.
@@ -479,6 +521,197 @@ mod tests {
         );
     }
 
+    /// Deterministic small PRNG (LCG) for reproducible synthetic-signal
+    /// tests -- mirrors the style already used in
+    /// `heartrate::tests::pure_noise_is_never_reported_valid`. Returns a
+    /// value in roughly `[-1, 1)`.
+    fn lcg_next(seed: &mut u64) -> f64 {
+        *seed = seed
+            .wrapping_mul(6_364_136_223_846_793_005)
+            .wrapping_add(1_442_695_040_888_963_407);
+        ((*seed >> 33) as f64 / (1u64 << 31) as f64) - 1.0
+    }
+
+    /// Issue #1422 bug-catching test.
+    ///
+    /// Reproduces the reported scenario at ESP32 defaults (56 subcarriers,
+    /// 100 Hz, 30s window): 60s of a real 0.25 Hz (15 BPM) signal with
+    /// per-subcarrier gain/phase (lock-on), then broadband noise-floor-only
+    /// residuals (the "empty room").
+    ///
+    /// `extract()` already returned `None` once the estimated frequency left
+    /// the breathing band (that part was not silently broken) -- the actual
+    /// defect was that the 30s `filtered_history` window only cleared by
+    /// *passively* flushing sample-by-sample, so a locked-on extractor kept
+    /// re-fusing whatever noise trickled in with a shrinking-but-still-large
+    /// fraction of stale real signal, letting a decreasingly-accurate
+    /// estimate keep being accepted right up to the range ceiling (30 BPM --
+    /// the exact value from the GH issue) before it finally rejected. Once
+    /// rejected, the *next* real subject would then have to wait out the
+    /// rest of that same stale window before a fresh, undiluted estimate
+    /// could dominate again (see `issue_1422_recovery_after_dropout_is_fast`
+    /// for that half of the regression).
+    ///
+    /// This test pins the fix at its source: the very first out-of-band
+    /// rejection after a real signal disappears must actively clear
+    /// `filtered_history` (not wait for it to passively drain), so no
+    /// stale majority-real-signal window can ever linger and re-validate a
+    /// ghost estimate near the ceiling.
+    #[test]
+    fn issue_1422_stale_lock_does_not_persist_after_subject_leaves() {
+        let n = 56usize;
+        let fs = 100.0;
+        let weights = vec![1.0f64; n];
+        let mut seed: u64 = 0x1422_1422;
+        let gain: Vec<f64> = (0..n).map(|_| 0.4 + 0.6 * lcg_next(&mut seed).abs()).collect();
+        let phase: Vec<f64> = (0..n)
+            .map(|_| lcg_next(&mut seed).abs() * 2.0 * std::f64::consts::PI)
+            .collect();
+        let mut ext = BreathingExtractor::esp32_default();
+
+        // 60s of a strong, real 15 BPM (0.25 Hz) breathing signal -- lock on.
+        let mut got_valid_lock = false;
+        for i in 0..6000usize {
+            let t = i as f64 / fs;
+            let residuals: Vec<f64> = (0..n)
+                .map(|c| {
+                    0.6 * gain[c] * (2.0 * std::f64::consts::PI * 0.25 * t + phase[c]).sin()
+                        + lcg_next(&mut seed) * 0.05
+                })
+                .collect();
+            if let Some(est) = ext.extract(&residuals, &weights) {
+                assert!(
+                    (est.value_bpm - 15.0).abs() < 5.0,
+                    "should track ~15 BPM while the subject is present, got {}",
+                    est.value_bpm
+                );
+                got_valid_lock = true;
+            }
+        }
+        assert!(got_valid_lock, "extractor must lock onto the real breathing signal first");
+        assert!(
+            ext.history_len() > 0,
+            "a locked-on extractor must carry a non-empty window into the empty-room phase"
+        );
+
+        // Empty room: feed noise-floor-only residuals one at a time until the
+        // *first* rejection (the first `None` here can only come from the
+        // frequency-band check, never "insufficient history", since the
+        // window is already far past `min_samples` from the lock-on phase).
+        let mut first_reject_at: Option<usize> = None;
+        let mut history_len_at_reject: Option<usize> = None;
+        for i in 0..12000usize {
+            let residuals: Vec<f64> = (0..n).map(|_| lcg_next(&mut seed) * 0.05).collect();
+            let outcome = ext.extract(&residuals, &weights);
+            if outcome.is_none() {
+                first_reject_at = Some(i);
+                history_len_at_reject = Some(ext.history_len());
+                break;
+            }
+        }
+        let first_reject_at =
+            first_reject_at.expect("pure noise must eventually be rejected as out of band");
+
+        // The fix: the window must be actively cleared in the *same* call
+        // that rejected the frequency -- not left to drain passively over
+        // the remaining ~30s - first_reject_at samples. Before the fix,
+        // `history_len()` here was still the full ~3000-sample stale window.
+        assert_eq!(
+            history_len_at_reject,
+            Some(0),
+            "the first out-of-band rejection (at sample {first_reject_at}) must reset the \
+             history window immediately, not leave the stale lock-on window in place \
+             (issue #1422)",
+        );
+
+        // And the window must not be allowed to silently regrow back into a
+        // large, majority-noise "lock" while noise keeps arriving: each
+        // rebuild-to-`min_samples` cycle must itself reject and reset, so
+        // `history_len()` never creeps back up toward the full window.
+        let min_samples = (fs * 10.0) as usize;
+        let mut max_history_len_after_reject = 0usize;
+        for _ in 0..(12000 - first_reject_at - 1) {
+            let residuals: Vec<f64> = (0..n).map(|_| lcg_next(&mut seed) * 0.05).collect();
+            ext.extract(&residuals, &weights);
+            max_history_len_after_reject = max_history_len_after_reject.max(ext.history_len());
+        }
+        assert!(
+            max_history_len_after_reject <= min_samples,
+            "history window regrew to {max_history_len_after_reject} samples while fed pure \
+             noise -- a stale majority-noise window should never be allowed to accumulate \
+             past the minimum warm-up size without being rejected and reset (issue #1422)",
+        );
+
+        // Finally: the extractor must be silent at the very end of the long
+        // empty-room period, not just momentarily quiet.
+        let final_residuals: Vec<f64> = (0..n).map(|_| lcg_next(&mut seed) * 0.05).collect();
+        assert!(
+            ext.extract(&final_residuals, &weights).is_none(),
+            "BreathingExtractor must report no signal at the end of a long empty-room period",
+        );
+    }
+
+    /// Issue #1422 companion regression: once the subject leaves (and the
+    /// extractor has rejected/reset), a *returning* subject must be
+    /// reacquired quickly -- not have to wait out the full stale 30s window
+    /// passively flushing via FIFO eviction, which is what produced the
+    /// reported "stayed at 30.0 BPM for roughly another 30s before starting
+    /// to track again" secondary symptom.
+    #[test]
+    fn issue_1422_recovery_after_dropout_is_fast() {
+        let n = 56usize;
+        let fs = 100.0;
+        let weights = vec![1.0f64; n];
+        let mut seed: u64 = 0xFEED_1422;
+        let gain: Vec<f64> = (0..n).map(|_| 0.4 + 0.6 * lcg_next(&mut seed).abs()).collect();
+        let phase: Vec<f64> = (0..n)
+            .map(|_| lcg_next(&mut seed).abs() * 2.0 * std::f64::consts::PI)
+            .collect();
+        let mut ext = BreathingExtractor::esp32_default();
+
+        let signal_residuals = |t: f64, seed: &mut u64| -> Vec<f64> {
+            (0..n)
+                .map(|c| {
+                    0.6 * gain[c] * (2.0 * std::f64::consts::PI * 0.25 * t + phase[c]).sin()
+                        + lcg_next(seed) * 0.05
+                })
+                .collect()
+        };
+        let noise_residuals = |seed: &mut u64| -> Vec<f64> {
+            (0..n).map(|_| lcg_next(seed) * 0.05).collect()
+        };
+
+        // Lock on.
+        for i in 0..6000usize {
+            ext.extract(&signal_residuals(i as f64 / fs, &mut seed), &weights);
+        }
+        // Long empty-room period.
+        for _ in 0..6000usize {
+            ext.extract(&noise_residuals(&mut seed), &weights);
+        }
+        // Subject returns.
+        let mut recovered_at = None;
+        for i in 0..6000usize {
+            let t = (12000 + i) as f64 / fs;
+            if ext.extract(&signal_residuals(t, &mut seed), &weights).is_some() {
+                recovered_at = Some(i);
+                break;
+            }
+        }
+
+        let recovered_at = recovered_at.expect("extractor must reacquire the returning subject");
+        // A passive-flush-only window (pre-fix) needs on the order of the
+        // full 30s window to dilute stale noise (measured ~29s); the active
+        // reset-on-rejection fix reacquires close to the 10s minimum warm-up
+        // instead (measured ~6s). Generous bound: well under half the window.
+        assert!(
+            recovered_at < 1500,
+            "recovery after a dropout took {recovered_at} samples (~{:.1}s) -- expected fast \
+             reacquisition (issue #1422 secondary symptom: slow recovery after a transient)",
+            recovered_at as f64 / fs,
+        );
+    }
+
     /// ADR-157 §A3 bug-catching test. Divergence needs the pole magnitude
     /// `|r| >= 1`, i.e. `bw >= 4`. At `fs = 0.5` Hz with the band widened to
     /// 0.1-0.9 Hz, `bw = 2*pi*(0.9-0.1)/0.5 = 10.05`, so the OLD pole radius
@@ -493,12 +726,28 @@ mod tests {
         ext.freq_high = 0.9;
         // Feed a unit step for 600 frames — enough for the un-clamped resonator
         // to overflow to inf.
+        //
+        // A constant unit step has essentially no periodic content once the
+        // resonator settles, so with the issue #1422 reset-on-rejection fix
+        // this can legitimately cycle `filtered_history` back to empty
+        // between checks (build up to `min_samples`, get rejected as
+        // out-of-band, reset, rebuild...). That's an intentional, separate
+        // behavior change -- this test's actual purpose (ADR-157 §A3) is the
+        // *filter's* numerical stability under extreme parameters, so it
+        // tracks the max history length reached and checks finiteness on
+        // every iteration instead of asserting a nonzero count only at the
+        // very end.
+        let mut max_history_len = 0usize;
         for _ in 0..600 {
             ext.extract(&[1.0, 1.0, 1.0, 1.0], &[0.25, 0.25, 0.25, 0.25]);
+            max_history_len = max_history_len.max(ext.history_len());
+            for (i, &v) in ext.filtered_history.iter().enumerate() {
+                assert!(v.is_finite(), "filtered_history[{i}] must be finite, got {v}");
+            }
         }
-        assert!(ext.history_len() > 0, "history should accumulate");
-        for (i, &v) in ext.filtered_history.iter().enumerate() {
-            assert!(v.is_finite(), "filtered_history[{i}] must be finite, got {v}");
-        }
+        assert!(
+            max_history_len > 0,
+            "history should have accumulated samples at some point during the run"
+        );
     }
 }

v2/crates/wifi-densepose-vitals/src/heartrate.rs

@@ -98,7 +98,17 @@ impl HeartRateExtractor {
     /// Returns a `VitalEstimate` with heart rate in BPM, or `None`
     /// if insufficient data or too few subcarriers.
     pub fn extract(&mut self, residuals: &[f64], phases: &[f64]) -> Option<VitalEstimate> {
-        let n = residuals.len().min(self.n_subcarriers).min(phases.len());
+        // `n` is driven by `residuals` (and the subcarrier cap) only, NOT by
+        // `phases.len()`. Before this fix, a missing/short `phases` slice
+        // (e.g. `phases=[]`, documented as meaning "equal weighting", mirroring
+        // `BreathingExtractor`'s `weights=[]`) truncated `n` down to
+        // `phases.len()`, so `phases=[]` forced `n == 0` and `extract()`
+        // silently returned `None` for every frame (issue #1423). Missing
+        // phase entries are now treated by `compute_phase_coherence_signal`
+        // as "no coherence information available" and fused with equal
+        // weight, exactly like `breathing::fuse_weighted_residuals`'s
+        // uniform-weight fallback for a missing/partial `weights` slice.
+        let n = residuals.len().min(self.n_subcarriers);
         if n == 0 {
             return None;
         }
@@ -249,29 +259,44 @@ impl HeartRateExtractor {
 /// Combines amplitude residuals with inter-subcarrier phase coherence
 /// to enhance the cardiac signal. Subcarriers with similar phase
 /// derivatives are likely sensing the same body surface.
+///
+/// `phases` may be shorter than `n` (including empty). Missing entries mean
+/// the caller has no per-subcarrier phase measurement to weight by, so that
+/// subcarrier is fused with full coherence (weight 1.0) instead of being
+/// excluded -- i.e. `phases=[]` degrades gracefully to equal weighting
+/// across all `n` residuals, exactly like `breathing::fuse_weighted_residuals`
+/// falling back to a uniform weight for a missing/partial `weights` slice
+/// (issue #1423; `phases=[]` is documented as meaning equal weights, the
+/// same as `BreathingExtractor`'s `weights=[]`).
 fn compute_phase_coherence_signal(residuals: &[f64], phases: &[f64], n: usize) -> f64 {
     if n <= 1 {
         return residuals.first().copied().unwrap_or(0.0);
     }
 
+    let phase_at = |i: usize| phases.get(i).copied();
+
     // Compute inter-subcarrier phase differences as coherence weights.
     // Adjacent subcarriers with small phase differences are more coherent.
+    // If either phase value needed for a pair is missing, treat the pair as
+    // fully coherent (weight 1.0) rather than panicking or excluding it.
     let mut weighted_sum = 0.0;
     let mut weight_total = 0.0;
 
-    for i in 0..n {
-        let coherence = if i + 1 < n {
-            let phase_diff = (phases[i + 1] - phases[i]).abs();
-            // Higher coherence when phase difference is small
-            (-phase_diff).exp()
+    for (i, &r) in residuals.iter().enumerate().take(n) {
+        let neighbor = if i + 1 < n {
+            Some(i + 1)
         } else if i > 0 {
-            let phase_diff = (phases[i] - phases[i - 1]).abs();
-            (-phase_diff).exp()
+            Some(i - 1)
         } else {
-            1.0
+            None
         };
 
-        weighted_sum += residuals[i] * coherence;
+        let coherence = match neighbor.and_then(|j| phase_at(i).zip(phase_at(j))) {
+            Some((a, b)) => (-(b - a).abs()).exp(),
+            None => 1.0,
+        };
+
+        weighted_sum += r * coherence;
         weight_total += coherence;
     }
 
@@ -561,4 +586,95 @@ mod tests {
             assert!(v.is_finite(), "filtered_history[{i}] must be finite, got {v}");
         }
     }
+
+    /// Issue #1423 bug-catching test.
+    ///
+    /// Reproduces the exact GH-issue repro: 56 subcarriers @ 100 Hz (ESP32
+    /// defaults), a noiseless 1.2 Hz (72 BPM) sine identical across every
+    /// subcarrier, fed frame-by-frame with an **empty** `phases` slice.
+    ///
+    /// Before the fix, `extract()`'s `n` was
+    /// `residuals.len().min(n_subcarriers).min(phases.len())`, so
+    /// `phases = []` forced `n == 0` and every single frame returned `None`
+    /// (0/4000 estimates) even though the identical call with
+    /// `phases = [1.0; 56]` produced thousands of valid estimates. `phases=[]`
+    /// must mean "no coherence weighting available", i.e. equal weighting --
+    /// the same documented fallback `BreathingExtractor` already honors for
+    /// `weights=[]` -- not "invalid input, refuse everything".
+    #[test]
+    fn issue_1423_empty_phases_yields_equal_weighting_not_silent_none() {
+        let n = 56usize;
+        let sample_rate = 100.0;
+        let heart_freq = 1.2; // 72 BPM
+
+        let mut ext = HeartRateExtractor::esp32_default();
+        let mut estimates_with_empty_phases = 0usize;
+        for i in 0..4000usize {
+            let t = i as f64 / sample_rate;
+            let base = (2.0 * std::f64::consts::PI * heart_freq * t).sin();
+            let residuals = vec![base; n];
+            if ext.extract(&residuals, &[]).is_some() {
+                estimates_with_empty_phases += 1;
+            }
+        }
+
+        assert!(
+            estimates_with_empty_phases > 0,
+            "HeartRateExtractor::extract() with phases=[] must not silently return None for \
+             every frame of a clean 72 BPM signal (issue #1423); got 0/4000 estimates",
+        );
+
+        // Sanity check against the issue's own comparison point: an
+        // equivalent uniform, non-empty `phases` slice (all subcarriers at
+        // the same phase, i.e. zero pairwise difference => full coherence,
+        // exactly what the equal-weighting fallback now produces for the
+        // empty case too) must yield a comparable number of estimates --
+        // the two should behave the same, not `0` vs `thousands`.
+        let mut ext2 = HeartRateExtractor::esp32_default();
+        let uniform_phases = vec![1.0_f64; n];
+        let mut estimates_with_uniform_phases = 0usize;
+        for i in 0..4000usize {
+            let t = i as f64 / sample_rate;
+            let base = (2.0 * std::f64::consts::PI * heart_freq * t).sin();
+            let residuals = vec![base; n];
+            if ext2.extract(&residuals, &uniform_phases).is_some() {
+                estimates_with_uniform_phases += 1;
+            }
+        }
+
+        assert_eq!(
+            estimates_with_empty_phases, estimates_with_uniform_phases,
+            "phases=[] (equal-weight fallback) must behave identically to a uniform, \
+             non-empty phases slice of the same length -- both represent 'no differential \
+             coherence information', got {estimates_with_empty_phases} vs \
+             {estimates_with_uniform_phases}",
+        );
+    }
+
+    /// Issue #1423 companion: a `phases` slice *shorter* than `residuals`
+    /// (partial coverage) must fall back to equal weighting for the missing
+    /// tail rather than truncating the whole fusion down to the phases that
+    /// happen to be present -- mirrors
+    /// `breathing::partial_weights_are_renormalized_not_scale_mixed`.
+    #[test]
+    fn partial_phases_do_not_truncate_subcarrier_count() {
+        // 8 residuals, only 2 phase values supplied.
+        let residuals = [1.0_f64; 8];
+        let phases = [0.0_f64, 0.0];
+        let fused = compute_phase_coherence_signal(&residuals, &phases, 8);
+
+        // All residuals are identical (1.0), so regardless of how coherence
+        // weights are distributed the fused value must still be 1.0 -- but
+        // this only holds if all 8 residuals are actually used. Before the
+        // fix, `n` would have been truncated to `phases.len() == 2`, so the
+        // caller-facing `extract()` never even reached this function with
+        // `n == 8`; this test pins `compute_phase_coherence_signal` itself
+        // to handle a short `phases` slice safely and correctly when called
+        // with the full `n`.
+        assert!(
+            (fused - 1.0).abs() < 1e-12,
+            "fusion with a partial phases slice must still average all {} residuals, got {fused}",
+            residuals.len(),
+        );
+    }
 }