Phase 12: spatial peer features rejected (panel +106, 0% selection); pm40 sweep closed

EXPERIMENTS.md

@@ -397,6 +397,45 @@ runtime splits live. Expected effect is largest on public/private scenarios
 near their data end; the panel contains only ~3 such origins, so the local
 delta (-14) understates the deployable one.
 
+Follow-up sweeps, both rejected by the panel: pm40 (1705.1, s_38's -721 does
+not survive the fresh-only restriction) and pm40/m1.0 (1715.1). pm25/m0.8 is
+the local optimum of the family. Docker all-48 verification of the adopted
+champion: **2175.4** (was 2202); late 1460 / early 451.
+
+## Phase 12 - spatial peer features (rejected: panel +106, 0% selection)
+
+User idea: cross-room/building features, age-scaled ("what would my peers
+have measured at my age?"), to catch fast plungers relatively. Attractive on
+paper because it fixes phase-6's fatal flaw: batch death-clocks needed peers'
+DEATHS (14-54% coverage), while peer VOLTAGE at matched age has ~100%
+coverage. Recon: rooms too thin (median 4 peers); buildings workable (median
+9, max 117); install-week batches age-match by construction (median 8).
+Building death rates genuinely cluster (4% to 100% across 24 buildings).
+
+Screen on the blind zone (11,599 healthy-voltage pairs, 24 silent deaths):
+
+| feature | blind AUC | all-pairs AUC |
+|---|---|---|
+| deficit vs building peers (age-regressed) | 0.761 | 0.869 |
+| deficit vs install-batch peers | 0.663 | 0.808 |
+| building death-rate prior (smoothed, leak-free) | 0.646 | 0.721 |
+| rng_30 (phase-8 incumbent) | 0.832 | 0.764 |
+| v_corr_last (already in FEATURES) | 0.867 | 0.945 |
+
+Additive test: blind logistic rng_30 alone 0.843; +peer features 0.825-0.837
+(worse). Panel adjudication anyway (logbag + deficit_bldg + bldg_rate on the
+phase-11 planner, 34 origins): **1807.6 vs 1702.0**, champion selected in
+100% of random and blocked splits. Per-origin AUC is unchanged (s_41: 0.967
+vs 0.968) - the features do not add ranking signal, only calibration noise,
+which the count rule converts into worse inclusion counts.
+
+Why it cannot work here: the master curve already performs fleet-level
+age-matching (tau_projected IS "voltage vs expected-at-this-point"); local
+peer medians re-estimate the same quantity from 5-20 samples instead of the
+fleet. The building death-rate signal is real but weak exactly where the
+misses live, and largely confounded with install batch (~90% of lifetime
+variance, phase 6).
+
 ## Test-look ledger
 
 8 looks total (now historical - see protocol change above); look 9 = the