Phase 55: temporal-purge CV is THE SCORE and sole validator (user directive); cv.py consolidated to the purge harness only

Protocol (session 59 implementation, user-specified): per scenario, one model
on ALL buildings' pairs with label windows fully outside the scenario window,
full-fleet plan, SCORE = ALL-48 mean. Champion 1972.0 (panel 1839.6).
all48/static/screen/lobo/ablate removed from cv.py - recover at 2000281.
Purge-vs-LOBO paired diagnosis recorded: same-device-fate channel ~-18/origin
on the panel for the linear champion, warm-up harsher via calendar starvation.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

EXPERIMENTS.md

@@ -2897,3 +2897,46 @@ foreign training data helps, self-building identity flatters by ~200.
 Everything is judged against 1877.3 paired per scenario from here, sched-flat
 rule in force. Public best remains 3c7b883 at 1661.45; private selection
 recommendation unchanged (score the hardened head publicly, then select).
+
+## Phase 55 - THE SCORE final: temporal-purge CV, sole validator (user directive)
+
+The CV settles for good, three user decisions in one afternoon session arc:
+
+1. **Protocol** (implemented by session 59): for each scenario, ONE model
+   fitted on ALL buildings' pairs whose 42d label windows lie fully outside
+   the scenario window (`origin+42 <= T or origin >= T+42` - label-overlap
+   purge), whole-fleet prediction, ONE full-fleet plan, cost per scenario.
+   SCORE = ALL-48 mean, floor off. Rationale (user): admits every forecasting
+   method (no fold plumbing), one-sentence protocol, no leak within the
+   scenario, and the temporal shape matches deployment (training data spans
+   before and after most scored origins - phase 43a measured 93.9% window
+   coverage). The building axis is deliberately not validated (user judgment:
+   same battery type across buildings).
+2. **Sole validator** (user, verbatim intent): "we only use purge score going
+   forward, nothing else to validate a new model or optimization method."
+   Documented as standing rule. LOBO's chimera-plan critique (24 stitched
+   calibrations, no per-building cost attribution, seams inflate the transfer
+   penalty) was the user's decisive argument against building-holdout cost.
+3. **Consolidation**: cv.py now contains ONLY the purge harness +
+   oofcand/oofreport. all48/static/screen/lobo/ablate/wf/self removed;
+   recover from git 2000281. exp_x29/exp_x30 no longer run as-is.
+
+**Champion on THE SCORE: 1972.0** (warmup 3560.3 / panel 1839.6 / nearend
+604.8). Level chain, never cross-compare: self-fit 1661.7 (floor on) <
+exact-LOBO 1877.3 < 5-fold-OOF 1913.3 < purge 1972.0.
+
+Paired purge-vs-LOBO diagnosis (59's run; LOBO reproduced 1877.3 exactly
+before removal): the purge is HARSHER overall (+94.7) - entirely warm-up
+(3560.3 vs 2875.3: purging the calendar-local +/-42d window starves early
+scenarios more than building-holdout does) - and modestly softer on the panel
+(-18.1/origin; sched 8.9 vs 9.2 flat, recall 0.468 vs 0.461, rec12 0.576 vs
+0.509). Reading: the same-device-fate channel exists but is ~-18/origin for
+the LINEAR champion - an order of magnitude below the +134/+216 self-fit
+flattery - because the label-overlap purge removes the direct channel and
+logbag cannot memorize identity. The known, accepted residual risk: flexible
+challengers (rf/gbm/dynamics) are flattered by same-battery training; the
+receipts are phases 51-54 and they are not to be re-argued unprompted.
+
+The leaderboard closures (appetite, cert-first, pooling) rest on public
+measurements and survive any CV change. Public best 3c7b883 at 1661.45;
+private selection recommendation unchanged.