Per spec §9.2 (3.5.5) post-amendment-2: replaces non-existent
episode-level metadata with per-bar signal that fires when
dd_pct(t) < dd_pct(t-1) AND dd_pct(t-1) > DD_TRAJECTORY_FLOOR — i.e.
transition is part of a recovery from non-trivial DD.
PER sampler (Phase 3.5.5.b follow-up) will read this and weight:
sampling_weight = base × (1 + RECOVERY_OVERSAMPLE_WEIGHT × signal)
so recovery transitions get amplified gradient signal, completing the
downward-spiral break-out chain (3.5.2 reward asymmetry → 3.5.3
cooldown gate → 3.5.4 plasticity → 3.5.5 PER recovery curriculum).
3 ISV slots: 439 DD_TRAJECTORY_DECREASING, 440 RECOVERY_OVERSAMPLE_
WEIGHT (2.0 sentinel; ISV-driven from current dd_pct in follow-up),
441 DD_TRAJECTORY_FLOOR (0.02 sentinel; ISV-driven 25th percentile
of running dd_pct distribution in Phase 3.5.5.c follow-up per
feedback_isv_for_adaptive_bounds).
New sp15_dd_trajectory_prev_dd MappedF32Buffer (size 1) tracks
prev_dd across kernel calls — mirrors Task 3.5.3 sp15_cooldown_
consecutive_losses non-ISV mapped-pinned scratch pattern.
4 fold-reset registry entries + dispatch arms (3 ISV + 1 scratch).
Per established Phase precedent: kernel + launcher land first; PER
sampler integration and 25th-percentile floor producer are purely
additive follow-ups per feedback_no_partial_refactor.
Anchor test 2.10 recovery_after_streak (Phase 2C / Phase 3.5 paired) —
fully green via 3.5.2 + 3.5.4 + 3.5.5 combined.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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