12 contiguous slots reserved for durable alpha-system infrastructure:
- 539-542: diagnostics (Q-spread, action entropy, return-vs-random,
early-Q-movement EMAs) — read by Phase E kill criteria
- 543-546: stacker-threshold controller (threshold, target, observed-rate,
Kelly attenuation) — engagement-rate self-correction
- 547-548: random-uniform baseline (mean, std) — anchor for kill criterion 541
- 549-550: reserved spare (absorb growth without bumping ISV_TOTAL_DIM)
Named `alpha_isv_slots` rather than `phase_e_isv_slots` because these slots
are intended to outlive any individual Phase E/F/G milestone — the SP4..SP22
naming was iteration-scoped, but this block is system-scoped infrastructure.
ISV_TOTAL_DIM bumped to 551. All indices validated in 4 unit tests
(bounds, membership, uniqueness, total-dim coverage). Audit doc
docs/isv-slots.md updated per Invariant-7.
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