feat(dqn-v2): D.2 per-branch gamma — GPU kernel + monitor (spec §4.D.2 + §4.C.6)
Replaces scalar GAMMA_EFF_INDEX=43 with 4 per-branch slots at 43-46
(DIR, MAG, ORD, URG). New per_branch_gamma_update_kernel.cu reads
per-branch v-range + health and writes 4 slots. Deletes
gamma_update_kernel.cu per feedback_no_partial_refactor.md.
Per-branch base/max: direction [0.92, 0.99] (trend horizon),
magnitude [0.88, 0.95], order [0.85, 0.93], urgency [0.80, 0.90]
(execution horizon). Kernel diverges each branch's γ from uniform
bootstrap based on its branch's Q-stats.
ISV slots downstream of 43 shift +3: KELLY (44→47), CQL_ALPHA (45→48),
PLAN_THRESHOLD (46→49), Q_P05_* (47→50..54), Q_P95_* (51→54..58),
fingerprint (55-56 → 58-59). ISV_TOTAL_DIM grows 57 → 60.
Layout fingerprint auto-recomputes from updated seed bytes.
c51_loss_kernel reads per-branch γ from ISV[43+d] inside the branch loop;
iql_compute_per_sample_support reads ISV[43+d] per-branch for half_w.
kelly_cap_update_kernel write index updated 44→47.
q_quantile_kernel slot bases updated 47/51 → 50/54.
state_layout.cuh ISV_PLAN_THRESHOLD_IDX updated 46→49.
CPU-side PerBranchGammaMonitor (gamma_monitor.rs) is read-only observer
of all 4 slots; read() returns mean, diagnose() exposes individual γ values
+ spread + health. No CPU-side γ computation (spec §4.C.6 GPU-drives).
Plan 2 Task 3. Spec §4.D.2 + §4.C.6.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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