The threshold-tuning smoke at 81decf40f produced n_trades=0 despite
74.6% of decisions having max_conv ≥ 0.30 — the linear-weighted-mean
aggregator in decision_policy_default is structurally dilution-bound
at cold-start (per spec §1).
Q1 stopgap: when sim_variants[i].use_cold_start_stopgap = true, the
harness uploads a max-confidence Strategy bytecode program for that
backtest, routing decisions through decision_policy_program with
OP_AGG_MAX_CONFIDENCE. Existing kernel; zero CUDA changes.
Field additions (atomically across BatchedSimConfig + UniformSimParams
+ ResolvedSimVariant + SweepBase.SimVariant) — every UniformSimParams
literal migrated to include use_cold_start_stopgap: false (default).
The sweep YAML's sim_variants entry sets it to true only for the
validation run; production deployability uses Q2's kernel fix instead.
Sweep YAML (config/ml/sweep_smoke.yaml) flipped to use_cold_start_stopgap=true
at threshold=0.0, cost=0.125 — same anchor as the threshold-tuning
smoke that produced n_trades=0, for direct comparison.
This is a VALIDATION step. Cluster smoke at this commit MUST produce
n_trades > 100 + finite metrics. Q2's kernel CBSW immediately follows
and deletes this entire stopgap atomically (field, harness branch,
YAML setting, every literal).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds the two sweep axes that the spec's deployability grid needs but
were missing from the kernels:
Threshold gate (decision_policy.cu, both kernels):
- New per-backtest `threshold_per_b` array kernel arg.
- Pre-Kelly prelude: if max_h |alpha[h] - 0.5| * 2 < threshold[b],
emit noop and return. Kept deterministic from alpha alone so the
threshold pre-registration step (p60-p95 absolute calibration on a
validation window, future P6) reflects exactly what gets gated in
deployment.
Per-fill cost integration (resting_orders.cu / apply_fill_to_pos):
- apply_fill_to_pos signature grows three args: b, cost_per_lot_per_side_per_b,
total_fees_per_b. Single insertion point at line 90.
- After the close-leg realized_pnl math runs (so the gross unwind P&L
is preserved), deduct fill_cost = filled_lots * cost_per_lot_per_side[b]
from pos.realized_pnl AND accumulate into total_fees_per_b[b].
- Net-of-cost semantics: isv_kelly_update_on_close reads realized_pnl
delta which is now net of cost — Kelly state learns from realistic
return distribution.
- All 3 apply_fill_to_pos call sites in step_resting_orders updated.
order_match.cu's submit_market_immediate path is dead code in the
post-P1 flow (everything routes through seed_inflight_limits_batched
→ step_resting_orders → apply_fill_to_pos) so not touched here.
BatchedSimConfig + UniformSimParams + BacktestHarnessConfig gain
threshold + cost_per_lot_per_side fields. All UniformSimParams
constructors in tests and main.rs updated with defaults (0.0, 0.0 =
gate disabled, frictionless).
Regression:
- threshold_gate_skips_low_conviction (p=0.51 + threshold=0.10 → noop)
- threshold_gate_allows_high_conviction (p=0.8 + threshold=0.10 → buy 1+)
- threshold_zero_is_passthrough (sanity)
- All P1+P2+P3 tests continue to pass via the new ABI.
cost_deducted_at_each_fill + kelly_state_sees_net_return end-to-end
tests deferred — they require a full submit_market → fill → close
sequence, which the production smoke exercises.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Migrates target_annual_vol_units, annualisation_factor, max_lots,
latency_ns, kelly_frac_floor, sharpe_weight_floor from scalar-broadcast
kernel args to per-backtest device arrays via BatchedSimConfig. Atomic
contract change per feedback_no_partial_refactor — kernel + sim + harness
+ all 3 existing test files migrate in this commit.
- crates/ml-backtesting/src/sim.rs → sim/mod.rs (directory module)
- crates/ml-backtesting/src/sim/batched_config.rs (NEW): BatchedSimConfig
+ UniformSimParams + validate(). from_uniform rebuilds the legacy
uniform-broadcast behaviour at n=1 (smoke/fixtures). from_grid lands
in P6 for the 140-variant sweep packing.
- LobSimCuda gains 6 per-backtest device buffers (target_annual_vol_units_d,
annualisation_factor_d, max_lots_d, latency_ns_d, kelly_frac_floor_d,
sharpe_weight_floor_d). step_decision_with_latency uploads from
BatchedSimConfig each call; both decision kernel launches now pass
per-backtest array pointers.
- decision_policy_default + decision_policy_program: scalar args become
const float* / const int* per_b arrays; first lines of each kernel
index by `b` into the arrays. Behaviour preserved at n=1 uniform.
- dispatch_latent_market_orders: reads latency per-backtest from
&BatchedSimConfig (host loop stays for P1; P2 replaces with kernel).
- step_decision_with_latency now ALWAYS dispatches through the latency
path; when cfg.latency_ns[b]=0 the in-flight slot's arrival_ts equals
current_ts and gets promoted immediately on next snapshot. Eliminates
the if/else branch and consolidates the launch path.
- harness.rs: BacktestHarness gains a sim_config field, built via
BatchedSimConfig::from_uniform at new() from the harness cfg's scalar
fields. The run loop passes &self.sim_config to step_decision_with_latency.
Regression coverage:
- parallel_sim_correctness::parallel_sim_equivalence_with_uniform_config
— n=8 with uniform config produces 8 bit-identical market_targets
(proves per-backtest indexing reduces correctly).
- Existing decision_floor_coldstart tests (3) all pass through the new
ABI — proves cold-start floor + variance-cap gate behaviour preserved.
- parallel_sim_independence_per_backtest deferred to P2 (needs
read_first_inflight_arrival_ts helper that depends on LimitSlot layout).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
