Phase E.0 Task 7b. Random-uniform policy reward baseline binary, plus a
small `ExecutionEnv::reset_at(seed, start_cursor)` extension so episodes
can sample random starting points across a long snapshot replay.
The binary loads MBP-10 snapshots, constructs SnapshotRow values (with
L2/L3 synthesized at ±0.25-tick offsets per the L1-only parser
limitation), loads the fitted FillModel from JSON, then runs N random
episodes from random start cursors. Reports mean / std / quintile
percentiles + kill threshold (mean + 2σ) for E.1 to exceed.
Smoke run (500 episodes, horizon 600, 100K snapshots):
mean = -5600 (dominated by terminal force-close variance + market-order
over-reliance because fit converged to β_spread = -40
→ limit fill probability ~0 at typical spreads)
std = 5383
p95 = -895
kill threshold (mean + 2σ) = +5167
The deeply negative baseline is correct *for this env* even though it
doesn't reflect realistic random-policy P&L. The DQN will face the same
env (same fill model, same cost structure), so the comparison stays
fair. Fitter regularisation (to prevent β_spread runaway) is a Phase E.1
follow-up.
Run:
cargo run -p ml --release --example phase_e_random_baseline -- \
--mbp10-dir /home/jgrusewski/Work/foxhunt/test_data/futures-baseline-mbp10/ES.FUT \
--fill-coeffs config/ml/phase_e_fill_coeffs.json \
--horizon 600 \
--n-episodes 10000 \
--out-path config/ml/phase_e_random_baseline.json
env.reset_at also called by reset() (1-line refactor); no behavior change.
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