# Per-spread prediction-market pilot

The local evidence supports a modest additive gain, conditional on preserving each branch when merging; it does not yet establish a gain on Paradigm’s unseen simulations. This report transcribes the five supplied results, rather than rerunning their experiments. [S1–S4]

Sources: [S1], [S2], [S3], [S4] and [T] below identify the supplied JSON results; field names make each figure traceable. All edges are signed: a less negative `arb_edge` means less arbitrage loss. Numbers in the tables preserve the items’ numeric values without rounding. Code size is computed as the UTF-8 byte length of each item’s `code` string, not the JSON file size. No strategy code is reproduced.

The four spread items report baseline reproduction on seeds 1000–1599, tuning scores over 4000–7999, and frozen-policy holdout scores over 50000–53999. Each reports zero failures in the final score and holdout batches and exact equality with the base outside its target spread. [S1–S4: `approach`, `score`, `holdout`, `tried`] The table item instead reports 600 runs over 4000–4599 and 600 over 50000–50599, citing runtime limits; its requested full 4000–7999 score is **missing**, and its baseline and spread breakdown must not be compared as if they used the larger holdout. [T: `approach`, `score`, `holdout`]

The task flags one external source cited by spread-4 as failing a later source check, without identifying the failed URL or passage. The supplied S4 JSON has no source list that resolves this. Its simulator measurements are therefore attributed as item-reported results, not independently verified measurements; its external-source claims receive no additional evidentiary weight here. This limits confidence in the spread-4 contribution and hence the proposed aggregate. No missing measurements or source verification are fabricated.

| Item / route | Reproduced base (`base_mean_edge`) | Base on its unseen runs (`base_holdout_mean_edge`) | Own seeds 4000–7999: mean; retail; arbitrage | Own unseen: mean; retail; arbitrage | Code bytes |
|---|---:|---:|---|---|---:|
| Spread 1: ordinary-quote margin and boundary probability floor [S1] | 109.27254289017199 | 98.28063388702982 | 98.9689746680761; 124.29013580906907; -25.321161141007252 | 98.52619137752235; 125.95607618418198; -27.4298848066588 | 14835 |
| Spread 2: coarser belief grid [S2] | 109.27254289017199 | 98.28063388702982 | 98.83942460660653; 124.34260207298652; -25.503177466397474 | 98.30682016589887; 126.04095539629678; -27.73413523039735 | 14777 |
| Spread 3: guarded demand estimate for tick-one stock [S3] | 109.27254289017199 | 98.28063388702982 | 98.84950498965385; 124.4013873695152; -25.551882379876773 | 98.47028967306635; 126.1276183775221; -27.657328704453427 | 16586 |
| Spread 4: immediate-cover horizon and queue threshold [S4] | 109.27254289017199 | 98.28063388702982 | 98.84752384692902; 124.52530289979967; -25.6777790528859 | 98.40769532192527; 126.21554314516477; -27.807847823237275 | 14974 |
| Offline table: per-spread arbitrage-loss weight [T] | 109.272542890172 | 97.06959828018033 | **Full range missing**; 4000–4599 only: 100.62054626478633; 127.584287384187; -26.9637411193865 | 97.03279922204433; 123.6284762471255; -26.59567702508067 | 14753 |

The following table copies `by_spread`: each item cell is **mean; difference ± paired standard error**, relative to that item’s matching base. S1–S4 share the base column and run counts. T has its own base and counts because its unseen sample is smaller. Zero differences outside the target spread are reported equality, not a fitted estimate. [S1–S4, T: `by_spread`]

| Spread | S1–S4 base (runs) | S1 | S2 | S3 | S4 | T base (runs) | T |
|---|---|---|---|---|---|---|---|
| 1 | 35.099921878704336 (1016) | 36.06668365229695; 0.9667617735926181 ± 0.24996913452108194 | 35.099921878704336; 0.0 ± 0.0 | 35.099921878704336; 0.0 ± 0.0 | 35.099921878704336; 0.0 ± 0.0 | 43.66184288153885 (157) | 43.521209538343946; -0.14063334319490464 ± 0.07301492695071997 |
| 2 | 83.51205221971222 (998) | 83.51205221971222; 0.0 ± 0.0 | 83.61700724523948; 0.10495502552725416 ± 0.11415515237099481 | 83.51205221971222; 0.0 ± 0.0 | 83.51205221971222; 0.0 ± 0.0 | 76.95587352704295 (156) | 76.95587352704295; 0.0 ± 0.0 |
| 3 | 122.97345583671554 (1017) | 122.97345583671554; 0.0 ± 0.0 | 122.97345583671554; 0.0 ± 0.0 | 123.71939796468614; 0.7459421279705998 ± 0.2441846966634406 | 122.97345583671554; 0.0 ± 0.0 | 141.71566301263334 (144) | 141.71566301263334; 0.0 ± 0.0 |
| 4 | 153.82041508580312 (969) | 153.82041508580312; 0.0 ± 0.0 | 153.82041508580312; 0.0 ± 0.0 | 153.82041508580312; 0.0 ± 0.0 | 154.34492049300826; 0.5245054072051594 ± 0.1582480941681672 | 132.69005518649442 (143) | 132.69005518649442; 0.0 ± 0.0 |

The gains add algebraically if the merged policy reproduces each frozen target branch: sum each target `diff × runs / 4000` from the second table. This gives a **derived** gain of approximately **0.58846099029355** per run and a combined local mean of approximately **98.86909487732337**, against the reported base **98.28063388702982**; neither is a measured merged-policy score. Spread 2’s difference is smaller than its standard error, while the other target differences exceed twice theirs. The original constants-copying plan is insufficient: spread 3 needs its guarded flow estimator and spread 4 its price-dependent queue rule. No merged run or aggregate paired standard error is supplied, and this arithmetic is not a forecast of leaderboard improvement. [S1–S4: `by_spread`, `approach`, `next`; aggregate calculated here]

The table route argues that fair-value fill scoring makes inventory value flat when cash constraints do not bind, reducing its proposed dynamic program to the base’s marginal quote-sizing rule. It shipped a small loss-weight table, choosing **0.9** for spread 1 and **0.7** elsewhere, rather than a large state-dependent policy. Its unseen spread-1 difference was **-0.14063334319490464 ± 0.07301492695071997**, and its whole-file mean was **97.03279922204433** against **97.06959828018033**. This gives no demonstrated improvement. The claim of a solved optimum remains the item’s modeling argument: a limited weight search and the abbreviated evaluation do not prove optimality for cash-constrained inventory and queue dynamics. [T: `approach`, `constants`, `holdout`, `by_spread`, `tried`, `next`]

A wide goal should first merge the frozen branches, verify exact preservation of other spreads, and test the combined policy on fresh shared seeds; the reported holdout is now spent. Preserve separate retail and arbitrage attribution and rare-jump losses. If that test supports expansion, pursue spread-specific belief calibration, demand-aware stock replenishment and inventory-aware queue exposure; use a calibrated jump mixture and a value function where cash binds. Complete the table route’s missing full-range evaluation before comparing it fairly, and resolve spread-4’s failed source check before treating its supporting claims as verified. The present evidence supports that validation stage, rather than funding a large constants-only sweep on the assumption that the additive gain has already transferred. [S1–S4, T: `next`, `approach`; validation sequence is this report’s recommendation]

Source keys (the supplied task inputs; no external page is used as independent confirmation):

- [S1]: [item-spread-1](../../../.imd/reads/artifacts/item-spread-1), supplied logical path `artifacts/goal/items/spread-1/result.json`; SHA-256 `5073494da3b5de0c65a054e476ecbfec02f31d29462de470587b675429b1e101`.
- [S2]: [item-spread-2](../../../.imd/reads/artifacts/item-spread-2), supplied logical path `artifacts/goal/items/spread-2/result.json`; SHA-256 `9b34e5921027c0ef5f8236b1bc81a622c602af34172ce31ef9d353cfcc29a36e`.
- [S3]: [item-spread-3](../../../.imd/reads/artifacts/item-spread-3), supplied logical path `artifacts/goal/items/spread-3/result.json`; SHA-256 `98e4760387ce818687aebc79b9ecb937360636d66e42cdcdf85fcc70e1f63d11`.
- [S4]: [item-spread-4](../../../.imd/reads/artifacts/item-spread-4), supplied logical path `artifacts/goal/items/spread-4/result.json`; SHA-256 `2e3943f3f77127c66a331c96328e4036b6cc44a1b058448c29ba3cc3fbe450e2`.
- [T]: [item-solve-table](../../../.imd/reads/artifacts/item-solve-table), supplied logical path `artifacts/goal/items/solve-table/result.json`; SHA-256 `27f30cc086acf1ff266b5fd3d29c724ec11c9bcaeb0184dfa8fc43aa8a907923`.