Dated SIU — SIU-2026a
$0.0089
13 Sep 2026
provisional
Correction notice — published after this print, disclosing a fact that does not change dated_siu:
3 corrections: 2 precision, 1 pricing
- 13 Sep 2026 — This print was published (2026-09-13, automated daily run) before two real bugs in this project's own code were fixed (commit 48ba69c), both affecting its own cost_of_production_usd. (1) RunRecord.usage.cached_input was captured by every provider adapter but never priced by this project's cost formula -- a real, unconditional gap, not specific to any one provider. For this print specifically: gemini-3.1-pro-preview: 84506 cached tokens, $0.016901; grok-4.6: 7296 cached tokens, $0.000004 -- together understating the published cost_of_production_usd ($1.4109) by $0.016905. This is not a hypothetical cache-adoption policy (see docs/methodology.md's sensitivity block, cachePolicyVariant, which is unrelated) -- this cache use actually happened and was actually billed. (2) Separately, and larger for gemini-3.1-pro-preview specifically: the Google adapter discarded a real, separately-billed API call's usage whenever Gemini's mandatory reasoning consumed the whole completion budget and triggered an internal retry with a bigger one -- only the retry's usage was recorded, not the first, truncated call's. This fires on nearly every gemini-3.1-pro-preview call. Its real input-token count and full raw response were never saved for this print's own run records (captured only after the fix), so this piece cannot be reconstructed precisely, unlike (1) above. Neither bug is corrected on this print's own signed cost_of_production_usd or dated_siu -- a published print's signed body is never edited -- so this print remains status: "provisional" permanently. See docs/methodology.md's Index governance for the full explanation.
- 25 Sep 2026 — dated_siu previously rounded to a fixed 4 decimal places rather than 4 significant figures — found live and fixed the same day, 2026-09-25 (docs/methodology.md's Rounding section). At this print's price level that was too coarse to show real day-to-day movement. This print's signed body is never edited — the published figure (0.0089) stands. Recomputed from this print's own published basket_costs and weights (Σ weight × basket_cost, rounded under the corrected 4-significant-figure rule, reproducible by anyone from this print's own published figures alone), the real value is 0.008856.
- 25 Sep 2026 — Correction to this print's own rounding correction note above: that note's phrase "the real value is X" overstated what the recomputation shows. It restores rounding precision only — the precision a fixed 4-decimal-place rounding rule removed, recovered by recomputing Σ weight × basket_cost from this print's own published figures. It is not a claim that the recomputed figure is this print's true economic value. This print's own basket_costs are also affected by the reasoning-token and/or cached-input pricing correction disclosed elsewhere in these notes — usage that was under-priced before that fix landed — so the recomputed rounding figure is the unrounded version of a value already known to need that separate correction too, which this recomputation does not make. See docs/methodology.md's Rounding section for the general statement of this limit.
— 0.0% since 12 Sep 2026 — Unchanged from the previous print.
Equal weighting, disclosed: basket costs span 35.9× across
the 10 qualifying constituents. 4 of 10 constituents
(40%) sit at or above the mean basket cost and together account for
79% of the summed basket cost Dated SIU is computed from — equal weighting still
gives each of them the same 1÷10 nominal share. Dated SIU therefore tracks the more
expensive end of the basket more closely than a demand-weighted index would. See the
methodology's Weighting section, and Frontier SIU / Commodity SIU, the tier prints published
alongside this one for exactly this reason.