SDR-0018: Summarize robustness within complete unit lanes
- Status: Accepted
- Date: 2026-07-27
- Decision owners: project maintainers
- Related schema: multiverse lane summary v1
Context
Separating divisive and subtractive estimates visually prevents an obvious unit error, but HTML alone is insufficient for reproducible downstream work. A global practical-effect threshold cannot express meaningful minima on distinct scales, and summaries calculated only over successful workflows reward pipeline failure.
Decision
Allow one practical-effect threshold and direction per declared unit lane. When a per-lane policy is present, require exactly one threshold for every lane and reject simultaneous use of the legacy global threshold.
Emit a versioned machine-readable lane-summary artifact. Calculate ranges and medians only from successful finite estimates, but use every compatible universe in that lane—including failed and blocked workflows—as the denominator for sign and practical-effect stability fractions. Retain explicit universe membership in each summary.
Consequences
Scientists and external tools can reproduce the report's unit-local claims without scraping presentation markup. Failure cannot inflate a robustness fraction. A lane with no successful workflows has null magnitude summaries while retaining its declared threshold and failure counts.
Alternatives considered
- Store thresholds by preprocessing label: rejected because multiple labels may share units and should occupy one interpretable lane.
- Omit failed workflows from fractions: rejected because fragility would improve the apparent result.
- Add fields only to the HTML: rejected because the scientific summary requires a stable machine interface.
Revisit trigger
Revisit the denominator policy if user research demonstrates that scientists need both conditional-on-success and all-declared-workflow fractions. If both are added, label them explicitly rather than changing the v1 meaning.
Evidence added later
None yet.