a11y(reports): include buyer-visible LeftoverPairList evidence in actionable button names

[seonghobae]

Buyer-visible gap

Exact serialized parent #828@7b6dbbb99a09d0523bce43c6872bbd9fa382a43a renders multiple persisted evidence badges inside each LeftoverPairList post button (R, Y/E, rank, U, U²/R², R̂²/R², 2R̂U/R², R̂, coordinates, distance), but the button also sets an explicit aria-label containing only pair kind/title/criterion. The current test suite explicitly queries that shortened accessible name while separately asserting the richer visible text. Assistive technology therefore cannot discover the same buyer-visible evidence from the actionable control name.

This is distinct from #829, which repairs the same composition defect only for grouping-comparison pair actions. Do not expand #829 or race its single-writer lane.

Domain / ownership boundary

LineageWeave owns this read-model composition and accessibility contract. Consume existing persisted values and existing formatters only. Do not derive psychometric values, add SQL/schema, copy fast-mlsirm/TEPP/RankWeave truth, or create a translation authority competing with #922/#929/#932.

Acceptance

1. Start from the then-current serialized product parent after feat(reports): preserve grouping comparison unexplained-share delta for serialized successor #829/feat(reports): preserve grouping comparison axis-singular delta for serialized successor #830 ancestry is settled; do not patch a stale historical head.
2. Add a realistic focused RED proving a finite visible evidence badge is absent from the pair button accessible name because the explicit parent aria-label overrides descendant text.
3. Apply the smallest composition repair so the actionable name contains the same finite buyer-visible evidence selected/rendered by the existing formatters, without duplicate accessibility-tree announcements. Missing/non-finite fields remain absent; do not invent or recompute values.
4. Preserve click semantics, deterministic identity, keyboard/focus behavior, pointer/touch behavior, dense/responsive rendering, and existing whole-population authorization boundaries.
5. Require current-head focused + full frontend GREEN, lint, production build, Storybook, browser keyboard/focus/a11y evidence, and translation-ledger consumer convergence before calling the UI complete.
6. Keep ADR/release identity collision-free and Proposed while Draft; update docs/product-technical-gap-baseline.md code-current when the source lane begins.

Exact evidence

At #828@7b6dbbb..., frontend/src/components/LeftoverPairList.tsx renders the persisted badges under a <button aria-label={tf("Open leftover {kind} pair: {title} · {criterion}", ...)}>. frontend/src/components/LeftoverPairList.test.tsx asserts that shortened role/name while also asserting richer visible R, Y/E, rank, U²/R², R̂²/R², cross-share, reconstruction, coordinates and distance text. No open issue matched LeftoverPairList aria-label before filing.

[seonghobae]

Draft successor #977 stacks this accessible-name repair on leftover-map single-writer #802. Grouping-comparison pair actions stay on #829/#830.

[seonghobae]

Fresh #977 review found two repair requirements before this issue can close. The PR carries a valid evidence-in-accessible-name delta, but its current base is still historical #802 rather than the serialized product parent required here; preserve it as Draft evidence and reconstruct after #830 converges. In addition, its explicit aria-label starts Open leftover {kind} pair… while the visible button text starts with the localized {kindLabel}: …, so the visible label is not contained in the programmatic name. That conflicts with WCAG 2.2 SC 2.5.3 Label in Name (Level A): https://www.w3.org/WAI/WCAG22/Understanding/label-in-name.html . Current-parent reconstruction should prefix the accessible name with the exact visible button label, then append localized action/evidence context, with a rendered role/name regression and the existing fail-closed non-finite metric cases. Review authority: #977 review 5131642217.