a11y: /analytics?tab=prefix-tool contrast violations exposed by #1706 coverage

[Kpa-clawbot]

Summary

PR #1711 added #/analytics?tab=prefix-tool to the M5/M6 axe-core color-contrast gate, exposing the two action buttons.

Allowlisted in #1711 to unblock CI coverage; fix is owed in this issue.

Failing run

https://github.com/Kpa-clawbot/CoreScope/actions/runs/27469371752/job/81198104145

Selectors + measured contrast

WCAG threshold: 4.5:1.

Selector	Notes
#ptCheckBtn	white on #4a9eff accent, measured ~2.75
#ptGenBtn	white on #4a9eff accent, measured ~2.75

8 cell failures (2 buttons × 4 cells).

Fix sketch

Same shared accent-button problem as subpaths / rf-health / clock-health filter. Fixing the shared token closes this one too.

Acceptance

• Remove both entries from tests/a11y-allowlist.yaml.
• node test-a11y-axe-1668.js passes net=0 on the 4 prefix-tool cells.

[Kpa-clawbot]

Severity: P3 — allowlisted; cosmetic-but-tracked debt.

Claim: confirmed. tests/a11y-allowlist.yaml carries #ptCheckBtn / #ptGenBtn on prefix-tool; both are white-on---accent (#4a9eff) ≈ 2.75:1.

Code today: Same shared "active accent button" pattern as #1713/#1716/#1717. Fix consolidated under #1719's P1 in open PR #1720 (.btn-active-accent shared rule, --text-on-accent/--accent-strong tokens → 4.95:1).

Findings:

• (tufte): one shared class beats N per-component overrides — fewer surfaces for drift. Worth confirming #ptCheckBtn/#ptGenBtn adopt the shared class in fix(#1719): contrast root causes — active-btn / skew-badge / role-swatch / status-green #1720 or stay as one-off violations after that merge.

Fix path: subsumed by PR #1720. After merge, drop both prefix-tool entries from tests/a11y-allowlist.yaml and rerun node test-a11y-axe-1668.js. Effort: S.

Dup check: dup of #1719 root cause P1. Should close on #1720 merge + allowlist removal.

Triage verdict: ready-to-fix (blocked on PR #1720)

[Kpa-clawbot]

Auto-fix chain dispatched (mirrors merged PRs #1722/#1723/#1730/#1731). Allowlist-deletion only; depends on PR #1720 root-cause fix already in master.

[Kpa-clawbot]

Auto-fix opened as PR #1736. The axe gate on /analytics?tab=prefix-tool reports net=0 on all 4 viewports — the fix works.

CI is RED but the failure is unrelated: test-issue-1630-reach-mobile-e2e.js ("no repeater with reach links found in fixture") is also failing on master (run 27637454126). Not auto-merging; needs operator decision on whether to merge anyway or wait for the fixture bug to be fixed first.