claude@clouddev1
65eab71439
Computing actual WCAG ratios surfaced two real accessibility defects in the shipped v0.2.0 light theme: tok_string (4.42:1) and tok_flag (3.15:1) fell below the 4.5:1 the scheme promises for normal text (NFR-5). Darken both to clear it with headroom (5.18 / 5.98). Also widen two dark-theme token pairs that were perceptually close despite distinct hex (hard to separate on good screens): tok_type and tok_function move from ΔE2000 ~14 to ~18-19 vs their neighbours. Add four gated tests in theme.rs: - all_text_colours_meet_wcag_aa_contrast: every text fg >= 4.5:1 on bg, both themes (the regression gate that would have caught this). - advanced_mode_border_meets_ui_contrast: 3:1 for the mode-alert border; plain border is decorative chrome, exempt. - delta_e_2000_matches_reference_vectors: validates the CIEDE2000 metric against Sharma et al. reference data. - syntax_token_colours_are_perceptually_distinct: ΔE2000 >= 15 for every token-class pair, both themes. Persist scripts/palette-preview.py: the true-colour swatch + contrast + ΔE2000 audit tool used to drive these changes (reads the live palette from theme.rs), for future palette work. Tests: 2513 passed / 0 failed / 1 ignored (was 2509; +4). clippy and fmt clean. Relates to NFR-5/NFR-7 (ADR-0057).