fix(web): bound OKLCH gamut mapping

[Lucenx9]

What Changed

Theme color gamut mapping now calculates its binary-search iteration count by subtracting base-2 logarithms instead of dividing chroma by the target resolution. This keeps the count finite for every finite OKLCH chroma accepted by the theme parser.

A focused regression imports a theme containing oklch(0.5 1e303 0), verifies that parsing preserves the magnitude, and checks the mapped sRGB result.

Verified with the 31-test themePalette suite, the web package typecheck, and focused lint and formatting checks.

Why

The previous chroma / resolution calculation could overflow to Infinity even when chroma itself was finite. That made the loop bound infinite and could hang the web or desktop renderer when an imported theme with extreme chroma was converted for the color editor.

The logarithm subtraction is algebraically equivalent for ordinary colors, preserves the existing chroma resolution, and avoids the overflowing intermediate value.

Checklist

• This PR is small and focused
• I explained what changed and why
• UI screenshots are not applicable
• UI motion video is not applicable

Made with GPT-5.6 using the Codex harness in T3 Code.

Note

Fix overflow in mapThemeOklchToSrgbGamut for extremely large OKLCH chroma values

The bisection step count in themePalette.ts previously computed log2(C / chromaResolution), which overflows to Infinity when C is extremely large (e.g. 1e303). This is fixed by computing log2(C) - log2(chromaResolution) instead, which avoids intermediate overflow while preserving the same effective resolution.

^{Macroscope summarized 335b00b.}

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Note

Low Risk
Localized numeric fix in theme color conversion with a targeted test; no auth, storage, or API surface changes.

Overview
Fixes a hang when imported themes contain OKLCH colors with astronomically large but finite chroma (e.g. oklch(0.5 1e303 0)).

mapThemeOklchToSrgbGamut now computes the bisection iteration count as log2(C) - log2(chromaResolution) instead of log2(C / chromaResolution). That avoids intermediate overflow to Infinity (which made the loop unbounded) while keeping the same effective resolution for normal colors.

A regression test parses extreme chroma through parseThemeFile, asserts the canonical OKLCH string is preserved, and checks themeColorToHex returns #b5005e.

^{Reviewed by Cursor Bugbot for commit 335b00b. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[macroscopeapp]

Approvability

Verdict: Approved 335b00b

This is a straightforward numerical bug fix that prevents overflow when processing extreme OKLCH chroma values. The change uses an equivalent mathematical formulation (log(a/b) = log(a) - log(b)) that avoids division overflow, with a test confirming the fix.

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