css: fix color(a98-rgb), srgb-linear relative colors and color-mix(in xyz-d50)

[robobun]

Problem

• color(a98-rgb 1 0 0) never parses: bun build emits no fallback for it and Bun.color("color(a98-rgb 1 0 0)", "css") returns null. Cause: the second color space match in parse_predefined_relative (src/css/values/color.rs:2356) spells the ident a99-rgb.
• color(from <color> srgb-linear r g b) never parses. SRGBLinear declares r as an angle channel (color.rs:1783), so the r keyword is rejected where a number is expected.
• color-mix(in xyz-d50, ...) interpolates in xyz-d65 (color.rs:2462). It returns color(xyz ...), and the d50 to d65 matrix turns a none channel of an xyz-d50 operand into 0 before the mix.

Fix

• a99-rgb becomes a98-rgb. r of SRGBLinear becomes a percentage channel like g and b. The XyzD50 arm of parse_color_mix interpolates in XYZd50, a type that already existed unused.
• Correct because lightningcss, which this parser ports, does all three. All three lines came from the original color.zig with "(sic)" comments.
• Nothing else reads the changed values: the ident only reaches this match, CHANNEL_TYPES is only read by RelativeComponentParser, and the xyz-d50 arm is only reached by color-mix(in xyz-d50, ...).
• Verified: test/js/bun/css/css.test.ts ports the two lightningcss 1.30.2 test loops that cover these spaces, test_relative_color over the five RGB-like spaces and test_color_mix over the XYZ spaces, plus the fallback and Bun.color() cases. 174 cases in css.test.ts and 9 in color.test.ts fail before. Also test/bundler/css/ and the other css suites.

Background

• color() (CSS Color 4) takes a predefined color space ident and three channels. parse_predefined_relative matches the ident twice: once to convert an optional from origin into the target space, once to build the PredefinedColor.
• In the relative form, color(from <origin> <space> r g b), a channel can be a keyword that names an origin channel. RelativeComponentParser resolves it by name and by declared channel type.
• color-mix(in <space>, a, b) converts both operands into the named space, fills none channels from the other operand, and interpolates there. xyz-d50 and xyz-d65 are XYZ under two white points.
• A value that fails to parse is kept as an unparsed token list and printed back. That is why the first two bugs look like missing fallbacks, not errors.

Notes

Repro without the test suite, on bun 1.4.0 and main:

$ printf 'a{color:color(a98-rgb 1 0 0)}\nb{color:color(from #c86432 srgb-linear r g b)}\nc{color:color-mix(in xyz-d50,color(xyz-d50 none .2 .3),color(xyz-d50 .3 .2 .1))}\n' > x.css && bun build --minify x.css
a{color:color(a98-rgb 1 0 0)}b{color:color(from #c86432 srgb-linear r g b)}c{color:#3e8788;color:color(display-p3 .319112 .523724 .529618);color:color(xyz .151353 .201952 .263819)}

a and b pass through unparsed. c is folded to the wrong color: the none channel became 0 on the way through xyz-d65. lightningcss gives color(xyz-d50 .3 .2 .2) for c. With this PR:

a{color:#ff6251;color:color(display-p3 1.0633 .238564 .167582);color:color(a98-rgb 1 0 0)}b{color:#c86432;color:color(display-p3 .733816 .413298 .243042);color:color(srgb-linear .577581 .127438 .031896)}c{color:#bf578b;color:color(display-p3 .696946 .366074 .536818);color:color(xyz-d50 .3 .2 .2)}

Why the angle type could never have mattered before: CHANNEL_TYPES is only consumed by RelativeComponentParser, and its callers for predefined spaces only ever ask for number or percentage channels. So r declared as an angle matched nothing. The conversion code, serialization and fallback logic for A98 and srgb-linear were already in place and are unchanged.

Tests. The two upstream loops are ported as data tables with {} for the color space, the rows copied from lightningcss 1.30.2 src/lib.rs. test_relative_color: 68 rows over srgb, srgb-linear, a98-rgb, rec2020, prophoto-rgb (340 cases, the expected literal normalized through the printer like the upstream test() helper). test_color_mix: 30 rows over xyz, xyz-d50, xyz-d65 (90 cases). Every row was also checked against the lightningcss 1.30.2 binary. The upstream color-mix loop also runs over srgb-linear. Those rows are left out: 8 of them mix none or out-of-range channels and hit the inverted converted_* flags in CssColor::interpolate, which #38508 fixes. The rest of css.test.ts: every predefined space in the absolute and relative form, a98-rgb fallbacks per target (chrome: 90, chrome: 87 + safari: 14, chrome: 111 which gets none), the alpha slot and light-dark() origins, cross-space origins into and out of a98-rgb and srgb-linear, a99-rgb staying unparsed, and sRGB operands mixed in xyz-d50. color.test.ts: the same through Bun.color(), plus the a98-rgb to xyz conversion (563/256 power curve) and percentage channels.

The rest of the upstream color corpus (test_color, the other loops of test_relative_color and test_color_mix) is not in the tree: the 2024 port of test_color was removed in #16486 and the other two were never ported. Porting them is separate work, since many of their cases depend on other open color fixes.

On the released bun: 174 of the css.test.ts cases fail (68 a98-rgb and 48 srgb-linear rows of the relative loop, all 30 xyz-d50 rows of the color-mix loop, and the targeted cases), 9 in color.test.ts. The srgb, rec2020, prophoto-rgb, xyz and xyz-d65 rows pass before and after.

#40725 fixed the a98-rgb part alone. It is closed in favor of this PR. Its cases that were not already here (the chrome: 111 target, the a98-rgb gamma conversion, percentage channels through Bun.color()) are folded in (c4b9e4d).

docs/bundler/css.mdx already documents the a98-rgb fallback this makes work. Its two hex values are corrected to what bun build emits for that input. The old hex values were not produced by any version. With the current default browser targets (Safari 14) bun build also emits a display-p3 intermediate for the a98-rgb color. The example does not show it: it depends on the default targets, which #40369 changes.

Cross-reference: #38488 makes Bun.color() convert color() values for the non-css output formats. Its round trip table covers 7 of the 9 space idents because a98-rgb and the srgb-linear relative form only parse with this PR. The two PRs touch different lines and merge in either order. Whichever lands second should add the a98-rgb and srgb-linear rows to that table.

Suites run with the debug build after the rebase onto d578a8c: test/js/bun/css/css.test.ts (1657 pass, 67 skip), test/js/bun/css/color.test.ts (1038 pass, 1 skip), test/bundler/css/ (235 pass), test/js/bun/css/css-loader.test.ts, test/js/bun/css/doesnt_crash.test.ts, and the css regression tests under test/regression/issue/ (11 pass).

[robobun]

^{Updated 7:30 PM PT - Aug 28th, 2026}

❌ @robobun, your commit 4715a4f has 2 failures in Build #108091 (All Failures):

• test/js/web/url/url.test.ts - code 1: TypeError: Invalid URL on 🍎 any x64
• step failed outside runner - exit 1 on 🍎 any aarch64 - test-bun

---

🧪   To try this PR locally:

bunx bun-pr 38487

That installs a local version of the PR into your bun-38487 executable, so you can run:

bun-38487 --bun

[robobun]

Reproduced on bun 1.4.0 and current main. USE_SYSTEM_BUN=1 bun test test/js/bun/css/css.test.ts -t 'color()' / -t 'color-mix()': 27 + 6 failures, all a98-rgb / a99-rgb / srgb-linear / xyz-d50; color.test.ts -t 'predefined color spaces': 7. Repro without the test suite:

$ printf 'a{color:color(a98-rgb 1 0 0)}\nb{color:color(from #c86432 srgb-linear r g b)}\nc{color:color-mix(in xyz-d50,color(xyz-d50 none .2 .3),color(xyz-d50 .3 .2 .1))}\n' > x.css && bun build --minify x.css
a{color:color(a98-rgb 1 0 0)}b{color:color(from #c86432 srgb-linear r g b)}c{color:#3e8788;color:color(display-p3 .319112 .523724 .529618);color:color(xyz .151353 .201952 .263819)}

a and b are passed through unparsed (no fallbacks, no folding); c is folded to the wrong color (the none channel became 0 on the way through xyz-d65).

With this PR (byte-identical to lightningcss 1.30.2 given the same browser targets):

a{color:#ff6251;color:color(display-p3 1.0633 .238564 .167582);color:color(a98-rgb 1 0 0)}b{color:#c86432;color:color(display-p3 .733816 .413298 .243042);color:color(srgb-linear .577581 .127438 .031896)}c{color:#bf578b;color:color(display-p3 .696946 .366074 .536818);color:color(xyz-d50 .3 .2 .2)}

Fix: #38487 (this PR).

[coderabbitai]

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• docs/bundler/css.mdx
• src/css/values/color.rs
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---

Walkthrough

Changes

The CSS color implementation now uses correct srgb-linear metadata, accepts a98-rgb, and interpolates xyz-d50 with XYZd50. Tests cover parsing, conversions, serialization, color mixing, and fallback documentation.

CSS color corrections

Layer / File(s)	Summary
Color parsing and conversion src/css/values/color.rs, test/js/bun/css/color.test.ts, test/js/bun/css/css.test.ts, docs/bundler/css.mdx	Corrects srgb-linear channel metadata and A98 RGB parsing. Tests cover predefined spaces, relative colors, conversions, serialization, and documented fallback values.
XYZ color-mix interpolation src/css/values/color.rs, test/js/bun/css/color.test.ts, test/js/bun/css/css.test.ts	Uses XYZd50 for xyz-d50 interpolation. Tests cover XYZ variants, weighting, alpha compositing, missing channels, out-of-range values, and RGB conversion.

Suggested reviewers: alii, jarred-sumner

Merge Risk: ⚪ Minimal · up to 4715a

This PR corrects parsing and color-mixing behavior for several CSS color spaces and adds regression coverage; no actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly summarizes all three primary fixes: a98-rgb parsing, srgb-linear relative colors, and xyz-d50 color-mix interpolation.
Description check	✅ Passed	The description provides detailed problem, fix, background, verification, test coverage, and related-issue information. It does not use the exact template headings, but it fully covers the required co…

Full details: Description check

Explanation

The description provides detailed problem, fix, background, verification, test coverage, and related-issue information. It does not use the exact template headings, but it fully covers the required content.

---

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[claude]

LGTM — two obvious typo fixes (a99-rgb→a98-rgb, CT_ANG→CT_PCT) with thorough test coverage against lightningcss output. The inline nit about the remaining (sic) at color.rs:2450 is worth a follow-up but doesn't block; it's pre-existing and in a different code path (color-mix interpolation, not color() parsing).

Extended reasoning...

Overview

Two one-token corrections in src/css/values/color.rs: the predefined-colorspace match arm b"a99-rgb" becomes b"a98-rgb", and SRGBLinear's r channel type changes from CT_ANG to CT_PCT. Both lines were annotated (sic) — kept for behavioral compatibility from the original Zig port; this PR corrects them and deletes the markers. New tests in css.test.ts and color.test.ts cover every predefined color space in absolute and relative form, a98-rgb fallback generation with browser targets, a98-rgb as a relative/color-mix origin, and srgb-linear relative colors referencing r.

Security risks

None. Pure CSS value parsing; no untrusted-length arithmetic, allocation, or I/O touched.

Level of scrutiny

Low. The change is two literal typo fixes whose correct values are unambiguous (CSS Color 4 spec spells it a98-rgb; every other RGB colorspace in the file uses CT_PCT for all three channels; lightningcss — the reference implementation — accepts both forms). The PR description traces both bugs to their Zig-port origin and confirms nothing else reads either value. Tests assert exact lightningcss 1.30.2 output and were verified to fail on the unfixed build (20 + 5 failures) per the robobun repro comment.

Other factors

The one finding is a nit: a third (sic) marker remains at color.rs:2450 (color-mix(in xyz-d50) interpolating in XYZd65). It's the same marker pattern in the same file, so REVIEW.md's "fix the whole class" guidance applies — but it's a different function (parse_color_mix vs parse_predefined_relative), a different mechanism (interpolation white-point vs ident matching), and pre-existing behavior this PR doesn't touch. Reasonable to fold in or leave for a follow-up; either way it doesn't affect the correctness of what's changed here. The other (sic) markers in length.rs/image.rs/ident.rs are clearly out of scope for a color-parsing PR.

[robobun]

The srgb-linear part of this PR is the same change as main...farm/d1dc9b63/css-srgb-linear-relative-color (identical types = (CT_PCT, CT_PCT, CT_PCT) edit), so that branch will not be opened as a PR. It has three srgb-linear cases that are not in this PR's tests, in case they are worth folding in: the alpha slot referencing a channel (color(from red srgb-linear r g b / r)), a light-dark() origin (color(from light-dark(red, blue) srgb-linear r g b), which goes through the second parse_predefined_relative call), and a prefix_test with chrome: 90 showing the srgb-linear relative form now gets the color: red / color: #bc0000 fallbacks.

[claude]

LGTM — the follow-up commit addresses the earlier note: color-mix(in xyz-d50, ...) now interpolates in XYZd50, and there are no (sic) markers left in color.rs.

What was reviewed:

• The three one-identifier fixes (a99-rgb→a98-rgb, SRGBLinear r channel CT_ANG→CT_PCT, XyzD50 interpolate XYZd65→XYZd50) — each now matches its siblings in the same match/macro block and lightningcss.
• New tests cover every predefined space in absolute and relative form, a98-rgb fallback emission, srgb-linear r keyword resolution, and color-mix(in xyz-d50) vs xyz-d65 — expected values are lightningcss 1.30.2 output.
• Grepped color.rs for remaining (sic)/behavioral compatibility markers — none.

Extended reasoning...

Overview

Three one-identifier corrections in src/css/values/color.rs, each removing a (sic) — kept for behavioral compatibility comment that had preserved a typo carried over from the original Zig implementation: (1) the b"a99-rgb" match arm in parse_predefined_relative becomes b"a98-rgb", (2) SRGBLinear's r channel type becomes CT_PCT to match g/b and every other RGB space in the file, and (3) ColorSpaceName::XyzD50 in parse_color_mix now dispatches to interpolate::<XYZd50> instead of XYZd65. Tests are added in test/js/bun/css/css.test.ts and test/js/bun/css/color.test.ts.

The third fix was added in a follow-up commit (a4b1afde) after my earlier review flagged it as the remaining same-class site; that feedback is now fully addressed, and a grep confirms no (sic) markers remain in the file.

Security risks

None. This is CSS color-space ident matching and channel-type metadata. The changed values are compile-time constants; no user input reaches new code paths, no allocation or bounds logic changes, and parse failures still fall through to the existing unparsed-token-stream path.

Level of scrutiny

Low-to-medium. Each source change is a single identifier substituted for the value every neighboring arm already uses, and each is validated against the reference implementation (lightningcss 1.30.2, per the PR description and robobun's byte-identical repro). The surrounding conversion, serialization, and fallback machinery for A98/SRGBLinear/XYZd50 already existed and is unchanged. The blast radius of being wrong is that a rarely-used CSS color form is folded to a slightly wrong value — not a crash, hang, or memory issue.

Other factors

Test coverage is thorough per REVIEW.md's variant-matrix guidance: the new color() block iterates every predefined space in both absolute and relative form (so a future regression in any sibling arm is caught), and there are targeted tests for a98-rgb as a relative-color origin/target, a98-rgb fallback emission under browser targets, srgb-linear relative colors referencing r in each channel position, and color-mix(in xyz-d50) producing xyz-d50 output distinct from xyz-d65. Expected values are stated to be lightningcss output, and the PR description confirms the new tests fail on the unfixed build (20 + 5 failures) and pass with the fix along with the WPT and regression suites. Tests use test.each, exact toBe assertions, and follow the existing minify_test/prefix_test conventions in the file.

[robobun]

Folded those in (a35e109): the alpha slot referencing a channel (for both srgb-linear and a98-rgb), a light-dark() origin for both spaces (the second parse_predefined_relative call), and the two chrome: 90 fallback cases for the srgb-linear relative form. All six fail on the unfixed build; expected values are lightningcss output.

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@test/js/bun/css/css.test.ts`:
- Around line 7816-7819: Extend the color-mix minification tests around the
existing xyz-d50 case to cover none on the second operand and none on the same
channel in both operands. Assert that a single missing channel is filled from
the other operand, while a channel missing in both remains none rather than
becoming zero, using expected outputs verified against lightningcss 1.30.2.

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• src/css/values/color.rs
• test/js/bun/css/color.test.ts
• test/js/bun/css/css.test.ts

[claude]

LGTM — the xyz-d50 arm and the extra none/light-dark()/alpha-slot cases are all in now, and no (sic) markers remain in color.rs.

What was reviewed:

• The three source edits are single-token corrections (a99-rgb→a98-rgb, CT_ANG→CT_PCT on SRGBLinear's r, XYZd65→XYZd50 in the XyzD50 color-mix arm) matching lightningcss.
• Confirmed the first a98-rgb match at color.rs:2325 was already correct, XYZd50 already implements the interpolation trait bounds and Into<PredefinedColor>, and CHANNEL_TYPES is only read by RelativeComponentParser — no other consumers of the changed values.
• Tests cover both entry points (bundler minify/prefix and Bun.color()), every predefined space in absolute and relative form, fallbacks with targets, and the none-on-either/both-operand xyz-d50 cases; expected strings are lightningcss 1.30.2 output.

Extended reasoning...

Overview

Three one-token corrections in src/css/values/color.rs, each removing a (sic) — kept for behavioral compatibility marker that documented a known-wrong value carried over from the original color.zig port:

• parse_predefined_relative's second colorspace match: b"a99-rgb" → b"a98-rgb" (line 2345). The first match at line 2325 already said a98-rgb, so the from conversion worked but the result-construction arm was unreachable.
• SRGBLinear's r channel type: CT_ANG → CT_PCT (line 1770). Every other RGB space in the file (SRGB, P3, A98, ProPhoto, Rec2020) declares all three channels CT_PCT; the angle type made the r keyword unresolvable in relative-color positions that expect number/percentage.
• parse_color_mix's ColorSpaceName::XyzD50 arm: interpolate::<XYZd65> → interpolate::<XYZd50> (line 2451). XYZd50 was already fully wired for interpolation (From/Into lattice, into_css, PredefinedColor::XyzD50), just unused by this arm.

Roughly 230 lines of new tests across test/js/bun/css/css.test.ts (bundler minify_test/prefix_test) and test/js/bun/css/color.test.ts (Bun.color()), with expected values taken from lightningcss 1.30.2.

Security risks

None. This is CSS color parsing/serialization; no filesystem, network, auth, or external-input handling beyond a color string that already flows through the existing parser. The changes narrow no validation and add no unsafe code.

Level of scrutiny

Low-to-medium. Each edit is a single identifier that was explicitly commented as wrong; the correct value is unambiguous (spec + lightningcss reference). I verified: the first a98-rgb match was already correct so this only fixes the second; XYZd50 already has impl From<XYZd50> for PredefinedColor and the full From lattice, so interpolate::<XYZd50> compiles and serializes as color(xyz-d50 ...); CHANNEL_TYPES is consumed only by RelativeComponentParser, whose predefined-space callers request number/percentage channels, so the old CT_ANG could never have matched anything and switching to CT_PCT cannot regress a working case. Grepping confirms no (sic)/behavioral compatibility markers remain in color.rs (the ones in length.rs are noted as tracked in #38489).

Other factors

My earlier review comment asking to fold in the third (sic) site (the xyz-d50 color-mix arm) was addressed in a4b1afd, and the follow-up requests (alpha-slot referencing a channel, light-dark() origin, chrome:90 fallback for srgb-linear relative, symmetric none on second/both operands) landed in a35e109 and fa22f74. All inline threads are resolved. Test coverage hits both the CLI/bundler path and the JS API path per REVIEW.md's variant-matrix guidance, and the PR description states the new cases fail on the unfixed build and pass with the fix. No CODEOWNERS cover src/css/. The robobun CI-failure comment references an earlier commit (a4b1afd), not the current tip.

[claude]

LGTM — the xyz-d50 fix I flagged earlier is in, and no (sic) markers remain in color.rs.

What was reviewed:

• The three source edits each make one value match its siblings and lightningcss: b"a98-rgb" in the second predefined match, CT_PCT for SRGBLinear's r, interpolate::<XYZd50> for the XyzD50 arm.
• Test coverage spans both entry points (bundler via css.test.ts, Bun.color() via color.test.ts), every predefined space in absolute and relative form, a98-rgb fallbacks/origins, srgb-linear r in every slot including alpha, and color-mix(in xyz-d50) with none on either/both operands; a99-rgb is pinned as rejected.
• Docs change replaces the previously-unreachable a98-rgb fallback example with the actual bundler output (now that a98-rgb parses, the display-p3 intermediate appears for Safari 14 targets).

Extended reasoning...

Overview

Three one-identifier fixes in src/css/values/color.rs correcting typos carried over from the original color.zig port, each previously annotated with a (sic) — kept for behavioral compatibility marker: (1) b"a99-rgb" → b"a98-rgb" in the second colorspace match of parse_predefined_relative, so color(a98-rgb ...) parses; (2) CT_ANG → CT_PCT for SRGBLinear's r channel type, so color(from ... srgb-linear r g b) resolves the r keyword; (3) interpolate::<XYZd65> → interpolate::<XYZd50> for the ColorSpaceName::XyzD50 arm of parse_color_mix, so color-mix(in xyz-d50, ...) interpolates in and yields xyz-d50 (and none channels are filled from the other operand rather than zeroed by the D65 conversion). Each fix makes the value match every sibling in the same table/match and match lightningcss, which this parser ports. docs/bundler/css.mdx updates the color() fallback example with the actual bundler output. ~230 lines of new tests across css.test.ts and color.test.ts.

Security risks

None. Pure CSS value parsing/serialization; no I/O, no allocation-shape changes, no user-controlled sizes. The changes narrow accepted input (a99-rgb is now rejected, pinned by a test) and route existing conversion machinery through a type that was already fully wired for interpolation.

Level of scrutiny

Low-to-moderate. The source diff is three one-token corrections, each replacing a value explicitly marked as wrong-but-kept with the value every neighboring line and the reference implementation use. Verified in the checkout that no (sic)/behavioral compatibility markers remain in color.rs, that both a98-rgb match sites (lines 2325 and 2345) now agree, and that the XyzD50 arm at line 2451 uses XYZd50. The A98 conversion matrices, XYZd50 colorspace definition, and serialization paths were already in place and are unchanged.

Other factors

My earlier review flagged the third (sic) site (xyz-d50); it was folded in with tests in a4b1afd, and the author noted the none-channel behavior difference it uncovered. CodeRabbit's request for symmetric none cases was addressed in fa22f74. The extra srgb-linear cases (alpha slot, light-dark() origin, chrome-90 fallback) from the parallel branch were folded in at a35e109. All review threads are resolved. Test coverage hits both API surfaces (bundler minify/prefix and Bun.color()), every predefined space, and the specific none-fill semantics the xyz-d50 fix changes; expected values are stated to be byte-identical to lightningcss 1.30.2.

[robobun]

Cross-reference: #38488 makes Bun.color() convert color() values for the non-css output formats (Bun.color("color(srgb 1 0 0)", "hex") currently returns the input string). Its round trip table in color.test.ts (color(from #336699 <space> ...) -> #336699 for hex / {rgb}) covers 7 of the 9 space idents because a98-rgb and the srgb-linear relative form only parse with this PR. The two PRs touch different lines of color.rs and different regions of color.test.ts, so they merge in either order; whichever lands second should add the a98-rgb and srgb-linear rows to that table.

[claude]

LGTM — the earlier note about the third (sic) marker (color-mix(in xyz-d50) interpolating in D65) is now addressed, and no (sic)/a99 markers remain in color.rs.

What was reviewed:

• The three color.rs value corrections (a99-rgb→a98-rgb, CT_ANG→CT_PCT for srgb-linear r, XYZd65→XYZd50 for the xyz-d50 mix arm) — XYZd50 is already in the Interpolate bound set with into_css wired to serialize as color(xyz-d50 …).
• New tests in css.test.ts/color.test.ts — they use the existing minify_test/prefix_test/test.each/expectChannels helpers, cover absolute/relative/none/alpha/light-dark/target-fallback variants, and pin that a99-rgb is now unknown.
• The docs example update and the newest commit's added cases (percentage channels, chrome≥111 no-fallback, a98→xyz gamma check).

Extended reasoning...

Overview

Three one-token corrections in src/css/values/color.rs, each deleting a pre-existing "(sic) — kept for behavioral compatibility" comment: the predefined-color match arm now spells a98-rgb instead of a99-rgb, SRGBLinear's r channel type is CT_PCT instead of CT_ANG, and the XyzD50 arm of parse_color_mix interpolates via XYZd50 instead of XYZd65. Test coverage lands in the existing test/js/bun/css/css.test.ts and test/js/bun/css/color.test.ts files, and docs/bundler/css.mdx updates its fallback example to what the bundler now emits. Grepping the file confirms all three (sic) markers are gone and no a99 string remains under src/.

Security risks

None. This is CSS color-space parsing/interpolation — no I/O, auth, allocation sizing, or FFI is touched. The changed lines swap constants inside existing match arms; control flow is unchanged.

Level of scrutiny

Low-to-moderate. The source diff is three literal-value fixes that align this port with its reference implementation (lightningcss), and the PR description states the asserted outputs are byte-identical to lightningcss 1.30.2. XYZd50 is already threaded through the Interpolate trait bounds (lines ~189/206), has into_css mapping to PredefinedColor::XyzD50, and has the full From lattice, so interpolate::<XYZd50> was already sound to call. The test additions follow the file's established helpers (minify_test, prefix_test, indoc, test.each, same/expectChannels) with no timing, network, or port use.

Other factors

My earlier inline comment asked for the third (sic) site (the xyz-d50 mix arm) to be folded in — commit 7284504c did that, with none-channel and alpha coverage added afterward. The only third-party review thread (coderabbitai on css.test.ts) is resolved by a non-author, and there are no CHANGES_REQUESTED reviews. CODEOWNERS covers none of the touched paths. The one commit since the last review round (c4b9e4de) is test-only: percentage channels via Bun.color, a chrome≥111 no-fallback case, and an a98→xyz gamma/matrix check citing the CSS Color 4 conversion tables. Exit reason was dry_streak.

[coderabbitai]

Note

GitHub couldn't provide a complete incremental comparison for this pull request, so CodeRabbit is performing a full review instead. This review may take a little longer.

[robobun]

The diff is ready for review. Three CI runs failed only on things the change does not touch: a pre-existing url.test.ts ICU failure (reported for triage), per-lane flakes that passed on retry, and one artifact download timeout on a darwin agent. All CSS tests pass on every lane that ran them.

[claude]

LGTM — the three production-code changes are one-line corrections of explicitly (sic)-annotated port typos, and the newly ported lightningcss test_relative_color/test_color_mix loops give them full coverage.

Checked: no (sic) markers remain in color.rs and no other a99-rgb/XYZd65-for-D50 sites exist; the srgb-linear channel-type tuple now matches every other RGB-like space; the docs example block updates both hex fallbacks (display-p3 and a98-rgb) to actual bundler output rather than only the a98-rgb one; the new test loops use the existing minify_test/prefix_test/test.each helpers with no timing waits, ports, or network.

Extended reasoning...

Overview

The PR touches four files. The production change in src/css/values/color.rs is three one-line fixes, each removing a comment that literally read "(sic) — kept for behavioral compatibility": SRGBLinear's r channel type goes from CT_ANG to CT_PCT (matching g and b), the second color-space match arm in parse_predefined_relative goes from b"a99-rgb" to b"a98-rgb", and the ColorSpaceName::XyzD50 arm of parse_color_mix interpolates via XYZd50 instead of XYZd65. docs/bundler/css.mdx updates two hex fallback values in an example to match what the bundler now emits. The remaining ~450 added lines are tests in the two existing CSS test files: a describe("color() predefined color spaces") block in color.test.ts exercising every predefined space through Bun.color(), and in css.test.ts a port of lightningcss 1.30.2's test_relative_color and test_color_mix loops over the RGB-like/XYZ predefined spaces plus targeted a98-rgb, srgb-linear, and color-mix(in xyz-d50) cases with browser-target fallback assertions.

Security risks

None. This is CSS color-value parsing and serialization — pure numeric/string transformation with no I/O, filesystem, network, credentials, or shell interaction. The changed match arms and channel-type constant are only reachable from the CSS parser's color() and color-mix() handling; failing to parse falls back to the pre-existing unparsed-token-stream path. No new unsafe, no allocation changes, no external-input length arithmetic.

Level of scrutiny

Low-to-moderate. The native changes are mechanical corrections of self-documented port typos, each verifiable against a single line of the reference implementation (lightningcss) and the CSS Color 4 spec. I confirmed no (sic) markers remain in the file and no other occurrence of the misspelling or the D65-for-D50 substitution exists (REVIEW.md's "fix the whole class"). The first match on the color-space ident in parse_predefined_relative (line 2333) already spelled a98-rgb correctly, so only the second match needed fixing. The test additions live in the existing module test files, use the file's established minify_test/prefix_test/indoc/test.each helpers, and have no setTimeout/sleep, hardcoded ports, network access, or per-test timeouts.

Other factors

Since the last automated review, commit 4715a4f landed the lightningcss test-loop port (~230 net test lines) and the docs hex corrections — a substantive addition worth acknowledging. The earlier concern this bot raised (the third (sic) for xyz-d50) was folded in and is now covered by both the color.test.ts and css.test.ts color-mix cases including none-channel fill-in. No CODEOWNERS entry covers the changed paths, there are no outstanding CHANGES_REQUESTED reviews, and the hunt exited on dry_streak. The PR description's evidence block shows 42 of the new assertions fail on main and pass on the debug build, satisfying the USE_SYSTEM_BUN=1 validity check.