An extremely fast CSS parser, transformer, bundler, and minifier written in Rust.
This report summarizes scanner evidence for parcel-bundler/lightningcss, a Rust project with 7,723 GitHub stars. SynthScan examined 143,826 lines of code across 212 source files, recording 156 pattern matches distributed across 4 syntactic categories. The legacy adjusted pattern signal is 1.1 (Low pattern signal); it is not an authorship estimate.
Use the findings to ask whether maintainers can explain intent, verify dependencies, simplify unnecessary scaffolding, and focus review effort. Risk Payload v1 adds ownership, supply-chain, over-engineering, and review-effort vectors when available. These are prompts for human verification, not probabilities, security findings, or measured maintenance costs.
Use each vector to guide manual verification of the underlying findings.
Payload schema: 1.0.0 · Engine: 2.0.0 · Scoring: heuristic-density-v1 · Scan date: 2026-10-31.
Can maintainers explain intent, assumptions, and trade-offs? 152 finding(s).
Are imports declared and package/API names verified? 4 finding(s).
Are wrappers, guards, and repeated structures necessary? 2 finding(s).
Which changes need focused human review? 156 finding(s).
This chart tracks the legacy adjusted pattern score across scan runs. Changes can reflect source changes, scan coverage, or detector/scoring versions; they do not measure AI adoption or prove that a team refactored code. Compare runs only when their scoring versions are compatible. The dashed line tracks the raw pattern-hit count.
Groups findings by configured severity weight. Severity is not a confidence estimate, security rating, or proof that a package is missing. Verify imports against the project's manifests and inspect each finding in its local design context.
This horizontal bar chart shows where configured pattern scores accumulate across directories. Treat the bars as locations to inspect, not as evidence of authorship or code quality. Use the file-level findings to decide whether a directory needs a focused ownership, dependency, complexity, or review check.
The scanner identified 156 distinct pattern matches across 4 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a detector match to inspect in context. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.
Reading the findings table: The Severity column indicates the configured finding weight (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — legacy comment-context matches receive a ×1.5 score weight. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier under the legacy scoring model.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | selectors/tree.rs | 121 | /// Returns whether this element matches `:empty`. | COMMENT |
| LOW | selectors/bloom.rs | 21 | /// A counting Bloom filter with parameterized storage to handle | COMMENT |
| LOW | selectors/bloom.rs | 41 | /// For reasonable assumptions (M large, kN large, which should both | COMMENT |
| LOW | selectors/parser.rs | 101 | COMMENT | |
| LOW | selectors/parser.rs | 581 | let result = parse_selector(parser, input, &mut child_state, NestingRequirement::None)?; | COMMENT |
| LOW | selectors/parser.rs | 701 | /// at the level of sequences of simple selectors separated by combinators. Most | COMMENT |
| LOW | selectors/parser.rs | 941 | /// or other impls of `Visit` as appropriate based on the fields of `Self`. | COMMENT |
| LOW | selectors/parser.rs | 1161 | /// combinator for this, we will need to fix up the way hashes are computed | COMMENT |
| LOW | selectors/parser.rs | 1421 | /// Pseudo-classes | COMMENT |
| LOW | selectors/parser.rs | 1441 | /// The `::part` pseudo-element. | COMMENT |
| LOW | selectors/parser.rs | 1461 | /// The `:is` pseudo-class. | COMMENT |
| LOW | selectors/parser.rs | 1801 | impl<'i, Impl: SelectorImpl<'i>> ToCss for Selector<'i, Impl> { | COMMENT |
| LOW | selectors/parser.rs | 1821 | let mut combinators_exhausted = false; | COMMENT |
| LOW | selectors/parser.rs | 2721 | None => break, | COMMENT |
| LOW | selectors/parser.rs | 2741 | // except those it is explicitly defined to match. If a | COMMENT |
| LOW | selectors/parser.rs | 3501 | // specificity(0, 0, 1), | COMMENT |
| LOW | selectors/matching.rs | 21 | COMMENT | |
| LOW | selectors/matching.rs | 121 | /// NotMatchedAndRestartFromClosestDescendant | COMMENT |
| LOW | selectors/matching.rs | 141 | /// It is raised when | COMMENT |
| LOW | selectors/builder.rs | 1 | /* This Source Code Form is subject to the terms of the Mozilla Public | COMMENT |
| LOW | selectors/builder.rs | 21 | use crate::sink::Push; | COMMENT |
| LOW | selectors/context.rs | 21 | /// of simple selectors. | COMMENT |
| LOW | selectors/context.rs | 101 | /// Input with the bloom filter used to fast-reject selectors. | COMMENT |
| LOW | napi/src/threadsafe_function.rs | 41 | /// | COMMENT |
| LOW | napi/src/threadsafe_function.rs | 61 | /// | COMMENT |
| LOW | src/declaration.rs | 41 | #[cfg(feature = "visitor")] | COMMENT |
| LOW | src/selector.rs | 501 | TargetWithin, | COMMENT |
| LOW | src/selector.rs | 941 | SearchText, | COMMENT |
| LOW | src/selector.rs | 1441 | { | COMMENT |
| LOW | src/error.rs | 401 | /// A printer error. | COMMENT |
| LOW | src/targets.rs | 1 | //! Browser target options. | COMMENT |
| LOW | src/targets.rs | 21 | /// ``` | COMMENT |
| LOW | src/targets.rs | 61 | ) -> Result<Option<Browsers>, browserslist::Error> { | COMMENT |
| LOW | src/lib.rs | 1 | //! Lightning CSS is a CSS parser, transformer, and minifier based on the | COMMENT |
| LOW | src/lib.rs | 761 | ); | COMMENT |
| LOW | src/lib.rs | 13661 | // ".foo{transform:matrix(1.41421,1.41421,-1.16485,1.66358,100,200)}", | COMMENT |
| LOW | src/lib.rs | 13681 | // minify_test( | COMMENT |
| LOW | src/lib.rs | 15421 | // error_test( | COMMENT |
| LOW | src/bundler.rs | 1 | //! CSS bundling. | COMMENT |
| LOW | src/bundler.rs | 1881 | // @import "b.css" supports(foo: bar) (orientation: horizontal); | COMMENT |
| LOW | src/vendor_prefix.rs | 1 | //! Vendor prefixes. | COMMENT |
| LOW | src/media_query.rs | 261 | /// A [media query](https://drafts.csswg.org/mediaqueries/#media). | COMMENT |
| LOW | src/media_query.rs | 1221 | } | COMMENT |
| LOW | src/printer.rs | 21 | #[cfg_attr(docsrs, doc(cfg(feature = "sourcemap")))] | COMMENT |
| LOW | src/printer.rs | 41 | /// | COMMENT |
| LOW | src/dependencies.rs | 1 | //! Dependency analysis. | COMMENT |
| LOW | src/dependencies.rs | 121 | #[derive(Debug)] | COMMENT |
| LOW | src/css_modules.rs | 201 | /// A literal string segment. | COMMENT |
| LOW | src/stylesheet.rs | 21 | use parcel_sourcemap::SourceMap; | COMMENT |
| LOW | src/stylesheet.rs | 41 | /// // Parse a style sheet from a string. | COMMENT |
| LOW | src/stylesheet.rs | 81 | /// The source map URL extracted from the original style sheet. | COMMENT |
| LOW | src/stylesheet.rs | 101 | /// ids, and `@keyframe` names. The declarations of these will be removed. | COMMENT |
| LOW | src/stylesheet.rs | 341 | } | COMMENT |
| LOW | src/stylesheet.rs | 361 | /// | COMMENT |
| LOW | src/main.rs | 21 | ))] | COMMENT |
| LOW | src/main.rs | 41 | custom_media: bool, | COMMENT |
| LOW | src/traits.rs | 301 | COMMENT | |
| LOW | src/traits.rs | 321 | type Prelude; | COMMENT |
| LOW | src/parser.rs | 241 | /// A @container prelude. | COMMENT |
| LOW | src/visitor.rs | 1 | //! Visitors for traversing the values in a StyleSheet. | COMMENT |
| 89 more matches not shown… | ||||
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | node/ast.d.ts | 6972 | kind: "placeholder"; | CODE |
| LOW | src/selector.rs | 288 | "placeholder" => Placeholder(VendorPrefix::None), | CODE |
| LOW | src/selector.rs | 1243 | dest.write_str("placeholder") | CODE |
| LOW | src/lib.rs | 31376 | kind: ParserError::SelectorError(SelectorError::UnsupportedPseudoClass("placeholder".into())), | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | node/composeVisitors.js | 58 | function wrapCustomAndUnknownAtRule(k, f) { | CODE |
| LOW | node/composeVisitors.js | 125 | function extractObjectsOrFunctions(visitors, key) { | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | wpt/read-html.py | 80 | CODE |