Repository Analysis

gildas-lormeau/zip.js

JavaScript library to zip and unzip files supporting parallel compression, web streams, pluggable compression engines, zip64, split files, data encryption, and deflate64 decompression.

7.1 Low AI signal View on GitHub

Analysis Overview

This report presents the forensic synthetic code analysis of gildas-lormeau/zip.js, a JavaScript project with 3,881 GitHub stars. SynthScan v2.0 examined 70,531 lines of code across 603 source files, recording 491 pattern matches distributed across 4 syntactic categories. The overall adjusted score of 7.1 places this repository in the Low AI signal band.

The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).

7.1
Adjusted Score
7.1
Raw Score
100%
Time Factor
2026-08-28
Last Push
3.9K
Stars
JavaScript
Language
70.5K
Lines of Code
603
Files
491
Pattern Hits
2026-08-29
Scan Date
0.00
HC Hit Rate

What These Metrics Mean

Adjusted Score
Primary synthetic code indicator. Raw score normalised per 1,000 lines of code and multiplied by the temporal discount factor. This is the definitive comparative metric — use it to rank repositories by AI authorship density.
Raw Score
The unmodified sum of all severity-weighted, context-multiplied pattern match scores before temporal discounting. Reflects the absolute signal strength independent of when the repository was last active.
Time Factor
The temporal discount multiplier (0–100%) applied to the raw score. Repositories last updated before ChatGPT's launch (Nov 2022) receive a 5% factor. Full signal is only assigned to repositories active in the post-adoption era (Jan 2024+).
Pattern Hits
Total count of individual pattern matches across all files and categories. A high hit count with a low score may indicate a very large codebase with isolated AI snippets; a low count with a high score indicates dense, concentrated AI signatures.
HC Hit Rate
High+Critical pattern hits per file, averaged across the repository. This orthogonal signal catches repositories where a few files are densely packed with high-severity AI tells — a strong indicator even when the normalised score appears moderate due to codebase size.
Lines of Code / Files
Total lines and files analysed. The scanner examines 94 file extensions. These denominators are used to normalise the score, enabling fair comparison between repositories of vastly different sizes.

Score History

This chart maps the temporal evolution of the adjusted synthetic code score across successive scan runs. An upward trajectory indicates ongoing incorporation of AI-generated code or expanding LLM-assisted scaffolding; a stable or declining trajectory may reflect active human refactoring, code removal, or the adoption of stricter authorship policies. The dashed secondary line (right axis) independently tracks total raw pattern hit count, which can diverge from the normalised score when codebase size changes significantly between scans.

Severity Breakdown

Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.

CRITICAL 0HIGH 0MEDIUM 0LOW 491

Directory Score Breakdown

This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.

Pattern Findings

The scanner identified 491 distinct pattern matches across 4 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. 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 diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.

Fake / Example Data296 hits · 297 pts
SeverityFileLineSnippetContext
LOWindex.d.ts4290 * const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tinciduCOMMENT
LOWindex.d.ts4290 * const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tinciduCOMMENT
LOWtests/web-streams-polyfill-runner.js9const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/web-streams-polyfill-runner.js9const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-split-data.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-split-data.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-overlapping-entries.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-overlapping-entries.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-export-options.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-export-options.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-worker-error-before-start.js9const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-worker-error-before-start.js9const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-metadata-roundtrip.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-metadata-roundtrip.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-version-made-by.js4const TEXT_CONTENT = "Lorem ipsum dolor sit amet";CODE
LOWtests/all/test-version-made-by.js4const TEXT_CONTENT = "Lorem ipsum dolor sit amet";CODE
LOWtests/all/test-crypto-tampered.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-crypto-tampered.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-unzip-store.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-unzip-store.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-comments.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-comments.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-register-codec.js12const LOREM_PREFIX = "Lorem ipsum";CODE
LOWtests/all/test-fs-export-password.js11const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-fs-export-password.js11const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-entry-data-out-of-bounds.js26 await zipWriter.add("filename.txt", new zip.TextReader("Lorem ipsum"), { compressionMethod });CODE
LOWtests/all/test-fs-arraybuffer.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-arraybuffer.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-remove-entry.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-remove-entry.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-export-progress.js12const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-fs-export-progress.js12const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-local-extra-field.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-local-extra-field.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit.";CODE
LOWtests/all/test-last-access-date.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-last-access-date.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-malformed-zip.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-malformed-zip.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-passthrough-aes-crc32.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-passthrough-aes-crc32.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-remove.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-fs-remove.js3const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-compression-stream-fallback.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-compression-stream-fallback.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-http-reader-resource-changed.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut laborCODE
LOWtests/all/test-http-reader-resource-changed.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut laborCODE
LOWtests/all/test-split-zip-streams.js10const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-split-zip-streams.js10const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-zip64-crypto.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-zip64-crypto.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-zstd-codec.js11const EXPECTED_PREFIX = "Lorem ipsum dolor sit amet";CODE
LOWtests/all/test-zstd-codec.js11const EXPECTED_PREFIX = "Lorem ipsum dolor sit amet";CODE
LOWtests/all/test-worker-error.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-worker-error.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-zip64.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-zip64.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
LOWtests/all/test-external-assets.js33 const expectedText = "lorem ipsum dolor ".repeat(CONTENT_REPETITIONS);CODE
LOWtests/all/test-golden-output.js24 await zipWriter.add("text.txt", new zip.TextReader("Lorem ipsum dolor sit amet"), { comment: "entry comment" });CODE
LOWtests/all/test-golden-output.js24 await zipWriter.add("text.txt", new zip.TextReader("Lorem ipsum dolor sit amet"), { comment: "entry comment" });CODE
LOWtests/all/test-foreign-streams.js5const TEXT_CONTENT = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt CODE
236 more matches not shown…
Hyper-Verbose Identifiers183 hits · 188 pts
SeverityFileLineSnippetContext
LOWrollup.config.js30function checkMangledPropertyNames() {CODE
LOWindex.d.ts283export function getSupportedCompressionMethods(): SupportedCompressionMethod[];CODE
LOWindex.d.ts772export function createSyncAccessHandleTempStream(options?: OPFSTempStreamOptions): () => TempStream;CODE
LOWtests/all/test-filename-validation.js28async function normalizationRepairsRejectedNames() {CODE
LOWtests/all/test-filename-validation.js45async function normalizationRunsAfterDecodingAndBeforeValidation() {CODE
LOWtests/all/test-filename-validation.js65async function normalizationDetectsCollisions() {CODE
LOWtests/all/test-filename-validation.js79async function filesystemInheritsNormalization() {CODE
LOWtests/all/test-filename-validation.js98async function levelsRejectExpectedNames() {CODE
LOWtests/all/test-filename-validation.js116async function defaultLevelRejectsEscapingNames() {CODE
LOWtests/all/test-filename-validation.js122async function strictnessDrivesTheDefaultLevel() {CODE
LOWtests/all/test-filename-validation.js132async function filesystemDropsRedundantPathComponents() {CODE
LOWtests/all/test-empty-entry-data-descriptor.js25async function skipsTheDataDescriptorForKnownEmptyEntries() {CODE
LOWtests/all/test-empty-entry-data-descriptor.js34async function keepsTheDataDescriptorElsewhere() {CODE
LOWtests/all/test-unix-extra-field-layout.js69async function checkInfoZipFieldSingleId() {CODE
LOWtests/all/test-register-codec.js105function checkRegisteredCodecURIStreams(expectStreams) {CODE
LOWtests/all/test-register-codec.js160async function checkWorkerCompressionOptions() {CODE
LOWtests/all/test-register-codec.js184async function checkDecompressionOptions() {CODE
LOWtests/all/test-register-codec.js243async function checkWorkerDecompressionOptions() {CODE
LOWtests/all/test-register-codec.js336async function checkEncryptedHighMethodRoundTrip() {CODE
LOWtests/all/test-fs-export-password.js31async function testReaderPasswordDecrypts(encryptedBlob) {CODE
LOWtests/all/test-fs-export-password.js41async function testTopLevelPasswordDoesNotDecrypt(encryptedBlob) {CODE
LOWtests/all/test-fs-export-password.js67async function testFileSystemHandlePasswords(encryptedBlob) {CODE
LOWtests/all/test-malformed-zip.js81function addCentralDirectoryExtraField(array, extraField, patchDirectoryRecord) {CODE
LOWtests/all/test-split-zip-strictness.js36async function readsASplitZipFileInStrictMode() {CODE
LOWtests/all/test-split-zip-strictness.js62async function acceptsTheMarkerAsTheArchiveStart(marker, description) {CODE
LOWtests/all/test-split-zip-strictness.js95async function extractsAnyOtherPrefixAsPrependedData(prefix) {CODE
LOWtests/all/test-http-reader-resource-changed.js123async function expectResourceChangedError(fetchFunction) {CODE
LOWtests/all/test-abort-buffered-flush-offset.js114function firstCentralDirectoryOffset(bytes) {CODE
LOWtests/all/test-abort-buffered-flush-offset.js124function endOfCentralDirectoryOffset(bytes) {CODE
LOWtests/all/test-writer-edge-cases.js52async function testDuplicateDirectoryName() {CODE
LOWtests/all/test-split-zip.js69async function testSpanningCentralDirectory(zip64) {CODE
LOWtests/all/test-passthrough-options.js27async function compressionMethodIsRequired() {CODE
LOWtests/all/test-passthrough-options.js44async function compressionMethodIsTakenFromTheWriterOptions() {CODE
LOWtests/all/test-passthrough-options.js52async function directoriesIgnorePassThrough() {CODE
LOWtests/all/test-passthrough-options.js82async function levelKeepsApplyingToTheOtherEntries() {CODE
LOWtests/all/test-passthrough-options.js120function getLocalCompressionMethod(zipData) {CODE
LOWtests/all/test-deprecated-check-signature.js26async function buildZipFileWithCorruptedData() {CODE
LOWtests/all/test-prevent-close.js85async function testEntriesConcatenatedIntoOneWritable() {CODE
LOWtests/all/test-option-validation.js124async function encryptionStrengthRejectsNonIntegers() {CODE
LOWtests/all/test-option-validation.js134async function strictnessRejectsUnknownValues() {CODE
LOWtests/all/test-option-validation.js144async function filenameValidationRejectsUnknownValues() {CODE
LOWtests/all/test-option-validation.js154async function maxAppendedDataSizeRejectsInvalidNumbers() {CODE
LOWtests/all/test-option-validation.js57async function levelRejectsValuesOutsideItsRange() {CODE
LOWtests/all/test-option-validation.js67async function numericStringsAreAccepted() {CODE
LOWtests/all/test-option-validation.js89async function levelAcceptsItsWholeRange() {CODE
LOWtests/all/test-option-validation.js101async function passwordRejectsOtherTypes() {CODE
LOWtests/all/test-option-validation.js110async function passwordKeepsAcceptingEmptyValues() {CODE
LOWtests/all/test-option-validation.js178async function msdosAttributesRejectOtherShapes() {CODE
LOWtests/all/test-option-validation.js188async function msdosAttributesKeepAcceptingValidValues() {CODE
LOWtests/all/test-option-validation.js208async function globalCommentRejectsOtherTypes() {CODE
LOWtests/all/test-option-validation.js237async function entryCommentRejectsOtherTypes() {CODE
LOWtests/all/test-option-validation.js253async function entryCommentKeepsAcceptingStrings() {CODE
LOWtests/all/test-option-validation.js281async function datesKeepAcceptingEmptyValues() {CODE
LOWtests/all/test-option-validation.js307async function extraFieldRejectsOtherShapes() {CODE
LOWtests/all/test-option-validation.js322async function extraFieldKeepsAcceptingValidMaps() {CODE
LOWtests/all/test-option-validation.js336async function functionOptionsRejectOtherValues() {CODE
LOWtests/all/test-option-validation.js352async function functionOptionsKeepAcceptingFalsyValues() {CODE
LOWtests/all/test-option-validation.js397async function signalKeepsAcceptingAbortSignals() {CODE
LOWtests/all/test-option-validation.js408async function signalAcceptsAnythingShapedLikeASignal() {CODE
LOWtests/all/test-option-validation.js424async function readerPasswordRejectsOtherTypes() {CODE
123 more matches not shown…
Over-Commented Block10 hits · 10 pts
SeverityFileLineSnippetContext
LOWtests/types/test-codec-types.ts1// Type-level test: the classes compressing and decompressing data must stay assignable wherever theCOMMENT
LOWtests/all/test-writer-backpressure.js1/* global ReadableStream, WritableStream, CountQueuingStrategy, setTimeout */COMMENT
LOWtests/all/test-writer-backpressure-worker.js1/* global ReadableStream, WritableStream, CountQueuingStrategy, setTimeout, btoa */COMMENT
LOWtests/api-symmetry/decisions.js1// The decisions taken about the symmetry between the read surface and the write surface.COMMENT
LOWtests/api-symmetry/mangling.js1// Audits the members of the public API against the two lists that decide whether minification keeps them.COMMENT
LOWtests/api-symmetry/shape.js1// Audits the agreement between the shapes declared in index.d.ts and the objects the library builds.COMMENT
LOWdocs/README.md41// Creates a BlobWriter object where the zip content will be written.COMMENT
LOWbenchmarks/bench-crc.js1// Write-path CRC strategy, native CompressionStream. Compares the two ways zip.js can obtain theCOMMENT
LOWbenchmarks/scan-bundle.sh1#!/usr/bin/env bashCOMMENT
LOWbenchmarks/bench-7z.js1// zip.js vs 7-Zip (CLI), disk-to-disk, for Deno and Bun (not Node — see bench.js for that harness).COMMENT
Overly Generic Function Names2 hits · 2 pts
SeverityFileLineSnippetContext
LOWtests/all/test-deprecated-check-signature.js57async function getData(zipFile, options) {CODE
LOWlib/core/zip-reader.js678 async function getData() {CODE