🤖 Headless UI for Virtualizing Large Element Lists in JS/TS, React, Solid, Vue and Svelte
This report presents the forensic synthetic code analysis of TanStack/virtual, a TypeScript project with 7,004 GitHub stars. SynthScan v2.0 examined 52,694 lines of code across 585 source files, recording 73 pattern matches distributed across 6 syntactic categories. The overall adjusted score of 2.9 places this repository in the Likely human-written 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).
Longitudinal tracking requires multiple scan runs. Once this repository is re-scanned after new commits land, this chart will visualise how the synthetic code signal evolves over time — enabling you to detect whether AI authorship is growing, stabilising, or being actively corrected by human engineers.
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.
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.
The scanner identified 73 distinct pattern matches across 6 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.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | packages/virtual-core/tests/index.test.ts | 514 | // ─── resizeItem / measurement cache invalidation ───────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 773 | // ─── elementsCache leak: disconnected node cleanup ─────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 943 | // ─── setOptions behavioral contract ────────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1085 | // ─── pending min pointer for measure storms ────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1158 | // ─── defaultRangeExtractor ─────────────────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1235 | // ─── Lazy fast path (lanes === 1) edge cases ───────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1426 | // ─── iOS momentum-safe scroll adjustments ─────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1591 | // ─── Phase 1: touch event distinction ──────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 1941 | // ─── Phase 2a: subpixel scrollTop reconciliation ───────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 2013 | // ─── Phase 2b: scrollTopMax elastic-overscroll clamp ───────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 2389 | // ─── scroll direction vs. self-write read-backs ───────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 2586 | // ─── end anchoring / chat-style reverse virtualization ────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 2953 | // ─── elementScroll / windowScroll public exports ───────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 3021 | // ─── observeElementOffset / observeWindowOffset ────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/index.test.ts | 3119 | // ─── Public-exports lockdown ───────────────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 25 | // ─── Exp 1: Cold-mount cost — getMeasurements with no measured items ───────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 61 | // ─── Layer 1: Map clone bug — resizeItem under measure storm ───────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 175 | // ─── Layer 2: setOptions per render ────────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 203 | // ─── Scroll loop: per-scroll-frame cost (calculateRange + memo machinery) ───── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 230 | // ─── Layer 6: defaultRangeExtractor ────────────────────────────────────────── | COMMENT |
| MEDIUM | packages/virtual-core/tests/bench.bench.ts | 247 | // ─── Multi-lane: cold-mount lane assignment (getFurthestMeasurement) ────────── | COMMENT |
| MEDIUM | packages/virtual-core/src/index.ts | 1207 | // ─── Fast path: single-lane lazy materialization ──────────────────── | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | examples/angular/infinite-scroll/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/dynamic/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/variable/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/sticky/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/fixed/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/table/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/window/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/padding/README.md | 9 | ## Code scaffolding | COMMENT |
| MEDIUM | examples/angular/smooth-scroll/README.md | 9 | ## Code scaffolding | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 13 | // Step 1: Expand A → should grow to ~160px | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 17 | // Step 2: Collapse A → back to ~36px | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 21 | // Step 3: Delete A | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 25 | // Step 4: Expand B → should grow to ~160px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 13 | // Step 1: Expand A → should grow to ~160px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 17 | // Step 2: Collapse A → back to ~36px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 21 | // Step 3: Delete A | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 25 | // Step 4: Expand B → should grow to ~160px | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 13 | // Step 1: Expand A → should grow to ~160px | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 17 | // Step 2: Collapse A → back to ~36px | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 21 | // Step 3: Delete A | COMMENT |
| LOW⚡ | …s/angular-virtual/e2e/app/test/measure-element.spec.ts | 25 | // Step 4: Expand B → should grow to ~160px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 13 | // Step 1: Expand A → should grow to ~160px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 17 | // Step 2: Collapse A → back to ~36px | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 21 | // Step 3: Delete A | COMMENT |
| LOW⚡ | …ges/react-virtual/e2e/app/test/measure-element.spec.ts | 25 | // Step 4: Expand B → should grow to ~160px | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | examples/svelte/infinite-scroll/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | examples/svelte/dynamic/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | examples/svelte/sticky/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | examples/svelte/fixed/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | examples/svelte/table/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | examples/svelte/smooth-scroll/src/vite-env.d.ts | 1 | /// <reference types="svelte" /> | COMMENT |
| LOW | benchmarks/src/lib/harness.ts | 241 | ) { | COMMENT |
| LOW | packages/virtual-core/tests/index.test.ts | 2381 | v['getMeasurements']() | COMMENT |
| LOW | packages/virtual-core/tests/index.test.ts | 2541 | // width animation re-wraps rows for several frames while the user sits | COMMENT |
| LOW | packages/virtual-core/tests/lane-equivalence.test.ts | 1 | // Differential ("oracle") test for the multi-lane lane-assignment optimization. | COMMENT |
| LOW | packages/virtual-core/src/index.ts | 421 | scrollOffset: number | null = null | COMMENT |
| LOW | packages/virtual-core/src/index.ts | 621 | } | COMMENT |
| LOW | packages/virtual-core/src/index.ts | 801 | // A scroll event that reports movement but lands on the offset we | COMMENT |
| LOW | packages/virtual-core/src/index.ts | 1201 | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | examples/react/dynamic/src/main.tsx | 292 | function RowVirtualizerExperimental() { | CODE |
| LOW | examples/react/variable/src/main.tsx | 107 | function ColumnVirtualizerVariable({ columns }: { columns: Array<number> }) { | CODE |
| LOW | examples/react/variable/src/main.tsx | 236 | function MasonryVerticalVirtualizerVariable({ rows }: { rows: Array<number> }) { | CODE |
| LOW | examples/react/variable/src/main.tsx | 287 | function MasonryHorizontalVirtualizerVariable({ | CODE |
| LOW | scripts/verify-links.ts | 51 | function fileExistsForMarkdownLink( | CODE |
| LOW | packages/angular-virtual/src/index.ts | 51 | function injectScheduleDomFlushViaAppRefTick() { | CODE |
| LOW | packages/virtual-core/tests/index.test.ts | 1613 | function makeIOSVirtualizerWithRealEl( | CODE |
| LOW | packages/virtual-core/tests/index.test.ts | 1816 | function makeIOSVirtualizerWithSwappableEl( | CODE |
| LOW | packages/virtual-core/tests/index.test.ts | 2401 | function createAdjustmentVirtualizer({ | CODE |
| LOW | packages/virtual-core/src/index.ts | 1935 | function findNearestBinarySearchFlat( | CODE |
| LOW | packages/virtual-core/src/lazy-measurements.ts | 10 | export function createLazyMeasurementsView( | CODE |
| LOW | packages/react-virtual/e2e/app/test/chat.spec.ts | 64 | async function waitForFirstVisibleAtOffset(page: Page, scrollTop: number) { | CODE |