The Index
The Review Tax Index
The claim you will hear is that AI-written code costs more review everywhere. The data says something more useful: the cost is a split — it lands hard on some repositories and not at all on others. This page measures where.
Repositories read
472
Merged PRs analyzed
46,235
Agent-native repos
14%
20%+ of merged work carries attribution
The split
For every repository with a readable comparison, attributed work is measured against the rest of the same repository — same reviewers, same conventions, same era. A multiple above 1x means the attributed side took more; below means it took less.
Time to merge, attributed / rest
71
repos above 1x
173
at or below 1x
0.6x
median
29% of comparable repos pay more review on attributed work; 71% pay the same or less. Middle half of the population: 0.2x to 1.2x.
Where the tax lands
Median detected share across the population is 3% — and that is a floor, not a share: attribution comes only from marks a tool leaves on a commit, so inline-completion work is invisible by construction.
By primary language
| Segment | Repos | Median detected share | Time to merge | Review rounds |
|---|---|---|---|---|
| JavaScript | 101 | 2% | 0.4x | — |
| TypeScript | 96 | 3% | 0.5x | — |
| Python | 82 | 4% | 0.6x | — |
| Go | 61 | 3% | 0.7x | — |
| Rust | 55 | 3% | 0.7x | — |
| Java | 24 | 1% | — | — |
A dash means the segment has too few comparable repos for that measure to publish — a median over a handful of ratios is noise wearing a number.
By project size
| Segment | Repos | Median detected share | Time to merge | Review rounds |
|---|---|---|---|---|
| 50k+ stars | 237 | 3% | 0.5x | — |
| 20k-50k stars | 233 | 2% | 0.7x | — |
A dash means the segment has too few comparable repos for that measure to publish — a median over a handful of ratios is noise wearing a number.
How to read this
- Attributed vs rest, never AI vs human. The comparison group contains AI-assisted work that leaves no trace, which narrows every gap shown here rather than widening it.
- The sample self-selects twice. These are repositories someone chose to scan plus a curated backfill of well-known projects — a population of repos people care about, not a random sample of software.
- Withheld beats invented. Repos below 10 analyzed PRs do not count; segments below 12 comparable repos publish no median.
Full method and every limitation: /methodology. Place your own repo against this population: /scan.