gave four Claude agents the same brief, let them build in isolation, then had three more judge the results from screenshots alone, completely BLIND. randomised labels, no source access, no answer key.

What it created in one sentence: **a dashboard where you drop an audio file in, the page measures it, and cuts a music video to what it found**

in essence, Claude built an audio-to-video editor using this loop:

`locked brief + 12 measurable dimensions` → `4 parallel builds in isolated directories` → `blind screenshot tournament + one critic per dimension` → `every dimension must score ≥8; averages don’t count` → `repeat for 4 rounds`

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Here's the technical details (written by Claude edited by me... don't hate me, i'm tired!):

The tournament identifies the strongest build. The critics determine whether it is actually good.

The result:

`audio` → `in-browser analysis` → `beat grid + sections` → `shot list` → `cut.json` → `Remotion render`

It’s a single page with no server, uploads, npm or build step. The timeline combines the analysis, cut list and visuals as one data model.

Audio analysis includes:

* Spectral-flux onset detection
* Autocorrelation tempo estimation
* Dynamic-programming beat tracking
* Self-similarity-based section detection
* Peak, RMS, crest factor, spectral centroid and stereo width

Six frequency bands map to real CRT phosphor chromaticities calculated at runtime. The main visual is a live vectorscope: decorative, but also informative.

It also exposes uncertainty. Below −45 dBFS it reports no BPM instead of guessing. It shows the runner-up tempo, labels 4/4 as assumed and distinguishes estimated lyrics from timed `.lrc` files.

`cut.json` contains the full analysis and every shot’s timing, section, energy, frequency profile, lyric and measurement-derived prompt. A separate Remotion composition renders the same edit reproducibly.

Across the same interleaved test harness:

|Metric|Before|After|
|:-|:-|:-|
|CLS|0.422|0.0099|
|Desktop frame time|33.4 ms|16.7 ms|
|Mobile, 4× throttle|49.5 ms|27.8 ms|
|Retained heap|259.7 MB|137.1 MB|

The main performance bug was a fractional `drawImage` offset causing two full-raster resampled blits per frame.

Final result: 12 of 13 dimensions passed, layout remained at 7, and the blind vote was 3–0.

The page refuses to report a BPM it can’t measure. The process refuses to report a score it can’t defend.

I made 4 Claude agents compete to build a music video editor. Then 3 more judged them blind.