The Build Log

Real engineering, failure modes and all.

Write-ups of the real systems we build: what broke, what we changed, and why. Published here in full; also on Substack for subscribers.

Analytics22 Jul 20262 min read

Retention Curves Are Lying to You: A Diagnostic Method for Short-Form Video

Why percentage-based retention charts mislead across videos of different lengths, and the absolute-seconds method that reveals the real problem.

Classifier logic21 Jul 20262 min read

Teaching Claude to Read Cold-Email Replies Like a Sales Rep, Not a Keyword Filter

Why a keyword filter can't tell a polite decline from real interest, the actual classifier logic that can, and an honest look at the one case it probably got wrong.

Self-healing systems21 Jul 20263 min read

The Self-Healing Content Pipeline

What happens when your AI avatar video comes back wrong: the real retry logic behind the daily pipeline, and the three questions worth asking about any AI system that matters.

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