newsletter-abtest: daily A/B digest for a running newsletter campaign

[ralyodio]

One email a day while a newsletter A/B test runs.

• Reads myna newsletter stats <id> --json for every issue matching a prefix, records a daily snapshot, and reports what moved since the last reading.
• Pools the arms across every issue of the campaign and runs a two-proportion z test on clicks, because one issue's arms are far too small alone.
• When a gap is not separable it prints the recipients per arm that would settle it. That is the number that decides the next issue's design: on the 5,140 list, 0.57% against 1.41% needs ~2,200 an arm and is decidable in one send; 0.93% against 1.18% needs ~26,000 and never will be.
• The month's sends live in a plan file, and the digest prints the myna newsletter blast command for whichever issue is next.

Installed on dev at 05:25 UTC daily for the Profullstack campaign; the cron line carries a note to delete it when the month is done. First digest sent and received.

🤖 Generated with Claude Code