Saturday, 18th April 2026
Adding a new content type to my blog-to-newsletter tool
Here's an example of a deceptively short prompt that got a quite a lot of work done in a single shot.
First, some background. I send out a free Substack newsletter around once a week containing content copied-and-pasted from my blog. I'm effectively using Substack as a lightweight way to allow people to subscribe to my blog via email.
I generate the newsletter with my blog-to-newsletter tool - an HTML and JavaScript app that fetches my latest content from this Datasette instance and formats it as rich text HTML, which I can then copy to my clipboard and paste into the Substack editor. Here's a detailed explanation of how that works. [... 902 words]
Anthropic publish the system prompts for Claude chat and make that page available as Markdown. I had Claude Code turn that page into separate files for each model and model family with fake git commit dates to enable browsing the changes via the GitHub commit view.
I used this to write my own detailed notes on the changes between Opus 4.6 and 4.7.
Changes in the system prompt between Claude Opus 4.6 and 4.7
Anthropic are the only major AI lab to publish the system prompts for their user-facing chat systems. Their system prompt archive now dates all the way back to Claude 3 in July 2024 and it’s always interesting to see how the system prompt evolves as they publish new models.
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