How we build the thing that publishes your changelog, your blog and your release notes.
A product changelog is read by people who will see the change on screen. An API changelog is read by people whose code will stop working, and that audience needs the symbol name, the date and a feed a machine can poll.
A tool error that says "invalid input" ends the run. One that quotes the rejected value, lists the accepted set and names the next move lets the assistant repair the call itself. Four real messages from one codebase, read closely.
Market4 turns one release note into a changelog page, a blog post, a mail-out and a week of social posts — and then tells you which of them brought anyone back.