Label AI-written blog posts, add authorship page, and add a blog style guide

[schacon]

• I provide my work under the project license.
• I grant such license of my work as is required for the purposes of future print editions to Ben Straub and Scott Chacon.

Changes

AI authorship labeling

• Add an automated boolean to the blog frontmatter schema (site/src/content.config.ts), defaulting to false.
• Show an authorship banner at the top of every blog post (site/src/pages/blog/[id].astro): automated posts get a prominent "This post was written by AI" banner with an AI badge; human posts get a subtle "Written by a human" banner. Both link to the new authorship page.
• Add a small "Written by AI" tag next to the date on the blog index (site/src/pages/blog/index.astro).
• Add /authorship/ (site/src/pages/authorship.astro), explaining that the book is written entirely by humans (per AGENTS.md), while some blog posts are automated to communicate project updates — and always labeled.
• Mark both existing blog posts as automated: true (both were committed by Cursor Agent).

Blog style guide

• Add site/BLOG_STYLE.md, a writing style guide for blog posts derived from the book's own voice — every trait is illustrated with a real sentence quoted from the book (second-person address, "let's" walkthroughs, rhetorical questions answered immediately, em-dash asides, sparing dry humor, one sentence per source line, and so on).
• Rewrite both existing posts to follow the guide.
• Add a "Blog posts are the exception — but read the style guide first" section to AGENTS.md requiring agents to load site/BLOG_STYLE.md before writing or editing any post, and to always set automated: true.
• Point the "Writing a blog post" section of site/README.md at the guide.

Context

The blog can carry agent-generated update posts, but readers should never have to guess who wrote what, and the posts should read like the book's authors wrote them. This makes AI authorship explicit at the top of each post, gives the label a destination that spells out the policy, and pins the blog's voice to the book's.

Verified locally with npm run build and browser walkthroughs of the preview site:

  

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