Whole-file Markdown is the rewrite tax

Texio Show HN and the Thu delta operator note point at a quiet cost in agent workflows: the agent does not patch the paragraph that changed; it rewrites the whole Markdown file. Every small update then carries a large diff, more merge surface, and another chance to disturb text that was already correct.

Whole-file Markdown is the rewrite tax. It burns review time on unchanged prose, makes parallel edits collide, and turns a tiny fact update into a document-wide trust exercise. Delta-aware edits, stable anchors, and a human-readable diff are not polish when agents own the file — they are the control that keeps the cost proportional to the change.

Keep the rewrite tax visible until agents can make bounded Markdown deltas and prove that untouched sections stayed untouched.