Module placeholder 

Placeholder leaves: the one hole in Day’s rendering that is invisible to a screenshot.

When a backend has no renderer for a kind it realizes a visible ⟨kind⟩ label rather than failing — the right runtime behaviour, but it means a missing renderer LOOKS like a rendered app: the walkthrough passes, and the gallery’s validator (which counts distinct colours) sees nothing wrong. That is how a stale skip_on: survived in the showcase walkthrough after the renderer it skipped had actually landed.

So every backend reports here instead of keeping its own warn-once set. The table is process- wide and append-only, which gives dayscript’s assert_no_placeholders something to assert on (crates/day-script) — a placeholder becomes a test failure instead of a silent gap.

Functions

report

Record that toolkit had no renderer for kind and warn — once per kind, however many nodes of it are realized. Call from a backend’s realize fallback arm.

seen

Every kind that has rendered a placeholder in this process, sorted. Empty is the goal.