- An empty replacement catalog is a real catalog: `renderCatalogUpdate()`
publishes zero entries when the last skill disappears, and falling back
would hide that every earlier name was retired.
- The opaque fallback keeps a `form` declaration this version cannot present.
It is the one place a newer or foreign log's declared shape would otherwise
vanish from the UI entirely, since the row marker is also absent there.
- An instruction change with an unrecognized `action` disqualifies the record.
The action decides the word the row shows, so an unknown one would be
presented as loaded or updated.
- The catalog list bounds itself and reports the withheld count. Entry count
is unbounded and the scrollport bounds height, not node count.
- A catalog message keeps content blocks this version does not know, instead
of dropping model-visible content the extensible union may carry.
- `core.md` defines `ContextFormed`, the interface actually carrying the
optional field, beside `ContextForm`.
- The superseded-in-part bullet states the affected clauses as one rule rather
than enumerating them; two rounds of enumeration each missed some, which is
the shape being fragile rather than the list being wrong.
- The note records the one migration case that does not self-heal: an
old-format catalog as the only one, with an empty current view, leaves a
stale catalog nothing replaces.