AGENTS.md has always said Prolog is a design tool for reasoning about tickets;
it was the least-used line in the file, because kb.pl was only ever written
retrospectively. `kb check --with <design.pl>` merges proposed facts into a
throwaway candidate and runs kb_consistent over the union, so a design can be
refused before any code exists. Nothing is written either way.
The model already derives rather than records -- illegal_dependency, may_use,
depends_transitively, portable, snapshot_safe, view_state_admits,
record_obligation, and eleven kb_error classes. Three proposals exercised it in
one sitting: one added dependency edge produced SIX layering violations through
the transitive closure; a proposal to declare decision/3 functional was refused,
correctly, because improvise-907 carries two decisions; and a mis-ordered
layer/2 argument was named rather than accepted.
Trying to model a design found a real defect in the tool. Keys were the functor
plus all arguments but the last, which is right for doctrine(Name,Text) and
wrong for any RELATION: crate_depends_on(A,B) keyed on A, so a crate depending
on two crates read as one key twice and was unaddable. It cannot be read off the
KB's functional/1 -- that keys an arity-3 predicate on its first argument, right
for crate/3 and wrong for decision/3 -- so key_arity/2 is a table, and anything
unlisted keys on the whole head, which is the safe direction.
kb-test.sh is 20 cases.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FC2jVn8Au7E9JPkw6bwXXH
Edward Langley
fc6d229dda