KILL (debt #4): the PRIMITIVE_TRAITS const and decide's leaf/string fallback
arm are deleted from coherence.rs — including the interner.resolve(...)
trait-name probe that arm carried. decide for a scalar leaf is now an
ordinary coherence-table probe, no leaf special case. DERIVABLE_TRAITS kept
(auto-derive is a separate concern). Unit test re-specified:
decide_primitive_probes_the_table_like_any_nominal. Consumers measured:
fields.rs auto-derive + predicate_check both satisfied by Prelude's real
Equals rows; the old Hash grant was unreachable-dead (no trait Hash exists
anywhere in the corpus).

ADD: tests/corpus/stdlib/Prelude.ck (mod Prelude): 18 trait declarations,
136 primitive impls with real one-line Floor::* bodies (typechecked and
lowered via T-1b). Omitted, owner-gated: Not trait+impl (debt #31 keyword
collision), heterogeneous delegating impls (debt #33 turbofish surface);
Concat/Pow/Convert/Show land as declarations only — no invented bodies.
Types.ck extends to the traits tier: Sized, Collection composes Sized,
composes clauses on String/List/Map/Set, data Option<T>, the Error tier.
World-types + Literal impls stay in slice 8. Debt #14 silence preserved.

Arch rule R7 (r7_deleted_primitive_trait_table_stays_dead, new
architecture/traits.rs): no name-keyed primitive-trait symbol in any crate's
src/ — error-level, red-proven by the orchestrator first-hand.

Fixture churn (honest): cons_positional now traps the real E0731 (Option is
a genuine 2-variant union); the two auto-derive fixtures state impl
Equals<Int> locally — the same law Prelude supplies globally, made explicit.

Gates (orchestrator-run): fmt 0 · clippy -D warnings 0 · 147/147 cargo
summaries ok · arch 15/15 (14 + R7) · stdlib_type_clean green non-vacuously
· ratchet 98 unchanged.

Net Rust delta: src/ -19 LoC (coherence.rs 38+/57-); gate layer +67 (R7 rule
+ harness registration). The primitive-trait knowledge now lives in
Prelude.ck, not Rust.

@@ -0,0 +44,4 @@
+/// well-formed `cklang;<passes>;<seconds>;1;…bits=1` line with a positive
+/// score and ≥ 5.0 s elapsed, freestanding.
+#[test]
+fn actor_races_five_seconds_bit_packed_and_reports_a_wellformed_drag_race_line() {

@@ -151,0 +162,4 @@
+        out.diagnostics
+    );
+    let i = find_first(&out.tree, SyntaxKind::ImplDecl).expect("ImplDecl");
+    let f = find_first(i, SyntaxKind::FnDecl).expect("FnDecl");

@@ -378,0 +410,4 @@
+    // arena: Arena |)` returning `(| h, a |)` must stay legal.
+    let handle = nominal(200, vec![]);
+    let arena = nominal(201, vec![]);
+    let positional = Ty::tuple(vec![handle.clone(), arena.clone()]);