iter 22-tidy.4: journal entry

docs/JOURNAL.md

@@ -12156,3 +12156,47 @@ Resolution:
   shape" in the JOURNAL queue.
 
 Milestone closed: drift items 1 and 3 tidied; item 2 queued.
+
+## 2026-05-10 — Iteration 22-tidy.4: primitive-name-set consolidation
+
+Closing the milestone-22 carried-debt item flagged in the 22b.3
+JOURNAL and re-flagged at milestone-22 audit close: the
+primitive-name set `{Int, Bool, Str, Unit}` was duplicated across
+five sites (`crates/ailang-codegen/src/subst.rs:169`,
+`crates/ailang-check/src/linearity.rs:143`,
+`crates/ailang-check/src/lib.rs:1279` and `:2261`,
+`crates/ailang-check/src/mono.rs:316-327`).
+
+This iteration introduces `crates/ailang-core/src/primitives.rs`
+exporting `is_primitive_name(&str) -> bool` plus
+`primitive_surface_name(&str) -> Option<&'static str>`. The four
+`matches!` consumer sites now route through the predicate; the
+mono-pass surface-name helper retains its outer zero-arity gating
+and delegates the inner mapping to the same module. A unit test
+`predicate_and_surface_name_agree` in `primitives.rs` pins the
+lockstep invariant between the two functions (a future regression
+where only one is extended fails the test before it can ship).
+
+Tasks (commit subjects):
+
+- 22-tidy.4: ailang-core::primitives — single home for the
+  primitive-name set
+- 22-tidy.4: pin lockstep invariant + tighten module doc
+- 22-tidy.4: route 4 matches! sites through is_primitive_name
+- 22-tidy.4: mono::primitive_surface_name delegates to ailang-core
+
+Acceptance: 4 `matches!` sites + 1 mono.rs site routed; full
+workspace test sweep 346 green (345 + the new lockstep test);
+bench gates 0/0/0; grep confirms no remaining duplicate predicate
+outside `crates/ailang-core/src/primitives.rs`.
+
+The audit-flagged milestone-22 carried-debt item closes; the
+remaining carried items (parse-fn/data/const strict
+duplicate-clause detection, Form-B prose printer arms for
+ClassDef/InstanceDef, defensive lib.rs gap-related sites) stay
+queued.
+
+Observation, not debt: `crates/ailang-codegen/src/drop.rs:379` has
+a `matches!(name.as_str(), "Str")` single-element check (not the
+4-set) — distinct invariant (heap-string-only semantics), out of
+scope for this consolidation.