iter ctt.1: env-overlay shape ratification + DuplicateCtor pin

docs/journals/INDEX.md

@@ -37,3 +37,4 @@
 - 2026-05-12 — iter hs.4: IR + checker + linker wiring — `int_to_str : (Int) -> Str` installed in checker + synth.rs lockstep partner; IR-header preamble unconditionally declares both `@ailang_int_to_str` / `@ailang_float_to_str`; `Emitter::lower_app` gets new `int_to_str` arm and replaces `float_to_str`'s `CodegenError::Internal` with the actual call emission; `is_static_callee` whitelist extends to `int_to_str`; `runtime/rc.c` hoisted out of `AllocStrategy::Rc` arm to the unconditional link path (the `__attribute__((weak))` on str.c's `ailang_rc_alloc` extern becomes the documented no-op); 2 new IR-shape pins + 4 new E2E (2 stdout-smoke + 2 RC-stats) + 4 `.ail.json` fixtures; `drop.rs` Str-arm comment refreshed to dual-realisation framing; 5 IR snapshots regen for the 2 new declare lines. Status: DONE_WITH_CONCERNS — heap-Str RC-discipline incomplete (slabs leak at program end) because plan's literal `ret_mode: Implicit` interacts with uniqueness analyser walking `Term::Do` args as `Position::Consume`. Test asserts weakened from `allocs == frees && live == 0` to `allocs >= 1`. Substantive fix requires spec-level effect-op arg-mode decision (deferred, bounce-back to user) → 2026-05-12-iter-hs.4.md
 - 2026-05-12 — iter eob.1: Effect-op args walked as Borrow (uniqueness.rs + linearity.rs + linearity.rs doc-comment); heap-Str RC discipline closes (int_to_str / float_to_str `ret_mode: Implicit` → `Own` at 4 lockstep sites across builtins.rs + synth.rs; `drop_symbol_for_binder` App-arm gets `Str` carve-out symmetric to `field_drop_call`'s existing one); 2 pre-existing RED tests at e2e.rs (commit 592d87b) flipped to GREEN unchanged with predicted concrete numbers (`allocs==1,frees==1,live==0` and `allocs==2,frees==2,live==0`); 2 new positive tests + fixtures (primitive-Int through `io/print_int`: zero RC traffic; heap-Str repeated borrow through 2× `io/print_str`: `allocs==1,frees==1,live==0`); DESIGN.md §Decision 10 anchors both arg-position rules together (Ctor=Consume, Do=Borrow, plus a paragraph linking Do=Borrow to ret_mode==Own letbinder-trackability); WhatsNew entry shipped, roadmap P1 `[milestone] Heap-Str ABI` checked off, Post-22-Prelude `depends on:` line removed; 7/7 tasks first-shot, zero review re-loops; lint side-effect surface (over-strict-mode on (own T) params used solely via effect-ops) was empty for the current corpus → 2026-05-12-iter-eob.1.md
 - 2026-05-12 — audit-eob: milestone close (heap-str-abi) — architect drift fixed inline as `eob.tidy` (3 DESIGN.md edits: float_to_str / int_to_str caveats dropped, "Str ABI" anchor added documenting both heap-Str and static-Str realisations with their shared consumer ABI and codegen-level non-RC invariant for static-Str); bench mixed (latency.explicit_at_rc improvement cluster reappears for the 3rd consecutive audit + new marginal bump_s regressions on list_sum/hof_pipeline 12% over 10% tol), baseline pristine for 3rd consecutive audit (conservative call: latency cluster has no identified cause across 3 audits — ratify-without-attribution would obscure future signal; bump_s cluster is first-sighting, observe next audit) → 2026-05-12-audit-eob.md
+- 2026-05-12 — iter ctt.1: env-overlay shape ratification — new DESIGN.md top-level section `## Env construction` anchors the `env.types` (owning) / `env.ctor_index` (reverse-index) split with the semantic rationale, plus the intentional check-side / mono-side asymmetry (mono-side narrowed at ct.3.2, check-side retains both halves because in-band `DuplicateCtor` consumes the per-module `env.ctor_index` rebuild); new behavioural-pin test `crates/ailang-check/tests/duplicate_ctor_pin.rs` ratifies the consumer; two P2 roadmap todos struck `[x]` (overlay shape question, per-module overlay narrowing); 3/3 tasks first-shot, zero review re-loops, no production-code edits → 2026-05-12-iter-ctt.1.md