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

docs/journals/2026-05-12-iter-ctt.1.md

@@ -0,0 +1,47 @@
+# iter ctt.1 — Env-overlay shape ratification
+
+**Date:** 2026-05-12
+**Started from:** 0a36294e61f08d8de85c084415d694d3736e0c67
+**Status:** DONE
+**Tasks completed:** 3 of 3
+
+## Summary
+
+Ratifies the two-overlay shape of the check environment (`env.types`
++ `env.ctor_index`) and pins its load-bearing consumer. The split
+decision now has a DESIGN.md anchor (§"Env construction") explaining
+the owning-index / reverse-index roles, the rationale for not
+collapsing into one variant-keyed map, and the intentional asymmetry
+with the mono side (narrowed to types-only at ct.3.2, because its
+runtime-ctor-lookup consumer story differs from the check side's
+in-band `DuplicateCtor` diagnostic). A new behavioural-pin test
+(`crates/ailang-check/tests/duplicate_ctor_pin.rs`) asserts
+`code == "duplicate-ctor"` plus message-substring coverage for a
+two-ADT-same-ctor fixture, going red if the per-module rebuild at
+`crates/ailang-check/src/lib.rs:1342-1384` is ever silently removed.
+Two P2 roadmap todos struck `[x]` with one-line forward-references to
+this iter. No production-code edits. `cargo test --workspace` green.
+
+## Per-task notes
+
+- iter ctt.1.1: New pinning test `crates/ailang-check/tests/duplicate_ctor_pin.rs` — builds a `Workspace` inline with one module declaring `type Cat = Twins` and `type Dog = Twins`, calls `check_workspace`, asserts a `Diagnostic` with `code == "duplicate-ctor"` plus message substring for `Twins` / `Cat` / `Dog`. PASS on first run, as the plan predicted (behaviour pre-exists).
+- iter ctt.1.2: Inserted new top-level section `## Env construction` in `docs/DESIGN.md` between `## Convention: qualified cross-module references` (line 1941) and `## Data model` (now line 1988, was 1959 pre-edit). Three paragraphs: split definition, rationale, check-side / mono-side asymmetry. Cross-references the pinning test.
+- iter ctt.1.3: Two `[ ]` → `[x]` strikes in `docs/roadmap.md` at lines 79 (overlay shape question) and 183 (per-module overlay narrowing). Each gains a one-line forward-reference suffix on its `context:` line pointing at iter ctt.1 and the closing artefact.
+
+## Concerns
+
+(none)
+
+## Known debt
+
+(none)
+
+## Files touched
+
+- `crates/ailang-check/tests/duplicate_ctor_pin.rs` (new)
+- `docs/DESIGN.md` (modified — `## Env construction` section inserted)
+- `docs/roadmap.md` (modified — two strikes)
+
+## Stats
+
+bench/orchestrator-stats/2026-05-12-iter-ctt.1.json

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