AILang/docs/journals/2026-05-16-iter-revert.md

iter revert — Iteration-discipline milestone surgical forward revert

Date: 2026-05-16 Started from: abf00131c1 Status: DONE Tasks completed: 11 of 11

Summary

The Iteration-discipline milestone (it.1 96db54d + it.2 a4be1e5) is fully backed out by a single forward iteration, with 1ff7e81 (the last commit before milestone-start 9973546) as the per-region byte oracle. main was never rewound — every restore is a forward working-tree edit, net-new it.1/it.2 surface is rm'd, DESIGN.md is hunk-edited in place (clause 3 / criterion section KEPT, never wholesale-restored). Feature-acceptance clause 3 and the F3 todo are retained; the clause-3 worked example is de-claimed from "shipped" to hypothetical-illustration form (in DESIGN.md and brainstorm SKILL.md in lockstep); one honest F1/F4 documentation note is added (the only net addition) and guarded by a doc-presence test. The correctness gate (Task 11) proved compiler behaviour pristine: all 164 surviving 1ff7e81-era fixtures ail check/ail run byte-identical to their pre-milestone behaviour; cargo test --workspace 600/0; zero residual it.1/it.2 production surface. AILang's iteration story is exactly the pre-9973546 state (structural / tail recursion; tail-app intact); the genuine total-recursion ambition is preserved on the roadmap as a deferred P2 milestone sequenced behind a future Nat/refinement-types milestone.

Per-task notes

• revert.1: AST node family + drift anchors + DESIGN.md §Data-model — removed Term::Loop/Term::Recur/struct LoopBinder + 2 serde units (ast.rs byte-identical to oracle); loop/recur exemplars + match arms removed from design_schema_drift.rs / spec_drift.rs / schema_coverage.rs (byte-identical); DESIGN.md §Data-model loop/recur JSON + it.1/it.2 prose removed (region byte-identical).
• revert.2: CheckError surface — 5 variants + doc comments, 5 code() arms, 3 dedicated ctx() arms deleted; _ => catch-all preserved; diagnostic.rs confirmed genuine no-op.
• revert.3: it.2 guardedness pass + Diverge-injection — STOP-gate cleared (all 6 named helpers it.2-net-new at oracle → all delete, no ambiguity). Removed the entire 687-line guardedness cluster (verify_structural_recursion, term_contains_loop, adt_families, referenced_con_names, mutual_structural_group, adt_param_positions, RecCall, TypeUnionFind, MutualGroup, et al.) plus the transitively-it.2 module_fns plumbing through check_module/check_def/check_fn signatures (oracle proved net-new; resolved via the plan's Oracle convention + recon-by-name mandate — see Concerns). 3 Diverge-injection sites restored byte-identical; lib.rs "Diverge" count 0 == oracle.
• revert.4: it.1 check surface — synth Loop/Recur arms + verify_loop_body deleted; loop_stack param + ~30 threaded calls + 9 local decls removed; verify_tail_positions survives, it.1 arms removed, byte-identical to oracle; substitute_rigids_in_term + post-mono name arms cleaned. Result: crates/ailang-check/src/lib.rs FULLY byte-identical to 1ff7e81.
• revert.5: 9 remaining walker files (lift/mono/linearity/uniqueness/ reuse_shape/pre_desugar_validation/builtins + core desugar/ workspace) restored to oracle, all byte-identical; pre-restore diff classification proved every hunk it.1/it.2-only.
• revert.6: surface + prose + form-A grammar — parse.rs/print.rs/ prose lib.rs/form_a.md restored to oracle byte-identical; each touched only by 96db54d (it.1) since 1ff7e81; surface+prose build clean.
• revert.7: codegen — lib.rs/escape.rs/lambda.rs + ail/main.rs restored to oracle byte-identical; block_terminated = true count == 8 == oracle (it.1 parallel setter gone; the 4 tail-driven + 4 control-flow setters survive). cargo build --workspace clean (first full-build gate, lockstep clustering worked as designed).
• revert.8: STOP-gate re-verify cleared (live git diff --stat matched plan's net-new/modified/absent classification exactly). Deleted 2 pin files + 16 fixtures + bench/it3-oracle via plain rm (no git-index touch). 2 RC fixtures restored byte-identical. e2e.rs + codegen_import_map_fallback_pin.rs + carve_out_inventory.rs restored byte-identical (carve = "Twelve carve-outs", last entry test_mut_var_captured_by_lambda.ail.json). it.{1,2,3} stats json KEPT. cargo test --workspace 599/0.
• revert.9: DESIGN.md Decision 3 → 1ff7e81 placeholder (byte-identical, hunk-only); clause-3 worked example de-claimed to hypothetical form (criterion section + clause-3 discriminator KEPT); brainstorm SKILL.md de-claimed in lockstep; F1/F4 note added verbatim; doc-presence test added verbatim, PASSES.
• revert.10: roadmap Iteration-discipline [~] block + blocking-fork sub-section removed; deferred "Iteration-totality story" entry added verbatim at top of P2 (per plan + spec sequencing); F3 + Stateful-islands untouched; superseded header prepended to the old spec; Step-4 STOP-check clean (no residual A1 amendment).
• revert.11 (correctness gate): 1ff7e81 ref compiler built in throwaway worktree; 164-fixture check/run oracle captured; post-revert compiler diffed byte-for-byte — fail=0, ZERO DRIFT, behaviour PRISTINE. cargo test --workspace 600/0. Residual it.1/it.2 production-surface grep clean. Worktree removed; main HEAD never moved.

Concerns

• revert.3: the plan's Task-3 file-map enumerated the guardedness helpers + call site but did NOT explicitly list the module_fns signature threading through check_module/check_def/check_fn. The 1ff7e81 oracle unambiguously proved that threading it.2-net-new; leaving it would have been dead it.2 surface referencing deleted helpers. Resolved correctly via the plan's own "Oracle convention"
  • "re-locate by symbol name, oracle is authority on every byte" mandate + the spec §Data-flow ("restored to pure pre-it.1 role"). This is the recon-map-drifts-but-oracle-is-authority mechanism working as designed, not a plan defect — no bounce. Flagged so the Boss is aware the plan file-map under-enumerated one signature edge; the end-state is verified correct (lib.rs byte-identical to oracle).
• revert.9: the plan's Task-9 Step-6 single-line grep heuristic (grep -c 'clauses 1 and 2 yet fail clause 3' ...) returned 0 because the verbatim-applied replacement text line-wraps ("yet fail\n clause 3"). The substantive acceptance criterion (clause-3 block retained, only de-claimed) is positively verified multiline + by the intact ## Feature-acceptance criterion section and "criterion 3 is the discriminator" sentence. Not a defect; flagged so the Boss does not misread the heuristic.

Known debt

(none — the revert is byte-pristine against 1ff7e81 for all production surface; behaviour is byte-identical over the surviving corpus.)

Blocked detail

(none — DONE.)

Files touched

90 working-tree paths (Boss commits all as one cohesive revert iter):

• Deleted (59): crates/ailang-check/tests/loop_recur_pin.rs, crates/ailang-check/tests/structural_recursion_pin.rs; 16 it.1/it.2 fixtures under examples/ (loop_.ail, struct_rec_.ail, test_recur_*.ail.json, test_loop_missing_diverge / test_mutual_cross_family / test_non_structural_recursion .ail.json); bench/it3-oracle/ (MANIFEST.tsv + 40 .out).
• Modified — source revert to 1ff7e81 (byte-identical): crates/ailang-core/src/ast.rs, desugar.rs, workspace.rs; crates/ailang-check/src/lib.rs, lift.rs, mono.rs, linearity.rs, uniqueness.rs, reuse_shape.rs, pre_desugar_validation.rs, builtins.rs; crates/ailang-codegen/src/lib.rs, escape.rs, lambda.rs; crates/ail/src/main.rs; crates/ailang-surface/src/parse.rs, print.rs; crates/ailang-prose/src/lib.rs; crates/ailang-core/specs/form_a.md.
• Modified — tests revert to 1ff7e81 (byte-identical): crates/ailang-core/tests/spec_drift.rs, schema_coverage.rs, carve_out_inventory.rs; crates/ail/tests/e2e.rs, codegen_import_map_fallback_pin.rs.
• Modified — net-add / hunk-edit: crates/ailang-core/tests/design_schema_drift.rs (loop/recur anchors removed + new doc-presence test added), docs/DESIGN.md (Decision 3 placeholder + clause-3 de-claim + F1/F4 note; hunk-edited, clause 3 kept), docs/roadmap.md (Iteration-discipline block removed, deferred P2 entry added), docs/specs/2026-05-15-iteration-discipline.md (superseded header), skills/brainstorm/SKILL.md (worked-example de-claim).
• Modified — fixtures restored to 1ff7e81: examples/rc_pin_recurse_implicit.ail, examples/rc_let_alias_implicit_param.ail.
• KEPT (no-op, Boss decision): bench/orchestrator-stats/2026-05-15-iter-it.{1,2,3}.json.

E2E coverage: none (revert iteration — the Task-11 behavioural- equivalence sweep over all 164 surviving fixtures is a stronger correctness proof than new E2E; the doc-presence test guards the only net-new artefact).

Stats

bench/orchestrator-stats/2026-05-16-iter-revert.json