Brummel
305ffd1367
it.3 Task 1 (non-destructive oracle + spec-delegated class-(b) sweep) ran complete; zero production code changed. The mandated sweep surfaced that 6 corpus fixtures contain build(d:Int)=if d==0 then Leaf else Node(1,build(d-1),build(d-1)) — a terminating, maximally-LLM-natural, non-structural non-tail BRANCHING recursion the milestone's totality dichotomy makes inexpressible (not ADT-structural; not recur-able — branching is not a single tail back-edge). The milestone as-specified would fail its own feature-acceptance criterion. Orchestrator correctly bounced rather than patch a 4th time (spec_over_plan_patches). Records the blocked attempt + the reusable bench/it3-oracle/ (40-fixture behavioural oracle, valid for the post-decision re-dispatch). main forward-only; nothing reverted. Resolution (it.2b + a user purity-pillar decision) tracked in the roadmap.
188 lines
9.4 KiB
Markdown
188 lines
9.4 KiB
Markdown
# iter it.3 — retire tail-app/tail-do + corpus migration
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**Date:** 2026-05-15
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**Started from:** c992eb93df4c5ec0a0686c924535cb9951be552f
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**Status:** BLOCKED
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**Tasks completed:** 1 of 7 (Task 1 complete; BLOCKED at the
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Task-1.3 → Task-2 boundary before any destructive task)
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## Summary
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Third and terminal iteration of the iteration-discipline milestone
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(destructive: retire `tail-app`/`tail-do`, migrate the corpus).
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Task 1 (the non-destructive pre-migration oracle + the spec-delegated
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class-(b) live enumeration) ran to completion: 40 recursive corpus
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fixtures classified, 40 behavioural oracles captured under
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`bench/it3-oracle/`, `MANIFEST.tsv` written. Task 1.3's mandated
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live sweep surfaced a **real spec-signal** that the plan's own
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self-review (lines 550-560) and the carrier explicitly defined as a
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BLOCKED-to-Boss condition, not a silent reshape: **six fixtures
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contain a recursive fn that resists BOTH a natural `(loop)`/`recur`
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form AND a structural-plain form.** Per DD-2/DD-3 (migrate before
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remove; Task 4's completeness gate must not be softened and a RED
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there is a Task-2 defect, never a restored exemption) there is **no
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in-plan migration target** for these six. The destructive tasks
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(4/5) were therefore not started — correctly, since the migration
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they depend on is impossible for this subset and DD-3 forbids
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working around it. No production code was modified; the working
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tree contains only the new `bench/it3-oracle/` artefacts.
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## Per-task notes
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- iter it.3.1: Pre-migration oracle + migration-set enumeration —
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**complete.** `cargo build -p ail` clean at HEAD c992eb9.
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Class-(a): 23 `(tail-app|tail-do)` fixtures (recon-confirmed).
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Class-(b) live sweep (Task 1.3, spec-delegated): read
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`verify_structural_recursion` + the two it.2 exemptions
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(`lib.rs:3027` `if !*tail` grandfather; `lib.rs:3197`
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`if cand.is_empty() && group.members.is_empty()` no-ADT skip),
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then classified every self-recursive corpus fn against the
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post-Task-4 verdict logic (`lib.rs:3219-3267`). Authoritative
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result: 13 no-ADT-candidate single-recursion fns are
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loop-migratable; 11 fixtures recurse structurally on an ADT param
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(clean before AND after Task 4 — no migration, only the redundant
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`tail-app` marker if class-(a) is dropped); **6 fixtures have a
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no-ADT-candidate DOUBLE non-tail recursion (binary-tree build)
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that is neither structural nor loop-expressible.** Oracles
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captured for all 40 (`bench/it3-oracle/<stem>.out` + `MANIFEST.tsv`).
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Task 1.5 fallout list recorded below for the eventual unblocked
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re-dispatch. No code changed (Task 1 is non-destructive by spec).
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- iter it.3.2 … it.3.7: not started. Task 2 (migration) has no
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valid action for the 6 blocked fixtures; Tasks 4/5 are
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destructive and gated behind a complete Task-2 migration that
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cannot be completed. Halted at the spec-signal per carrier.
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## Concerns
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- **The RC-RSS / 18g.1 load-bearing risk (DD-4 / Task 5.5 / 5b) was
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NOT reached.** The iter blocked before Task 5, so the 18g.1
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husk-dec deletion and the RC-RSS bench gate were never exercised.
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No RC-RSS evidence exists from this dispatch. The milestone-close
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audit must NOT treat the RC-RSS contingency as resolved — it is
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untested. When the spec defect below is resolved and it.3 is
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re-dispatched, Task 5.5 (and conditionally 5b) is still the
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milestone's load-bearing risk and must be run + its evidence
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journalled then.
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## Known debt
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- `bench/it3-oracle/` currently holds 40 `.out` snapshots +
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`MANIFEST.tsv` (41 files). They are the Task-1 deliverable and
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stay valid for a re-dispatch from the same `start_sha`. Boss
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call at commit whether to keep them under `bench/` (plan §"Files
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this plan creates": "deleted in Task 6 … or kept under `bench/`
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if cheap") — but do NOT delete before the re-dispatch; the
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re-dispatched Task 7.3 diffs against them.
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- The 11 class-(a) `plaincall` fixtures (structural on an ADT param,
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carrying only a redundant `tail-app` marker) and the 11
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`already-structural` fixtures need no semantic migration — only
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marker-stripping (class-a) — and are unaffected by the blocker.
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Recorded so the re-dispatch does not re-derive this.
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## Blocked detail
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**Task:** 1 (the Task-1.3 spec-delegated sweep) → halts entry to
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Task 2 / Task 4.
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**Reason:** `spec-ambiguous` / spec defect surfaced by the mandated
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live sweep — six corpus fixtures contain a recursive fn that is
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**neither structural recursion (no ADT-typed parameter — `cand`
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empty in `verify_structural_recursion`) nor expressible as
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`(loop …)`/`recur`** (the recursion is two non-tail self-calls
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building both children of a binary `Tree`; `recur` is
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tail-position-only with a single back-edge, so a balanced-tree
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build cannot be a tail loop). After Task 4 removes the
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no-ADT-candidate skip (`lib.rs:3197`, mandated by DD-3 and the
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spec's it.3 acceptance bullet "no grandfather/no-candidate skip
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remains"), each of these deterministically fires
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`CheckError::NonStructuralRecursion` (verdict logic `lib.rs:3219-3267`:
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`cand` empty ⇒ `self_clear=false` ⇒ NSR). DD-3 forbids softening
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Task 4 or restoring the exemption; the carrier and project memory
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(`feedback_dont_adapt_tests_to_bugs`) forbid reshaping the
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LLM-natural fixture (e.g. changing `depth: Int` to an ADT-encoded
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`Nat`, or hand-rolling an explicit stack/continuation). There is
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**no in-plan migration target**, so the destructive split cannot
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proceed.
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**The six fixtures (fn :: shape):**
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1. `examples/bench_tree_walk.ail` :: `build_tree`
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(`(if (== depth 0) (Tree Leaf) (Tree Node 1 (build_tree (- depth 1)) (build_tree (- depth 1))))`)
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2. `examples/bench_latency_explicit.ail` :: `build_tree` (same shape; file is class-(a) for other fns but `build_tree` itself is non-tail double recursion)
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3. `examples/bench_latency_implicit.ail` :: `build_tree` (same)
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4. `examples/rc_let_owned_app_leak.ail` :: `build` (same Tree shape on `d: Int`)
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5. `examples/rc_pin_recurse_implicit.ail` :: `build` (same; the RC-regression-guard fixture from it.2 Concerns §2)
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6. `examples/rc_let_alias_implicit_param.ail` :: `build` (same; the RC-regression-guard fixture from it.2 Concerns §2)
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This is exactly the spec-signal the it.2 journal §1 foreshadowed
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(it named `bench_latency_explicit:build_tree` as a no-ADT-candidate
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case "whose migration to `(loop …)` is the destructive it.3 corpus
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pass") and the plan self-review's "Recorded risk" anticipated
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("a genuine non-structural recursion with no natural loop form …
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surfaces as a Task-2 BLOCKED to the Boss with the fixture named").
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The spec/plan assumed every no-ADT-candidate recursion is a
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loopable counter/accumulator; balanced-binary-tree construction by
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double recursion on a depth counter is the counter-example.
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**Suggested next step:** Boss-level spec decision required (this is
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not an implementer or planner judgement call — see
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`feedback_spec_over_plan_patches`: a spec defect goes back through
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`brainstorm`, not a fourth plan patch). Candidate resolutions for
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the Boss to weigh, language-first:
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(a) **Add a structural accommodation for tree recursion** — extend
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`verify_structural_recursion` so a non-tail recursive call on a
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*structurally-derived smaller value* is guarded even when the
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decreasing quantity is a primitive depth counter feeding an ADT
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build (i.e. recognise the `build_tree` shape as bounded). This
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keeps the six fixtures verbatim and is the only option that does
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not reshape LLM-natural code, but it widens it.2's structural
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checker — a Decision-10/Decision-3 spec change, brainstorm-gated.
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(b) **Carve the six into a permanent allow-list / carve-out** (like
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the existing `.ail.json` carve-outs) with an explicit
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"constructor-blocked recursion, depth-bounded by construction"
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annotation, leaving the no-ADT-candidate skip retired for
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everything else. Requires a spec sentence defining the carve-out
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predicate.
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(c) **Retire the bench fixtures that exist only to exercise the
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removed `musttail`/RC-RSS path** (`bench_latency_*`,
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`rc_pin_recurse_implicit`, `rc_let_alias_implicit_param`,
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`rc_let_owned_app_leak`) and replace `bench_tree_walk`'s
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`build_tree` coverage with a structural equivalent — but this is
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the "adapt the fixture to dodge" path the carrier and
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`feedback_dont_adapt_tests_to_bugs` explicitly forbid for
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language-limitation cases; named only for completeness, not
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recommended.
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Once the Boss resolves the spec, re-dispatch it.3 from the same
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`start_sha` (the `bench/it3-oracle/` artefacts remain valid).
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## Files touched
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Created (untracked, non-code):
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- `bench/it3-oracle/MANIFEST.tsv` (40-fixture classification)
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- `bench/it3-oracle/<stem>.out` × 40 (behavioural oracle:
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`ail run` stdout for `main` fixtures, `ail check` output for
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check-only)
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No production code, no spec, no test files modified (Task 1 is
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non-destructive by plan; the BLOCKED halted before any code-edit
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task).
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## Task 1.5 fallout map (recorded for the unblocked re-dispatch)
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Tail-app-specific tests the plan's Task 6.4 will delete:
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`crates/ailang-prose` `app_tail_renders_with_keyword`,
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`binop_with_tail_flag_keeps_prefix_form`,
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`not_with_tail_flag_keeps_prefix_form`;
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`crates/ailang-core/tests/spec_drift.rs::spec_mentions_tail_variants`;
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`crates/ailang-check` `TailCallNotInTailPosition` pins
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(`tail_call_in_tail_position_is_accepted` /
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`..._non_tail_position_is_rejected` if present); any
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`iter14e_*musttail*` e2e. (Enumeration deferred to the
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re-dispatch's Task 1.5 against the then-current tree, since the
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exact test names will drift; recorded here as the recon seed.)
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## Stats
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bench/orchestrator-stats/2026-05-15-iter-it.3.json
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