# Iter form-a.0 — Prelude Pilot

**Date:** 2026-05-13
**Parent spec:** `docs/specs/2026-05-13-form-a-default-authoring.md`
**Parent plan:** `docs/plans/2026-05-13-iter-form-a.0.md`
**Started from:** 4c2a3c5d0811aafb1bce5d6de8ad9a938fd98681

## Outcome

`examples/prelude.ail` rendered from `examples/prelude.ail.json` via
`ail render` (116 lines / 6386 bytes — exact recon match). The two
auto-discovering roundtrip tests in
`crates/ailang-surface/tests/round_trip.rs` both pass on the new
fixture without test-code changes:

- `every_ail_fixture_matches_its_json_counterpart` — green; the
  `prelude.ail` parses to canonical bytes byte-equal to
  `prelude.ail.json`.
- `parse_then_print_then_parse_is_idempotent_on_every_ail_fixture`
  — green; the Form-A printer is idempotent over prelude.

`prelude.ail.json` is retained on disk per spec §A2; iter 1 deletes
it alongside the bulk test-infrastructure refactor. This is the
only iteration in the milestone where a fixture is dual-form.

## Why this iter is the pilot

Spec §A2 names prelude as the pilot because it exercises the widest
cross-section of language features in a single file: typeclasses
with superclasses (`Ord extends Eq`), polymorphic free functions
with constraints (`forall<a> where Show a fn print`), IO-effect
signatures, primitive ctor patterns, and the loader's auto-injection
path. A green roundtrip on prelude is strong evidence the bulk
migration in iter 1+ will not surface render or parse bugs.

## Verifications run

- `cargo run -q --bin ail -- render examples/prelude.ail.json > examples/prelude.ail` — exit 0
- `wc -lc examples/prelude.ail` — `116 6386` (exact recon prediction)
- `head -n 5 examples/prelude.ail` — first line `(module prelude`, second `  (data Ordering` (exact recon prediction)
- `cargo test -p ailang-surface --test round_trip every_ail_fixture_matches_its_json_counterpart` — PASS (1/1)
- `cargo test -p ailang-surface --test round_trip parse_then_print_then_parse_is_idempotent_on_every_ail_fixture` — PASS (1/1)
- `cargo test --workspace` — PASS, **558 tests green**, identical to pre-iter baseline (audit-24 / iter-24.tidy lineage).

## Scope NOT touched

Per spec §"Iteration scope": no test-infrastructure changes, no
CLAUDE.md / DESIGN.md edits, no deletion of `prelude.ail.json`,
no migration script yet. Those land in iter 1.

## INDEX append — Boss-side

Plan Task 2 Step 2 asks for an INDEX.md append. Per the
`ailang-implement-orchestrator` Iron Law, `docs/journals/INDEX.md`
is Boss-only. The orchestrator does not touch it. The Boss appends
the line at commit time. Suggested INDEX line (from the plan
verbatim, byte/line counts confirmed by Task 1 Step 2):

```
- 2026-05-13 — iter form-a.0: prelude pilot for Form-A-as-default-authoring milestone — examples/prelude.ail rendered (116 lines / 6386 bytes) via `ail render`; two auto-discovering roundtrip tests (every_ail_fixture_matches_its_json_counterpart + parse_then_print_then_parse_is_idempotent_on_every_ail_fixture) green on the new fixture without test-code changes; prelude.ail.json retained per spec §A2 (singular dual-form iter, deletion lands iter 1 with bulk test-infra refactor); cargo test --workspace green → 2026-05-13-iter-form-a.0.md
```

## Files touched

- `examples/prelude.ail` (new, ~6386 bytes / 116 lines)
- `docs/journals/2026-05-13-iter-form-a.0.md` (this file)
- `bench/orchestrator-stats/2026-05-13-iter-form-a.0.json` (stats)

## Stats

`bench/orchestrator-stats/2026-05-13-iter-form-a.0.json`
