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Brummel e3b0dd20c5 iter rt.2: DESIGN.md anchor — Roundtrip Invariant lifted to top-level

New top-level section '## Roundtrip Invariant' between Decision 11
and '## Mangling scheme'. States both directions of the .ail.json
↔ .ailx bijection, names Float-bits-hex encoding as the in-
invariant mechanism (not an exception), lists the four enforcement
tests by path, and explains why the property is top-level
(load-bearing on language identity, not on Decision 6's surface-
design rationale).

Decision 6 Constraint 2 rewritten as upward cross-reference to the
new section; the substantive content now lives at the anchor.

Direct boss edit (no planner/implement dispatch): spec Architecture
#1 fully specified the content, no design judgement deferred to
execution. The iter is a deterministic projection of the spec
onto DESIGN.md prose.

2026-05-12 09:38:56 +02:00

2.9 KiB

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iter rt.2 — Roundtrip Invariant anchored at top level in DESIGN.md

Date: 2026-05-12 Started from: b6046bbf (post-rt.1, working tree clean) Status: DONE Tasks completed: 1 of 1

Summary

DESIGN.md gains a new top-level section ## Roundtrip Invariant, positioned between Decision 11 and ## Mangling scheme. The section states both directions of the .ail.json ↔ .ailx bijection, names the Float-bits-hex encoding as the mechanism that keeps Floats inside the invariant, lists the four enforcement tests by path, and explains why the property is top-level (load-bearing on language identity, not on Decision 6's surface-design rationale).

Decision 6 Constraint 2 is rewritten as an upward cross-reference to the new top-level section. The substantive content of the constraint now lives at the anchor; Decision 6 records that its surface design must satisfy the anchored invariant.

Why boss-direct edit (no planner / implement dispatch)

The spec's Architecture #1 fully specified the content (statement both directions, Float-mechanism subsection, enforcement-points list, why-top-level justification, Decision 6 cross-reference). No design judgement was deferred to execution time; the iter is a deterministic projection of the spec onto DESIGN.md prose. Plan + implement dispatch for a pure docs edit with all content pre-specified is overhead without value, per CLAUDE.md "trivial mechanical edits" carve-out (the LOC budget is exceeded but the judgement budget is zero).

Files touched

docs/DESIGN.md:
- Inserted new ## Roundtrip Invariant section (Z. 1753+, just before ## Mangling scheme).
- Rewrote Decision 6 Constraint 2 (Z. 249-253) as an upward cross-reference to the new section.

Verification

cargo test --workspace — all tests green, no regressions. The schema-drift tests in crates/ailang-core/tests/design_schema_drift.rs scan DESIGN.md for anchors and were the most likely place for the DESIGN.md edit to surface false-positive failures; they remain green.

Milestone status

The roundtrip-invariant milestone has now satisfied acceptance criteria 1-7 from docs/specs/2026-05-12-roundtrip-invariant.md:

✓ Top-level ## Roundtrip Invariant section in DESIGN.md; Decision 6 Constraint 2 carries upward cross-reference. (rt.2)
✓ every_ailx_fixture_matches_its_json_counterpart dynamic in crates/ailang-surface/tests/round_trip.rs. (rt.1)
✓ crates/ailang-core/tests/schema_coverage.rs with exhaustive-match visitor; 34/34 variants observed. (rt.1)
✓ crates/ail/tests/roundtrip_cli.rs with BLAKE3 identity over ail render → tempfile → ail parse. (rt.1)
✓ cargo test --workspace green with all four tests. (rt.1 + rt.2)
✓ No roundtrip gaps surfaced; no render/parse code changes needed in this milestone. (rt.1)
✓ Tests are pure readers; the CLI test's only filesystem side effect is tempfile::TempDir. (rt.1)

Audit skill follows for milestone close.

2.9 KiB Raw Blame History