Validation cases

The generality benchmark: domain specs written with no domain keywords, desk-checked against the specification alone — every point where writing them stalls is a specification defect by definition (requirements §4). These files are review artifacts of Phase 0; in Phase 1 they seed the test corpus.

Case	File	Status
1. Hardware interconnect	01_interconnect.decl	written, desk-checked — ports a real 2x2 crossbar fixture
2. API/config schema	02_config.decl	written, desk-checked
3. Test fixture generation	03_fixtures.decl	written, desk-checked

Feature coverage

• Case 1: hierarchical node graph as records + maps (recursive types), edges as ref<Port> records instead of parsed strings, connection-based width propagation as one derived member over $referrers (replacing the legacy fixture’s ~20 @readonly lambdas), internal wiring as derived Edge[] members, an & constraint layer (EdgeHost) shared by both container roles, owner-dependent flow rules via place equality, locality via std.ref.path + starts_with, address-map destination validity via map-key membership, fan-in/out counts, discriminated node unions.
• Case 2: open records with opaque pass-through, defaults at every member, optional-vs-null (cert_path?), conditional constraints (when + in presence guard), quantities with defaults, pattern-keyed maps, environment layering with with (including nested with for depth), outputs as shared baselines, external validation of the same schema.
• Case 3: comprehension-parameterized generation (a 4×8 sweep of 32 cases × 16 packets), range-iteration typing, literal-union element types with the annotation they require, derived aggregation (std.array.sum over a projection), uniqueness asserts, conditional expression in generation.

Desk-check findings

Defects found by writing these cases (each already fixed in the spec — the point of the exercise):

1. Comprehension variables had no typing rule — for p in 0..<8 inferring p: int would make priority: p fail statically against 0..7. Fixed: the iteration variable of a range takes the range itself as its type (spec §4.8).

2. std.object.merge cannot layer schemas with defaults — the patch argument is an evaluated value, so its filled defaults win over the base’s explicit values. Fixed by documentation, not mechanism: the defaults trap is now stated in spec §13.7, and layering uses with (as case 2 demonstrates).

3. Sibling references in typed construction were unstated — case drafting (and the guide before it) relied on source: services[0] inside an output literal; the rule is now explicit in spec §4.2.

4. ref positions collided with the maybe-absent discipline — source: ports["si0"] (map access) would have been a compile error, making map-keyed ports unreferenceable. Fixed: a navigation in a ref<T> position denotes a place regardless of maybe-absent steps; whether the target exists is the dangling-reference check, not absence discipline (spec §4.10, §7.4).

5. No narrowing through && — the own-port idiom k in ports && ports[k] == e.source was ill-typed. Fixed: narrowing flows through && (and negated through ||) (spec §4.10).

6. Union common-member access was unstated — e.source.width on ref<ExtPort | IntPort> needed a rule. Fixed: access is legal when every arm declares the member, typing as the union of member types (spec §4.3).

7. Reference targets’ paths were unobservable — locality constraints (“edge endpoints lie inside me”) were inexpressible. Fixed: std.ref.path added, with std.string.starts_with (spec §13.6, §13.9) — additions justified by the §0.3 scope rule (the corpus now uses them).

OQ3 evidence from case 1: every constraint the legacy fixture family actually enforces — widths, flow direction, locality, fan counts, destination validity — is one-hop; no transitive closure was needed, and the legacy fixture never checked reachability either (it could not). Source-to-sink reachability remains a plausible want for richer versions; the spike should still measure it, but the ported corpus alone does not justify std.graph.*.

Ergonomics observations (not defects; recorded for the spike): overriding one sub-member of a defaulted record member requires restating the whole member (no deep default merge — related to the §13.7 merge trap); the own-port test reads heavily (any(keys(...), (k) => k in ... && ...)) — a containment or same-owner predicate may deserve stdlib entry if the spike confirms the pain.