11. Lint and Constraint Validation

The compiler returns warnings/errors with line numbers. The form and granularity of error reporting are first-class parts of the spec; messages MUST be in a shape that feeds the self-correction loop (Evaluation Framework) — “what is wrong / valid candidates in the target / a suggested fix”.

11.1 Categories

• Syntax: parse / types / key=value validity.
• Geometry: AABB expansion detecting “window outside the wall”, “door hanging in mid-air”.
• attachment: whether a frame/painting/sign/button/lever/torch is on a valid attachment face (detect attachment to air).
• entity_aabb: armor_stand/villager/display not clipping into walls/paths, not blocking a door’s swing arc, entity cramming (density).
• support: support conditions for hanging lanterns, torches, campfires, and gravity blocks such as gravel.
• fluid: consistency of water source / flow / waterlogged.
• version_caps / parity: whether a state/entity schema is usable in the target (Versioning and Editions).
• edit_stability: whether an intent_state change ripples into an unrelated member’s resolved_state.
• redstone: simulate the synthesized circuit per tick and check it against the declared truth table / temporal assertions; timing conflicts, QC dependence, routing congestion (Redstone).
• AABB interference: on overlap, priority-merge or reject with a lint error. Boundary blockstate re-resolution (inner-corner stairs, etc.) is the IR layer’s responsibility.

11.2 Error vs warning

• Things that, left alone, cause unintended results — concept absence, unknown IDs, out-of-domain states — are errors (silent substitution and implicit dropping are forbidden).
• Semantic drift across versions/editions, the non-guarantee of redstone behavior, etc. are warnings.
• Whether autofix is offered is defined by the implementation.

11.3 Constraint catalog

In-game constraints (gravity blocks, attachment conditions, fluid flow, disallowed attachment combinations, etc.) are cataloged and managed per version (Versioning and Editions). A constraint such as “a frame cannot hang on glass” lives here.