# Constructive materials and identity

- **Material metadata** lives on goods as `material: MaterialInfo` —
 only CONSTRUCTIVE materials carry it (iron_ingot, timber, leather,
 cloth, mithral_ingot). Class tags are open ids resolving
 against `tables/material_classes.ron`: metal, wood,
 leather, cloth (stone reserved for masonry's arrival). The class
 is the FAMILY WALL — a `Class("leather")` input can never be
 satisfied by a metal; mithral makes daggers, not gloves. The
 class baseline is its common material (factors 1.0); rare materials
 deviate (mithral: weight 0.5, value 10.0, work_difficulty +5,
 quality_bias +4, min_tier Master, RareRegional).
- **The constructive-identity contract** (engine implements in
 0066-a/b): output identity is CONSTRUCTED from what was consumed —
 template × actual material = the concept ("Iron Dagger", "Mithral
 Dagger"), MINTED LAZILY at first craft (no upfront cross-product;
 respected because the mint is the recorded decision). The
 FIRST-LISTED class input is the naming material (the dagger is named
 for its blade, not its grip). Stats and price derive: value =
 template cost × material value_factor × quality value_factor; weight
 = template weight × material weight_factor. Templates never
 enumerate materials.
- **Durability — the axis material OWNS **: things can
 break, and material decides how hard that is. Object toughness
 (the AC to strike or force) = `10 + class hardness + material
 toughness_bonus`; object integrity (hp) = `weight_lb × class
 integrity_per_lb × material integrity_factor` — more matter, more
 to break through. The one-writer wall from extends: TIER
 writes performance (pick DC, attack, worn AC, work), MATERIAL
 writes substance (weight, worth, toughness, integrity). A
 legendary iron lock and a legendary mithral lock pick at the same
 DC 24 — but only one of them survives a sledgehammer. The numbers
 are OURS: 5e's object-statistics chapter is DMG material, outside
 the CC-BY SRD corpus (the CR precedent), so nothing is
 transcribed. The engine consumes this in 0066-b, where breaking is
 the 0058-ledgered force path — and a jammed lock finally has a
 remedy: smash and refit.
- **The reification threshold**: mundane output is FUNGIBLE — stacks
 keyed (concept, quality). Masterwork and Legendary REIFY: an
 individual item node with provenance (crafted-by, crafted-at,
 material origin) — story-bearing objects for theft, loot, and
 inheritance; the named-cast pattern applied to things.
 Chronicle-headline worthy at birth.