Constructive materials and identity

The content tree — the contract for the data/ tree.

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.