AnvilCalc

Simulates exactly one Minecraft anvil operation — combining `item` (the base, left slot) with `sacrifice` (the right slot), optionally renaming the result — with no search or planning: it's a direct simulation of that specific in-game anvil use, not a 'find the cheapest way to reach X' query. Returns the XP-level cost, feasibility, and the resulting enchantments. A sacrifice enchantment the base item cannot take (e.g. Efficiency from a book onto a sword) is ignored by the anvil: cost 0, `transferred: false`. For finding the cheapest multi-step path from a current state to a target enchantment set, use anvil_migration_path instead.

Compute the cheapest Minecraft anvil combine path to migrate an item's existing enchantments (and prior-work penalty count) to a target enchantment set. sourceItem and targetItem must be the same item id (e.g. both 'diamond_sword') — a mismatch is a tool error, not a silent conversion. Inventory usage is set by two optional inputs: with no availableSources the inventory is not used ("Don't use": every needed book/item is assumed obtainable); with availableSources the plan may use them when they help and assumes the rest is obtainable ("May use"); with inventoryOnly: true, which is never implied, only the listed items are considered, lower levels may be combined into higher ones (two same-level books into the next level) but no outside book is ever assumed ("Only use"; a plan the inventory cannot complete comes back as error 'blocked_plan'). Optional `objective`: 'min_xp' (default, fewest XP levels) or 'min_prior_work' (fewest anvil operations on the finished item so it stays cheap to upgrade later, then fewest XP levels); when set, the response also reports the objective used, the total XP and the result's prior-work count. Returns ordered combine steps, per-step and total cost, feasibility, and a plain-language summary. Fails clearly, as a tool error, if the target requires downgrading an enchantment level (not possible on a vanilla anvil).