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Major Moves · Major Purchases
Home Renovation ROI
Which renovations actually add value?
The model behind this calculator
spec v1.1.0 · 250 open casesThis calculator runs a published model: its inputs, formulas, assumptions, and exclusions are documented in a versioned specification, and it is Concordance-tested — an independent second implementation, built from that spec alone, must agree with it on 250 open test cases before any change ships. The same model is callable by AI assistants and developers.