HORIZON SHIELD

HORIZON SHIELD checks whether a Japanese construction or renovation estimate is fair. Give it a work type and a quoted price in JPY and it returns the typical price range, a verdict on the quote (ok, watch or alert, or ambiguous when candidates disagree), known overcharge and high-pressure sales tactics in the wording of an estimate or sales pitch, and contractors in Japan that passed the same independent check.

Every fair-price verdict carries a SHA-256 hash that anyone can recompute, and price ranges come with the source row ids and the formula. The ranges are built on JCCDB, an open construction-cost dataset (v5.1, 526,128 records, CC BY 4.0) curated by Toshikatsu Oga from thirty years of site experience.

Intended for homeowners and the people helping them read a quote. Limits: fair-price verdicts cover Japan only, in JPY; work names match best in Japanese; a verdict is a reference range for the homeowner to act on and does not declare a contractor dishonest. Two tools (verify_fair_price and create_ap2_fairness_attestation) append a record to a public ledger; every other tool only reads. Detailed public cost data for Japan and the U.S. is served by a separate server, HORIZON SHIELD Construction Cost Data.