Rule: the seam vs the public-data register — this brief is INSIDE the box. Do NOT re-catalog the OUTSIDE proxies (HPI / StatsCan / Teranet / municipal open data / consumer sold portals)

Rule. When publishing on MLS data, respect the seam: the project's "Ontario real-estate data source register" documents the OUTSIDE of the box (HPI, StatsCan, Teranet, municipal open data, post-2018 consumer sold portals). This brief is the INSIDE (credentialed account + DLA/AUA-fenced data). Do not re-catalog the public proxies.

Why. Duplicating the register weakens the seam and the editorial discipline. The point of separating them is that the same underlying sold/historical data now appears on both sides — that tension IS the article. Re-cataloging buries it.

How to apply. Reference the register; do not restate it. When the article wants to gesture at the public layer (e.g., "the headline price is on HouseSigma; the relisting-chain pattern is not"), point at the register rather than reproducing it. Caveat: the register itself could not be located in Drive during the source session — confirm contents before any final publication (Gaps: MLS-data inside-the-box brief (June 2026) — public-data register not located; counsel items).