Two Users Became One, Or One Became Two

The failure these share

Identity gets decided by comparing strings, and nothing raises when the comparison is wrong. You get a duplicate account, or a destructive merge, and both look like ordinary rows.

• Unicode Fold Key — two strings a human would call the same produce different keys, so one person quietly becomes two accounts.
• Sybil / Duplicate Account Scorer — exact-match on email catches nobody who is actually trying.
• Address Normalize — `"123 Main St E"` and `"123 Main St W"` score as near-identical: one character apart, two different streets, and the merge is destructive.
• Event Identity Resolver — the same concert from four ticket APIs, resolved into one event without merging the tribute band into the headliner.
• URL Dedup Key — your crawler re-fetches the same page once per `utm_source`, and the duplicate filter reports nothing because the fingerprints genuinely differ.
• Entity Identity Key — the stable key underneath all of it.

Why buy them together

Under-matching and over-matching are the same bug with the sign flipped, and a fix for one usually makes the other worse. These six cover both directions across people, places, events and URLs.

Each ships with its own tests and is sold separately. This is the set, below the sum.