Property-fingerprint classifier

classify:property-fingerprint computes Jaccard similarity between each record's top-level property key set and a pre-computed fingerprint per class. Useful when records lack an explicit _type discriminator and structural rules would be brittle — the shape of the property set itself becomes the signal.

Fingerprints are loaded from a JSON file at construction time and compiled into Set<string> instances. The per-record path computes |A ∩ B| / |A ∪ B| against each fingerprint and emits a proposal when the score meets or exceeds minMatchScore.

Config slot

Under classification.propertyFingerprint:

{
  "classification": {
    "propertyFingerprint": {
      "fingerprintsFrom": "./schemas/fingerprints.json",
      "minMatchScore":    0.85,
      "priority":         32
    }
  }
}

Field	Type	Required	Default	Notes
fingerprintsFrom	string	yes		Path to the fingerprints JSON file, resolved relative to the config directory.
minMatchScore	number [0,1]	no	0.85	Jaccard threshold; matches at or above this score emit a proposal.
priority	integer ≥ 0	no	32	Numeric priority written onto every emitted proposal.

Fingerprints file

A JSON object mapping className → { keys: string[] }:

{
  "feat":  { "keys": ["name", "type", "level", "description"] },
  "spell": { "keys": ["name", "tradition", "level", "components"] }
}

Each entry's keys array must have at least one element. The classifier strips _source from the record's key set before computing similarity, so source metadata never skews the score.

Emitted proposal

{
  "source":     "classify:property-fingerprint",
  "className":  "feat",
  "priority":   32,
  "confidence": 0.892,
  "reasons":    ["fingerprint:feat jaccard=0.892"]
}

confidence is the Jaccard score of the winning fingerprint. When multiple fingerprints exceed the threshold, the highest-priority (then highest-score) one wins the slot; every match appears in reasons.

Edge cases

• Empty fingerprints file. Construction throws at startup.
• Empty keys array on a class. Construction throws naming the className.
• No record keys. Jaccard of two empty sets returns 0; falls below any positive threshold; routes no-match.

See also

• Classifier cascade
• Configuration