Purity Thresholds

Arcform owns and enforces all purity thresholds. Signal providers (e.g. LumenSeed) supply raw values — Arcform determines whether those values qualify for badge issuance. These thresholds are immutable platform rules, not configuration.

Threshold Reference

Metric	Field	Operator	Verified Tier	Hard Limit	Description
Drift	drift	≤	0.10	0.30	Measures signal stability over time. Lower is better. Drift above the hard limit means the signal is too unstable for any badge.
Clarity	clarity	≥	0.75	—	Semantic clarity of the attested page. Higher means the page content is unambiguous and well-structured.
Coherence	coherence	≥	0.70	—	Structural coherence of the page layout. Measures whether sections relate logically to each other.
Confidence	confidence	≥	0.90	—	Engine confidence in its reading of the page. A low confidence means the signal engine is uncertain about its assessment.

Badge Tier Assignment

🟢

Verified

All four thresholds met: drift ≤ 0.10, clarity ≥ 0.75, coherence ≥ 0.70, confidence ≥ 0.90

🟡

Normal

Basic drift check passes (≤ 0.30) but one or more strict thresholds not fully met

🔴

Denied

Drift exceeds hard limit (> 0.30) — not eligible for any badge

Error Behaviour

422 — Badge Issuance Denied

Returned when drift exceeds the hard limit (0.30). The response includes a reason field with the exact drift value and the threshold it violated. This is not retryable without improving the underlying signal.

Normal Tier (downgrade from Verified)

When drift passes the hard limit but one or more strict thresholds fail, the badge is still issued at the "normal" tier. No error is returned — the tier field in the response indicates the downgrade.

API Response Example

{
  "badge_id": "arc_A1b2C3d4E5f6G7h8I9j0K1l2",
  "tier": "verified",
  "trust_envelope": {
    "drift": 0.05,
    "clarity": 0.88,
    "coherence": 0.82,
    "confidence": 0.95,
    "thresholds": {
      "drift_max": 0.1,
      "clarity_min": 0.75,
      "coherence_min": 0.7,
      "confidence_min": 0.9
    }
  },
  "issued_at": "2026-07-23T12:00:00.000Z",
  "expires_at": "2026-08-22T12:00:00.000Z"
}

The trust_envelope always includes both the actual values and Arcform's thresholds, so verifiers can independently confirm why a badge was issued at a given tier.