Semantics

Failure taxonomy and deterministic actions

Qubanta expresses reliability as operational semantics. It classifies failure states, computes confidence as a pressure signal, and emits an action directive that downstream systems treat as a control contract.

Reliability model Governance

Control directive (authoritative)

The action field is the enforcement surface: accept, warn, review_recommended, fallback, blocked. This prevents ambiguous “low confidence” behavior in automation.

State (operational risk)

The state field represents system posture: stable, unstable, drift_suspected, constraint_invalid, weak_grounding. State is not a model judgement; it is an operational classification.

Flags (auditable reasons)

flags carry explicit causes: schema_invalid, missing_required_field, high_variance, contradiction_detected, retrieval_gap, dependency_degraded. Flags are logged as structured evidence.

Reliability bands

Bands translate continuous confidence into deterministic thresholds for policy. Bands are stable across model/provider churn.

band: high       confidence ≥ 0.80  → action=accept
band: moderate   0.55 ≤ confidence < 0.80 → action=accept | warn
band: low        0.35 ≤ confidence < 0.55 → action=review_recommended | fallback
band: critical   confidence < 0.35 → action=blocked | fallback

Hard collapse (weakest-link)

Certain conditions collapse confidence to zero regardless of other signals: schema invalidity, missing required fields, policy violation, forbidden content, or explicit constraint breach.

Pressure signals (0–1 bounded)

Confidence is derived from observable pressures: stability index, grounding strength, consistency index, anomaly penalty, and system health. Signals are bounded and logged.

No truth-probability claims

Qubanta does not claim correctness probability. It produces reliability control semantics suitable for safe routing, human review, and incident analysis.

Failure taxonomy

Taxonomy is designed for deterministic routing. A failure class maps directly to control actions and operator workflows.

constraint_invalid
  - schema_invalid
  - missing_required_field
  - policy_violation
  => action=blocked (always)

unstable
  - high_variance (requery divergence)
  - structured_field_drift
  - format_instability
  => action=review_recommended | fallback

weak_grounding
  - retrieval_gap
  - citation_absent (when required)
  - context_misalignment
  => action=review_recommended | fallback

drift_suspected
  - distribution_shift
  - dependency_degraded
  - latency_or_error_spike
  => action=warn | review_recommended (policy)

contradiction_detected
  - internal_conflict
  - cross_source_conflict
  => action=review_recommended (never silent accept)

Confidence computation (sketch)

Confidence uses weakest-link behavior. The system becomes unsafe when any critical signal collapses or degrades sharply.

C = 1.0
if constraint_integrity == 0: C = 0.0
else:
  C *= stability_index
  C *= grounding_strength
  C *= consistency_index
  C *= system_health
  C *= (1 - anomaly_penalty)

band = map_to_band(C)
action = policy(band, state, flags)

Developer contract Placement