Module slo 

SLO schema, breach detection, and safe-mode enforcement (bd-2xj.2).

Provides machine-readable SLO definitions with data-plane and decision-plane budgets. Integrates with the metrics registry (BuiltinCounter::SloBreachesTotal) and structured tracing (slo.check span).

Architecture

slo.yaml  ──parse──▶  SloSchema
                         │
        observations ──▶ check_breach() ──▶ BreachResult
                                              │
                         batch ──▶ check_safe_mode() ──▶ SafeModeDecision
                                                           │
                                  emit_slo_check() ──▶ tracing span + event

Tracing contract

• Span: slo.check with fields metric_name, metric_type, baseline, current, ratio, severity.
• WARN event for breach, ERROR event for safe-mode trigger.
• METRICS: ftui_slo_breaches_total counter incremented on breach.

Structs

BreachResult

Result of a breach check for a single metric.

MetricSlo

Per-metric SLO definition.

SloSchema

Validated SLO configuration parsed from slo.yaml.

Enums

BreachSeverity

Severity of a detected breach.

MetricType

Metric type for SLO enforcement.

SafeModeDecision

Safe-mode decision from batch breach evaluation.

SloSchemaError

Schema validation error.

Functions

check_breach

Check a single metric observation against its SLO.

check_safe_mode

Evaluate safe-mode trigger from a batch of breach results.

emit_slo_check

Emit a tracing span for SLO check and log appropriate events.

parse_slo_yaml

Parse and validate slo.yaml content.

run_slo_check

Run a full SLO check batch: parse schema, check all metrics, evaluate safe-mode.