scenario-synthesizer·execution·active

Scenario Synthesizer

Builds ramp-up, soak, spike, and chaos scenarios from a single SLO definition. Wires them to ARIA's reporting pipeline by default.

LEOtrigger · agent
Scenario Synthesizer
Builds ramp-up, soak, spike, and chaos scenarios from a single SLO definition. Wires them to ARIA's reporting pipeline by default.
When this skill fires
·An engineer pastes an SLO into LEO:"99.5% of checkout requests under 800ms p95 sustained for 5 minutes"
·A new service is onboarded and needs a baseline scenario suite
·A regression is detected and LEO needs to regenerate scenarios with tighter thresholds
SLO decomposition
An SLO has three components: objective (latency, error rate, throughput), threshold (the number), and window (the time it must hold). Scenarios cover each combination.
Ramp-up scenarios
Find the user count at which the SLO starts to bend. Output is the bend point — the concurrency level where p95 latency crosses the threshold. Engineering acts on this number, not the raw curve.
Soak scenarios
Hold load constant at 80% of the bend point for 1 hour, 4 hours, or overnight. Surfaces:
·Memory leaks (steady upward heap growth)
·Connection pool exhaustion
·File-descriptor leaks
·Slow DB index growth
Spike scenarios
Sudden 10× load increase, sustained for 1 minute, then back to baseline. Tests:
·Auto-scaling responsiveness (does the new capacity arrive before the SLO breaks?)
·Cache cold-start behavior
·Connection pool ramp-up
Chaos scenarios
Inject one failure during sustained load:
·Kill a downstream service
·Add 500ms latency to the database
·Drop 10% of network packets to a dependency
·Saturate disk I/O on one node
Chaos scenarios run only in environments explicitly tagged chaos-safe. LEO refuses to inject failures into prod without a documented approval.
Reporting pipeline integration
By default, every scenario writes its metrics to a structured run document that ARIA'sCross-Agent Synthesizer consumes. Engineers don't manually pipe load test results into the quality report — it happens by default.
What it produces
For a given SLO, a scenario suite of 4–8 scripts:
·One ramp-up to find the bend point
·One soak at 80% of the bend point
·One spike at 10× baseline
·1–4 chaos scenarios depending on the service's dependency surface
Each scenario is a complete, runnable artifact (k6 / JMeter / Locust) tagged with the SLO it derives from. ARIA can later cite"this scenario, in this run, on this date" when explaining a regression.