Observability engineering · 2026 · Solo — research, systems design, build, verification
Tail Scope
Tune error, latency, route, fallback, and capacity policy, then see exactly which completed traces survive.
The problem
Tail sampling can use information from a completed distributed trace, but ordered criteria and resource pressure make configuration difficult to reason about from text alone. Tail Scope turns that bounded decision into a local comparison without claiming OpenTelemetry Collector parity or production capacity estimates.
Architecture
Key decisions
Evaluate the whole trace in one pure engine
Span aggregation, ordered matching, stable hashing, and budget eviction return one evidence record. The UI does not re-derive policy decisions, which keeps behavior deterministic and testable.
Preserve high-signal decisions under pressure
When capacity drops, error and latency matches outrank route and probabilistic fallback matches. Every eviction still records the rule it matched before the budget gate.
Bound the model instead of overstating it
The release uses six English-only fixtures and four rule kinds. It explicitly excludes OTLP ingestion, Collector configuration parity, production memory estimates, export, and persistence.
Make publication evidence transactional
The private product repository is separate from this portfolio site. Production behavior, rendered English, responsive screenshots, and the Vercel status attached to the pushed Git SHA passed before this case study was added.