# Optimize Object-Backed APIs and Design an LLM Observability Platform First, improve POST and GET endpoints that currently read a large JSON object from object storage and scan strings for offsets, reducing a roughly twenty-second path toward a five-to-seven-second target with benchmark evidence. Then design an observability platform for LLM traces, token usage, latency, billing, alerts, and anomaly detection. ### Constraints & Assumptions - Object storage is durable but not a low-latency row database. - Optimizations must preserve API correctness and be justified by measured data. - Observability events can arrive late or duplicated. - Dashboards tolerate modest delay, while monthly billing and alert deduplication require exact state. ### Clarifying Questions to Ask - Which operation dominates the current latency: object transfer, parsing, search, serialization, or write-back? - Can the storage format or API contract change? - What are the alert window, threshold, notification, and reset semantics? ### Part 1 — Endpoint optimization Describe a benchmark, profiling plan, candidate storage and indexing changes, and a report that attributes each improvement. #### What This Part Should Cover - Representative workload and percentile latency - Network, parse, search, and persistence breakdown - Correctness regression tests and cost trade-offs ### Part 2 — Observability platform Design trace ingestion, tagged metrics, dashboards, token billing, threshold alerts, anomaly detection, late-data handling, and duplicate suppression. #### What This Part Should Cover - Durable event identity and tenant isolation - Streaming aggregates plus exact billing ledger - Windowed alert state, notification deduplication, and anomaly evaluation ### What a Strong Answer Covers - Evidence-linked performance changes - Separate approximate observability from exact accounting - Alert state that survives retries and restarts ```hint Optimize the measured bottleneck A faster string search cannot meet the target if most time is object transfer or full-object rewrite. Measure the full request path before choosing the index. ``` ### Follow-up Questions - When should the JSON object be replaced by a database? - How would you prevent a late event from sending a duplicate alert?