Make the failure visible first

The move: instrument the path before arguing about the fix. A full-stack request crosses multiple ownership zones. The browser knows the click happened. The API knows the request arrived. The database knows whether the query was slow. A third-party service knows whether it accepted the call. Unless those events are connected, every layer can appear innocent. Use the three-signal mental model. Logs explain discrete events with context. Metrics show rates, counts, and latency over time. Traces connect spans into a single journey. The most valuable instrumentation sits at boundaries because boundaries are where assumptions break. Start with the question you…

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