Explain why a TeamCity build failed and what to do: classifies the failure (agent/pod scheduling, OOM or disk or timeout, dependency/registry, compile, tests, configuration, flaky suspect) from the build log, build problems and failed tests, with quoted evidence lines; also produces a failure-class histogram over recent failed builds to find systemic waste (builds that fail for infrastructure reasons and get rerun). Use when a build is red, when developers rerun builds "to see if it passes", and for weekly CI health reviews.
