Debug using logs and allocate tasks

You inherit a service where unit tests pass locally, but production logs show intermittent errors. Without a debugger, outline a step-by-step debugging plan that relies primarily on logs. Include: setting log levels, adding structured and contextual logging (correlation IDs), identifying signal from noisy logs, building a minimal reproducible case, and using feature flags or canaries to isolate changes. Explain how you would divide and assign investigation tasks across the team, establish a triage board, and track hypotheses to resolution. Walk through how you would confirm root cause, implement the fix, add regression tests/alerts, and run a blameless postmortem.