Add logging to code you did not write

Here's a module I inherited and now have to support: {{paste the code}}. It currently logs {{nothing / everything at debug}}.

Propose targeted logging, not a rewrite. For each suggested line give me: the exact placement, the level, the message, and the structured fields — and one sentence on the question that log line answers at 3am.

Cover: every entry point with its inputs summarised (never the full payload), every external call with its duration and outcome, every branch where the code silently swallows a failure, and the exit with the result shape.

Hard rules: no secrets, tokens, emails or full request bodies. No logging inside a tight loop without a sample rate. Nothing at ERROR that the code recovers from on its own.

Then list the three log lines that would have the highest value if I could only add three — I'll start there.