Adding another workflow is usually the cheap answer, until it isn't. Six signals that a GoHighLevel account has outgrown the builder, the honest case for staying in it, and the three levels of code to try before committing to a marketplace app.
A backfill that exits zero can still be missing a week of data, and nothing will tell you. This is a practical guide to the failure families behind silent gaps: pagination drift under a mutating source, retries that duplicate pages, prefix layouts designed for writes instead of reads, the seam where backfill meets live ingest, and the storage class rules that make mistakes expensive. Includes deterministic key derivation, S3 conditional writes, Athena partition projection, and a per-window manifest pattern that turns completeness into something you can query.
Third-party API spend is the one production signal with no error rate attached to it, which is why it creeps up quietly. This is a working engineer's guide to reducing SaaS API costs by changing the shape of your calls: reading the billing unit before you optimise anything, killing pointless polling with conditional requests and webhooks, collapsing N+1 patterns, caching with stampede protection and per-tenant keys, stopping your own retry amplification, and attributing spend so you can prove the work paid off.