In Part 3, I mapped the kinds of sources that can feed a Second Brain. That raised the next practical problem: How do I know what entered the system, what happened to it, and what still needs my attention? I’m working with two lightweight tools for this: a Second Brain Ingestion Log Lite and a Source Review Queue Lite. They sound similar, but they serve different purposes. The ingestion log is the receipt. It records meaningful captures and maintenance events, not every typo, wording change, or small edit. The goal is to preserve enough state to understand what happened and resume safely if the work stops halfway through. A useful log entry might answer: - What kind of source entered? - What action was taken? - Where did the resulting material go? - Is the work complete, partial, or blocked? - Where should I resume? This matters because a successful capture can still leave unfinished work. A source may have been saved but not synthesized. A note may have been updated while related material still needs checking. A maintenance pass may have started without reaching a safe conclusion. The log helps me avoid relying on memory to reconstruct that state later. The Source Review Queue Lite is different. It is not primarily about recording activity. It is a decision lane for captured material that may still require judgment. An item might need to be: - synthesized with related material; - merged into a canonical note; - adopted into the working knowledge base; - retained for reference only; - held for approval; - or intentionally ignored. That last option matters. An AI-ready Second Brain should not create an obligation to process everything. Some material will not be useful enough to justify more attention. The queue makes that an intentional decision rather than an accidental omission. The relationship between the two tools is simple: The log answers: What entered? What happened? Where do I resume? The queue answers: What deserves judgment? What should happen next?