Say memory on one of your Node services just keeps climbing in production. How would you dig into that without bouncing the process?

I'd start with process.memoryUsage() and look at which number is actually growing. RSS is the total resident memory the process is holding. heapUsed is how much of the V8 heap is in use, and external is memory from C++ objects bound to JavaScript, Buffers mostly. If heapUsed keeps growing it's probably a JavaScript leak, objects being retained that should have been collected. So I'd take heap snapshots at intervals and compare them in Chrome DevTools to see what's piling up. Usual suspects are unbounded caches, event listeners nobody removed, closures holding references, that kind of thing. If it's external that's growing, that points at Buffers or native memory instead. Basically look at what allocates over time and whether the references ever get released, then fix whatever code is holding them. Restarting just masks it, so the goal is finding the actual retention.