Hands-On · Building a Memory-Enabled AI Writing Partner (Part 4): Observability (Metrics + Logs + Trace + Cost)

Thu, 05 Feb 2026 16:00:00 +0800

In the previous post, we discussed the security of RAG systems and prompt injection protection. Today, let’s dive into another engineering deep-water zone: Observability.

When a system evolves from “it works” to “it works reliably long-term,” you will inevitably encounter three types of problems:

Slow: Is retrieval slow? Is the LLM slow? Or is some Agent stuck in a retry loop?
Expensive: Is token consumption being silently drained by a specific chain? Why doesn’t this month’s API bill add up?
Strange: Intermittent bugs that can’t be reproduced, leaving you to fix code based on “gut feeling.”

At this stage, I chose to build a complete Metrics + Logs system, rather than just sprinkling in a few print statements.

Observability - Tag - Shengxu · Cloud Architecture & DevOps

Hands-On · Building a Memory-Enabled AI Writing Partner (Part 4): Observability (Metrics + Logs + Trace + Cost)