Adding Langfuse Observability to Hermes Agent (Self-Hosted, the Hard Parts Included)

Langfuse observability for Hermes Agent is the way to see, per query, what your self-hosted agent actually does: which model it called, how many tokens it burned and what it cost. Hermes Agent is not built on LangChain, so it reports traces through Langfuse’s native OpenTelemetry support instead of a framework plugin. In this post I wire self-hosted Langfuse into a self-hosted Hermes Agent on a single Hetzner VPS, and share the gotchas that only show up when you actually run it. My Hermes agent runs 24/7 on my own VPS. It answers me on Telegram, fires cron jobs at 3 AM and swaps between half a dozen models depending on the task. Here is the embarrassing part: I had no idea if it was costing me ₹50 a month or ₹5,000. For someone who is an AI Observability Architect by profession, being blind to my own agent’s spend felt a bit like a dentist walking around with a toothache. I use the OpenCode provider for Hermes. My default profile runs on deepseek-v4-flash, which is cheap per token.…