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Foglamp prices every span the moment it arrives, using the token counts the provider reported. Cost is never recomputed later, so what you see in a trace is what was calculated when it landed.

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How pricing works

Each usage dimension is priced on its own against a model price table sourced from OpenRouter and refreshed every 24 hours. The priced dimensions are prompt, completion, request, image, web search, reasoning, cache-read, and cache-write tokens. The span detail panel shows a pricing source so you can see where each cost came from.
A model Foglamp can’t find a price for shows as (unknown) in cost breakdowns, never as $0. The Overview’s ”% priced” number tells you what share of LLM spans got a price; a low number usually means you’re running a model OpenRouter doesn’t list yet.

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Where cost shows up

  • Overview: total cost, cost over time stacked by model, and per-model and per-agent cost tables.
  • Traces: per-span cost and pricing source.
  • Agents and Workflows: cost totals per agent and per run.
  • Alerts: alert on cost over a time window.