Agent Cache Meter

Prompt-Cache Meter

Agent Cache Meter is a prompt-cache meter for omp and Claude Code. It shows how many tokens each request read from the cache, wrote to it and sent uncached, and counts down to the cache’s expiry. When the cache goes cold, it shows what rebuilding it costs and whether /compact pays for itself. A plugin for Tern, Stencil’s terminal, shows every agent’s cache in one place.

Agent Cache Meter is a prompt-cache meter for omp and Claude Code. It shows how many tokens each request read from the cache, wrote to it and sent uncached, and counts down to the cache’s expiry. When the cache goes cold, it shows what rebuilding it costs and whether /compact pays for itself. A plugin for Tern, Stencil’s terminal, shows every agent’s cache in one place.

Location

Cluj-Napoca

Oct 2026 - Present

Industry

AI Developer Tools

View on GitHub

Challenge

Every request sends the whole conversation again. The prompt cache makes that cheap, since cached tokens cost a tenth of normal input, but the cache lives only an hour after the last request (five minutes on an API key).

Coming back after it expires costs one full rebuild. In a real 487k-token session, that first request cost $3.63, the price of 30 normal requests. A large context also costs on every request, even with a warm cache. None of this was visible while working, so there was no way to tell when to continue and when to compact.

Results

• One-line meter: sits above the composer and redraws every second, with read, write and uncached tokens, the hit rate and an expiry countdown.

• Four clear states: warm, expires soon, cold and reset by /compact, each with its own badge and next step.

• Continue or compact: on a cold cache, the meter compares both paths and recommends /compact only when it pays for itself.

• /cache panel: per-turn reads, writes, hit rate and cost, what the cache saved this session, plus /cache settings.

• Three parts: an omp extension, a Claude Code status line on npm (claude-cache-meter) and a Tern plugin with tab countdowns, expiry toasts and a canvas listing every agent.

Stack

Stack

Stack

Conclusion

Agent Cache Meter makes prompt-cache costs visible at the moment they matter: before the cache expires, and right after it has. Instead of guessing, you see what the next request will cost and whether compacting first is cheaper.

The omp extension and the Claude Code status line each work on their own in any terminal, and the figures in the docs are redrawn from the packages’ own price tables.

Agent Cache Meter makes prompt-cache costs visible at the moment they matter: before the cache expires, and right after it has. Instead of guessing, you see what the next request will cost and whether compacting first is cheaper.

The omp extension and the Claude Code status line each work on their own in any terminal, and the figures in the docs are redrawn from the packages’ own price tables.