Cheap per call, expensive per hour

Why the spend is invisible until it is large

Per call, an agent is trivially cheap — small enough that nobody checks. Per hour, with several agents each re-reading files, retrying, and carrying long context, it is not. Neither number is hidden, exactly; they are just kept somewhere you never look, in units that do not add up to a question you would ask. "Was this week expensive?" is not answerable from a list of API calls.

The provider dashboard does not close the gap either. It knows what your account spent; it does not know which agent, which repository, or which session spent it. When the bill is higher than expected, that is precisely the breakdown you need — and precisely the one nobody has.

One ledger, on your machine

Because every model call already passes through a local proxy, it can be written down where it happens. Mirasim keeps one ledger of every call — tokens, cache hits, estimated cost — decoded and computed on your machine and nowhere else. Pick a window (today, 7, 30 or 90 days) and it leads with the numbers that answer the question directly.

• Calls, total tokens, output tokens, cache hit rate and estimated cost — each shown against the previous period, so "more than usual" is a fact rather than a feeling.
• The same window broken down by agent, model, account, workspace and session. This is the part a provider dashboard cannot give you.
• The same calls split by route: Mirasim's platform quota or your own account, so you can see which one is paying for what.

What it changes in practice

What you get is attribution: once spend is broken down by model and by session, the expensive habits become visible and specific: one long-context loop that re-reads the same tree every turn; a reasoning level left high on a task that never needed it; a cache hit rate that dropped because a prompt now changes every call.

It also lets you test a model choice. Sessions carry their own model and reasoning level, so the cheaper option is one switch away — and after a week you can look at the ledger and see whether the cheaper one actually cost you anything in results.