35 lines
1.2 KiB
Markdown
35 lines
1.2 KiB
Markdown
---
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name: agent-cost
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description: >-
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Measure what an agent session actually costs in tokens using bin/agents/cost.
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Use before and after changing documentation, skills or context layout, and when
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a session feels unexpectedly expensive.
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---
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# agent-cost
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```bash
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bin/agents/cost # every project, YAML
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bin/agents/cost --repo brain-ui # only sessions whose cwd matches
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bin/agents/cost --json | jq .cursor.by_tool
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bin/agents/cost --snapshot after-x --repo brain-ui # append a row to docs/CONTEXT-BUDGET.md
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```
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Reads local session storage from OpenCode and Cursor transcripts. Reports the
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always-loaded baseline, cache hit/miss/thrash, and which tools moved the most
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bytes.
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## How to read it
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- **Baseline** is what every single message pays for: `AGENTS.md` plus anything
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eagerly linked from it. Keep it small; it multiplies by message count.
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- **Cache thrash** matters more than raw size. Editing a file that sits early in
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the context invalidates the prompt cache for the whole session.
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- **by_tool bytes** shows where the real spend is. Usually it is unfiltered
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command output, not documentation.
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## Rule
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Measure before and after. A claim that something "reduces tokens" without a
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before and an after number is an opinion, not a result.
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