--- title: "Using a behaviour index to help AI coding agents explore your code" url: https://daily.dev/posts/using-a-behaviour-index-to-help-ai-coding-agents-explore-your-code-njc2lzak1 source_url: https://itnext.io/using-a-behaviour-index-to-help-ai-coding-agents-explore-your-code-f02ecbf6f2ef type: article source: "ITNEXT" published: 2026-06-25T08:05:18.693Z updated: 2026-06-25T08:05:44.833Z tags: ["testing", "ai-agents", "vitest"] reading_time: 13 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Using a behaviour index to help AI coding agents explore your code **[ITNEXT](https://daily.dev/sources/itnext)** · 13 min read · 0 upvotes · 0 comments ## Summary A 'behaviour index' is a Markdown file (BEHAVIOR.md) auto-generated from test names and file locations that helps AI coding agents and humans navigate a codebase. Instead of searching raw code lines (expensive in tokens) or file paths (low information density), agents search the behaviour index to quickly understand what a concept means in the app and where its implementation lives. The post compares token costs across three search strategies using the Codex CLI repo, shows how to generate the index via test reporters or regex scripts, and covers limitations like weak test suites, parameterised test names, and agents that ignore custom search instructions. Optimisation tips include embedding code symbols in test names and maintaining separate AI and human versions of the index. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#testing](https://daily.dev/tags/testing), [#ai-agents](https://daily.dev/tags/ai-agents), [#vitest](https://daily.dev/tags/vitest) [View this post on daily.dev](https://daily.dev/posts/using-a-behaviour-index-to-help-ai-coding-agents-explore-your-code-njc2lzak1)