Agent Prompt Observatory

Claude Code Prompt Observatory

[](https://github.com/ftvision/agent-prompt-observatory/actions/workflows/update-data.yml) [](https://github.com/ftvision/agent-prompt-observatory/actions/workflows/deploy.yml)

Live:

A research interface for exploring how Claude Code's system prompt has evolved across every published version. Prompt captures come from [marckrenn/claude-code-changelog](https://github.com/marckrenn/claude-code-changelog) (the rolling `cc-prompt.md` plus its commit history); historical versions through 2.1.112 were originally captured from `cchistory.mariozechner.at` before that archive went offline. A Python analyzer parses each capture into a structured model, and a Vite static UI renders that model as two views.

Views

**Structure** — single-version inspector. The current prompt rendered as a 3D layered model, stacked top-to-bottom in Anthropic's [prompt-cache order](https://platform.claude.com/docs/en/build-with-claude/prompt-caching): Tools at the top, System Prompt sections in the middle, User Prompt slabs at the bottom. Click any slab to read its prose / schema / metadata in the side panel.

**Evolution** — temporal stream graph across the entire 289-version range. Each row is a component (User Message total, System Prompt sections, every individual tool); the bar at each version's column has height proportional to character count. Empty cells mark releases where a section was absent. A model-release axis above the version axis labels Claude 4 → 4.7 launches with vertical guides threading through the matrix, so you can see when prompt changes correlate with model releases. Click any component name to expand a change-log timeline below it; click any change-log entry to see the line-level diff of that ve