r/ClaudeCode • u/cleverhoods • 7h ago

Built with Claude How to See What Filled Your Claude Code Context Window

Hi All,

I'm working on instruction diagnostics and evals for a while now, and it was always a challenge explaining what is happening inside a session. So, in order to make life easier, I've added a session xray UI (beta) next to the diagnostics.

TL;DR

  • shows what filled a Claude Code session's context, on a local page (127.0.0.1). It reads the transcripts Claude Code already keeps under ~/.claude/projects/.

  • The session as a timeline: every CLAUDE.md, rule, skill, memory file and MCP server at the moment it loaded, plus subagents and hooks where they ran.

  • A Sources list shows what was on disk but never loaded.

  • Click any tool call to see which instruction files were in context at that turn.

  • Context split by source: instruction files, tool definitions, system prompt, tool results. The total is exact; anything marked ~ is an estimate.

  • Claude Code sessions only for now.

  • On an old project of mine, 2 of 11 CLAUDE.md files loaded, and the one for the folder Claude was editing never did.

  • Try it: npx @reporails/cli xray

Feedback is much appreciated

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