.claudeignore Doesn't Exist. Here's What Does. — Daily DevOps & .NET
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Claude Code does not support a .claudeignore file — Claude hallucinated this feature, and the misinformation spread widely across blogs, Stack Overflow, and wikis. Developers who added .claudeignore files believing they were protecting secrets were getting no protection at all. The actual mechanism in Claude Code is permissions.deny in .claude/settings.json, but this only restricts the Read tool, not Glob or Grep. GitHub Copilot has a content exclusion feature but it requires Business/Enterprise tier and doesn't apply to agent workflows. OpenAI Codex has no built-in exclusion mechanism. For .NET projects, .gitignore provides broader coverage for build artifacts, while the real security answer is never storing credentials in the repository in the first place.
Table of contents
The Problem: Claude Hallucinated Its Own FeatureClaude Code: permissions.deny in SettingsGitHub Copilot: Exists, But Read the Fine PrintOpenAI Codex: NothingWhat This Means for .NET ProjectsThe Feature That Should Exist But Doesn’tSort: