A context-aware permission guard for Claude Code
We needed something like --dangerously-skip-permissions that doesn’t nuke your untracked files, exfiltrate your keys, or install malware. Claude Code's permission system is allow-or-deny per tool, but that doesn’t really scale. Deleting some files is fine sometimes. And git checkout is sometimes not fine. Even when you curate permissions, 200 IQ Opus can find a way around it. Maintaining a deny list is a fool's errand. nah is a PreToolUse hook that classifies every tool call by what it actually does, using a deterministic classifier that runs in milliseconds. It maps commands to action types…
In plain words
Nah is a permission system for Claude Code that classifies tool calls by their actual effects rather than allowing or denying entire tools. It uses a fast deterministic classifier to map commands to action types—like filesystem operations, package execution, and database writes—then applies policies to each action: allow, ask, block, or context-dependent. This lets developers permit some file deletions while blocking others, or allow git commands selectively. For ambiguous cases, it can escalate to an LLM for judgment. It's designed for developers who want granular control over AI code execution without maintaining deny lists.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
We needed something like --dangerously-skip-permissions that doesn’t nuke your untracked files, exfiltrate your keys, or install malware. Claude Code's permission system is allow-or-deny per tool, but that doesn’t really scale. Deleting some files is fine sometimes. And git checkout is sometimes not fine. Even when you curate permissions, 200 IQ Opus can find a way around it. Maintaining a deny list is a fool's errand. nah is a PreToolUse hook that classifies every tool call by what it actually does, using a deterministic classifier that runs in milliseconds. It maps commands to action types like filesystem_read, package_run, db_write, git_history_rewrite, and applies policies: allow, context (depends on the target), ask, or block. Not everything can be classified, so you can optionally escalate ambiguous stuff to an LLM, but that’s not required. Anything unresolved you can approve, and configure the taxonomy so you don’t get asked again. It works out of the box with sane defaults, no config needed. But you can customize it fully if you want to. No dependencies, stdlib Python, MIT. pip install nah && nah install https://github.com/manuelschipper/nah
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