Tool registry

The harness exposes a small local tool registry. Each tool is classified as read-only or mutating so permission modes can make reliable decisions.

Tool classes

Tool	Class	Purpose
`fs_read`	Read-only	Read files and directory summaries
`fs_glob`	Read-only	Find files by glob pattern
`fs_grep`	Read-only	Search file contents
`git_status`	Read-only	Inspect working tree state
`git_diff`	Read-only	Inspect diffs
`voss_check`	Read-only	Run Voss checks
`fs_write`	Mutating	Write a file
`fs_edit`	Mutating	Patch an existing file
`shell_run`	Mutating	Run an allowlisted shell command

File write tools produce a diff preview before permission decisions. This keeps risky changes inspectable before approval.

voss tools

The command shows registered tools and whether each one mutates state.

Tool mutability is data in the registry. Voss should not infer safety from a tool name alone.

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