hook-write-existing-file-guard

To prevent accidental overwrites, configure a filesystem guard that blocks the Write tool from replacing existing files. This mechanism forces the LLM to use the Edit tool instead, ensuring modifications preserve original content and prevent regressions in collaborative codebases.

Blocking full file rewrites while allowing generated files is best handled by configuring exemption patterns. You can specify patterns like *.lock, *.generated.*, or *.min.js to safely permit overwrites for specific files while enforcing edits on the rest.

An overwrite guard works by intercepting the Write tool to block full file replacements, forcing the LLM to use the Edit tool instead. This ensures only targeted modifications are applied, protecting existing content from being lost.

Yes, you can use overwrite protection in large repositories by enabling the guard with specific exemptions. Configuring exemption patterns allows safe overwrites for necessary files while maintaining overwrite protection across the broader codebase.

You should not use a filesystem guard to block file overwrites when working with files that require full content regeneration, unless you have configured exemption patterns. Files like *.min.js or *.lock need full rewrites and must be exempted.