Safe fs edit

Skill MichaelAdamGroberman/mac-mcp/skills/safe-fs-edit

Use BEFORE any fs_write with mode='overwrite' or mode='append' on a file that already exists, especially user documents, source code, dotfiles, or anything not under version control. Snapshots the original to a timestamped path so the change is reversible without relying on the user's Time Machine.From its SKILL.md

Install

npx -y skills add MichaelAdamGroberman/mac-mcp --skill safe-fs-edit

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

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SKILL.md

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Safe overwrite for mac-mcp filesystem edits

fs_write with mode='overwrite' is destructive — it replaces the file's contents in one atomic operation with no undo. fs_delete defaults to Trash so it's recoverable; fs_write does not. This skill adds a recovery layer.

Workflow

Before calling fs_write on an existing file:

Stat the target to confirm it exists and is reasonable size:
```
fs_stat path=<target>
```
If kind != "file" or size > 50_000_000, abort and ask the user.

Snapshot it to a timestamped path under ~/.mac-mcp/snapshots/:

fs_make_dir path="~/.mac-mcp/snapshots/<YYYY-MM-DD-HHMMSS>" parents=true
fs_copy src=<target> dst="~/.mac-mcp/snapshots/<ts>/<basename>"

Then perform the write:

fs_write path=<target> mode="overwrite" text=<new content>

Tell the user in the response message what you snapshotted and where, so they can fs_copy it back if needed:

Saved snapshot at ~/.mac-mcp/snapshots/2026-04-17-014203/foo.swift before overwriting.

When to skip

The file is in a git working tree and git diff would show the change (the user has version control)
mode='create' (file doesn't exist yet — nothing to lose)
The user explicitly says "don't snapshot, just write"

Cleanup

Don't auto-delete snapshots — the user does that. If they ask "clean up mac-mcp snapshots", call fs_delete path="~/.mac-mcp/snapshots/<old>" (trash, not permanent).