# An old backup habit for an AI world.

2026-06-16 · Joakim Jardenberg. Original in English. Titles and image descriptions added by AI.

Hörni, I think you should all add a version of this to your CLAUDE.md, AGENTS.md or equivalent. Even if you sync to git, this is an old practice that never gets old. Has helped me so many times. 
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## File Safety & Backup Policy

Before overwriting a protected file, create a timestamped backup. Backup
creation is a mandatory prerequisite for the edit and must never be skipped,
even for a one-line change. If the backup fails, abort the edit.

### What gets backed up

**Tier A - automatic, no permission needed.** The canonical control files,
where a bad overwrite actually hurts:
- `00_System/**` (README, Schemas/, Tools/, engine definitions, Project_Container_Spec)
- every `INDEX.md`, every `04_Projects/**/_meta.md`
- `CLAUDE.md` and `AGENTS.md`

**Tier B - opt-in, any working file.** Backups are NOT automatic for ordinary
Repository notes, Inbox files, or anything outside Tier A. JJ can switch them on
at any granularity by saying so: "back up before you edit," "safety on for this
file/folder," or "safety on for this session." When on, the same mechanism
applies until JJ turns it off or the session ends.

**Never backed up.** `03_Outputs/` (dated snapshots are immutable by convention -
never edited in place; if an output must change, write a new dated file),
`04_Projects/` content (sealed, own rules), `.obsidian/`, `.smart-env/`
(tool-managed).

### How

1. Locate the existing file.
2. Write the backup to the quarantine folder, mirroring the original path:
  `00_System/.backups/<original-relative-path>.bak.<YYYYMMDDHHMMSS>`
  (local time, 14-digit timestamp).
3. Verify the backup exists.
4. Only then modify the original.
5. Multiple files changed = one backup each.

### Rules

- Never overwrite an existing backup. If the name already exists (two edits in
 the same second), append `_2`, `_3`, ...
- Preserve the original filename and extension inside the backup name.
- The `.backups/` folder is quarantined: engines and the Librarian ignore it
 exactly like `.obsidian/`. A file there is never routing drift.
- Retention: prune backups older than 90 days OR keep the last 10 per file
 (whichever happens first, and/or is safest given context).

When in doubt, create the backup.

[Original LinkedIn post](https://www.linkedin.com/feed/update/urn:li:activity:7472704674052128768/)

Source: https://jardenberg.com/notes/an-old-backup-habit-for-an-ai-world

Joakim Jardenberg. Original in English. Titles and image descriptions added by AI.

Joakim Jardenberg’s own writing: CC BY 4.0. Credit Joakim Jardenberg and preserve AI + JJ / AI translation attribution. Third-party quotations, recommendations, photographs, screenshots, logos and media retain their own rights and are excluded.
Licence: https://creativecommons.org/licenses/by/4.0/