Update README

README.md

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+[![Licence](https://img.shields.io/badge/GPL--3.0-orange?label=Licence)](https://git.sysmd.uk/guardutils/chguard/src/branch/main/LICENCE)
+[![Gitea Release](https://img.shields.io/gitea/v/release/guardutils/chguard?gitea_url=https%3A%2F%2Fgit.sysmd.uk%2F&style=flat&color=orange&logo=gitea)](https://git.sysmd.uk/guardutils/chguard/releases)
+[![pre-commit](https://img.shields.io/badge/pre--commit-enabled-blue?logo=pre-commit&style=flat)](https://git.sysmd.uk/guardutils/chguard/src/branch/main/.pre-commit-config.yaml)
+
+# chguard
+
+**chguard** is a safety-first command-line tool that snapshots and restores
+filesystem ownership and permissions.
+
+Think of it as a guardrail around `chmod` and `chown`:
+it records the current state, shows you exactly what would change, and only
+applies changes after explicit confirmation.
+
+## Features
+
+### Snapshots ownership and permissions
+Records numeric `uid`, `gid`, and file mode for files and directories.
+
+### Preview before restore
+Always shows a clear, readable table of differences before applying changes.
+
+### Interactive confirmation
+A single confirmation prompt at the end of a restore (default: **No**).
+
+### Dry-run mode
+Preview restore operations without prompting or applying changes.
+
+### Scope control
+Restore:
+* both ownership and permissions (default)
+* permissions only
+* ownership only
+
+### Safe by design
+* Never creates, deletes, or moves files
+* Missing files are ignored
+* New files are ignored
+* Symbolic links are skipped entirely
+* Requires sudo **only when necessary**
+
+## Non-Goals
+
+`chguard` deliberately does **not**:
+
+* restore deleted files
+* remove newly created files
+* track file contents or checksums
+* manage ACLs or extended attributes
+* provide full “undo” semantics
+
+It only concerns itself with **ownership** and **permissions**.
+
+
+## Installation
+
+### From GuardUtils package repo
+
+This is the preferred method of installation.
+
+### Debian/Ubuntu
+
+#### 1) Import the GPG key
+
+```bash
+sudo mkdir -p /usr/share/keyrings
+curl -fsSL https://repo.sysmd.uk/guardutils/guardutils.gpg | sudo gpg --dearmor -o /usr/share/keyrings/guardutils.gpg
+```
+
+The GPG fingerprint is `0032C71FA6A11EF9567D4434C5C06BD4603C28B1`.
+
+#### 2) Add the APT source
+
+```bash
+echo "deb [arch=amd64 signed-by=/usr/share/keyrings/guardutils.gpg] https://repo.sysmd.uk/guardutils/debian stable main" | sudo tee /etc/apt/sources.list.d/guardutils.list
+```
+
+#### 3) Update and install
+
+```
+sudo apt update
+sudo apt install chguard
+```
+
+### Fedora/RHEL
+
+#### 1) Import the GPG key
+
+```
+sudo rpm --import https://repo.sysmd.uk/guardutils/guardutils.gpg
+```
+
+#### 2) Add the repository configuration
+
+```
+sudo tee /etc/yum.repos.d/guardutils.repo > /dev/null << 'EOF'
+[guardutils]
+name=GuardUtils Repository
+baseurl=https://repo.sysmd.uk/guardutils/rpm/$basearch
+enabled=1
+gpgcheck=1
+repo_gpgcheck=1
+gpgkey=https://repo.sysmd.uk/guardutils/guardutils.gpg
+EOF
+```
+
+#### 4) Update and install
+
+```
+sudo dnf upgrade --refresh
+sudo dnf install chguard
+```
+
+### From PyPI
+```
+pip install chguard
+```
+
+### From this repository
+
+```bash
+git clone https://git.sysmd.uk/guardutils/chguard.git
+cd chguard/
+poetry install
+```
+
+This installs the chguard CLI into the Poetry environment.
+
+## Usage
+
+### Save a state
+```
+chguard --save /srv/app --name app-baseline
+```
+
+If the path contains root-owned files, saving requires sudo.
+
+### List saved states
+```
+chguard --list
+```
+
+Example output:
+```
+app-baseline   /srv/app   2025-12-20 18:11:08 +00:00
+```
+
+### Restore a state (preview only)
+```
+chguard --restore app-baseline
+```
+
+This shows a table of ownership and permission differences.
+
+### Restore with confirmation
+```
+chguard --restore app-baseline
+```
+
+You will be prompted:
+```
+Do you want to restore this state? (y/N)
+```
+
+The default answer is No.
+
+### Dry-run
+```
+chguard --restore app-baseline --dry-run
+```
+
+### Restore only permissions or only ownership
+```
+chguard --restore app-baseline --permissions
+chguard --restore app-baseline --owner
+```
+
+## Privilege model
+
+`chguard` never escalates privileges automatically
+
+* Saving fails if root-owned files are present and the user is not root
+* Restoring fails if changes require elevated privileges
+* Preview and dry-run operations never require sudo
+
+## Storage
+
+Snapshots are stored in a local SQLite database containing:
+
+* relative path
+* file type (file or directory)
+* numeric uid / gid
+* numeric mode
+
+Usernames and permission strings are resolved only for display.
+
+## pre-commit
+This project uses [**pre-commit**](https://pre-commit.com/) to run automatic formatting and security checks before each commit (Black, Bandit, and various safety checks).
+
+To enable it:
+```
+poetry install
+poetry run pre-commit install
+```
+This ensures consistent formatting, catches common issues early, and keeps the codebase clean.