# diffier
[](https://github.com/spencerjireh/diffier/actions/workflows/ci.yml)
[](LICENSE)
A live diff feed for Claude Code. Run it in a second pane and every Edit, Write,
MultiEdit, and NotebookEdit shows up as a full diff the moment it lands: side
by side, with syntax colors, word-level highlights, and line numbers.
## Install
```sh
cargo install diffier
diffier install
```
`cargo binstall diffier` downloads the prebuilt binary for your platform from
the [releases page](https://github.com/spencerjireh/diffier/releases) instead of
compiling; the tarballs there can also be unpacked by hand. To build from the
development branch, use `cargo install --git https://github.com/spencerjireh/diffier`.
The binary lands in `~/.cargo/bin`. If `diffier` is not found afterwards, add
that directory to your `PATH`.
`diffier install` registers `diffier hook` in `~/.claude/settings.json` by the
absolute path of the binary, preserving everything else in that file and
writing a one-time `settings.json.bak`. Restart any running Claude Code session
so the hooks load. Run it again if you move the binary; it also removes the
`~/.claude/hooks/diffier.sh` script that versions before 0.2 installed.
## Use
Run `diffier` in any second terminal, in the repository you run `claude` in. A
tmux pane is one way to get that terminal; a separate window, tab, or editor
terminal panel works the same, because the monitor reads a spool file and does
not talk to the multiplexer.
```sh
cd ~/Projects/some-repo
tmux split-window -h diffier # then run claude in the other pane
```
It follows every session in the git repository it started in, including other
worktrees and subdirectories, replaying their recent edits before following new
ones. Once a second session has made an edit, each card carries a session tag
(the last six characters of the session id, prefixed with the worktree name
when it differs). Outside a repository, or with `--cwd-only`, it follows only
sessions whose working directory matches its own.
Edits to files in Claude Code's temp directories (`/tmp/claude-*`, the
scratchpad) are hidden by default; the status bar counts them and `o` shows
them. Files outside the repository anywhere else stay visible.
| `j` / `k`, arrows, wheel | scroll |
| `Ctrl-d` / `Ctrl-u`, PgDn / PgUp | half page / page |
| `g` / `G` | top / bottom, and resume follow |
| `p` | toggle follow |
| `n` / `N` | next / previous card |
| `Enter` | collapse / expand the current card |
| `z` | collapse / expand every card |
| `v` | toggle side-by-side / unified |
| `w` | toggle wrapping of long lines |
| `o` | show / hide edits in Claude Code temp directories |
| `Tab` | cycle the session filter: all, then each session |
| `?` | key reference |
| `q`, Esc, `Ctrl-c` | quit |
The current card is the one at the top of the view; its header stays pinned
while its body scrolls. Diffs are side by side by default and unified with
`--unified`. Side by side needs about 100 columns; below that the feed draws
unified until the terminal is wide enough again. Colors assume a dark
terminal background. Scrolling up pauses follow. Mouse capture is on for the
wheel, so select text with tmux copy mode or shift-drag.
The hook records edits whether or not a monitor is running, so you can also skip
the live view and print the cards after the fact:
```sh
diffier dump # print the current sessions' cards and exit
diffier dump --session ab12cd # only one session, by tag or id prefix
diffier dump --side-by-side --width 120 # two columns instead of unified
diffier dump --no-wrap # cut long lines instead of wrapping them
diffier dump --all-files # include edits in Claude Code temp directories
diffier run --unified # one column of -/+ lines
diffier run --cwd-only # ignore other worktrees of this repository
diffier uninstall # remove the hook and its settings entries
```
`diffier --help` covers the rest.
## More
- [docs/design.md](docs/design.md) — how the hook, spool, and snapshots fit together
- [CONTRIBUTING.md](CONTRIBUTING.md) — running the checks CI runs
- MIT licensed. See [LICENSE](LICENSE).