delta

A terminal-based diff review tool for AI-assisted development workflows.

When an AI agent finishes a coding task and checks in with you, delta gives you a structured way to review its changes, leave targeted feedback on specific hunks of code, and export that feedback in a format you can hand directly back to the agent.

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The Problem

Reviewing AI-generated code changes typically looks like this:

1. Agent makes changes and checks in
2. You hunt through files manually to find what changed
3. You copy file paths and write a long unstructured message back
4. Agent iterates — repeat

Steps 2–4 are friction. delta replaces them with a focused review session that produces structured output.

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Workflow

delta <from> [<to>]

Opens a terminal UI showing all files changed between <from> and <to> (defaults to HEAD). You navigate the diff, leave notes on specific hunks, and when you quit, delta writes your feedback — anchored to file, hunk, and code context — to stdout (or a file). Feed that output back to the agent.

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Installation

Option 1 — Install script

Linux (bash):

curl -sSf https://raw.githubusercontent.com/tbrittain/delta/main/install.sh | bash

Installs to ~/.local/bin. To install elsewhere:

curl -sSf https://raw.githubusercontent.com/tbrittain/delta/main/install.sh | bash -s -- --install-dir /usr/local/bin

Windows (PowerShell 5.1+):

iwr -useb https://raw.githubusercontent.com/tbrittain/delta/main/install.ps1 | iex

Installs to %LOCALAPPDATA%\Programs\delta\ and adds it to your user PATH.

Option 2 — Download a release binary

Download the binary for your platform from the Releases page and place it on your PATH.

Platform	File
Linux x86_64	delta-vX.Y.Z-x86_64-unknown-linux-gnu.tar.gz
Windows x86_64	delta-vX.Y.Z-x86_64-pc-windows-msvc.zip

macOS and Linux ARM64 are not supported targets.

Option 3 — Build from source

Requires the Rust toolchain and Git.

git clone https://github.com/tbrittain/delta.git
cargo install --path delta

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Usage

delta <base-ref>

Examples:

delta                   # latest commit (HEAD~ vs HEAD) — the default
delta main              # current branch vs main
delta origin/main       # current branch vs remote main
delta HEAD^             # same as bare delta
delta HEAD~3            # changes across the last 3 commits
delta abc1234           # current branch vs a specific commit hash
delta HEAD^2            # current branch vs the second parent of a merge commit
delta abc1234 def5678   # diff between two arbitrary commits
delta main feature      # diff between two branch tips

Both <from> and <to> accept anything git understands as a commit reference. <from> defaults to HEAD~ and <to> defaults to HEAD when omitted.

Note: delta compares committed history only. Staged or unstaged working tree changes are not in scope — commit your changes first, then run delta.

Options:

Flag	Description
--output <file>	Write feedback to a file instead of stdout
--json	Export as JSON instead of markdown

Export to a file:

delta main --output review.md

Pipe output directly into a Claude Code conversation:

Run delta via Claude Code's ! command prefix. Because delta is a TUI, it will automatically open a new terminal window for the review session. When you quit, the output is piped back into the conversation:

! delta main

Leave your notes in the terminal window, press q to quit, and the review appears in the chat for Claude to act on immediately.

To save to a file instead:

! delta main --output review.md

If no terminal window appears, set $TERMINAL to your preferred emulator:

export TERMINAL=gnome-terminal   # or xterm, kitty, alacritty, etc.

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Export Format

Markdown (default)

The following are code review notes from a human reviewer. Please address each item before proceeding.

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## `src/auth.rs` · `@@ -42,6 +42,9 @@`

\```diff
-    log::debug!("token: {}", token);
+    log::debug!("authenticated");
\```

> **Human:** The refresh token was being logged in plaintext. Make sure no other sensitive fields are logged nearby.

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JSON (--json)

{
  "notes": [
    {
      "file": "src/auth.rs",
      "hunk": "@@ -42,6 +42,9 @@",
      "code": "-    log::debug!(\"token: {}\", token);\n+    log::debug!(\"authenticated\");",
      "note": "The refresh token was being logged in plaintext."
    }
  ]
}

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Design

Delta does one thing: a human reviews AI-generated code and produces structured output to feed back to the agent. That is the entire scope.

Every feature must be directly central to the review → structured-output → agent-feedback loop. Improvements to diff viewing, hunk navigation, comment input, and export format are in scope. Everything else — AI integrations, theme engines, commit tooling, ancillary utilities — is not.

What delta is:

• A terminal-first, local-first diff review tool
• An orchestration layer between human reviewers and AI coding agents
• Git-centric: operates on committed branch changes vs a base ref
• Read-only: never modifies files

What delta is not:

• A text editor or merge tool
• A replacement for GitHub/GitLab code review
• A persistent review platform — feedback is ephemeral, scoped to one session
• An AI-integrated tool — no built-in LLM calls, no provider integrations
• A git difftool driver

Design principles: local-first (no server, no accounts), terminal-first (optimized for tmux/SSH environments), ephemeral review state, git-centric.

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Status

Early development. Core review workflow is functional; rough edges may exist.