Zero-Overhead Host
Swift and AppKit — no Electron, no V8, no renderer process. Your agents get the RAM. Launches instantly and stays out of the way.
What’s New
v0.3.0August 25, 2026 — eight measured themes, system appearance following, split-pane dimming, and typography controls.
Community Themes
Catppuccin Mocha, Nord, and Dracula — ported verbatim from their upstream specs and gated by the contrast harness (474 assertions).
"preset": "catppuccin-mocha"Auto Dark / Light
Follow macOS appearance automatically. Umber switches between a dark and light palette when System Settings changes.
"preset": "auto"Split-Pane Dimming
Unfocused split panes dim to visually distinguish the active pane. Fully configurable.
"unfocusedPaneOpacity": 0.85Typography Controls
Font dilation for white-on-black text (the same technique Terminal.app uses) and configurable line height.
"fontThicken": true, "lineHeight": 1.2Terminal Padding
Configurable inner margin around terminal content with seamless background color matching.
"padding": 8Built for AI agents
The best terminal agents run in your shell, not in a browser. Umber gives them a fast, native host that stays out of their way.
Claude Code
Anthropic's terminal-native coding agent. Runs entirely in your shell.
Codex
OpenAI's CLI agent for code generation and multi-file edits.
Agent AFK
Autonomous agent runtime with daemon, Telegram, and REPL surfaces.
Hermes
Terminal agent framework with tool use and conversation memory.
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agents run in terminals — the terminal shouldn't compete with them for CPU, RAM, or your attention.
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OSC 133 command tracking — see which agent task succeeded or failed at a glance, across every tab.
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Split panes — run an agent and its supervisor side by side. ⌘⇧\ to split, ⌘⇧H/J/K/L to navigate.
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Dual engines — SwiftTerm or libghostty, same window. Pick the emulator that fits the workload.
Features
No AI built in — on purpose. The intelligence belongs to your agent, not the terminal chrome.
Agent Workspaces
One Space per project root. Multiple agent sessions inside. Switch projects without losing context — real macOS window tabs, not a custom layer.
Sidebar File Tree
Browse files alongside the terminal with git status badges on every row. See what your agent changed without leaving the window.
Measured Themes
Eight palettes tested for readability — every color verified against contrast standards. Includes Catppuccin Mocha, Nord, and Dracula. Long sessions reading agent output stay legible.
GPU or CPU Rendering
Switch between Metal (GPU-accelerated) and Core Text rendering with one config line and ⌘R. High-throughput agent output stays smooth.
Agent Status at a Glance
Background tabs show a green dot when a command succeeds, red when it fails. OSC 133 shell integration — no polling, no tab switching.
More than a terminal
Open files from the sidebar into editor tabs that sit alongside your terminals. Syntax highlighting, code folding, symbol outline, multi-cursor — enough to review and edit without switching apps.
Agent workspaces in action
Each project gets its own Space with a full file tree, git status, and as many terminal tabs as you need. Your agents see the same directory structure you do.
- Sidebar follows the focused shell's working directory automatically
- Git status badges on every file — staged, modified, untracked, deleted
- Double-click any file to open it in the built-in editor
Edit without leaving the terminal
Open files from the sidebar directly into a syntax-highlighted editor tab. Review what your agent wrote, make a quick fix, and get back to the terminal — no app switching.
- Syntax highlighting for 23 languages with tree-sitter grammars
- Line numbers, indent guides, and a column guide at 80 characters
- Auto-indent, bracket matching, and indent-rainbow coloring
Syntax Highlighting
23 languages out of the box — Swift, TypeScript, Python, Rust, Go, Markdown, and more. Tree-sitter grammars with scope-aware token coloring.
Command Palette & Symbols
⌘⇧P fuzzy-filters every app command. ⌘⇧O jumps to symbols. ⌘L goes to a line number. All keyboard-driven, no mouse required.
Code Folding & Navigation
Indent-based fold and unfold with ⌘⌥[ and ⌘⌥]. Sticky scroll keeps the enclosing scope visible. Bracket pair highlighting.
Multi-Cursor Editing
⌘D selects the next occurrence. Full multi-cursor support for parallel edits across a file — the same muscle memory as VS Code.
Themes
Five palettes ship out of the box. Each is gated by 345 contrast assertions.