A native macOS terminal multiplexer built for parallel CLI agents and long-running tasks.
Powered by libghostty.

About · Features · Build · Configuration · Acknowledgments · License

Forge is a terminal multiplexer for macOS that organizes your shells the way you actually think about them: Projects (a directory you work in) hold Tabs (an activity inside that project), which hold Panes (a single terminal, optionally split). All of it is native SwiftUI on top of libghostty, so cells render at GPU speed and key handling has no shim layer.

It is designed around two things modern terminal use has gotten harder without:

• Sessions that survive an app restart. A sidecar daemon (forged) holds the PTY master file descriptors over a Unix-domain socket. Quitting Forge — or it crashing — does not SIGHUP your shells. Relaunch and pick back up exactly where you left off.

• Knowing which terminal needs you. With several long-running tasks or AI coding agents in flight, the hard problem is no longer "how do I see them all" but "which one is waiting on me right now." Forge watches every pane for terminal bells, command completion, and interactive prompts, and surfaces them through an attention queue and an optional stack mode that pops the most-recently-attention-grabbing tab to the front.

Forge embeds libghostty rather than shelling out to tmux. There is no multiplexer process, no control-mode protocol, no escape-sequence re-encoding — just PTYs that Forge owns directly through Ghostty's embedding API.

Workspace model

• Projects with working directories, tabs, splits, and per-project sort order. Persisted to ~/.config/forge/workspace.json.
• Arbitrary pane nesting — horizontal splits inside vertical splits inside horizontal splits, drag dividers to resize.
• Browser panes alongside terminal panes (WebKit), with full / slim / hidden chrome modes and a quick URL palette.

Session persistence

• forged daemon dups every PTY's master fd so shells survive a Forge quit, crash, or upgrade. On relaunch, surfaces reconnect to the existing fds in Ghostty's EXTERNAL_FD mode.
• Workspace structure (projects, tabs, splits, proportions) saves continuously and restores on launch.

Attention system

• Bell (0x07) detection per pane.
• Regex / exact-string content matches for common interactive prompts ("Allow once?", "(y/N)", Claude Code's tool-use prompts, etc.). Patterns are user-extensible.
• Command-completion detection: a pane's foreground process transitions from active → idle and you get notified the task is done.
• Native macOS notifications with configurable sound and badge color.
• A notification panel and per-tab badges in the sidebar.

Stack mode

• An alternative to the sidebar/tab UI: the frontmost queued tab is displayed full-screen with a Done / Hide / Move-to-Back toolbar.
• Designed for monitoring N agents at once — work with whichever is asking for input, dismiss it, get the next one.

Themes and fonts

• Bundles 31 themes (Catppuccin, Tokyo Night, Dracula, Gruvbox, Nord, Rose Pine, Solarized, GitHub, Ayu, Everforest, Monokai, and more) imported verbatim from iTerm2-Color-Schemes.
• User themes drop into ~/.config/forge/themes/*.conf. Format is Ghostty-compatible (background=#hex, foreground=#hex, palette=N=#hex, cursor-color=#hex) — see ADR 0005.
• Font resolution: configured family → Ghostty config → Nerd Font fallbacks → system monospaced. Ligatures and line height configurable.

Other niceties

• Command palette (⌘⇧P) and tab switcher (⌘P).
• Customizable keyboard shortcuts (recorder UI in Settings → Shortcuts).
• Active-process close confirmation — closing a pane / tab / project that has a foreground process other than the shell prompts before terminating. Each level (never / whenActive / always) is configurable.
• Git branch in the title bar for the active project.
• Inline rename for projects and tabs.
• Sidebar reorderable by drag; tabs reorderable by drag.

Requirements:

• macOS 14 (Sonoma) or newer
• Xcode 16 or Swift 6.0+ toolchain
• Zig — required to build libghostty (brew install zig)

git clone https://github.com/rsml/forge.git
cd forge
git submodule update --init vendor/ghostty
make run          # release build + launch
# or
make dev          # debug build + launch
swift test        # run domain tests

make handles building GhosttyKit.xcframework from vendor/ghostty (cached by SHA in ~/.cache/forge/ghosttykit/) and copying the forged daemon into the app bundle. Bare swift build compiles, but make is what produces a working .app.

Logs land at /tmp/forge.log. Categories: [app], [ghostty], [daemon], [attention], [debug].

Forge keeps its config at ~/.config/forge/config.json. Most settings are editable through Settings (⌘,). Notable ones not in the UI:

• nativePTY: true — the only supported mode going forward.
• shortcuts: { ... } — override any default keybinding by id (see Sources/Infrastructure/Config/KeyboardShortcuts.swift for the list).

User themes go in ~/.config/forge/themes/*.conf.

Forge is not affiliated with or endorsed by any of the projects below. They are named here to credit their authors and to make it clear what makes Forge work.

Forge embeds libghostty, the terminal library extracted from Ghostty, for terminal surface rendering, PTY ownership in EXEC mode, and input encoding. Ghostty is MIT-licensed; copyright Mitchell Hashimoto and Ghostty contributors. The Ghostty name, ghost icon, and brand are not used as Forge's branding.

Bundled themes are imported from mbadolato/iTerm2-Color-Schemes (MIT, copyright Mark Badolato 2011–Present). Each theme is the work of its original author — Dracula Theme, Catppuccin, folke (Tokyo Night), Arctic Ice Studio (Nord), Pavel Pertsev (Gruvbox), Rosé Pine, Ethan Schoonover (Solarized), Sainnhe Park (Everforest), Wimer Hazenberg (Monokai), and many others. See the upstream CREDITS.md for full per-theme attribution.

Forge implements the Kitty keyboard progressive enhancement protocol designed by Kovid Goyal. Forge does not bundle or derive from the Kitty terminal — only the public protocol specification.

Verbatim license text for every third-party component bundled with Forge lives in LICENSES/.

Forge is released under the MIT License. Copyright (c) 2026 Ross Miller.