ymacs

A GNU Emacs fork on libyggterm written in Common Lisp. Modern defaults. ELPA & MELPA compatibility measured honestly on a pinned GNU ELPA corpus. Uncompromising speed, concurrency, and deep observability.

What is ymacs?

ymacs reimagines the timeless power of Emacs on a modern, ultra-fast substrate:

• Common Lisp Core: Compiled performance, true native multithreading, and interactive meta-programming on a modern Lisp runtime.
• libyggterm Integration: Runs seamlessly inside yggterm desktop and remote terminal sessions via OSC 7717, leveraging high-performance visual document surfaces and sidebars.
• ELPA & MELPA Compatibility (measured): Plug-and-play access to the Emacs Lisp package ecosystem is the stated goal. Measured on a pinned GNU ELPA corpus (2026-09-04): 1/75 corpus files load, 797/1944 forms evaluate — numbers, method and gap queue in docs/elpa-compat-measurement.md, status ledger in Status.
• Discard the Old: No 1980s legacy clutter. Clean modern keymaps, instant sub-15ms startup, smart completion out of the box, and sensible defaults.
• Deep Observability: Built-in ytrace dynamic probes for measuring redisplay cycles, evaluation latency, and buffer mutations.
• Bidirectional yggterm Orchestration: Control yggterm terminals directly from Lisp forms, and let AI agents interact with live buffers deterministically.
• Literate Book Init: Default configuration is authored as an interactive Org mode book (init.org).
• Single Sidebar Window Model: Buffers, project navigators, and org trees live in a dedicated, collapsible sidebar rather than cluttering the editor pane.

Quick Start

curl -fsSL https://raw.githubusercontent.com/yggdrasilhq/yggterm/main/scripts/install.sh | sh
ynpx @ygghq/ymacs

Running ymacs

# Launch interactive ymacs session
ymacs

# Open file directly
ymacs path/to/file.lisp

# Open with specific literate configuration
ymacs --config ~/.config/ymacs/init.org

# Headless evaluation / agent execution
ymacs --eval "(+ 40 2)"

Key Highlights

| Feature | Classic Emacs | ymacs | |---|---|---| | Core Runtime | C + Elisp bytecode | Native Common Lisp (SBCL/ECL) + Elisp compat layer | | Concurrency | Mostly single-threaded / cooperative | True native multithreading & async task workers | | Surface | X11 / Wayland / ncurses TUI | libyggterm Tier A document & sidebar surfaces | | Buffer Listing | Splits main window into *Buffers* | Single collapsible sidebar rail (max 1 in view) | | Observability | elp.el / profiler | In-process ytrace microsecond probes | | Agent Access | Requires external socket / IPC hacks | First-class headless verbs and deterministic buffer RPC |

Status (honest ledger — 2026-09-02)

Verified by audit; details in docs/spec-primitives.md §5.

• Real: daemon/client split, OSC 7717 surfaces, control server, sidebar panes, rope buffer core with value_key persistence, kill-ring/undo/isearch modules, init.org tangle, headless --eval verbs, ytrace probes, CI.
• Skeleton / not yet real: keystroke input plane, working macro recorder, projectile/magit/treemacs (name-only stubs), emd-renderer buffer ownership, frame=row, settings system.
• Design law for the rebuild: Primitives spec — Frame/Window/Buffer with ymacs superpowers, M-x macro-safety law, config layering.

Documentation

• Primitives Law (design SSOT)
• Architecture Overview
• ELPA & MELPA Compatibility Guide
• Sidebar and Buffer Management
• Agent & Automation Contract
• Manual · Vendored Emacs manuals · Divergence ledger
• Literate Book Configuration
• Agent Operating Contract

License & Legal

• Source Code: Licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later).
• Documentation: Licensed under the GNU Free Documentation License v1.3 or later (GFDL-1.3-or-later) with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
• Third-Party Notices: See THIRD-PARTY-NOTICES.md.
• Trademarks: See TRADEMARKS.md.