Philosophy

#The one-line test

Every proposed feature must pass:

Does it help someone run ten agents and know which one needs them?

If no, it doesn't go in. This test is the product.

#Principles

1. Mac-only, Metal-only, forever. No portability layer, no abstraction over a second platform that will never exist. This is a feature: every line of the app can assume AppKit, CoreText, Metal, and kqueue.
2. Agents talk through standards, not integrations. The entire "agent support" surface is escape sequences that already exist. They are implemented impeccably; there is no per-agent adapter and no "agent SDK". Nothing has to fight this terminal because there is nothing to fight.
3. Opinions, not configuration. One config file, hot-reloaded, short. Where a choice exists, it is made once. The sidebar is vertical and can be hidden; there is no horizontal tab mode.
4. Remove before adding. Speed and sleekness come from absence.
5. Determinism. A frame is a pure function of terminal state. The VT core is a pure function of its input bytes. Same bytes, same state, same pixels.

#What we deliberately do not build

• Profiles, settings UI, or a themes gallery: there is one config file
• Horizontal tabs and general splits. The sidebar is the layout; the only exception is a single, non-nesting, two-session side-by-side pair
• tmux integration or control mode
• Ligatures: no text shaping at all, which keeps rendering simpler and faster
• Sixel, iTerm2 images, or a general media layer. Kitty graphics is the one exception, because it is an open protocol used by real agent workflows
• Broadcast input, triggers, per-agent UI, AI features of any kind
• In-process plugins: they are how terminals get slow and crashy

#On speed

Boring Terminal does not try to out-benchmark Alacritty or Ghostty, and does not need to: every serious terminal is already fast enough that speed is table stakes. It competes on the workflow instead.

#Design records

Every non-trivial decision is written down before it is built. The RFCs live in docs/rfcs in the repository, including the rejected alternatives and why.