The first working engine: a multi-PTY terminal with a tiling grid and ANSI/vte parsing, the concept engine for matching output, and the settings, sidebar and icon basics around them. Everything in this chain shipped.

v0.1.0 - Core Engine

Done	Area	Item
✅	TERM	Multi-PTY terminal emulator - spawn and manage multiple shell sessions in a tiling grid. Each session is an independent PTY with its own shell process, environment, and working directory.
✅	GUI	Tiling grid layout - split panes horizontally or vertically, resize by dragging splitter handles. Built on a Rust tile layout engine that enforces minimum pane dimensions and redistributes space when panes are added or removed.
✅	TERM	ANSI/vte parsing - full SGR color and cursor positioning via alacritty_terminal. Handles 16-color, 256-color, and true color (24-bit) sequences. Strips escape sequences for concept matching.
✅	CONCEPT	Concept engine - regex-based trigger/action matching with label routing. Every line of PTY output is tested against registered concept patterns. Matching lines broadcast events on a pub-sub channel; panes with matching labels execute the associated action. (Command execution removed in v0.5.3 - concepts are capture-and-route only.)
✅	CONCEPT	SingleLine capture mode - each matching line triggers an event on the pub-sub channel. Receiving panes inject the action’s command template into their PTY stdin, enabling cross-pane automation. (The mode and its injection path were removed in v0.5.3; it never delivered an action before then - labels were always empty and every pane shared id 1.)
✅	GUI	Settings persistence - font size, cursor shape, window mode, and other preferences saved to user://settings.json. Settings auto-load on startup and auto-save on change via a debounced save timer.
✅	GUI	Phosphor icon set - 100+ icons for toolbar, sidebar, and pane action buttons. Unicode PUA codepoints rendered via the bundled Phosphor Regular font. Icons are exposed as const strings in icons.gd.
✅	GUI	Sidebar with pane list - collapsible left panel showing all tiles with focus, kill, minimize, and swap buttons per pane. Also exposes window mode toggle and per-pane-type spawn buttons.
✅	TERM	Control-based renderer - terminal grid drawn in GDScript via _draw(). Rust packs cell data (chars, foreground, background, attributes) into flat arrays; GDScript unpacks and renders them line-by-line with damage tracking for incremental updates.