A node was a Lua table of ~625 bytes, of which 21 keys pushed it over a
power-of-two hash boundary and eight were style copies inheritance had
splattered down from its parent. A 400 node screen cost ~250 KB and could not
coexist with wifi's buffers.
The tree now lives in src/ui/layout.h as a 16 byte struct in a flat arena, and
splits by lifetime: Node holds what hit testing and repainting need forever,
Spec holds what only measure/place read and is dropped when layout ends. Style
is sparse and resolved by walking parents, so a node naming no colours costs
nothing. Re-layout rebuilds from Lua rather than retaining the inputs.
401 nodes: 8218 B steady, 21050 B peak
Lua: ~250000 B steady
sdcard/lib/ui.lua stays the toolkit and keeps every constructor signature, but
returns integer handles: 627 lines to 374. Composition, the palette and custom
painters are still Lua on the SD card; only primitives now need a reflash.
BREAKING CHANGE: ui constructors return handles, not tables. Use
ui.setText(id, text) and keep per-node app data in a table keyed by id.
Remove OpenFontRender, embedded Meslo assets, custom-font APIs, and their runtime allocation overhead. Keep the taller status layout and compact card grid, with used RAM, aligned faded WiFi bars, and tighter telemetry rows.
Embed a Latin-1 Meslo LG S default and use OpenFontRender for anti-aliased text with an explicit pixel size on each draw and measurement call. Apps may replace the one retained face with an SD-backed TTF and restore Meslo with nil. Refresh UI sizing, status telemetry, Settings typography, tests, documentation, and font license notices.
Use a two-row 44px status bar with a full-height back button, centered app name, WiFi beside the clock, and free/total RAM below. Expand grids to three portrait and four landscape columns with consistent card text and left-to-right partial rows.
Make sys.launch push the current path and argument, sys.replace switch without pushing, and sys.back restore the previous route. The status-bar chevron uses the same back action, failed child apps return to their caller, and history is capped at eight routes. Remove the redundant Settings back card.
The directory name is what the status bar and the launcher cards display, so Home,
Hello and Settings read as titles without a lookup table. Updates the firmware's home
path, the launcher's self-exclusion and the host tests that load the settings app.
Also brings the bar's next repaint forward when an app renames itself or the frame
rotates. The bar still decides what changed; this only stops the answer waiting most of
a second for the next tick.
evan