`seat_text_measurer`'s own doc says what it is for: *"so `GetStringWidth` right after `SetText`
measures, as the reference answers it inline (`0x79e510` → `0x772890`). Also seated before the
manifest loads, for every `<OnLoad>`."* It was not seated. `UiFontAtlas` is inserted by an
`Update` system through `Commands`, so it appears at the next command flush — and the interface
load runs on the `InWorld` state transition, which comes first. `seat_raster_seam_for_load` then
took its `else { return }` and the VM went through the whole load with **no text measurer at
all**, which `ensure_measured` answers by returning at its first line.
So for the entire UI load — all of FrameXML and every addon — `FontString:GetWidth()`,
`GetHeight()` and `GetStringWidth()` answered **0** for a string that plainly had text. Measured
on grom's install: dozens of them, including every unit-popup entry, every `StaticPopup` button
and the four radio labels this was found through.
What it costs is any `<OnLoad>` that lays something out from a label's width, which is an ordinary
thing for an addon to do. `AdvancedTradeSkillWindow2.lua:1642` puts its Name radio button at
`ATSWDifficultySortCheckboxText2:GetWidth() + 5` to the right of the Difficulty one: the stored
offset came out **5.0** where it should be 53.8, so "Difficulty" was drawn across "Category" 37 px
to its left. grom, 2026-11-05: *"its loading now, but barely functioning."* Re-running
`ATSW_OnLoad()` by hand from a live session gave 53.8 — the same code, the same frame, a measurer
away.
`ensure_font_atlas(&mut World)` is `init`'s body for a caller that holds the world, called from
`seat_raster_seam_for_load`; `init` keeps its own path for every later frame. A world that still
cannot build one (no chain, no window) now warns instead of loading the interface in silence.
Verified: the ATSW2 offset is 53.8 at load, and a walk of the whole loaded interface finds **0**
FontStrings that have text and measure 0 (dozens before). benilla-app 4243 pass / 12 fail, the
recorded baseline with an identical name set.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn
gromandClaude Opus 5
8c6fb4e425