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fix(harness-letratag): derive diagnostic width from engine headDots #2

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Merged
mannes merged 1 commit into from
May 30, 2026
Merged

fix(harness-letratag): derive diagnostic width from engine headDots #2

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7 changes: 3 additions & 4 deletions apps/harness-letratag/src/diagnostic-print.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -43,10 +43,9 @@ export function buildDiagnosticImage(input: DiagnosticPrintInput): RawImageData
// back defensively so a future registry edit doesn't crash.
const headDots = engine?.headDots ?? 30;
const dpi = engine?.dpi ?? 200;
// Every LT cassette is 12 mm with `printableDots: 30` — read it
// off the media descriptor so we honour any future edge-case
// narrowing (e.g. iron-on cassettes that print fewer rows).
const widthDots = Math.min(input.media.printableDots, headDots);
// Printable head height is an engine fact (`headDots`), not a
// per-cassette one — every LT cassette images the same 30 dots.
const widthDots = headDots;
return buildShared({
widthDots,
heightDots: Math.round((TAPE_DEFAULT_MM * dpi) / 25.4),
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