One more

lib/EpdFont/SdCardFont.cpp

@@ -574,7 +574,7 @@ int32_t SdCardFont::findGlobalGlyphIndex(const PerStyle& s, uint32_t codepoint)
 
 // --- Prewarm ---
 
-int SdCardFont::prewarm(const char* utf8Text, uint8_t styleMask, bool metadataOnly) {
+int SdCardFont::prewarm(const char* utf8Text, uint8_t styleMask, bool metadataOnly, bool loadKernLigatureData) {
   if (!loaded_) return -1;
 
   unsigned long startMs = millis();
@@ -624,10 +624,9 @@ int SdCardFont::prewarm(const char* utf8Text, uint8_t styleMask, bool metadataOn
   }
 
   // Add ligature output codepoints from all styles being prewarmed.
-  // Skip during metadata-only prewarm (layout measurement) to avoid loading
-  // kern/lig data for all styles upfront (~22KB per style). Kern/lig is
-  // loaded per-style in prewarmStyle() during the full render prewarm instead.
-  if (!metadataOnly) {
+  // Load ligature metadata when either doing a full prewarm or when
+  // metadata-only layout measurement needs applyLigatures()/getKerning().
+  if (!metadataOnly || loadKernLigatureData) {
     for (uint8_t si = 0; si < MAX_STYLES; si++) {
       if (!(styleMask & (1 << si)) || !styles_[si].present) continue;
       auto& s = styles_[si];
@@ -669,7 +668,7 @@ int SdCardFont::prewarm(const char* utf8Text, uint8_t styleMask, bool metadataOn
   int totalMissed = 0;
   for (uint8_t si = 0; si < MAX_STYLES; si++) {
     if (!(styleMask & (1 << si)) || !styles_[si].present) continue;
-    totalMissed += prewarmStyle(si, codepoints.get(), cpCount, metadataOnly);
+    totalMissed += prewarmStyle(si, codepoints.get(), cpCount, metadataOnly, loadKernLigatureData);
   }
 
   stats_.prewarmTotalMs = millis() - startMs;
@@ -702,7 +701,8 @@ bool SdCardFont::allCpsCovered(const PerStyle& s, const uint32_t* codepoints, ui
   return true;
 }
 
-int SdCardFont::prewarmStyle(uint8_t styleIdx, const uint32_t* codepoints, uint32_t cpCount, bool metadataOnly) {
+int SdCardFont::prewarmStyle(uint8_t styleIdx, const uint32_t* codepoints, uint32_t cpCount, bool metadataOnly,
+                             bool loadKernLigatureData) {
   auto& s = styles_[styleIdx];
 
   // ---- Fast-path coverage check ----
@@ -1104,10 +1104,10 @@ int SdCardFont::prewarmStyle(uint8_t styleIdx, const uint32_t* codepoints, uint3
   // Full render prewarm: load the persistent kern classes + ligatures (one-time
   // per style, small — the big matrix is NOT loaded here) and then build the
   // per-page mini kern matrix restricted to class pairs reachable from this
-  // page's codepoints. Skip during metadata-only prewarm — layout only needs
-  // advanceX and the mini kern would be thrown away before rendering.
+  // page's codepoints. Also do this during layout-only metadata prewarm when
+  // kern/ligature metadata is explicitly requested.
   bool kernLigOk = false;
-  if (!metadataOnly) {
+  if (!metadataOnly || loadKernLigatureData) {
     if (loadStyleKernLigatureData(s)) {
       kernLigOk = buildMiniKernMatrix(s, codepoints, cpCount);
     }

lib/EpdFont/SdCardFont.h

@@ -22,8 +22,11 @@ class SdCardFont {
   // styleMask: bitmask of styles to prewarm (bit 0=regular, 1=bold, 2=italic, 3=bolditalic).
   // Default 0x0F = all present styles.
   // When metadataOnly=true, only glyph metrics are loaded (no bitmap data).
+  // If loadKernLigatureData=true, kern/ligature metadata is also loaded so layout
+  // measurement calls that use applyLigatures()/getKerning() produce correct results.
   // Returns number of glyphs that couldn't be loaded (0 on full success).
-  int prewarm(const char* utf8Text, uint8_t styleMask = 0x0F, bool metadataOnly = false);
+  int prewarm(const char* utf8Text, uint8_t styleMask = 0x0F, bool metadataOnly = false,
+              bool loadKernLigatureData = false);
 
   // Free mini data for all styles, restore stub EpdFontData.
   void clearCache();

lib/GfxRenderer/GfxRenderer.cpp

@@ -43,7 +43,8 @@ void GfxRenderer::ensureSdCardFontReady(int fontId, const char* utf8Text) const
     // Metadata-only: loads glyph metrics (advanceX) without bitmap data.
     // Saves ~50-100KB heap vs full prewarm — layout only needs advance widths.
     // Prewarm all present styles (0x0F) for layout measurement.
-    int missed = it->second->prewarm(utf8Text, 0x0F, /*metadataOnly=*/true);
+    int missed = it->second->prewarm(utf8Text, 0x0F, /*metadataOnly=*/true,
+                                     /*loadKernLigatureData=*/true);
     if (missed > 0) {
       LOG_DBG("GFX", "ensureSdCardFontReady: %d glyph(s) not found", missed);
     }