fix(fonts): add font fallbacks in template; patch theme file inside uploaded/repo zip during debug compile when needed

app.py

@@ -736,7 +736,7 @@ def debug_compile_uploaded_zip(zip_file):
         logs.append("❌ No .tex file found in uploaded zip")
         _write_logs(LOG_PATH, logs)
         return "<div style='color:#b00'>No .tex found in uploaded zip</div>"
-    # Disable logoleft if missing
+    # Disable logoleft if missing; also patch local theme fonts if present
     try:
         logos_dir = tex_path.parent / "logos"
         has_left = False
@@ -753,6 +753,19 @@ def debug_compile_uploaded_zip(zip_file):
                 if new_txt != txt:
                     tex_path.write_text(new_txt, encoding="utf-8")
                     logs.append("ℹ️ No left_logo found; disabled \\logoleft in uploaded project.")
+        # Patch theme font fallbacks if the zip includes the theme file
+        for sty in work_zip_dir.rglob("beamerthemegemini.sty"):
+            try:
+                s = sty.read_text(encoding="utf-8")
+                if "\\newfontfamily\\Raleway" in s or "\\newfontfamily\\Lato" in s:
+                    import re as _re
+                    s = _re.sub(r"\\newfontfamily\\Raleway\[[^\]]*\]\{Raleway\}", r"\\IfFontExistsTF{Raleway}{\\newfontfamily\\Raleway[Ligatures=TeX]{Raleway}}{\\newfontfamily\\Raleway[Ligatures=TeX]{DejaVu Sans}}", s)
+                    s = _re.sub(r"\\newfontfamily\\Lato\[[^\]]*\]\{Lato\}", r"\\IfFontExistsTF{Lato}{\\newfontfamily\\Lato[Ligatures=TeX]{Lato}}{\\newfontfamily\\Lato[Ligatures=TeX]{DejaVu Sans}}", s)
+                    s = _re.sub(r"\\setsansfont\{Lato\}\[[^\]]*\]", r"\\IfFontExistsTF{Lato}{\\setsansfont{Lato}[UprightFont=*-Light,ItalicFont=*-LightItalic,BoldFont=*-Regular,BoldItalicFont=*-Italic]}{\\IfFontExistsTF{DejaVu Sans}{\\setsansfont{DejaVu Sans}[BoldFont=*-Bold,ItalicFont=*-Oblique,BoldItalicFont=*-BoldOblique]}{\\setsansfont{Latin Modern Sans}}}", s)
+                    sty.write_text(s, encoding="utf-8")
+                    logs.append(f"🛠️ Patched fonts in {sty.relative_to(work_zip_dir)}")
+            except Exception as e:
+                logs.append(f"⚠️ Font patch failed for {sty}: {e}")
     except Exception as e:
         logs.append(f"⚠️ left_logo adjust failed: {e}")
     # Compile

template/beamerthemegemini.sty

@@ -15,17 +15,39 @@
 % Fonts
 % ====================
 
-\newfontfamily\Raleway[Ligatures=TeX]{Raleway}
-\newfontfamily\Lato[Ligatures=TeX]{Lato}
-
+% Prefer Raleway/Lato if available; otherwise fall back to DejaVu or Latin Modern Sans
 \usefonttheme{professionalfonts}
 
-\setsansfont{Lato}[
-  UprightFont=*-Light,
-  ItalicFont=*-LightItalic,
-  BoldFont=*-Regular,
-  BoldItalicFont=*-Italic
-]
+\IfFontExistsTF{Raleway}{
+  \newfontfamily\Raleway[Ligatures=TeX]{Raleway}
+}{
+  \newfontfamily\Raleway[Ligatures=TeX]{DejaVu Sans}
+}
+
+\IfFontExistsTF{Lato}{
+  \newfontfamily\Lato[Ligatures=TeX]{Lato}
+}{
+  \newfontfamily\Lato[Ligatures=TeX]{DejaVu Sans}
+}
+
+\IfFontExistsTF{Lato}{
+  \setsansfont{Lato}[
+    UprightFont=*-Light,
+    ItalicFont=*-LightItalic,
+    BoldFont=*-Regular,
+    BoldItalicFont=*-Italic
+  ]
+}{
+  \IfFontExistsTF{DejaVu Sans}{
+    \setsansfont{DejaVu Sans}[
+      BoldFont=*-Bold,
+      ItalicFont=*-Oblique,
+      BoldItalicFont=*-BoldOblique
+    ]
+  }{
+    \setsansfont{Latin Modern Sans}
+  }
+}
 
 \setbeamerfont{headline}{family=\Raleway}
 \setbeamerfont{headline title}{size=\Huge,series=\bfseries}