The _should_include filter inside _merge_arduino_libs_to_component
rejected every subdirectory of a library except 'utility/' when the
library lacked a src/ layout. That blocked legitimate header dirs like
Adafruit_GFX_Library/Fonts/, breaking compiles that use any GxEPD2
example with a custom font (#include <Fonts/FreeMonoBold12pt7b.h>).
The earlier filter at the top of the function already excludes
docs/examples/tests/etc. via excluded_dirs, so anything that survives
that check is presumed to be buildable source. Letting all remaining
subdirs through restores Fonts/, gfxfont/, and similar conventional
auxiliary header directories that Adafruit-style libs rely on.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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