When a sketch's external library headers were only referenced from
project headers (e.g. esp32-eyes.ino includes Common.h, Common.h
includes <ESP32Servo.h>), the compile failed with
fatal error: ESP32Servo.h: No such file or directory
because _detect_external_includes was only called on main_content
(the processed .ino). Project .h/.cpp files were never scanned, so
ESP32Servo / DHT / Adafruit_Sensor referenced only transitively
through user code never reached _resolve_library_components and
never landed in user_libs_all/.
Fix: collect ext_headers from main_content PLUS every uploaded
.h/.hpp/.ino/.c/.cpp file before resolving libraries. Lib resolver
already walks transitive includes inside the lib bundle once it's
copied; this just makes sure the first-level set covers user
project headers too.
Repro: open https://velxio.dev/example/robot-desktop-eyes, click
Compile. Before this commit: 13 errors starting at ESP32Servo.h.
After: ext_headers includes ESP32Servo.h on the first pass and the
build proceeds.
f4b7776cd6