interp_capture's FLIP decision moves into frame_flip_is_new_frame()
(frame_interpolation.c), unit-tested in frame_interpolation_schedule_test.
A new source guard, frame_interpolation_flip_source (recompiler ctest),
pins what no unit test reaches: main.cpp hands the session's source to the
renderer at every session start, right after its interpolation settings;
interp_capture feeds the origin and the redraw test to the decision and the
tracker and returns before the copy on a duplicate; both present paths pass
the display origin and present_dirty_test; a source change restarts the
history. Deleting the hand-off, or never returning on a duplicate, now fails
the guard (both passed every test before).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Shokunin