diff --git a/CMakeLists.txt b/CMakeLists.txt
index b7ac6df..97b98f0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -117,8 +117,17 @@ add_test(NAME smoke COMMAND test_smoke)
 add_executable(test_idct_bitexact tests/test_idct_bitexact.c)
 target_link_libraries(test_idct_bitexact PRIVATE daedalus_decoder)
 target_compile_options(test_idct_bitexact PRIVATE -O2)
+
+# 320x240 QVGA — fast inner-loop test (300 MBs, sub-second).
 add_test(NAME idct_bitexact COMMAND test_idct_bitexact)
 
+# 1920x1088 1080p — deployment-scale test (8160 MBs, ~0.25 s on hertz).
+# Validates the per-MB block index + pixel offset math at full coded
+# height (1088, not 1080 — see daedalus_decoder.h on H.264 coded vs
+# displayed dims).  Cheap enough to run unconditionally; if it ever
+# gets slow we'll split into a CTest LABEL for opt-in.
+add_test(NAME idct_bitexact_1080p COMMAND test_idct_bitexact 1920 1088)
+
 # ---- Install ------------------------------------------------------
 #
 # Library + public header.  Stage 2/3 will add a pkg-config file and