--- a/sway/desktop/output.c
+++ b/sway/desktop/output.c
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <inttypes.h>
 #include <stdlib.h>
 #include <strings.h>
 #include <time.h>
@@ -358,6 +359,12 @@
 	return false;
 }
 
+// WHY: SceneFX's wlr_scene_output_commit is bypassed by SwayFX's repaint
+// path. This private ordinal timestamps the actual accepted output commit.
+// CONTRACT: it is a local probe counter, not a native transaction/frame ID.
+// INVARIANT: repaint and commit decisions are unchanged by the trace.
+static uint64_t temporal_output_commit_ordinal;
+
 static int output_repaint_timer_handler(void *data) {
 	struct sway_output *output = data;
 
@@ -394,7 +401,16 @@
 		}
 	}
 
-	if (!wlr_output_commit_state(output->wlr_output, &pending)) {
+	bool commit_ok = wlr_output_commit_state(output->wlr_output, &pending);
+	struct timespec temporal_now;
+	clock_gettime(CLOCK_MONOTONIC, &temporal_now);
+	sway_log(SWAY_INFO, "TEMPORAL_OUTPUT_COMMIT ordinal=%" PRIu64
+		" ns=%" PRIu64 " output=%s accepted=%d",
+		++temporal_output_commit_ordinal,
+		(uint64_t)temporal_now.tv_sec * UINT64_C(1000000000) +
+			(uint64_t)temporal_now.tv_nsec,
+		output->wlr_output->name, commit_ok);
+	if (!commit_ok) {
 		sway_log(SWAY_ERROR, "Page-flip failed on output %s", output->wlr_output->name);
 	}
 	wlr_output_state_finish(&pending);