diff --git a/emulator/firmware-decomp/IGC-ENCODING-DERIVATION.md b/emulator/firmware-decomp/IGC-ENCODING-DERIVATION.md
index 7e8d229..fe5e072 100644
--- a/emulator/firmware-decomp/IGC-ENCODING-DERIVATION.md
+++ b/emulator/firmware-decomp/IGC-ENCODING-DERIVATION.md
@@ -264,3 +264,10 @@ MEMintoENAB, SHIFTL-family, send_em's DMA emit). Output: the op table
 2. execute per-tile via igc_array.py (pixel-memory model exists there);
 3. acceptance 1 = SMPTE bars from the cap7 bench stream; acceptance 2 = the
    fxtest asset frame.
+
+## Overnight experiment log (2026-07-18)
+- Multi-frame convergence: NEGATIVE — 5 iterations of the 4-block tile program
+  are state-stable; nothing implemented propagates s145(x) into texz/texu.
+- Next suspect: OPF2 = 0x3a90f291 reads addr 145 (the SCMEMA x-target!) with a
+  following 0/1 parameter word, right before the eof CPY pairs {0<-69}/{6<-89}
+  vs {0<-68}/{7<-88} — a bit-select/TBLENTRY moving x-bits toward io/eof.