docs: close the bit-level flag question in the backlog

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMRJjbxLqZtsb5Vb7KunPE

docs/re/BACKLOG.md

@@ -302,7 +302,12 @@ is what the autopilot needs in order to CHOOSE a target. One run in:
   single **bit** ORed into a word that also varies (the test needs an exact
   shared value), anything outside that window, and anything on entities
   `entities2` cannot see — it types by position *changing*, so stationary
-  objectives are invisible. A bit-level differential is the follow-on. 🔎 **Built**
+  objectives are invisible. 🔴 **The bit-level differential is REFUTED too**
+  (2026-08-24): two independently selected transitions in one run — scan at 4
+  filtered on 4→8 (29 of 710 survive), scan at 8 filtered on 8→12 (2 of 197) —
+  and the **intersection is empty**. No per-entity bit in either polarity tracks
+  the counter; 16 of pass 1's survivors were the same word `+0x250` with
+  different bits, i.e. a *shared value*, not a flag. Earlier note: 🔎 **Built**
   (`ob_bitflag.py`, 2026-08-24) and run three times with **no verification
   yet**: one window was spent on a mission that had already ended in GAME OVER,
   one hit the same dead mission, and the third had the counter at a different