CB: record the two planned runs that were not made, and why

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ARBgSooAfokKUy6wKUKEyZ

findings/subsystems/turncommands-capture.md

@@ -318,6 +318,22 @@ Rules for consuming it, in order of how much they cost to get wrong:
 
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+### 7.1 Two planned runs that were not made, and why
+
+* **C2, the `ModCount` trap set** (`watch=on` alongside the block dump). Planned as a second,
+  independent check on the stream — predicted 10 bumps on the canonical turn, attributed per EIP.
+  **Not run.** Lane RB got there first from the other side: replaying this capture puts
+  `/Sim/ModCount` on **24 exactly with zero residual** on the canonical pair, which is a stronger
+  statement than a trap multiset would have been (it checks the *arithmetic over the whole stream*,
+  not the *sites*). The trap run would still add one thing nothing else has — per-EIP attribution,
+  which would say *which handler* pays, not just that the total is right — and it remains a cheap
+  hour for whoever wants it. `shim.cfg.cbtrap` is built and staged.
+* **C4, a second unpinned turn-1 run.** Planned to give P5's "two streams differing in exactly one
+  word". **Superseded.** The pinned pair answers the same question and answers it better: an
+  unpinned pair shows that two runs *can* differ, while the pinned triple shows *what makes them
+  differ* and removes it. P5 as written is unresolved and should stay on the board that way — this
+  lane has one unpinned turn-1 stream, not two.
+
 ## 8. The guest, left as found (and one thing that was not preserved)
 
 VM146 stopped, `binkw32.dll` restored to lane L5's build (md5 `F8DFC4AE…`, verified equal to