docs(adr): ADR 009 makes the client pruning recipe conditional and restores the dropped-connection test (improvise-felo.4)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

context/adr/009-incremental-evaluation.md

@@ -190,11 +190,11 @@ and dimensions. The window is never state, and a request costs O(visible).
 displayed values is hidden. This replaces today's whole-grid `prune_empty`. The model
 answers one restricted successor query: "the next k rows after position p with a value
 in a column of S", and the same for columns. A per-column sorted index of occupied rows
-answers it in O(|S| log n + k|S|), holding O(occupied cells). The client prunes its
-window, fills forward with that query, and finds a new top-left when scrolling up or left
-by galloping backwards in doubling jumps (about 14 to 28 probes at density 10⁻⁴). Whether
-pruning runs on the client and which parameters travel are ADR 008's questions. This
-design supports either answer.
+answers it in O(|S| log n + k|S|), holding O(occupied cells). Whether pruning runs on
+the client and which parameters travel are ADR 008's questions, and this design supports
+either answer. If the client prunes, it prunes its window, fills forward with that
+query, and, when scrolling up or left, finds a new top-left by galloping backwards in
+doubling jumps (about 14 to 28 probes at density 10⁻⁴).
 
 **The change notice.** After each accepted batch the host emits one notice to every
 client, addressed to none. It carries:
@@ -283,7 +283,8 @@ Step 8's required tests:
 - `[AddItem, SetCell]` publishes one notice, and no client refetches;
 - a dropped notice is detected;
 - a reconnect after a host restart refetches;
-- a refused frame consumes no publication number.
+- a refused frame consumes no publication number;
+- a dropped connection forces a refetch.
 
 ## Open questions