improvise-y5eb: read the declined cell through the frame's own origin

declined_at indexed the cache with the cursor's offsets, which the
client's own outgoing frame moves before the host's projection arrives.
A wrapping Down read the old window's top row and closed an editor on
Revenue/Feb with Profit's refusal. projected_at reads against
AxisFrame::first, so a stale cache answers None instead.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

crates/improvise-protocol/src/resolve.rs

@@ -1040,13 +1040,21 @@ fn reopened_at(state: &ClientState, row: usize, col: usize, mode: AppMode) -> Ve
 /// Why `i` declines the cell the host projected at `(row, col)`. `None` for an
 /// editable cell, and for one not projected yet, which the fold settles later.
 pub(crate) fn declined_at(state: &ClientState, row: usize, col: usize) -> Option<String> {
-    match cell_at(state, row, col)?.id.as_ref()? {
+    match projected_at(state, row, col)?.id.as_ref()? {
         CellId::Aggregate(_) => Some(AGGREGATE_DECLINE.to_string()),
         CellId::Derived { target } => Some(derived_decline(target)),
         CellId::Record(_) | CellId::Create(_) | CellId::Coordinate => None,
     }
 }
 
+/// The cell the host projected at an absolute position, read against the frame's
+/// own origin: offsets the client has scrolled ahead of the cache cannot alias it.
+fn projected_at(state: &ClientState, row: usize, col: usize) -> Option<&crate::CellDisplay> {
+    let r = row.checked_sub(state.grid.row_frame.first)?;
+    let c = col.checked_sub(state.grid.col_frame.first)?;
+    state.grid.cell(r, c)
+}
+
 /// What the host says of an aggregate, the fold of a collapsed group included.
 const AGGREGATE_DECLINE: &str =
     "Cannot write to an aggregate — it combines several records, so there is no one cell to write";