2 files changed, 16 insertions, 2 deletions

diff --git a/src/client/games/roulette.rs b/src/client/games/roulette.rs
index ec9573c..f0ed816 100644
--- a/src/client/games/roulette.rs
+++ b/src/client/games/roulette.rs
@@ -95,7 +95,7 @@ impl Cursor {
     pub fn target(&self) -> Option<BetTarget> {
         match self {
             Cursor::Zero => Some(BetTarget::Straight { number: 0 }),
-            Cursor::Lattice { x, y } => felt_target(*x, *y),
+            Cursor::Lattice { x, y } => target_at(*x, *y),
             Cursor::Dozen(index) => Some(BetTarget::Dozen {
                 index: *index as u8,
             }),
@@ -171,7 +171,11 @@ fn cell_number(column: usize, row: usize) -> Option<u8> {
 }
 
 /// Bet under a point of the fine grid.
-fn felt_target(x: usize, y: usize) -> Option<BetTarget> {
+///
+/// Both frontends use this: the terminal moves a cursor over the lattice, and
+/// the GUI snaps a mouse position to it. Odd coordinates are cell centres,
+/// even coordinates are the lines where a split or corner chip sits.
+pub fn target_at(x: usize, y: usize) -> Option<BetTarget> {
     if !(1..=FELT_X_MAX).contains(&x) || !(1..=FELT_Y_MAX).contains(&y) {
         return None;
     }
diff --git a/src/roulette.rs b/src/roulette.rs
index 6b73c2a..b697e31 100644
--- a/src/roulette.rs
+++ b/src/roulette.rs
@@ -226,6 +226,16 @@ impl Bets {
         }
     }
 
+    /// Take `amount` back from one target, dropping the chip when it empties.
+    ///
+    /// This is the felt undo: a right or middle click removes one chip.
+    pub fn reduce(&mut self, target: &BetTarget, amount: u64) {
+        if let Some(chip) = self.chips.iter_mut().find(|chip| &chip.target == target) {
+            chip.amount = chip.amount.saturating_sub(amount);
+        }
+        self.chips.retain(|chip| chip.amount > 0);
+    }
+
     /// Total returned for a winning number, including returned stakes.
     pub fn winnings(&self, number: u8) -> u64 {
         self.chips.iter().fold(0u64, |total, chip| {