Build 42: block over-balance sends + roomier search icon

Guard against paying more than the spendable balance at every entry: the Pay
tab, the send-flow amount step, and the Review screen all render the amount in
red with "You don't have enough grin" and refuse to proceed, so a payment that
would only fail later at the node is stopped up front. On Android the phone
gives a short error buzz on the blocked tap — new VIBRATE bridge
(PlatformCallbacks::vibrate_error -> MainActivity.vibrateError); no-op on
desktop. Grim silently clamped the amount and showed nothing.

Also enlarge and vertically center the magnifier in the "Send to" search field
(an 18px muted label became a 22px centered glyph).

android/app/src/main/AndroidManifest.xml

@@ -8,6 +8,7 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.VIBRATE" />
     <uses-permission android:name="android.permission.CAMERA"/>
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" tools:ignore="ScopedStorage"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" tools:ignore="ScopedStorage"/>

android/app/src/main/java/mw/gri/android/MainActivity.java

@@ -510,6 +510,21 @@ public class MainActivity extends GameActivity {
         startActivity(Intent.createChooser(intent, "Share data"));
     }
 
+    // Called from native code to play a short "error" haptic (rejected payment).
+    public void vibrateError() {
+        Vibrator vibrator = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
+        if (vibrator == null || !vibrator.hasVibrator()) {
+            return;
+        }
+        // Two short pulses read as "no" / rejected, distinct from a tap.
+        long[] pattern = new long[]{0, 40, 70, 40};
+        if (Build.VERSION.SDK_INT >= 26) {
+            vibrator.vibrate(VibrationEffect.createWaveform(pattern, -1));
+        } else {
+            vibrator.vibrate(pattern, -1);
+        }
+    }
+
     // Called from native code to set status-bar icon color to contrast the
     // in-app theme. white = light icons for a dark background. The app draws
     // edge-to-edge, so the OS status-bar background is the app's own content;

src/gui/platform/android/mod.rs

@@ -207,6 +207,10 @@ impl PlatformCallbacks for Android {
 			&[JValue::Bool(white as u8)],
 		);
 	}
+
+	fn vibrate_error(&self) {
+		let _ = self.call_java_method("vibrateError", "()V", &[]);
+	}
 }
 
 lazy_static! {

src/gui/platform/mod.rs

@@ -47,4 +47,8 @@ pub trait PlatformCallbacks {
 	/// Set the status-bar icon color to contrast the current theme. `white` =
 	/// light icons (for a dark background). No-op off Android.
 	fn set_status_bar_white_icons(&self, _white: bool) {}
+
+	/// Play a short "error" haptic (e.g. a rejected over-balance payment).
+	/// No-op off Android.
+	fn vibrate_error(&self) {}
 }

src/gui/views/goblin/mod.rs

@@ -323,7 +323,7 @@ impl GoblinWalletView {
 			.show_inside(ui, |ui| {
 				w::centered_column(ui, Content::SIDE_PANEL_WIDTH * 1.2, |ui| match self.tab {
 					Tab::Home => self.home_ui(ui, wallet, cb, wide_desktop),
-					Tab::Pay => self.pay_ui(ui, wallet),
+					Tab::Pay => self.pay_ui(ui, wallet, cb),
 					Tab::Activity => self.activity_ui(ui, wallet, cb),
 					Tab::Receive => self.receive_ui(ui, wallet, cb),
 					Tab::Me => self.me_ui(ui, wallet, cb),
@@ -806,7 +806,7 @@ impl GoblinWalletView {
 	}
 
 	/// Pay tab: amount-first combined pay/request surface.
-	fn pay_ui(&mut self, ui: &mut egui::Ui, _wallet: &Wallet) {
+	fn pay_ui(&mut self, ui: &mut egui::Ui, wallet: &Wallet, cb: &dyn PlatformCallbacks) {
 		let t = theme::tokens();
 		ui.add_space(8.0);
 		ui.horizontal(|ui| {
@@ -848,8 +848,22 @@ impl GoblinWalletView {
 			self.pay_amount.clone()
 		};
 		let tall = ui.available_height() > 560.0;
+		// Block paying more than the spendable balance: red amount + a message
+		// + an error buzz on tap (Request is unguarded — you can request more
+		// than you hold).
+		let spendable = wallet
+			.get_data()
+			.map(|d| d.info.amount_currently_spendable)
+			.unwrap_or(0);
+		let over = grin_core::core::amount_from_hr_string(&self.pay_amount)
+			.map(|a| a > spendable)
+			.unwrap_or(false);
 		ui.add_space(if tall { 56.0 } else { 24.0 });
-		w::amount_text_centered(ui, &display, 76.0);
+		if over {
+			w::amount_text_centered_ink(ui, &display, 76.0, t.neg, t.neg);
+		} else {
+			w::amount_text_centered(ui, &display, 76.0);
+		}
 		if let Ok(grin) = display.parse::<f64>() {
 			if let Some(preview) = pairing_preview(grin) {
 				ui.add_space(6.0);
@@ -862,6 +876,16 @@ impl GoblinWalletView {
 				});
 			}
 		}
+		if over {
+			ui.add_space(6.0);
+			ui.vertical_centered(|ui| {
+				ui.label(
+					RichText::new("You don't have enough grin")
+						.font(FontId::new(14.0, fonts::regular()))
+						.color(t.neg),
+				);
+			});
+		}
 		ui.add_space(if tall { 32.0 } else { 16.0 });
 
 		// Numpad at narrow (mobile-shell) widths, typed input on the wide
@@ -912,10 +936,14 @@ impl GoblinWalletView {
 				)),
 				|ui| {
 					if w::big_action(ui, "Pay", false).clicked() && valid {
-						let mut f = SendFlow::default();
-						f.prefill_amount(self.pay_amount.clone());
-						self.pay_amount.clear();
-						self.send = Some(f);
+						if over {
+							cb.vibrate_error();
+						} else {
+							let mut f = SendFlow::default();
+							f.prefill_amount(self.pay_amount.clone());
+							self.pay_amount.clear();
+							self.send = Some(f);
+						}
 					}
 				},
 			);

src/gui/views/goblin/send.rs

@@ -278,10 +278,14 @@ impl SendFlow {
 		}
 		.show(ui, |ui| {
 			ui.horizontal(|ui| {
-				ui.label(
-					RichText::new(MAGNIFYING_GLASS)
-						.font(FontId::new(18.0, fonts::regular()))
-						.color(t.surface_text_mute),
+				let (icon_rect, _) =
+					ui.allocate_exact_size(egui::Vec2::new(24.0, 42.0), egui::Sense::hover());
+				ui.painter().text(
+					icon_rect.center(),
+					egui::Align2::CENTER_CENTER,
+					MAGNIFYING_GLASS,
+					FontId::new(22.0, fonts::regular()),
+					t.surface_text_dim,
 				);
 				ui.add_space(8.0);
 				let mut te = TextEdit::new(egui::Id::from("send_search"))
@@ -716,6 +720,16 @@ impl SendFlow {
 		}
 		let recipient = self.recipient.clone().unwrap();
 
+		// Block sends over the spendable balance: red amount + a message + an
+		// error buzz on tap, rather than letting it fail later at the node.
+		let spendable = wallet
+			.get_data()
+			.map(|d| d.info.amount_currently_spendable)
+			.unwrap_or(0);
+		let over = amount_from_hr_string(&self.amount)
+			.map(|a| a > spendable)
+			.unwrap_or(false);
+
 		// Recipient chip, centered per the design.
 		let name_label = format!("To {}", recipient.name);
 		let name_galley = ui.painter().layout_no_wrap(
@@ -743,7 +757,11 @@ impl SendFlow {
 		} else {
 			self.amount.clone()
 		};
-		w::amount_text_centered(ui, &display, 64.0);
+		if over {
+			w::amount_text_centered_ink(ui, &display, 64.0, t.neg, t.neg);
+		} else {
+			w::amount_text_centered(ui, &display, 64.0);
+		}
 		if let Ok(grin) = display.parse::<f64>() {
 			if let Some(preview) = super::pairing_preview(grin) {
 				ui.add_space(6.0);
@@ -756,6 +774,16 @@ impl SendFlow {
 				});
 			}
 		}
+		if over {
+			ui.add_space(6.0);
+			ui.vertical_centered(|ui| {
+				ui.label(
+					RichText::new("You don't have enough grin")
+						.font(FontId::new(14.0, fonts::regular()))
+						.color(t.neg),
+				);
+			});
+		}
 		ui.add_space(16.0);
 
 		// Quick chips.
@@ -815,7 +843,11 @@ impl SendFlow {
 			.unwrap_or(false);
 		ui.add_enabled_ui(valid, |ui| {
 			if w::big_action(ui, "Review", false).clicked() {
-				self.stage = Stage::Review;
+				if over {
+					cb.vibrate_error();
+				} else {
+					self.stage = Stage::Review;
+				}
 			}
 		});
 		false
@@ -836,6 +868,18 @@ impl SendFlow {
 		let amount = self.amount.clone();
 		let hero_tex = tex_for(avatars, ui.ctx(), wallet, &recipient.name);
 
+		// Over-balance guard: every path that reaches Review (including the
+		// Pay-tab / scan prefill that jumps straight here, skipping the amount
+		// step) must not offer a completable send for more than the spendable
+		// balance. Re-checked each frame so a mid-flow balance drop disables it.
+		let spendable = wallet
+			.get_data()
+			.map(|d| d.info.amount_currently_spendable)
+			.unwrap_or(0);
+		let over = amount_from_hr_string(&amount)
+			.map(|a| a > spendable)
+			.unwrap_or(false);
+
 		w::card(ui, |ui| {
 			ui.set_min_width(ui.available_width());
 			ui.add_space(8.0);
@@ -871,16 +915,34 @@ impl SendFlow {
 		w::info_row(ui, "Delivery", "Encrypted nostr DM over Tor");
 		ui.add_space(16.0);
 
-		if self.hold.ui(ui, "Hold to send") {
-			self.dispatch(wallet);
-			self.stage = Stage::Sending;
+		if over {
+			ui.vertical_centered(|ui| {
+				ui.label(
+					RichText::new("You don't have enough grin")
+						.font(FontId::new(14.0, fonts::regular()))
+						.color(t.neg),
+				);
+			});
+			ui.add_space(8.0);
 		}
+		// Greyed out while over balance; the `&& !over` also refuses the send in
+		// case the hold widget ignores the disabled state.
+		ui.add_enabled_ui(!over, |ui| {
+			if self.hold.ui(ui, "Hold to send") && !over {
+				self.dispatch(wallet);
+				self.stage = Stage::Sending;
+			}
+		});
 		ui.add_space(6.0);
 		ui.vertical_centered(|ui| {
 			ui.label(
-				RichText::new("Press and hold to confirm")
-					.font(FontId::new(12.0, fonts::regular()))
-					.color(t.text_mute),
+				RichText::new(if over {
+					"Go back and lower the amount"
+				} else {
+					"Press and hold to confirm"
+				})
+				.font(FontId::new(12.0, fonts::regular()))
+				.color(t.text_mute),
 			);
 		});
 		false