fix(phase-strip): make cache rate truthful

Keep the community cache-rate addition while labeling the chip, respecting the configured Cache status item, and hiding it at compact widths. Widen the counters before percentage math so saturated u32 telemetry cannot exceed 100%.

Add render coverage for visibility, configuration, compact layout, rounding, and overflow.

Co-authored-by: dmitri-0 <[email protected]>

Signed-off-by: Hunter B <[email protected]>

crates/tui/src/tui/phase_strip.rs

@@ -112,6 +112,19 @@ fn working_detail(app: &App) -> Option<String> {
     }
 }
 
+fn session_cache_hit_percentage(app: &App) -> Option<u8> {
+    let hit = u64::from(app.session.total_cache_hit_tokens);
+    let miss = u64::from(app.session.total_cache_miss_tokens);
+    let total = hit + miss;
+    if total == 0 {
+        return None;
+    }
+
+    // Round to the nearest whole percent. Widen before adding so sessions
+    // with saturated u32 telemetry counters can never render above 100%.
+    Some(((hit * 100 + total / 2) / total) as u8)
+}
+
 fn count_running_tools(cell: &HistoryCell) -> usize {
     let HistoryCell::Tool(tool) = cell else {
         return 0;
@@ -127,8 +140,8 @@ fn count_running_tools(cell: &HistoryCell) -> usize {
 }
 
 /// Paint the one-line phase band. Owns phase, optional working detail, cost,
-/// and detail-key hints — never route/context (header) or Tasks/To-do
-/// (work surface).
+/// configured session cache rate, and detail-key hints — never route/context
+/// (header) or Tasks/To-do (work surface).
 pub fn render(area: Rect, buf: &mut Buffer, app: &mut App) {
     if area.width == 0 || area.height == 0 {
         return;
@@ -216,16 +229,18 @@ pub fn render(area: Rect, buf: &mut Buffer, app: &mut App) {
         ));
     }
 
-    // Cache hit percentage right after cost, e.g. "(98%)"
-    let total = app.session.total_cache_hit_tokens
-        .saturating_add(app.session.total_cache_miss_tokens);
-    if total > 0 {
-        let pct = (app.session.total_cache_hit_tokens as f64 * 100.0
-            / total as f64).round() as u8;
+    if tier != ShellTier::Compact
+        && app.status_items.contains(&crate::config::StatusItem::Cache)
+        && let Some(pct) = session_cache_hit_percentage(app)
+    {
         left.push(Span::styled(
-            format!(" ({pct}%)"),
+            " · ",
             Style::default().fg(app.ui_theme.text_dim),
         ));
+        left.push(Span::styled(
+            format!("cache {pct}%"),
+            Style::default().fg(app.ui_theme.text_muted),
+        ));
     }
 
     // Live phases keep the strip quiet: no detail-key chorus competing with
@@ -425,4 +440,68 @@ mod tests {
             "completion hid unresolved warning: {text}"
         );
     }
+
+    #[test]
+    fn cache_percentage_uses_wide_arithmetic_and_rounds() {
+        let mut app = test_app();
+        assert_eq!(session_cache_hit_percentage(&app), None);
+
+        app.session.total_cache_hit_tokens = 2;
+        app.session.total_cache_miss_tokens = 1;
+        assert_eq!(session_cache_hit_percentage(&app), Some(67));
+
+        app.session.total_cache_hit_tokens = u32::MAX;
+        app.session.total_cache_miss_tokens = u32::MAX;
+        assert_eq!(session_cache_hit_percentage(&app), Some(50));
+    }
+
+    #[test]
+    fn cache_chip_is_labeled_configurable_and_hidden_when_compact() {
+        let mut app = test_app();
+        app.status_items = vec![crate::config::StatusItem::Cache];
+        app.session.total_cache_hit_tokens = 7;
+        app.session.total_cache_miss_tokens = 3;
+
+        let backend = TestBackend::new(80, 1);
+        let mut terminal = Terminal::new(backend).expect("terminal");
+        terminal
+            .draw(|frame| render(frame.area(), frame.buffer_mut(), &mut app))
+            .expect("draw");
+        let text = terminal
+            .backend()
+            .buffer()
+            .content()
+            .iter()
+            .map(|cell| cell.symbol())
+            .collect::<String>();
+        assert!(text.contains("cache 70%"), "{text}");
+
+        app.status_items.clear();
+        terminal
+            .draw(|frame| render(frame.area(), frame.buffer_mut(), &mut app))
+            .expect("draw without cache");
+        let text = terminal
+            .backend()
+            .buffer()
+            .content()
+            .iter()
+            .map(|cell| cell.symbol())
+            .collect::<String>();
+        assert!(!text.contains("cache"), "{text}");
+
+        app.status_items = vec![crate::config::StatusItem::Cache];
+        let backend = TestBackend::new(50, 1);
+        let mut compact = Terminal::new(backend).expect("compact terminal");
+        compact
+            .draw(|frame| render(frame.area(), frame.buffer_mut(), &mut app))
+            .expect("compact draw");
+        let text = compact
+            .backend()
+            .buffer()
+            .content()
+            .iter()
+            .map(|cell| cell.symbol())
+            .collect::<String>();
+        assert!(!text.contains("cache"), "compact strip: {text}");
+    }
 }