fix(renderer): drop spacing separator stranded against a flex-separator

src/utils/__tests__/renderer-separator-collapse.test.ts

@@ -199,6 +199,41 @@ describe('renderer separator collapse around empty widgets', () => {
         expect(out).toContain('C');
     });
 
+    it('drops a spacing separator stranded against a flex separator when the widget between renders empty', () => {
+        const space: WidgetItem = { id: 'space', type: 'separator', character: ' ' };
+        const widgets: WidgetItem[] = [
+            T('a'),
+            space,
+            T('b'),
+            { id: 'flex', type: 'flex-separator' },
+            T('c')
+        ];
+        const settings = createSettings({ colorLevel: 0 });
+        const context: RenderContext = { isPreview: false, terminalWidth: 0 };
+        const preRenderedWidgets = makePreRendered(widgets, { 0: 'A', 2: '', 4: 'C' });
+        const out = stripSgrCodes(renderStatusLine(widgets, settings, context, preRenderedWidgets, []));
+
+        expect(out).toBe('A | C');
+    });
+
+    it('keeps a stranded spacing separator when a known-width flex separator allocates no space', () => {
+        const space: WidgetItem = { id: 'space', type: 'separator', character: ' ' };
+        const widgets: WidgetItem[] = [
+            T('a'),
+            space,
+            T('hidden'),
+            { id: 'flex', type: 'flex-separator' },
+            T('c')
+        ];
+        const settings = createSettings({ colorLevel: 0, flexMode: 'full' });
+        // Full mode reserves six columns, leaving a ten-column render width.
+        const context: RenderContext = { isPreview: false, terminalWidth: 16 };
+        const preRenderedWidgets = makePreRendered(widgets, { 0: 'AAAAA', 2: '', 4: 'CCCCC' });
+        const out = stripSgrCodes(renderStatusLine(widgets, settings, context, preRenderedWidgets, []));
+
+        expect(out).toBe('AAAAA C...');
+    });
+
     it('does not borrow visible content across a flex separator', () => {
         const widgets: WidgetItem[] = [
             T('left'),

src/utils/renderer.ts

@@ -1196,6 +1196,23 @@ export function renderStatusLine(
         elements.pop();
     }
 
+    // When width detection fails, flex separators fall back to their own ' | '
+    // boundary. Drop any spacing-only separator stranded directly beside one so
+    // that fallback does not render a duplicate space. With a known width, keep
+    // the separator: a fully occupied line can leave the flex gap at zero columns,
+    // making this space the only boundary between the surrounding content.
+    if (!terminalWidth) {
+        for (let i = elements.length - 1; i >= 0; i--) {
+            if (elements[i]?.type !== 'separator'
+                || !isSpacingSeparator(elements[i]?.widget, settings.defaultSeparator)) {
+                continue;
+            }
+            if (elements[i - 1]?.type === 'flex-separator' || elements[i + 1]?.type === 'flex-separator') {
+                elements.splice(i, 1);
+            }
+        }
+    }
+
     // Apply default padding and separators
     const finalElements: string[] = [];
     const padding = settings.defaultPadding ?? '';