fix(desktop): preserve Mermaid shapes and summary truncation

Keep auto-quoting slash labels for generated Mermaid paths while preserving slash-delimited flowchart shapes.
Restore truncation on activity summary values so the compact summary layout and tests agree.

Tested: cd desktop && bun run test -- src/pages/ActivitySettings.test.tsx src/components/chat/MermaidRenderer.test.tsx src/components/chat/MermaidRenderer.integration.test.tsx
Tested: bun run check:desktop
Confidence: high
Scope-risk: narrow

desktop/src/components/chat/MermaidRenderer.test.tsx

@@ -78,6 +78,40 @@ describe('MermaidRenderer', () => {
     expect(arrow?.getAttribute('style') ?? '').not.toContain('stroke:')
   })
 
+  it('quotes generated slash labels that Mermaid would parse as invalid shape syntax', async () => {
+    render(
+      <MermaidRenderer
+        code={[
+          'flowchart TD',
+          '  D1[/api/dcl] --> D2[直接调用 dclService]',
+        ].join('\n')}
+      />,
+    )
+
+    await waitFor(() => {
+      expect(renderMock).toHaveBeenCalledWith(
+        expect.any(String),
+        [
+          'flowchart TD',
+          '  D1["/api/dcl"] --> D2[直接调用 dclService]',
+        ].join('\n'),
+      )
+    })
+  })
+
+  it('preserves slash-delimited Mermaid flowchart shapes', async () => {
+    const code = [
+      'flowchart TD',
+      '  A[/Manual input/] --> B[OK]',
+    ].join('\n')
+
+    render(<MermaidRenderer code={code} />)
+
+    await waitFor(() => {
+      expect(renderMock).toHaveBeenCalledWith(expect.any(String), code)
+    })
+  })
+
   it('fits oversized diagrams inside the chat message surface', async () => {
     const originalClientWidth = Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'clientWidth')
     Object.defineProperty(HTMLElement.prototype, 'clientWidth', {

desktop/src/components/chat/MermaidRenderer.tsx

@@ -60,8 +60,17 @@ function isQuotedFlowchartLabel(label: string) {
   )
 }
 
+function isSlashDelimitedFlowchartShape(label: string) {
+  const trimmed = label.trim()
+  return trimmed.length >= 2 && trimmed.startsWith('/') && trimmed.endsWith('/')
+}
+
 function shouldQuoteFlowchartLabel(label: string) {
-  return !isQuotedFlowchartLabel(label) && UNQUOTED_FLOWCHART_LABEL_UNSAFE.test(label)
+  return (
+    !isQuotedFlowchartLabel(label) &&
+    !isSlashDelimitedFlowchartShape(label) &&
+    UNQUOTED_FLOWCHART_LABEL_UNSAFE.test(label)
+  )
 }
 
 function escapeFlowchartLabel(label: string) {

desktop/src/pages/ActivitySettings.tsx

@@ -772,9 +772,9 @@ export function ActivitySettings() {
                   style={{ animationDelay: `${index * 45}ms` }}
                 >
                   <div className="flex min-h-[68px] flex-col items-center justify-center gap-1.5">
-                    <div className={`activity-summary-value max-w-full min-w-0 font-semibold leading-none tracking-tight text-[var(--color-text-primary)] tabular-nums ${
+                    <div className={`activity-summary-value max-w-full min-w-0 truncate font-semibold leading-none tracking-tight text-[var(--color-text-primary)] tabular-nums ${
                       isPrimary ? 'text-[23px]' : 'text-[22px]'
-                    }`} style={{ overflow: 'visible', whiteSpace: 'normal', textOverflow: 'clip' }}>
+                    }`}>
                       {metric.value}
                     </div>
                     <div className="min-w-0 truncate text-[13px] font-medium leading-tight text-[var(--color-text-secondary)]">