diff --git a/src/utils/__tests__/claude-settings.test.ts b/src/utils/__tests__/claude-settings.test.ts
index 0630ba2a..1b858af5 100644
--- a/src/utils/__tests__/claude-settings.test.ts
+++ b/src/utils/__tests__/claude-settings.test.ts
@@ -351,6 +351,19 @@ describe('installStatusLine refreshInterval', () => {
         await installStatusLine({ commandMode: 'auto-npx', supportsRefreshInterval: true });
         expect(readInstalledRefreshInterval()).toBe(5);
     });
+
+    it('should preserve existing refreshInterval when version is unsupported', async () => {
+        writeRawClaudeSettings(JSON.stringify({
+            statusLine: {
+                type: 'command',
+                command: CCSTATUSLINE_COMMANDS.NPM,
+                padding: 0,
+                refreshInterval: 5
+            }
+        }));
+        await installStatusLine({ commandMode: 'auto-npx', supportsRefreshInterval: false });
+        expect(readInstalledRefreshInterval()).toBe(5);
+    });
 });
 
 describe('refreshInterval', () => {
diff --git a/src/utils/claude-settings.ts b/src/utils/claude-settings.ts
index 8aaecfce..5ab6f7c0 100644
--- a/src/utils/claude-settings.ts
+++ b/src/utils/claude-settings.ts
@@ -421,9 +421,13 @@ export async function installStatusLine({
         padding: 0
     };
 
-    // Only set refreshInterval if Claude Code version supports it (>=2.1.97)
-    if (supportsRefreshInterval) {
-        settings.statusLine.refreshInterval = existingRefreshInterval ?? 10;
+    // Default refreshInterval only on supported versions (>=2.1.97), but always keep an
+    // existing value - the version probe also returns false when `claude --version` fails.
+    const refreshInterval = supportsRefreshInterval
+        ? (existingRefreshInterval ?? 10)
+        : existingRefreshInterval;
+    if (refreshInterval !== undefined) {
+        settings.statusLine.refreshInterval = refreshInterval;
     }
 
     await saveClaudeSettings(settings);