⚡ Optimize LocalDatabase retry latency for transient file locks

src/NodeRadarPro/Data/LocalDatabase.cs

@@ -95,16 +95,8 @@ public LocalDatabase(string? customDbPath = null, string? customPassword = null)
             }
             catch (IOException)
             {
-                // Transient file lock (antivirus, backup process) — retry once after backoff
-                System.Threading.Thread.Sleep(500);
-                try
-                {
-                    _db = new LiteDatabase($"Filename={_dbPath};Password={_dbPassword};Connection=shared;");
-                }
-                catch
-                {
-                    _db = new LiteDatabase(new MemoryStream());
-                }
+                // Transient file lock (antivirus, backup process) — retry with fine-grained backoff
+                _db = OpenDatabaseWithRetry(_dbPath, _dbPassword);
             }
             catch
             {
@@ -115,6 +107,37 @@ public LocalDatabase(string? customDbPath = null, string? customPassword = null)
         }
     }
 
+
+    private static LiteDatabase OpenDatabaseWithRetry(string dbPath, string dbPassword, int timeoutMs = 500, int pollIntervalMs = 10)
+    {
+        var sw = System.Diagnostics.Stopwatch.StartNew();
+        while (sw.ElapsedMilliseconds < timeoutMs)
+        {
+            System.Threading.Thread.Sleep(pollIntervalMs);
+            try
+            {
+                return new LiteDatabase($"Filename={dbPath};Password={dbPassword};Connection=shared;");
+            }
+            catch (IOException)
+            {
+                // Continue retry polling until timeout
+            }
+            catch
+            {
+                return new LiteDatabase(new MemoryStream());
+            }
+        }
+
+        try
+        {
+            return new LiteDatabase($"Filename={dbPath};Password={dbPassword};Connection=shared;");
+        }
+        catch
+        {
+            return new LiteDatabase(new MemoryStream());
+        }
+    }
+
     internal void DisposeConnection()
     {
         lock (SyncRoot)

tests/NodeRadarPro.Tests/Data/LocalDatabaseTests.cs

@@ -753,4 +753,40 @@ public void PruneOldData_DefaultArguments_UsesSettingsValues()
         Assert.DoesNotContain(remaining, l => l.Message == "Expired Log");
         Assert.Contains(remaining, l => l.Message == "Valid Log");
     }
+    [Fact]
+    public void DefaultConstructor_WhenTransientIOExceptionIsResolvedQuickly_RecoversFast()
+    {
+        string myDocuments = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
+        string myFolder = Path.Combine(myDocuments, "PyPie Studio", "NodeRadar Pro");
+        Directory.CreateDirectory(myFolder);
+        string dbPath = Path.Combine(myFolder, "noderadar.db");
+
+        using var readyEvt = new ManualResetEventSlim(false);
+        using var releaseEvt = new ManualResetEventSlim(false);
+
+        var lockTask = Task.Run(() =>
+        {
+            using var fs = new FileStream(dbPath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
+            readyEvt.Set();
+            releaseEvt.Wait(3000);
+        });
+
+        readyEvt.Wait(1000);
+
+        // Schedule lock release after 20ms
+        _ = Task.Run(async () =>
+        {
+            await Task.Delay(20);
+            releaseEvt.Set();
+        });
+
+        var sw = System.Diagnostics.Stopwatch.StartNew();
+        using var db = new LocalDatabase();
+        sw.Stop();
+
+        lockTask.Wait(1000);
+
+        Assert.NotNull(db);
+        Assert.True(sw.ElapsedMilliseconds < 450, $"Expected recovery in < 450ms, took {sw.ElapsedMilliseconds} ms");
+    }
 }