fix: make Windows SQLite file lock retry more aggressive

Increased retry attempts and improved cleanup for Windows file locking:

Changes:
- Increased max attempts from 10 to 20
- Increased initial delay from 50ms to 100ms
- Capped max delay at 2 seconds
- Added SqliteConnection.ClearAllPools() before and during retries
- Added second GC.Collect() to clean up finalizer queue
- ErrorPathTests: Also delete WAL/SHM files

Windows + SQLite WAL mode can hold locks for several seconds after
disposal. These changes give more time for Windows to release locks.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: sakrut

AiCodeGraph.Tests/ErrorPathTests.cs

@@ -17,9 +17,11 @@ private static void DeleteFileWithRetry(string path)
             return;
 
         // On Windows, SQLite may keep files locked briefly after connection disposal
+        Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
+
         var attempts = 0;
-        var maxAttempts = 10;
-        var delay = 50; // ms
+        var maxAttempts = 20; // Increased for Windows
+        var delay = 100; // Start with 100ms
 
         while (attempts < maxAttempts)
         {
@@ -29,16 +31,25 @@ private static void DeleteFileWithRetry(string path)
                 {
                     GC.Collect();
                     GC.WaitForPendingFinalizers();
+                    GC.Collect(); // Second GC to clean up finalizer queue
+                    Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
                     Thread.Sleep(delay);
                 }
 
                 File.Delete(path);
+
+                // Also try to delete WAL and SHM files if they exist
+                var walPath = path + "-wal";
+                var shmPath = path + "-shm";
+                if (File.Exists(walPath)) File.Delete(walPath);
+                if (File.Exists(shmPath)) File.Delete(shmPath);
+
                 return; // Success
             }
             catch (IOException) when (attempts < maxAttempts - 1)
             {
                 attempts++;
-                delay *= 2; // Exponential backoff
+                delay = Math.Min(delay * 2, 2000); // Cap at 2 seconds
             }
         }
 

AiCodeGraph.Tests/TempDirectoryFixture.cs

@@ -24,10 +24,12 @@ public virtual void Dispose()
             return;
 
         // On Windows, SQLite WAL mode keeps files locked briefly after disposal
-        // Retry deletion with delays to allow locks to be released
+        // Clear connection pools and retry deletion with delays to allow locks to be released
+        Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
+
         var attempts = 0;
-        var maxAttempts = 10;
-        var delay = 50; // ms
+        var maxAttempts = 20; // Increased for Windows
+        var delay = 100; // Start with 100ms
 
         while (attempts < maxAttempts)
         {
@@ -38,6 +40,8 @@ public virtual void Dispose()
                 {
                     GC.Collect();
                     GC.WaitForPendingFinalizers();
+                    GC.Collect(); // Second GC to clean up finalizer queue
+                    Microsoft.Data.Sqlite.SqliteConnection.ClearAllPools();
                     Thread.Sleep(delay);
                 }
 
@@ -47,7 +51,7 @@ public virtual void Dispose()
             catch (IOException) when (attempts < maxAttempts - 1)
             {
                 attempts++;
-                delay *= 2; // Exponential backoff
+                delay = Math.Min(delay * 2, 2000); // Cap at 2 seconds
             }
         }