Implement SPLADE sparse encoder and associated database migrations

- Added `splade_encoder.py` for ONNX-optimized SPLADE encoding, including methods for encoding text and batch processing.
- Created `SPLADE_IMPLEMENTATION.md` to document the SPLADE encoder's functionality, design patterns, and integration points.
- Introduced migration script `migration_009_add_splade.py` to add SPLADE metadata and posting list tables to the database.
- Developed `splade_index.py` for managing the SPLADE inverted index, supporting efficient sparse vector retrieval.
- Added verification script `verify_watcher.py` to test FileWatcher event filtering and debouncing functionality.

codex-lens/verify_watcher.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+"""Verification script for FileWatcher event filtering and debouncing."""
+
+import time
+from pathlib import Path
+from codexlens.watcher.file_watcher import FileWatcher
+from codexlens.watcher.events import WatcherConfig, FileEvent
+
+def test_should_index_file():
+    """Test _should_index_file filtering logic."""
+    print("Testing _should_index_file filtering...")
+
+    # Create watcher instance
+    config = WatcherConfig()
+    watcher = FileWatcher(
+        root_path=Path("."),
+        config=config,
+        on_changes=lambda events: None,
+    )
+
+    # Test cases
+    test_cases = [
+        # (path, expected_result, description)
+        (Path("test.py"), True, "Python file should be indexed"),
+        (Path("test.txt"), True, "Text file should be indexed"),
+        (Path("test.js"), True, "JavaScript file should be indexed"),
+        (Path("test.ts"), True, "TypeScript file should be indexed"),
+        (Path("src/test.py"), True, "Python file in subdirectory should be indexed"),
+        (Path(".git/config"), False, ".git files should be filtered"),
+        (Path("node_modules/pkg/index.js"), False, "node_modules should be filtered"),
+        (Path("__pycache__/test.pyc"), False, "__pycache__ should be filtered"),
+        (Path(".venv/lib/test.py"), False, ".venv should be filtered"),
+        (Path("test.unknown"), False, "Unknown extension should be filtered"),
+        (Path("README.md"), True, "Markdown file should be indexed"),
+    ]
+
+    passed = 0
+    failed = 0
+
+    for path, expected, description in test_cases:
+        result = watcher._should_index_file(path)
+        status = "✓" if result == expected else "✗"
+
+        if result == expected:
+            passed += 1
+        else:
+            failed += 1
+
+        print(f"  {status} {description}")
+        print(f"    Path: {path}, Expected: {expected}, Got: {result}")
+
+    print(f"\nResults: {passed} passed, {failed} failed")
+    return failed == 0
+
+def test_debounce_and_dedup():
+    """Test event debouncing and deduplication."""
+    print("\nTesting event debouncing and deduplication...")
+
+    received_events = []
+
+    def on_changes(events):
+        received_events.append(events)
+        print(f"  Received batch: {len(events)} events")
+
+    # Create watcher with short debounce time for testing
+    config = WatcherConfig(debounce_ms=500)
+    watcher = FileWatcher(
+        root_path=Path("."),
+        config=config,
+        on_changes=on_changes,
+    )
+
+    # Simulate rapid events to same file (should be deduplicated)
+    from codexlens.watcher.events import ChangeType
+
+    test_path = Path("test_file.py")
+    for i in range(5):
+        event = FileEvent(
+            path=test_path,
+            change_type=ChangeType.MODIFIED,
+            timestamp=time.time(),
+        )
+        watcher._on_raw_event(event)
+
+    # Wait for debounce
+    time.sleep(0.6)
+
+    # Force flush to ensure we get the events
+    watcher._flush_events()
+
+    if received_events:
+        batch = received_events[0]
+        # Should deduplicate 5 events to 1
+        if len(batch) == 1:
+            print("  ✓ Deduplication working: 5 events reduced to 1")
+            return True
+        else:
+            print(f"  ✗ Deduplication failed: expected 1 event, got {len(batch)}")
+            return False
+    else:
+        print("  ✗ No events received")
+        return False
+
+if __name__ == "__main__":
+    print("=" * 60)
+    print("FileWatcher Verification")
+    print("=" * 60)
+
+    test1 = test_should_index_file()
+    test2 = test_debounce_and_dedup()
+
+    print("\n" + "=" * 60)
+    if test1 and test2:
+        print("✓ All tests passed!")
+    else:
+        print("✗ Some tests failed")
+    print("=" * 60)