Use SQLite for GetGmailIDsByFilter to ensure accurate deletion status

DuckDBEngine.GetGmailIDsByFilter now delegates to SQLiteEngine instead
of querying the Parquet cache. This ensures deleted messages are properly
excluded even when the Parquet cache is stale.

The Parquet cache only captures deleted_from_source_at at build time.
Messages deleted after the cache was built would still appear in staging
queries. By using SQLite (the source of truth), we guarantee accurate
results for deletion staging in both TUI and MCP.

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

Author: robelkin-rational-partners

internal/query/duckdb.go

@@ -1502,11 +1502,20 @@ func (e *DuckDBEngine) Search(ctx context.Context, q *search.Query, limit, offse
 	return results, nil
 }
 
-// GetGmailIDsByFilter returns Gmail IDs matching a filter from Parquet files.
-// Uses EXISTS subqueries for efficient semi-join filtering.
+// GetGmailIDsByFilter returns Gmail IDs matching a filter.
+// This method delegates to SQLite for authoritative deletion status.
+// The Parquet cache may be stale if messages were deleted after the last cache build,
+// so we use SQLite directly to ensure deleted messages are properly excluded.
 func (e *DuckDBEngine) GetGmailIDsByFilter(ctx context.Context, filter MessageFilter) ([]string, error) {
+	// Delegate to SQLite for authoritative deletion status.
+	// Parquet cache may be stale if deletions occurred after the last build.
+	if e.sqliteEngine != nil {
+		return e.sqliteEngine.GetGmailIDsByFilter(ctx, filter)
+	}
+
+	// Fall back to Parquet if no SQLite engine available (shouldn't happen in practice)
 	if e.analyticsDir == "" {
-		return nil, fmt.Errorf("GetGmailIDsByFilter requires Parquet data: pass analyticsDir to NewDuckDBEngine")
+		return nil, fmt.Errorf("GetGmailIDsByFilter requires SQLite or Parquet data")
 	}
 
 	var conditions []string

internal/query/duckdb_test.go

@@ -1665,9 +1665,9 @@ func TestDuckDBEngine_SubAggregate_MultipleEmptyTargets(t *testing.T) {
 	}
 }
 
-// TestDuckDBEngine_GetGmailIDsByFilter_NoParquet verifies error when analyticsDir is empty.
-func TestDuckDBEngine_GetGmailIDsByFilter_NoParquet(t *testing.T) {
-	// Create engine without Parquet
+// TestDuckDBEngine_GetGmailIDsByFilter_NoDataSource verifies error when no SQLite or Parquet available.
+func TestDuckDBEngine_GetGmailIDsByFilter_NoDataSource(t *testing.T) {
+	// Create engine without SQLite or Parquet
 	engine, err := NewDuckDBEngine("", "", nil)
 	if err != nil {
 		t.Fatalf("NewDuckDBEngine: %v", err)
@@ -1677,10 +1677,10 @@ func TestDuckDBEngine_GetGmailIDsByFilter_NoParquet(t *testing.T) {
 	ctx := context.Background()
 	_, err = engine.GetGmailIDsByFilter(ctx, MessageFilter{Sender: "test@example.com"})
 	if err == nil {
-		t.Fatal("expected error when calling GetGmailIDsByFilter without Parquet")
+		t.Fatal("expected error when calling GetGmailIDsByFilter without SQLite or Parquet")
 	}
-	if !strings.Contains(err.Error(), "requires Parquet") {
-		t.Errorf("expected 'requires Parquet' error, got: %v", err)
+	if !strings.Contains(err.Error(), "requires SQLite or Parquet") {
+		t.Errorf("expected 'requires SQLite or Parquet' error, got: %v", err)
 	}
 }