feat: wire GraphRAG API handlers, activities, and database layer

pkg/db/db.go

@@ -454,3 +454,82 @@ func (db *DB) FetchActivityTraces(ctx context.Context, executionID string) ([]Ac
 
 	return traces, rows.Err()
 }
+
+// GetWorkflowRelations retrieves all relations for a workflow version
+func (db *DB) GetWorkflowRelations(ctx context.Context, workflowID string, version int) ([]WorkflowRelation, error) {
+	var relations []WorkflowRelation
+
+	query := `
+		SELECT id, workflow_id, version, source_node_id, target_node_id, 
+		       relation_type, label, relation_wording, metadata, created_at
+		FROM workflow_relations
+		WHERE workflow_id = $1 AND version = $2
+		ORDER BY created_at DESC
+	`
+
+	rows, err := db.conn.QueryContext(ctx, query, workflowID, version)
+	if err != nil {
+		return nil, fmt.Errorf("failed to query relations: %w", err)
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var rel WorkflowRelation
+		if err := rows.Scan(
+			&rel.ID,
+			&rel.WorkflowID,
+			&rel.Version,
+			&rel.SourceNodeID,
+			&rel.TargetNodeID,
+			&rel.RelationType,
+			&rel.Label,
+			&rel.RelationWording,
+			&rel.Metadata,
+			&rel.CreatedAt,
+		); err != nil {
+			return nil, fmt.Errorf("failed to scan relation: %w", err)
+		}
+		relations = append(relations, rel)
+	}
+
+	return relations, rows.Err()
+}
+
+// GetRelationVersions retrieves version history for a specific relation
+func (db *DB) GetRelationVersions(ctx context.Context, workflowID string, edgeID string) ([]WorkflowRelationVersion, error) {
+	var versions []WorkflowRelationVersion
+
+	query := `
+		SELECT id, workflow_id, edge_id, version_num, operation, snapshot, 
+		       changed_at, changed_by, fields_changed
+		FROM workflow_relation_versions
+		WHERE workflow_id = $1 AND edge_id = $2
+		ORDER BY version_num ASC
+	`
+
+	rows, err := db.conn.QueryContext(ctx, query, workflowID, edgeID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to query relation versions: %w", err)
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var v WorkflowRelationVersion
+		if err := rows.Scan(
+			&v.ID,
+			&v.WorkflowID,
+			&v.EdgeID,
+			&v.VersionNum,
+			&v.Operation,
+			&v.Snapshot,
+			&v.ChangedAt,
+			&v.ChangedBy,
+			&v.FieldsChanged,
+		); err != nil {
+			return nil, fmt.Errorf("failed to scan version: %w", err)
+		}
+		versions = append(versions, v)
+	}
+
+	return versions, rows.Err()
+}