This book constitutes the refereed proceedings of the tracks and workshops which complemented the 20th European Conference on Software Architecture, ECSA 2026, held in Bolzano, Italy, during September 7–11, 2026.

The 15 full papers and 12 short papers presented in this volume were carefully reviewed and selected from 43 submissions. 

They are grouped into the following topics: Doctoral Symposium; Tools and Demos; CASA@ECSA Workshop; IDEA-ARCH Workshop and ASISAS Workshop 

In addition, it includes the proceedings of the three workshops 
co-located with ECSA 2026:

– 1st International Workshop on Architecting Secure, Intelligent, and Sovereign Agentic Systems 
(ASISAS)

– 9th Context-Aware, Autonomous and Smart Architectures International Workshop (CASA@ECSA 
2026)

– 1st International Workshop on Intelligent and Data-driven Engineering for Software Architecture 
(IDEA-ARCH)