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.The book includes the proceedings of the following tracks and workshops co-located with ECSA 2026:– ECSA/ESOCC Doctoral Symposium– Tools and Demos Track– 1st International Workshop on Architecting Secure, Intelligent, and Sovereign Agentic Systems(ASISAS)– 9th Context-Aware, Autonomous and Smart Architectures International Workshop (CASA@ECSA2026)– 1st International Workshop on Intelligent and Data-driven Engineering for Software Architecture(IDEA-ARCH)

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.The book includes the proceedings of the following tracks and workshops co-located with ECSA 2026:– ECSA/ESOCC Doctoral Symposium– Tools and Demos Track– 1st International Workshop on Architecting Secure, Intelligent, and Sovereign Agentic Systems(ASISAS)– 9th Context-Aware, Autonomous and Smart Architectures International Workshop (CASA@ECSA2026)– 1st International Workshop on Intelligent and Data-driven Engineering for Software Architecture(IDEA-ARCH)