Public-sector modernization initiatives frequently fail despite technically successful implementations because legacy systems function as more than software platforms. They also operate as repositories of institutional memory, tacit operational knowledge, informal workflow adaptation, and organizational continuity. Existing modernization approaches often underestimate the socio-technical risks created when these systems are replaced without deliberate continuity planning. This paper introduces Continuity-Centered Modernization (CCM), a framework that reframes legacy systems as institutional memory infrastructure rather than purely technical artifacts. Drawing from organizational memory theory, tacit knowledge literature, socio-technical systems research, and public-sector modernization practice, the paper identifies several recurring continuity failure modes — including tacit knowledge concentration, exception-path loss, informal authority collapse, shadow-system dependency, and institutional grief associated with system transition — and argues that modernization failure is fundamentally a continuity failure problem, not merely a technical one. The paper proposes a nine-dimension operational framework for identifying, assessing, and mitigating institutional continuity risk during modernization initiatives, and argues that institutional memory preservation should be treated not as a secondary change-management concern but as a core operational resilience and governance function. Finally, the paper explores the role of AI-assisted knowledge systems in preserving institutional continuity while warning against the risks of decontextualized or synthetic institutional memory. Published by BDB Labs ORCID: 0009-0001-6994-6828.

Notes: Companion pieces in development: Mapping Informal Authority in Legacy System Transitions and AI-Assisted Institutional Knowledge Indexing: Design Principles for Public-Sector Continuity Systems. This paper is a publication of BDB Labs.