How Claude Code Remembers (And Forgets): The Memory and Persistence Architecture

Claude Code processes thousands of lines of code, generates insights, solves bugs, discovers architecture — then the session ends and it forgets everything. The next session starts from scratch. The model re-reads the same files, re-traces the same execution paths, re-discovers the same patterns. Nothing compounds. This is the fundamental limitation of a context-window-only architecture. The context window is working memory: capacious, fast, but volatile. When it fills up, old content is compressed or discarded. When the session ends, everything goes. The naive solution: just save everything to disk. But "everything" is too much. A 200-turn debugging session produces megabytes of tool calls, error messages, failed attempts, and dead ends. Loading all of that into the next session would waste most of the context window on irrelevant history. You need selectivity — keep the lessons, discard the scaffolding. The opposite extreme: save nothing. Let the model re-derive knowledge from the co