Codex Memory Internals: What It Remembers, Who Decides, and How It Compares to OpenCode

I began this investigation with a specific question: can Codex autonomously add, modify, and delete its own memories? The product documentation already says that it has memory. What I wanted to know was who actually decides what survives. When an old chat contains a useful build command, does deterministic application code copy it into a database? Does the active coding model call a memory tool? Does another model summarize the chat later? When the command becomes obsolete, is the old fact overwritten, invalidated, aged out, or simply left where future agents may still find it? Those questions led to a more interesting result than a feature checklist. Codex has a genuine cross-session memory subsystem, but its behavior is split between model judgment and deterministic lifecycle code. Models decide what a rollout means and how durable guidance should be rewritten. Runtime code decides which rollouts are eligible, which evidence remains in the working set, when old records are deleted, and when the consolidation model is allowed to run. That makes the short answer precise: With local memories enabled, Codex can autonomously add, modify, merge, and remove persistent memory without a user approving each write. User-requested corrections follow a separate append-only note path, while retention, thread deletion, and reset provide additional forms of forgetting. The rest of this article explains why each word in that answer matters. This analysis is pinned to OpenAI Codex commit 8444cf63b50a8a88521e0d2970d49f659b48eac7 , checked on August 25, 2026. The feature is marked stable in that source tree but remains off by default, so this describes implemented behavior, not behavior every Codex user is currently receiving. Key Takeaways Codex local memory is a background two-model pipeline. One model extracts reusable material from each eligible rollout. A second model consolidates those outputs into a global file-based memory workspace. The LLM owns semantic CRUD, but not lifecy