Model baseline: gpt-5.5 remains the recommended Codex default in the official Models page.
Key deltas checked: 0.145.0~0.146.0 paginated history/forks, named and pinned threads, side switching, expanded import, Agent Plugins/marketplaces, remote Code Mode, custom-provider web search, executor skills, broad proxy handling, MCP/App refresh, and replay preservation.
Current command-reference delta checked: /copy, /rename, /pets (/pet), Windows-only /setup-default-sandbox, and /app, plus /subagents and /btw aliases.