What’s new in Codex 0.151.0

Official releaseReleased Aug 29, 2026Original notes on GitHub

New features

Added a configurable grace period for discovering tools from optional MCP servers. (#41199)
Extensions can now inspect or replace MCP tool results before they reach the model. (#41202)
Plugin catalogs now combine per-repository configuration and report invalid project marketplaces without hiding valid plugins. (#41208)

Preserved restored permission profiles across TUI turns and prevented /cd from weakening sandbox restrictions. (#41192)
Kept tool availability and reasoning effort correct when switching models or falling back to another model. (#41195, #41206)
Improved remote sandbox enforcement using the executor’s actual home directory, operating system, and path conventions. (#41196, #41204, #41207, #41209)
Preserved structured MCP tool and resource errors in app-server responses. (#41196)
Counted nested subagent token usage toward root goal budgets. (#41183)
Prevented stale Guardian classifications from authorizing actions after permission state changes. (#41196)

Added telemetry for escalated stdin reviews and remote executor MCP discovery. (#41189, #41205)
Stabilized Guardian WebSocket and core fixture tests under slow or highly concurrent CI. (#41191, #41194)