Codex Knowledge Base
Codex CLI MCP Sandbox-State Metadata: Building Context-Aware Tool Servers
MCP servers connected to Codex CLI traditionally operate without knowledge of their execution context. A database migration tool behaves identically whether.
MCP Parallel Tool Calls in Codex CLI: Unlocking Concurrent Execution with supports_parallel_tool_calls
Since v0.121.0, Codex CLI has shipped a quietly powerful configuration flag for MCP servers: supports_parallel_tool_calls. When enabled, it allows tools.
Codex CLI Config Lockfiles: Reproducible Agent Sessions with Export, Replay, and Drift Detection
Every senior engineer has encountered the it worked on my machine problem with build tools.
The Goblin Incident: What Reward Signal Leakage in GPT-5.5 Teaches Codex CLI Practitioners
On 28 April 2026, Google engineer Barron Roth noticed something odd in his Codex CLI sessions: the model kept inserting the word goblin into code.
WebSocket Mode in Codex CLI: How Persistent Connections to the Responses API Cut Agent Loop Latency by 40%
Every Codex CLI session is, at its core, a tight loop: send context to the Responses API, receive a model response, execute any requested tool calls, feed.
Codex CLI Sandbox Internals: How Seatbelt, Bubblewrap, Landlock and Windows DACL Keep Agent Commands in Check
When Codex CLI runs a shell command on your behalf, it does not simply call exec and hope for the best. Every command executes inside a platform-native.
Codex CLI Non-Interactive Pipelines: Production Automation with exec, resume, and Structured Output
The interactive TUI gets all the attention, but codex exec is where Codex CLI earns its keep in production.
Codex CLI MultiAgentV2: Custom Roles, Thread Orchestration, and Production Parallel Workflows
Codex CLI's subagent system moved from a simple fire-and-forget spawner to a governed orchestration layer with the introduction of MultiAgentV2 in v0.128.0.
Codex CLI Multi-File Editing Strategies: Coordinating Changes Across Large Pull Requests with apply_patch and Subagents
Every senior developer knows the pain: a rename that touches forty files, an API migration that ripples through three service boundaries, a framework.
The Codex CLI Model Landscape in May 2026: A Practitioner's Routing Guide
Three months ago, Codex CLI users chose between GPT-5-Codex and its Spark variant. Today the model picker lists five production options — six if you count.