tomevault-io Codex CLI Agent Deployment
Use the OpenAI Codex CLI to deploy autonomous coding agents. Codex agents read files, explore the codebase, and write code independently.
Quick Reference
Non-interactive mode (for background/parallel tasks):
codex exec -c model_reasoning_effort="xhigh" --dangerously-bypass-approvals-and-sandbox "<prompt>"
Interactive mode (requires a TTY — cannot run from background tasks):
codex -c model_reasoning_effort="xhigh" --yolo "<prompt>"
IMPORTANT: Interactive mode (codex without exec) requires a TTY. When running from Claude Code's Bash tool with run_in_background: true, you MUST use codex exec instead. The interactive TUI will fail with "stdin is not a terminal" in background mode.
Key Flags
| Flag | Purpose |
|---|---|
exec |
Non-interactive subcommand (required for background execution) |
-c model_reasoning_effort="xhigh" |
Maximum reasoning effort |
-c model="<model>" |
Override model (default: gpt-5.2-codex) |
--dangerously-bypass-approvals-and-sandbox |
Skip all prompts, no sandbox (use for trusted repos) |
--full-auto |
Sandboxed auto-execution (safer alternative to bypass) |
--yolo |
Interactive mode equivalent of bypass (TTY only) |
-C <dir> |
Set working directory |
-i <file> |
Attach image(s) to the prompt |
--search |
Enable web search tool |
-s <mode> |
Sandbox: read-only, workspace-write, danger-full-access |
-o <file> |
Write last agent message to file |
--json |
Output JSONL events to stdout |
Deployment Patterns
Single background agent
codex exec -c model_reasoning_effort="xhigh" --dangerously-bypass-approvals-and-sandbox "Read issues/008-image-paste-in-chat.md and implement it. Read all relevant files before making changes."
Run with run_in_background: true in the Bash tool, then check output with TaskOutput.
Multiple parallel agents
Launch several codex exec commands simultaneously using parallel Bash tool calls, each with run_in_background: true. Each gets its own task ID for monitoring.
Resume a session
codex exec resume --last # Resume most recent
codex resume # Interactive picker (TTY only)
Code review
codex exec review # Review current changes
codex review # Interactive review (TTY only)
Prompt Best Practices
- Always tell codex to read the relevant files first: "Read X.swift and Y.swift, then implement..."
- Reference issue files by path: "Read issues/008-image-paste-in-chat.md carefully, then..."
- Be specific about scope: List exact requirements rather than vague instructions
- Mention the architecture: "This is a SwiftUI app using STTextView for editing..."
Monitoring Background Agents
After launching with run_in_background: true:
- Use
TaskOutputwithblock: falseto check status without waiting - Use
TaskOutputwithblock: trueto wait for completion - Read the output file path directly with the
Readtool for full logs
Other Subcommands
| Command | Purpose |
|---|---|
codex apply / codex a |
Apply the latest diff from a codex session as git apply |
codex cloud |
Browse Codex Cloud tasks |
codex fork |
Fork a previous session |
codex debug |
Debugging tools |
codex mcp |
Run as MCP server |
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