Codex
Start Codex from an initiative, bug, or todo, with the goal and context already in the prompt. Send one item to Codex when you want to stay hands-on, or set up a local Codex agent to run assigned work on your machine.
Choose how to use Codex
| Path | Best for | What happens |
|---|---|---|
| Send to Codex | Starting one task now. | Codex opens with a generated prompt based on the initiative, bug, or todo. |
| Local Codex agent | Letting Codex work through assigned tasks. | One Horizon starts Codex on your machine, prepares the code workspace, and records progress on the run. |
| Open in Codex | Reviewing a local Codex run later. | The run opens the recorded Codex thread when a thread ID is available. |
Start with the work item
The initiative, bug, or todo is the prompt source for Send to Codex and local agent runs. Add the outcome, important links, known constraints, and what counts as done. For planned implementation work, spec-driven development gives Codex a tighter brief.
Send one work item to Codex
Enable Codex before it appears in Send to…:
- Open Settings → Preferences → Coding tools.
- Enable Codex.
- Open an initiative, bug, or todo and choose Send to… → Codex.
- Codex opens with a structured prompt built from the work item. The prompt can use mode-specific instructions such as plan, build, or review.
Preferences control whether Codex appears in that menu.
Codex receives the One Horizon work item as a structured prompt.
Run Codex as a local agent
For guided setup in Desktop, open Workflows, go to the agents page, select Add agent, and choose Codex. Pick a task mode, set Agent access, choose the repository folder, and decide whether One Horizon should create PRs or MRs after successful runs. The same setup modal is available from an agent step in the workflow designer.
From the terminal, after you install the CLI and sign in:
one agent createone agent doctorone agent watch
Run one agent create before one agent watch or one agent start. Creating the agent registers it and writes its local settings and a starter workflow file. one agent doctor then checks sign-in, workspace, workflow file, registration, and the Codex command.
Codex is bundled with One Horizon, so you do not need to install it separately. If you set your own codex as the harness command, that one is used instead. Workflow steps can target the same agent. Local Agents covers presets, access levels, worktrees, and pull request settings, and Monitoring covers the run lifecycle, recovery actions, and when session details show token counts.
Local agents are experimental. Keep tasks small and review code, tests, and pull requests before you merge.
Open a Codex thread
A local Codex agent run stores a Codex thread ID. Open in Codex opens that thread with codex://threads/..., while Send to Codex launches codex://new?prompt=....
Open the run from Agents or Work queue. On run details for a Codex run with a thread ID, Open in Codex is the primary action. In run lists, it can appear in the actions menu.
If Codex does not open, see Why does Codex not open?.
The local agent records token usage from Codex app-server events while the session is active.
Load workspace capabilities in sessions you start yourself
One Horizon Desktop can connect Codex so sessions you start yourself load the skills, MCP servers, and plugins your workspace assigns to that repository. Open Settings → Integrations → Coding tools, then select Connect on Codex. Without Desktop, run one capabilities connect codex. Sessions One Horizon starts for you load capabilities without this step.
Codex shows Not qualified yet until One Horizon has tested the installed version, and Connect stays unavailable until then. Agent capabilities covers repository assignments and each status.
Codex and ChatGPT
Both are OpenAI products. Codex runs work items through Send to…, Open in Codex, or a local agent. ChatGPT connects through the MCP connector in ChatGPT Developer Mode for broader tool calling.