Agents and models
Rivets runs two coding agents: Claude Code and Codex. Both run on your workers with your own logins, so every model call is billed to your subscription. This page covers the models each agent offers, the options you can set per run, and how to move a conversation to another agent or worker.
Agents
| Agent | Sign in on the worker | Notes |
|---|---|---|
| Claude Code | claude auth login |
Steering is delivered into the running process. |
| Codex | codex login |
Runs a process per turn. Steering stops the current turn and resumes the session with your message. |
A worker only offers the agents it finds installed and signed in. If you choose an agent no online worker can run, the task cannot start.
Models
Claude Code
Rivets offers a curated list of Claude models:
| Model | Fast mode |
|---|---|
| Opus 5.5 (default) | Yes |
| Fable 5.1 | |
| Fable 5 | |
| Opus 5 | Yes |
| Opus 4.8 1M | Yes |
| Opus 4.7 1M | |
| Opus 4.6 1M | |
| Sonnet 5.5 | |
| Sonnet 5 1M | |
| Sonnet 4.6 1M | |
| Sonnet 4.6 | |
| Haiku 4.5 |
Models marked 1M use the one-million-token context variant. A Claude job that names no model runs on Opus 5.5.
Codex
Codex models are discovered from the Codex CLI on each worker, newest generation first: GPT-6 Astra, Sol, and Luna, then the GPT-5.x line. Codex’s own default model is marked as the default. The list therefore follows the Codex version installed on the worker.
Adding models on a worker
Worker operators can extend or replace the lists with environment variables set for the worker process:
| Variable | Effect |
|---|---|
RIVETS_CLAUDE_MODELS |
Comma-separated Claude model IDs to offer in addition to the built-in list. |
RIVETS_CODEX_MODELS |
Comma-separated Codex model IDs, used when discovery returns nothing. |
Per-run options
Set these in the New task dialog or the composer. They apply to the next run.
| Option | Values | Notes |
|---|---|---|
| Reasoning effort | low, medium, high, xhigh, max for Claude. Codex adds ultra on models that support it. |
Higher effort thinks longer. ultra is Codex’s top level and lets it spawn sub-agents. |
| Fast mode | On or off | Shown only when the selected model supports it. |
| Plan mode | On or off | The agent plans before it edits. |
Account-wide defaults
Set your preferred agent, model, and reasoning effort under Settings › Agent defaults. They are preselected whenever you start a task or a conversation, on every device signed in to your account.
Each field falls back independently:
- Your saved default, if the worker that picks up the task still offers it.
- Otherwise, the model the worker marks as default: Codex’s own default, or Opus 5.5 for Claude.
- If a provider marks no default, no model is sent and the CLI chooses.
Context meter
The composer shows how much of the model’s context window the conversation is using, based on the usage the agent reports. It shows nothing until the agent has reported usage.
Warm Claude processes
After a Claude job finishes, the worker keeps its Claude Code process alive for up to 2 hours and reuses it for the next message in the same conversation. This avoids restarting the CLI and keeps Claude’s prompt cache warm. A worker keeps at most 8 idle processes. Changing the model, effort, fast mode, or plan mode starts a new process that resumes the same session.
Operators can tune this with RIVETS_CLAUDE_SESSION_IDLE_MS (minimum 1 second) and RIVETS_CLAUDE_MAX_IDLE_SESSIONS (1 to 64).
Sub-agents and background work
When Claude delegates to a sub-agent, Rivets nests everything the sub-agent does under the call that spawned it, at any depth. Work Claude starts in the background shows as Running in background until it reports back. While background tasks are still running, the conversation shows Waiting on N background tasks instead of appearing finished.
Handoff
Hand off to another agent
Choose Hand off to another agent in the task header to continue the conversation with a different agent or model. Rivets opens a linked draft in a new conversation. The new conversation starts with a bounded copy of the transcript so the next agent has the context. Attachments cannot be added to a handoff draft.
Continue on another worker
If a task’s worker goes offline, the header shows Worker offline · paused and offers Continue on another worker. Rivets picks another compatible worker, stops the old run, creates a linked task and conversation, applies the latest file changes, and imports the transcript so far.