Default Model Provider - Documentation

Once you’ve configured one or more model providers, you can choose which one Cyrus uses by default for every Linear issue and agent run.

Change the default model provider

Go to Behaviours settings

Navigate to app.atcyrus.com/settings/behaviours.

Select a provider

Find the Default Model Provider dropdown and select the provider you want Cyrus to use by default (e.g. Claude, OpenAI/Codex, Cursor).

This setting applies globally — every new issue and agent run will use the selected provider unless overridden per-issue.

Override the provider per issue

You can override the default provider for a specific issue in two ways:

Using an inline tag in the issue description

Add one of the following tags anywhere in your Linear issue description:

[agent=claude]
[agent=codex]
[agent=cursor]
[agent=gemini]

Using a Linear label

Apply the provider name as a label on the issue:

claude
codex
cursor
gemini

Override the model per issue

You can also override the specific model (not just the provider) for a given issue, either with a [model=...] description tag or a Linear label of the same name.

Supported models by provider

Claude (Anthropic)

Alias	Model
`fable`	Claude Fable 5
`opus`	Claude Opus 4.8
`sonnet`	Claude Sonnet 4.6
`haiku`	Claude Haiku 4.5

Default: opus. Fallback: sonnet. When fable is selected, the fallback chain is fable → opus → sonnet. You can also save fable as your team’s default Claude model from the Behaviours settings page. Codex (OpenAI)

Model	Notes
`gpt-5.5`	Latest frontier model. Unifies Codex and non-Codex — no `gpt-5.5-codex`.
`gpt-5.3-codex`	Default.
`gpt-5.2-codex`	Automatic fallback.
`gpt-5-codex`	Earlier Codex generation.
`gpt-5`	Earlier non-Codex GPT-5.

Any gpt-*-codex or gpt-* name is accepted, so newer Codex releases can be selected by name. Gemini

Model	Notes
`gemini-2.5-pro`	Default. Alias: `gemini-2.5`.
`gemini-2.5-flash`	Faster, lighter.
`gemini-2.5-flash-lite`	Lightweight.
`gemini-3-pro-preview`	Aliases: `gemini-3`, `gemini-3-pro`.

Default: gemini-2.5-pro. Fallback: gemini-2.5-flash. Cursor (Cursor) Runs composer-2. Per-issue model overrides are not currently exposed.

Examples

Inline tag:

[model=fable]
[model=opus]
[model=gpt-5.3-codex]
[model=gemini-2.5-pro]

Linear label:

fable
opus
gpt-5.3-codex
gemini-2.5-flash

If a [model=...] is set without an [agent=...], Cyrus infers the provider from the model name. For more, see Labels and Routing.

Agent sessions

The agent (provider) cannot be switched within an active agent session. If you need to use a different provider on the same issue, a new agent session will be spawned with the selected agent.

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​Change the default model provider

​Override the provider per issue

​Using an inline tag in the issue description

​Using a Linear label

​Override the model per issue

​Supported models by provider

​Examples

​Agent sessions