Models

Select and configure AI models in Xum

Xum supports multiple AI providers. Configure provider API keys in Settings → Providers — see Providers for setup.

First-class Models

Xum ships with curated models kept up to date with the frontier. Use any custom model with /model <provider:model_id>.

Model	ID	Aliases	Default
Fable 5.1	anthropic:claude-fable-5-1	fable
Mythos 5.1	anthropic:claude-mythos-5-1	mythos
Opus 5	anthropic:claude-opus-5	opus	✓
Sonnet 5	anthropic:claude-sonnet-5	sonnet
Haiku 4.5	anthropic:claude-haiku-4-5	haiku
GPT-5.6 Sol	openai:gpt-5.6-sol	gpt, sol
GPT-5.6 Terra	openai:gpt-5.6-terra	terra
GPT-5.6 Luna	openai:gpt-5.6-luna	luna
GPT-6 Astra	openai:gpt-6-astra	astra, gpt-6-astra
GPT-5.5 Pro	openai:gpt-5.5-pro	gpt-pro, gpt-5.5-pro
GPT-5.4 Mini	openai:gpt-5.4-mini	gpt-mini
GPT-5.4 Nano	openai:gpt-5.4-nano	gpt-nano
Codex 5.3	openai:gpt-5.3-codex	codex, codex-5.3
Spark 5.3	openai:gpt-5.3-codex-spark	spark
Codex Mini 5.1	openai:gpt-5.1-codex-mini	codex-mini
Codex Max 5.1	openai:gpt-5.1-codex-max	codex-max
Daybreak Blue Latest	openai:daybreak-blue-latest	—
Daybreak Red Latest	openai:daybreak-red-latest	—
Gemini 3.1 Pro Preview	google:gemini-3.1-pro-preview	gemini, gemini-pro
Gemini 3.8 Flash	google:gemini-3.8-flash	gemini-flash
Grok 4.6	xai:grok-4.6	grok, grok-4.6
DeepSeek V4 Pro	deepseek:deepseek-v4-pro	deepseek, deepseek-pro, deepseek-v4, deepseek-v4-pro
DeepSeek V4 Flash	deepseek:deepseek-v4-flash	deepseek-flash, deepseek-v4-flash
Kimi K3	moonshotai:kimi-k3	kimi, k3, kimi-k3
GLM 5.3 Flash	zai:glm-5.3-flash	glm, glm-flash, glm-5.3-flash

Pro reasoning mode (GPT-5.6 and GPT-6 Astra)

GPT-6 Astra and every GPT-5.6 model (Sol, Terra, and Luna) support OpenAI’s pro reasoning mode. Open the reasoning selector next to the model picker and enable Pro mode (or run “Toggle Pro Reasoning Mode” from the Command Palette) to send reasoning.mode: "pro" with each request. The setting is saved per workspace. Pro mode can consume more tokens and responses can take noticeably longer. Pro is available on supported direct OpenAI Responses API routes. Gateway routes, Chat Completions, and Codex OAuth use standard mode.

For advisor calls, enable the Advisor Tool experiment and use its Reasoning picker under Settings → Experiments. Advisor Pro mode is saved independently of reasoning effort and the calling chat’s mode.

Model Selection

Keyboard shortcuts:

• Cycle models
  • macOS: Cmd+/
  • Windows/Linux: Ctrl+/

To choose a specific model, click the model pill in the chat footer.

Alternatively, use the Command Palette (Cmd+Shift+P / Ctrl+Shift+P):

1. Type “model”
2. Select “Change Model”
3. Choose from available models

Models are specified in the format: provider:model-name

One-shot Overrides

Override the model or thinking level for a single message using slash commands. The override applies only to that message — workspace settings stay unchanged.

Syntax

Command	Effect
/sonnet explain this code	Use Sonnet for one message
/opus+high deep review	Use Opus with high thinking
/haiku+0 quick answer	Use Haiku at its lowest thinking level
/+2 analyze this	Keep current model, set thinking level 2

Thinking levels

Append +level to any model alias. Levels can be named (off, low, medium/med, high, max) or numeric (0–9).

Numeric levels are model-relative — they map to the model’s allowed thinking range:

• 0 = model’s lowest allowed level (e.g., off for Sonnet, medium for GPT-5.5 Pro)
• Higher numbers select progressively higher levels, clamped to the model’s maximum

This means /sonnet+0 disables thinking while /gpt-pro+0 sets thinking to medium (GPT-5.5 Pro’s minimum).

Use /+level (no model) to override thinking on the current model: /+0 quick answer

CLI

The xum run CLI accepts the same thinking levels via --thinking:

xum run -t 0 "Quick fix"          # Lowest thinking for the model
xum run -t high "Deep analysis"   # Named level

Next Steps

Configure Providers

Set up API keys for Anthropic, OpenAI, Google, and other providers.