Runtime Switching¶

Missy supports switching between providers at runtime without restarting. This lets you route different queries to different backends based on cost, speed, or capability needs.

Switching providers¶

Per-command¶

Override the provider for a single command:

# Use Ollama for a quick local query
missy ask "What time is it in Tokyo?" --provider ollama

# Use Anthropic for a complex task
missy ask "Analyze this codebase and suggest refactoring" --provider anthropic

Interactive switching¶

During a missy run session, the provider can be switched for subsequent messages.

Default provider¶

Set the default provider that is used when no --provider flag is given:

missy providers switch anthropic

The registry validates that the provider is registered and available before making it the default.

How it works¶

The ProviderRegistry maintains a _default_name that can be changed at runtime via set_default(). When the agent runtime processes a request:

1. If a specific provider was requested (via --provider flag), that provider is used.
2. Otherwise, the default provider is used.
3. If no default is set, the first available provider is selected.

Provider availability is checked via is_available(), which verifies that credentials are present and (for some providers) that the upstream service is reachable.

ModelRouter: automatic tier selection¶

The ModelRouter can automatically route queries to different model tiers within the same provider:

providers:
  anthropic:
    name: anthropic
    model: "claude-sonnet-4-6"        # Primary tier
    fast_model: "claude-haiku-4-5"     # Fast tier
    premium_model: "claude-opus-4-6"   # Premium tier

The router scores prompt complexity based on:

API key rotation¶

When a provider has multiple API keys configured, the registry can rotate to the next key:

providers:
  anthropic:
    api_keys:
      - "sk-ant-key1..."
      - "sk-ant-key2..."
      - "sk-ant-key3..."

Rotation happens round-robin via registry.rotate_key("anthropic"), typically triggered after a rate limit error from the provider.

Config hot-reload¶

Missy watches ~/.missy/config.yaml for changes and reloads the provider configuration automatically. The ConfigWatcher polls the file every second and applies changes after a 2-second debounce window.

This means you can update provider settings (add a new provider, change models, update API keys) by editing the config file, and the changes take effect without restarting Missy.

Checking provider status¶

# List all providers with availability status
missy providers

# System health check (includes provider connectivity)
missy doctor