Module fallback 

Fallback chain configuration for agent fault tolerance.

This module defines the FallbackConfig structure that controls how Ralph handles agent failures. It supports:

• Agent-level fallback (try different agents)
• Provider-level fallback (try different models within same agent)
• Exponential backoff with cycling

Structs

FallbackConfig

Agent chain configuration for preferred agents and fallback switching.

ResolvedDrainBinding

Concrete runtime chain binding for one drain.

ResolvedDrainConfig

Fully resolved drain configuration consumed by the runtime.

Enums

AgentDrain

Runtime consumer of an agent chain.

AgentRole

Agent role (developer, reviewer, or commit).

DrainMode

Drain-local execution mode.