Struct AgentChainState 

pub struct AgentChainState {
    pub agents: Vec<String>,
    pub current_agent_index: usize,
    pub models_per_agent: Vec<Vec<String>>,
    pub current_model_index: usize,
    pub retry_cycle: u32,
    pub max_cycles: u32,
    pub current_role: AgentRole,
    pub rate_limit_continuation_prompt: Option<String>,
}

Agent fallback chain state (explicit, not loop indices).

Tracks position in the multi-level fallback chain:

• Agent level (primary → fallback1 → fallback2)
• Model level (within each agent, try different models)
• Retry cycle (exhaust all agents, start over with exponential backoff)

Fields

agents: Vec<String>

current_agent_index: usize

models_per_agent: Vec<Vec<String>>

current_model_index: usize

retry_cycle: u32

max_cycles: u32

current_role: AgentRole

rate_limit_continuation_prompt: Option<String>

Prompt context preserved from rate-limited agent for continuation.

When an agent hits 429, we save the prompt here so the next agent can continue the same work instead of starting from scratch.

Implementations

impl AgentChainState

pub fn initial() -> Self

pub fn with_agents( self, agents: Vec<String>, models_per_agent: Vec<Vec<String>>, role: AgentRole, ) -> Self

pub fn with_max_cycles(self, max_cycles: u32) -> Self

Builder method to set the maximum number of retry cycles.

A retry cycle is when all agents have been exhausted and we start over with exponential backoff.

pub fn current_agent(&self) -> Option<&String>

pub fn current_model(&self) -> Option<&String>

Get the currently selected model for the current agent.

Returns None if:

• No models are configured
• The current agent index is out of bounds
• The current model index is out of bounds

pub fn is_exhausted(&self) -> bool

pub fn advance_to_next_model(&self) -> Self

pub fn switch_to_next_agent(&self) -> Self

pub fn switch_to_next_agent_with_prompt(&self, prompt: Option<String>) -> Self

Switch to next agent after rate limit, preserving prompt for continuation.

This is used when an agent hits a 429 rate limit error. Instead of retrying with the same agent (which would likely hit rate limits again), we switch to the next agent and preserve the prompt so the new agent can continue the same work.

pub fn clear_continuation_prompt(&self) -> Self

Clear continuation prompt after successful execution.

Called when an agent successfully completes its task, clearing any saved prompt context from previous rate-limited agents.

pub fn reset_for_role(&self, role: AgentRole) -> Self

pub fn reset(&self) -> Self

pub fn start_retry_cycle(&self) -> Self

Trait Implementations

impl Clone for AgentChainState

fn clone(&self) -> AgentChainState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AgentChainState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for AgentChainState

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for AgentChainState

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.