Struct FallbackChain 

pub struct FallbackChain<I, O> { /* private fields */ }

Ordered list of LLM providers to try in sequence.

Each provider is a (name, callable) pair. call tries them in order until one returns Ok. Returns a ChainResult describing what won and what failed. If every provider returns Err, an AllProvidersFailed error is returned.

Implementations

impl<I, O> FallbackChain<I, O>

pub fn new<S: Into<String>>( providers: Vec<(S, SyncProvider<I, O>)>, ) -> Result<Self, &'static str>

Build a new chain from an ordered list of (name, provider) pairs.

Returns Err if providers is empty.

pub fn with_should_fall_back<F>(self, f: F) -> Self

where F: Fn(&DynError) -> bool + Send + Sync + 'static,

Set the predicate that decides whether a given error should cause fallback. Default falls back on any error.

pub fn with_on_fallback<F>(self, f: F) -> Self

where F: Fn(&str, &DynError, &str) + Send + Sync + 'static,

Set the audit callback fired after each fallback. Called with (failed_name, error, next_name) before the next provider is tried.

pub fn with_skip<P>(self, predicate: P) -> Result<Self, &'static str>

where P: Fn(&str) -> bool,

Skip a provider entirely when predicate(&name) returns true. Useful when an upstream circuit breaker says a provider is open. Returns Err if the filter removes every provider.

pub fn names(&self) -> Vec<&str>

Provider names in order.

pub fn call(&self, input: &I) -> Result<ChainResult<O>, DynError>

Try each provider in order until one returns Ok.