Enum FallbackReason 

pub enum FallbackReason {
    CredentialRejected,
    CredentialAbsent,
    RateLimited,
    QuotaExhausted,
    TimedOut,
    Failed,
}

Why the chain moved past a candidate.

Coarse on purpose. The point is to distinguish causes an operator would ACT on differently — sign in, wait, configure a key, look at the provider — not to reproduce every provider’s error taxonomy. Anything unrecognized is FallbackReason::Failed rather than being forced into a bucket it does not belong in.

Variants

CredentialRejected

A credential exists and was REFUSED — an expired Parslee session, or a provider rejecting an API key (ProviderAccount 401/403).

Deliberately broader than InferenceResult::auth_fallback_from’s predicate, which names only the subset a person clears by signing in. car auth login does not fix a bad OpenAI key, so this variant must not be read as “run that” — the remedy depends on which credential was refused.

CredentialAbsent

No credential is configured for that lane at all. A different fix from CredentialRejected: nothing expired, nothing was ever set.

RateLimited

The provider rate-limited the call (429 / “too many requests”). Clears by waiting.

QuotaExhausted

The account is out of credits or over quota (402).

Separate from FallbackReason::RateLimited because an empty balance does NOT clear by waiting — the remedy is to top up. Folding it in told an operator to wait out a billing problem.

TimedOut

The call exceeded its deadline.

Only when a deadline is what was actually hit. A transport failure with no status — connection refused, DNS, TLS, a truncated body — is FallbackReason::Failed, because telling someone their call timed out when the endpoint was never up sends them to raise a timeout instead of starting the runtime.

Failed

Anything else — a 5xx, a malformed request, a panicked runner, an unreadable credential store. The honest bucket, and it has to STAY honest: a first version of this classifier matched substrings and silently absorbed every ProviderAccount rejection here, which is the opposite of what this variant is for.

Trait Implementations

impl Clone for FallbackReason

fn clone(&self) -> FallbackReason

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for FallbackReason

impl Debug for FallbackReason

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for FallbackReason

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for FallbackReason

impl PartialEq for FallbackReason

fn eq(&self, other: &FallbackReason) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for FallbackReason

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for FallbackReason