af_llm/
error.rs

1//! Error type for the LLM client.
2
3use thiserror::Error;
4
5/// Everything that can go wrong on the way to a completion.
6///
7/// Mirrors the failure modes of the Python `llm_completion` wrapper, but where
8/// that returned `None` and swallowed the cause, we keep a typed error so the
9/// caller decides how to degrade.
10#[derive(Debug, Error)]
11pub enum LlmError {
12    /// Caller cancelled the provider attempt.
13    #[error("llm request cancelled")]
14    Cancelled,
15
16    /// Caller deadline elapsed before the provider attempt settled.
17    #[error("llm request deadline exceeded")]
18    DeadlineExceeded,
19    /// Circuit breaker is open — we fail fast without hitting the provider.
20    #[error("llm circuit breaker is open; failing fast")]
21    CircuitOpen,
22
23    /// Transport-level failure (connection, TLS, timeout).
24    #[error("llm transport error: {0}")]
25    Transport(#[from] reqwest::Error),
26
27    /// Provider returned a non-2xx status.
28    #[error("llm api error: status {status}, body: {body}")]
29    Api {
30        /// HTTP status returned.
31        status: u16,
32        /// Response body, truncated for logs.
33        body: String,
34    },
35
36    /// Response body could not be decoded into the expected shape.
37    #[error("llm response decode error: {0}")]
38    Decode(#[from] serde_json::Error),
39
40    /// A streaming response violated the SSE completion contract.
41    #[error("llm stream protocol error: {0}")]
42    StreamProtocol(String),
43
44    /// A streaming response contained bytes that were not valid UTF-8.
45    #[error("llm stream utf-8 error: {0}")]
46    InvalidUtf8(#[from] std::string::FromUtf8Error),
47}
48
49impl LlmError {
50    /// Whether retrying this error class could plausibly succeed.
51    ///
52    /// A 4xx (except 408/429) is the caller's fault and will fail identically on
53    /// retry; transport errors and 5xx/408/429 are worth another attempt.
54    pub fn is_retryable(&self) -> bool {
55        match self {
56            LlmError::Transport(_) | LlmError::StreamProtocol(_) | LlmError::InvalidUtf8(_) => true,
57            LlmError::Api { status, .. } => {
58                *status == 408 || *status == 429 || (500..600).contains(status)
59            }
60            // Circuit-open and decode failures are not improved by retry.
61            LlmError::CircuitOpen
62            | LlmError::Decode(_)
63            | LlmError::Cancelled
64            | LlmError::DeadlineExceeded => false,
65        }
66    }
67}
68
69/// Result alias for this crate's error.
70pub type Result<T> = std::result::Result<T, LlmError>;
af_llm/error.rs

af_llm/
error.rs
