Errors that can occur when interacting with LLM providers.
# Variants
## Authentication
- **`MissingApiKey`** -- A required environment variable (e.g. `ANTHROPIC_API_KEY`) is not set.
- **`InvalidApiKey`** -- The API key format is invalid or was rejected by the provider.
- **`OAuthError`** -- OAuth authentication failed (when the `oauth` feature is enabled).
## Request/Response
- **`HttpClientCreation`** -- Failed to create the HTTP client (e.g. TLS configuration error).
- **`ApiRequest`** -- The HTTP request to the provider failed (network error, timeout).
- **`ApiError`** -- The provider returned an error response (rate limit, server error).
- **`ContextOverflow`** -- The prompt exceeded the model's context window. Contains a [`ContextOverflowError`] with provider, model, and token details.
## Parsing
- **`JsonParsing`** -- Failed to parse or serialize JSON (response body, tool arguments).
- **`ToolParameterParsing`** -- Failed to parse tool parameters for a specific tool.
- **`IoError`** -- IO error while reading the response stream.
## Content
- **`UnsupportedContent`** -- The message contained only content types this provider doesn't support (e.g. sending audio to a text-only model).
## Model parsing
- **`UnknownProvider`** -- Provider name is not registered with the model parser.
- **`EmptyModelSpec`** -- The model spec did not yield any usable provider.
- **`DuplicateProvider`** -- A single-model-only config field was reused across multiple models of the same provider within one alloy spec (e.g. bedrock `inferenceProfileArn` or openai-compatible `requestModel`).
- **`InvalidModelSpec`** -- A `provider:model` identity could not be parsed.
- **`MissingProviderUrl`** -- Provider endpoint URL has not been configured.
- **`ProviderRequest`** -- A provider request body could not be constructed (e.g. an SDK builder rejected the input or contained malformed data).
- **`InvalidArgument`** -- An upstream client library rejected an argument as invalid.
# `From` implementations
`LlmError` converts automatically from common error types: `reqwest::Error`, `serde_json::Error`, `std::io::Error`, `reqwest::header::InvalidHeaderValue`, `async_openai::error::OpenAIError`, and `OAuthError` (with the `oauth` feature).
# Type alias
The crate provides `type Result<T> = std::result::Result<T, LlmError>` for convenience.