## webc
### Goal
The `webc` module provides a low-level, internal web client layer utilizing `reqwest`. Its primary role is to abstract standard HTTP requests (GET/POST) and manage complex streaming responses required by various AI providers, especially those that do not fully conform to the Server-Sent Events (SSE) standard (`text/event-stream`). It handles standard JSON requests/responses and custom stream parsing.
### Public Module API
The `webc` module is primarily an internal component, only exposing its dedicated error type publicly.
- `pub use error::Error;`
- `Error`: An enum representing all possible errors originating from the web communication layer (e.g., failed status codes, JSON parsing errors, reqwest errors, stream clone errors).
(All other types like `WebClient`, `WebResponse`, `WebStream`, and `Result` are exported as `pub(crate)` for internal library use.)
### Module Parts
The module consists of three main internal components:
- `error.rs`: Defines the `Error` enum and the module-scoped `Result<T>` type alias. It captures network/HTTP related failures and external errors like `reqwest::Error` and `value_ext::JsonValueExtError`.
- `web_client.rs`: Contains the `WebClient` struct, a thin wrapper around `reqwest::Client`. It provides methods (`do_get`, `do_post`) for non-streaming standard HTTP communication, which assumes the response body is JSON and is parsed into `serde_json::Value`. It also defines `WebResponse`, which encapsulates the HTTP status and parsed JSON body.
- `web_stream.rs`: Implements `WebStream`, a custom `futures::Stream` implementation designed for handling non-SSE streaming protocols used by some AI providers (e.g., Cohere, Gemini). It defines `StreamMode` to specify how stream chunks should be parsed (either by a fixed delimiter or specialized handling for "Pretty JSON Array" formats).
### Key Design Considerations
- **Internal Focus:** The module is designed strictly for internal use (`pub(crate)`) except for the public error type. This shields the rest of the library from direct `reqwest` dependency details.
- **Custom Streaming:** `WebStream` exists specifically to manage streaming protocols that deviate from the standard SSE format, providing message splitting based on `StreamMode`. This ensures compatibility with providers like Cohere (delimiter-based) and Gemini (JSON array chunking).
- **Generic JSON Response Handling:** `WebResponse` abstracts successful non-streaming responses by immediately parsing the body into `serde_json::Value`. This allows adapter modules to deserialize into their specific structures subsequently.
- **Error Richness:** The `Error::ResponseFailedStatus` variant includes the `StatusCode`, full `body`, and `HeaderMap` to provide comprehensive debugging information upon API failure.
- **Async Implementation:** All network operations rely on `tokio` and `reqwest`, ensuring non-blocking execution throughout the I/O layer. `WebStream` leverages `futures::Stream` traits for integration with standard Rust async infrastructure.