Enum Error 

#[non_exhaustive]
pub enum Error {
    Spawn(BoxError),
    Install(BoxError),
    Login(BoxError),
    Cancel(BoxError),
    Other(String),
}

Why a Harness operation failed. Returned by install / run / login / RunControl::cancel so a consumer can branch on the kind of failure — offer install vs sign-in vs surface the message — instead of string-matching.

Each category carries the real underlying error as a source (via the BoxError field), so a consumer that wants more than the category can walk .source() or downcast_ref::<cli_stream::StreamError>() / ::<bob_rs::BobError>(). The Display still flattens the source into the message ("failed to start the agent: <source>"), so a consumer that just stringifies at a boundary (e.g. a Tauri command’s .to_string()) gets the same full message as before. #[non_exhaustive] so adding a variant later isn’t a breaking change.

use harness::{Error, StreamError};
use std::error::Error as _; // for `.source()`, without shadowing `harness::Error`

// Box any typed source under a category constructor:
let err = Error::spawn(StreamError::PipeNotCaptured { stream: "stdout" });

// Stringifying at a boundary flattens the source into the message
// (so a Tauri command's `.to_string()` keeps its full text)…
assert!(err.to_string().starts_with("failed to start the agent: "));

// …while the real typed cause stays reachable for a consumer that wants
// to branch on it rather than parse a string.
let source = err.source().expect("Command carries a source");
assert!(source.downcast_ref::<StreamError>().is_some());

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Spawn(BoxError)

The harness’s CLI couldn’t be started — not installed, not on PATH, or an OS-level spawn failure.

Install(BoxError)

A one-time install step failed.

Login(BoxError)

Interactive sign-in failed.

Cancel(BoxError)

Cancelling an in-flight run failed.

Other(String)

Any other adapter/runtime failure (e.g. a backend SDK error that doesn’t map onto the cases above). Carries a message rather than a source — it’s the catch-all when there’s nothing typed to preserve.

Implementations

impl Error

pub fn spawn(source: impl Into<BoxError>) -> Self

Categorize a source error as a Spawn failure. Accepts anything boxable — a typed StreamError/BobError, or a String/&str for adapters with nothing typed to carry.

pub fn install(source: impl Into<BoxError>) -> Self

Categorize a source error as an Install failure.

pub fn login(source: impl Into<BoxError>) -> Self

Categorize a source error as a Login failure.

pub fn cancel(source: impl Into<BoxError>) -> Self

Categorize a source error as a Cancel failure.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.