codex/codex-rs/thread-store/src/error.rs

use codex_protocol::ThreadId;
use codex_protocol::protocol::ThreadHistoryMode;

/// Result type returned by thread-store operations.
pub type ThreadStoreResult<T> = Result<T, ThreadStoreError>;

pub(crate) fn reject_paginated_history_mode(
    history_mode: ThreadHistoryMode,
) -> ThreadStoreResult<()> {
    if matches!(history_mode, ThreadHistoryMode::Paginated) {
        return Err(ThreadStoreError::Unsupported {
            operation: "paginated_threads",
        });
    }
    Ok(())
}

/// Error type shared by thread-store implementations.
#[derive(Debug, thiserror::Error)]
pub enum ThreadStoreError {
    /// The requested thread does not exist in this store.
    #[error("thread {thread_id} not found")]
    ThreadNotFound {
        /// Thread id requested by the caller.
        thread_id: ThreadId,
    },

    /// The caller supplied invalid request data.
    #[error("invalid thread-store request: {message}")]
    InvalidRequest {
        /// User-facing explanation of the invalid request.
        message: String,
    },

    /// The operation conflicted with current store state.
    #[error("thread-store conflict: {message}")]
    Conflict {
        /// User-facing explanation of the conflict.
        message: String,
    },

    /// The store implementation does not support this operation yet.
    #[error("thread-store unsupported operation: {operation}")]
    Unsupported {
        /// Stable operation name for callers that need to map unsupported operations.
        operation: &'static str,
    },

    /// The store cannot return the requested result within a required resource limit.
    #[error("thread-store resource exhausted: {message}")]
    ResourceExhausted {
        /// User-facing explanation of the exhausted resource.
        message: String,
    },

    /// Catch-all for implementation failures that do not fit a more specific category.
    #[error("thread-store internal error: {message}")]
    Internal {
        /// User-facing explanation of the implementation failure.
        message: String,
    },
}