post-cortex-daemon 0.3.1

// Copyright (c) 2025, 2026 Julius ML
// Licensed under the MIT License. See LICENSE at the workspace root.

//! Typed error hierarchy for `post-cortex-daemon`.
//!
//! Carries variants for the transport surface (HTTP / gRPC / MCP /
//! stdio) and delegates domain errors downward. [`Error::grpc_status`]
//! maps each variant to a `tonic::Status`; [`Error::http_status`] gives
//! the matching `http::StatusCode` for axum handlers.

use thiserror::Error;

/// Errors produced by the daemon's transport layer.
#[derive(Debug, Error)]
pub enum Error {
    /// Caller request failed validation (invalid UUID, missing field).
    #[error("invalid request: {0}")]
    InvalidRequest(String),

    /// Memory / orchestrator error.
    #[error(transparent)]
    Memory(#[from] post_cortex_memory::error::Error),

    /// MCP tool error.
    #[error(transparent)]
    Mcp(#[from] post_cortex_mcp::error::Error),

    /// Storage error surfaced to the transport.
    #[error(transparent)]
    Storage(#[from] post_cortex_storage::error::Error),

    /// I/O error (stdio bridge, TCP, file).
    #[error("io error: {0}")]
    Io(#[from] std::io::Error),

    /// Catch-all for migrating call sites that still use `anyhow`.
    #[error(transparent)]
    External(#[from] anyhow::Error),
}

/// Crate-level result alias.
pub type Result<T, E = Error> = std::result::Result<T, E>;

impl Error {
    /// A stable discriminant for metrics / structured logs.
    #[must_use]
    pub fn kind(&self) -> &'static str {
        match self {
            Self::InvalidRequest(_) => "invalid_request",
            Self::Memory(_) => "memory",
            Self::Mcp(_) => "mcp",
            Self::Storage(_) => "storage",
            Self::Io(_) => "io",
            Self::External(_) => "external",
        }
    }

    /// Map this error to a `tonic::Status` for the gRPC surface.
    #[must_use]
    pub fn grpc_status(&self) -> tonic::Status {
        match self {
            Self::InvalidRequest(msg) => tonic::Status::invalid_argument(msg),
            Self::Memory(post_cortex_memory::error::Error::SessionNotFound(_)) => {
                tonic::Status::not_found(self.to_string())
            }
            Self::Memory(post_cortex_memory::error::Error::Timeout { .. }) => {
                tonic::Status::deadline_exceeded(self.to_string())
            }
            Self::Memory(post_cortex_memory::error::Error::Backpressure { .. })
            | Self::Memory(post_cortex_memory::error::Error::WorkerShutdown { .. }) => {
                tonic::Status::resource_exhausted(self.to_string())
            }
            _ => tonic::Status::internal(self.to_string()),
        }
    }

    /// Map this error to an HTTP status code for the axum surface.
    #[must_use]
    pub fn http_status(&self) -> u16 {
        match self {
            Self::InvalidRequest(_) => 400,
            Self::Memory(post_cortex_memory::error::Error::SessionNotFound(_)) => 404,
            Self::Memory(post_cortex_memory::error::Error::Timeout { .. }) => 504,
            Self::Memory(post_cortex_memory::error::Error::Backpressure { .. })
            | Self::Memory(post_cortex_memory::error::Error::WorkerShutdown { .. }) => 503,
            _ => 500,
        }
    }
}