Rehome error types to their layer

AGENTS.md

@@ -29,7 +29,7 @@ This file contains crucial context for AI agents working in this repository.
 - **Execution Flow**: `src/main.rs` initializes an `axum` router and spawns two decoupled background `tokio` tasks:
   1. `polling/`: Periodically checks remote git repositories for updates.
   2. `trigger/`: Receives update events from the polling engine via `mpsc` channels and triggers GitHub Action workflows on target repositories.
-- **Error Handling**: Use domain-specific error enums (`HandlerError`, `FatalError`) defined in `src/error.rs` using the `thiserror` crate. Ensure `IntoResponse` is implemented for any errors that bubble up to Axum handlers.
+- **Error Handling**: Use `thiserror` for domain-specific error enums, defined in the layer they belong to: `HandlerError` in `src/http/error.rs`, repository errors in `src/repository/error.rs`, engine errors in `src/{polling,trigger}/error.rs`, and value-validation errors in `src/domain/`. Boot-time errors (`FatalError`, `SetupError`) live in `src/error.rs`. Implement `IntoResponse` for any error that bubbles up to an Axum handler.
 
 ## Reviews
 

src/domain/accept_header.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent an HTTP Accept header.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use http::header::HeaderValue;
 use serde::{Deserialize, Serialize};
 

src/domain/api_version.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a GitHub API version in YYYY-MM-DD format.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use chrono::NaiveDate;
 use serde::{Deserialize, Serialize};
 

src/domain/branch_name.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a Git branch name.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use validator::Validate;

src/domain/commit_hash.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a git commit hash.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 

src/domain/event_type.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a GitHub's `repository_dispatch` `event_type`.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use validator::Validate;

src/domain/mod.rs

@@ -8,6 +8,7 @@ pub mod event_type;
 pub mod non_empty_string;
 pub mod repo_url;
 pub mod target_repo;
+pub mod validation_error;
 
 pub use accept_header::AcceptHeader;
 pub use api_version::ApiVersion;
@@ -17,6 +18,7 @@ pub use event_type::EventType;
 pub use non_empty_string::NonEmptyString;
 pub use repo_url::RepoUrl;
 pub use target_repo::TargetRepo;
+pub use validation_error::ValidationError;
 
 /// Derives `sqlx` trait implementations for a type that implements `TryFrom<String>`.
 ///

src/domain/non_empty_string.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a non-empty string.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use serde::{Deserialize, Serialize};
 use validator::Validate;
 

src/domain/repo_url.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a GitHub repository URL.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use validator::Validate;

src/domain/target_repo.rs

@@ -1,6 +1,6 @@
 //! Domain type to represent a target repository hosted on GitHub.
 
-use crate::error::ValidationError;
+use crate::domain::ValidationError;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 

src/domain/validation_error.rs

@@ -0,0 +1,11 @@
+//! Validation error type for domain values.
+
+use thiserror::Error;
+
+/// Validation error.
+#[derive(Debug, Error)]
+pub enum ValidationError {
+    /// Invalid field value.
+    #[error("Validation error: {0}")]
+    InvalidValue(String),
+}

src/error.rs

@@ -1,64 +1,10 @@
-//! Definitions for common error types.
+//! Definitions for fatal and setup errors.
 
 use crate::repository::RepositoryError;
-use axum::{
-    http::StatusCode,
-    response::{IntoResponse, Response},
-};
 use config::ConfigError;
-use rovo::aide::OperationOutput;
 use thiserror::Error;
 use validator::ValidationErrors;
 
-/// Validation error.
-#[derive(Debug, Error)]
-pub enum ValidationError {
-    /// Invalid field value.
-    #[error("Validation error: {0}")]
-    InvalidValue(String),
-}
-
-impl IntoResponse for ValidationError {
-    fn into_response(self) -> Response {
-        (StatusCode::UNPROCESSABLE_ENTITY, self.to_string()).into_response()
-    }
-}
-
-/// An error happened inside an Axum handler.
-#[derive(Debug, Error)]
-pub enum HandlerError {
-    /// Database query execution failure.
-    #[error("Repository Error: {0}")]
-    DbQuery(RepositoryError),
-
-    /// Requested resource not found.
-    #[error("Not Found")]
-    NotFound,
-}
-
-impl From<RepositoryError> for HandlerError {
-    fn from(err: RepositoryError) -> Self {
-        match err {
-            RepositoryError::NotFound => HandlerError::NotFound,
-            other => HandlerError::DbQuery(other),
-        }
-    }
-}
-
-impl OperationOutput for HandlerError {
-    type Inner = ();
-}
-
-impl IntoResponse for HandlerError {
-    fn into_response(self) -> Response {
-        let status = match self {
-            HandlerError::DbQuery(_) => StatusCode::INTERNAL_SERVER_ERROR,
-            HandlerError::NotFound => StatusCode::NOT_FOUND,
-        };
-        (status, self.to_string()).into_response()
-    }
-}
-
 /// An error that requires the server to be shut down.
 #[derive(Debug, Error)]
 pub enum FatalError {
@@ -147,73 +93,3 @@ impl From<dotenvy::Error> for FatalError {
 #[derive(Debug, Error)]
 #[error(transparent)]
 pub struct ClientCreationError(#[from] reqwest::Error);
-
-/// Error in retrieving a commit or its info using `git ls-remote`.
-#[derive(Debug, Error)]
-pub enum CommitHashError {
-    /// Validation error.
-    #[error("Validation error: {0}")]
-    Validation(#[from] ValidationError),
-
-    /// I/O error while spawning the process.
-    #[error("I/O error in `git ls-remote`: {0}")]
-    Io(#[from] std::io::Error),
-
-    /// Unexpected exit status.
-    #[error("Unexpected `git ls-remote` exit status: {0}")]
-    UnexpectedStatus(String),
-
-    /// Unexpected output format.
-    #[error(
-        "Unexpected `git ls-remote` output format. Repo: {repo_url}; Branch: {branch}; Stdout: {stdout}"
-    )]
-    UnexpectedOutput {
-        /// The process output text.
-        stdout: String,
-        /// The relevant git repository URL.
-        repo_url: String,
-        /// The relevant git branch.
-        branch: String,
-    },
-
-    /// Failed to find remote.
-    #[error("Failed to find remote: {0}")]
-    // Error is boxed because it is very large
-    RemoteAt(Box<gix::remote::init::Error>),
-
-    /// Failed to connect to remote.
-    #[error("Failed to connect to remote: {0}")]
-    // Error is boxed because it is very large
-    Connect(Box<gix::remote::connect::Error>),
-
-    /// Failed to map refs.
-    #[error("Failed to map refs: {0}")]
-    // Error is boxed because it is very large
-    RefMap(Box<gix::remote::ref_map::Error>),
-
-    /// Failed to parse refspec.
-    #[error("Failed to parse refspec: {0}")]
-    RefSpecParse(#[from] gix::refspec::parse::Error),
-
-    /// Git operation failed using gix.
-    #[error("Git operation failed: {0}")]
-    Git(String),
-}
-
-impl From<gix::remote::init::Error> for CommitHashError {
-    fn from(e: gix::remote::init::Error) -> Self {
-        CommitHashError::RemoteAt(Box::new(e))
-    }
-}
-
-impl From<gix::remote::connect::Error> for CommitHashError {
-    fn from(e: gix::remote::connect::Error) -> Self {
-        CommitHashError::Connect(Box::new(e))
-    }
-}
-
-impl From<gix::remote::ref_map::Error> for CommitHashError {
-    fn from(e: gix::remote::ref_map::Error) -> Self {
-        CommitHashError::RefMap(Box::new(e))
-    }
-}

src/http.rs

@@ -1,5 +1,6 @@
 //! HTTP networking: router wiring, server runtime, and the outbound HTTP client.
 
+pub mod error;
 pub mod handler;
 pub mod router;
 pub(crate) mod server;

src/http/error.rs

@@ -0,0 +1,45 @@
+//! Error types for the HTTP layer.
+
+use axum::{
+    http::StatusCode,
+    response::{IntoResponse, Response},
+};
+use rovo::aide::OperationOutput;
+use thiserror::Error;
+
+use crate::repository::RepositoryError;
+
+/// An error happened inside an Axum handler.
+#[derive(Debug, Error)]
+pub enum HandlerError {
+    /// Database query execution failure.
+    #[error("Repository Error: {0}")]
+    DbQuery(RepositoryError),
+
+    /// Requested resource not found.
+    #[error("Not Found")]
+    NotFound,
+}
+
+impl From<RepositoryError> for HandlerError {
+    fn from(err: RepositoryError) -> Self {
+        match err {
+            RepositoryError::NotFound => HandlerError::NotFound,
+            other => HandlerError::DbQuery(other),
+        }
+    }
+}
+
+impl OperationOutput for HandlerError {
+    type Inner = ();
+}
+
+impl IntoResponse for HandlerError {
+    fn into_response(self) -> Response {
+        let status = match self {
+            HandlerError::DbQuery(_) => StatusCode::INTERNAL_SERVER_ERROR,
+            HandlerError::NotFound => StatusCode::NOT_FOUND,
+        };
+        (status, self.to_string()).into_response()
+    }
+}

src/http/handler.rs

@@ -55,7 +55,7 @@ mod tests {
     use super::list::{ListSubscriptionsQuery, list_subscriptions_inner};
     use super::update::update_subscription_inner;
     use crate::domain::{BranchName, EventType, RepoUrl, TargetRepo};
-    use crate::error::HandlerError;
+    use crate::http::error::HandlerError;
     use crate::http::state::AppState;
     use crate::model::{CreateSubscription, UpdateSubscription};
     use crate::test_utils::create_test_db;

src/http/handler/create.rs

@@ -1,7 +1,7 @@
 //! Create a new subscription handler.
 
 use super::map_to_hal;
-use crate::error::HandlerError;
+use crate::http::error::HandlerError;
 use crate::http::state::AppState;
 use crate::model::{CreateSubscription, SubscriptionHal};
 use crate::repository::subscription::SubscriptionRepository;

src/http/handler/delete.rs

@@ -1,6 +1,6 @@
 //! Delete a subscription handler.
 
-use crate::error::HandlerError;
+use crate::http::error::HandlerError;
 use crate::http::state::AppState;
 use crate::repository::subscription::SubscriptionRepository;
 use axum::extract::{Path, State};

src/http/handler/get.rs

@@ -1,7 +1,7 @@
 //! Get a single subscription handler.
 
 use super::map_to_hal;
-use crate::error::HandlerError;
+use crate::http::error::HandlerError;
 use crate::http::state::AppState;
 use crate::model::SubscriptionHal;
 use crate::repository::subscription::SubscriptionRepository;

src/http/handler/list.rs

@@ -1,7 +1,7 @@
 //! List subscriptions handler.
 
 use super::map_to_hal;
-use crate::error::HandlerError;
+use crate::http::error::HandlerError;
 use crate::http::state::AppState;
 use crate::model::{HalLink, SubscriptionHal, SubscriptionPage, SubscriptionPageLinks};
 use crate::repository::subscription::SubscriptionRepository;

src/http/handler/update.rs

@@ -1,7 +1,7 @@
 //! Update an existing subscription handler.
 
 use super::map_to_hal;
-use crate::error::HandlerError;
+use crate::http::error::HandlerError;
 use crate::http::state::AppState;
 use crate::model::{SubscriptionHal, UpdateSubscription};
 use crate::repository::subscription::SubscriptionRepository;

src/polling/branch.rs

@@ -1,6 +1,10 @@
 //! Utilities for checking whether a branch has updated.
 
-use crate::{domain::CommitHash, error::CommitHashError, model::Branch, polling::git::GitFetcher};
+use crate::{
+    domain::CommitHash,
+    model::Branch,
+    polling::{CommitHashError, git::GitFetcher},
+};
 
 /// Enables comparison between a git branch row, and the newly fetched branch.
 pub(super) struct BranchInfo {