diff --git a/apps/app_api/src/api.rs b/apps/app_api/src/api.rs
index 97c8167..3402e84 100644
--- a/apps/app_api/src/api.rs
+++ b/apps/app_api/src/api.rs
@@ -1,5 +1,6 @@
 use crate::state::AppState;
-use axum::Router;
+use axum::{Json, Router, http::StatusCode, response::IntoResponse};
+use serde::Serialize;
 use std::sync::Arc;
 
 pub mod dictionary;
@@ -12,3 +13,32 @@ pub fn routes() -> Router<Arc<AppState>> {
         .nest("/api", dictionary::routes())
         .nest("/api", major_pl::routes())
 }
+
+// --- Error Response ---
+
+#[derive(Debug, Serialize)]
+pub struct ErrorResponse {
+    pub error: String,
+}
+
+impl IntoResponse for ErrorResponse {
+    fn into_response(self) -> axum::response::Response {
+        (StatusCode::INTERNAL_SERVER_ERROR, Json(self)).into_response()
+    }
+}
+
+impl From<anyhow::Error> for ErrorResponse {
+    fn from(err: anyhow::Error) -> Self {
+        Self {
+            error: err.to_string(),
+        }
+    }
+}
+
+impl From<applib::RepositoryError> for ErrorResponse {
+    fn from(err: applib::RepositoryError) -> Self {
+        Self {
+            error: err.to_string(),
+        }
+    }
+}
diff --git a/apps/app_api/src/api/dictionary.rs b/apps/app_api/src/api/dictionary.rs
index ae7afcb..dc3c067 100644
--- a/apps/app_api/src/api/dictionary.rs
+++ b/apps/app_api/src/api/dictionary.rs
@@ -1,7 +1,8 @@
-use axum::{Json, Router, extract::State, http::StatusCode, response::IntoResponse, routing::get};
+use axum::{Json, Router, extract::State, routing::get};
 use serde::Serialize;
 use std::sync::Arc;
 
+use super::ErrorResponse;
 use crate::state::AppState;
 
 // --- DTOs ---
@@ -17,33 +18,6 @@ pub struct DictListEntryResponse {
     pub entry_count: u64,
 }
 
-#[derive(Debug, Serialize)]
-pub struct ErrorResponse {
-    pub error: String,
-}
-
-impl IntoResponse for ErrorResponse {
-    fn into_response(self) -> axum::response::Response {
-        (StatusCode::INTERNAL_SERVER_ERROR, Json(self)).into_response()
-    }
-}
-
-impl From<anyhow::Error> for ErrorResponse {
-    fn from(err: anyhow::Error) -> Self {
-        Self {
-            error: err.to_string(),
-        }
-    }
-}
-
-impl From<applib::RepositoryError> for ErrorResponse {
-    fn from(err: applib::RepositoryError) -> Self {
-        Self {
-            error: err.to_string(),
-        }
-    }
-}
-
 // --- Handlers ---
 
 pub async fn list_dicts_handler(
diff --git a/apps/app_api/src/api/health.rs b/apps/app_api/src/api/health.rs
index d4b9bc1..99834d5 100644
--- a/apps/app_api/src/api/health.rs
+++ b/apps/app_api/src/api/health.rs
@@ -1,8 +1,6 @@
 use axum::{
     Json, Router,
     extract::State,
-    http::StatusCode,
-    response::IntoResponse,
     routing::{get, post},
 };
 use chrono::Utc;
@@ -10,6 +8,7 @@ use serde::Serialize;
 use serde_json::Value;
 use std::sync::Arc;
 
+use super::ErrorResponse;
 use crate::state::AppState;
 
 // --- DTOs ---
@@ -26,25 +25,6 @@ pub struct VersionResponse {
     pub version: String,
 }
 
-#[derive(Debug, Serialize)]
-pub struct ErrorResponse {
-    pub error: String,
-}
-
-impl IntoResponse for ErrorResponse {
-    fn into_response(self) -> axum::response::Response {
-        (StatusCode::INTERNAL_SERVER_ERROR, Json(self)).into_response()
-    }
-}
-
-impl<E: std::error::Error> From<E> for ErrorResponse {
-    fn from(err: E) -> Self {
-        Self {
-            error: err.to_string(),
-        }
-    }
-}
-
 // --- Handlers ---
 
 pub async fn echo_handler(
diff --git a/apps/app_api/src/api/major_pl.rs b/apps/app_api/src/api/major_pl.rs
index c4caad0..c93917b 100644
--- a/apps/app_api/src/api/major_pl.rs
+++ b/apps/app_api/src/api/major_pl.rs
@@ -1,8 +1,7 @@
+use super::ErrorResponse;
 use axum::{
     Json, Router,
     extract::{Path, Query, State},
-    http::StatusCode,
-    response::IntoResponse,
     routing::get,
 };
 use serde::{Deserialize, Serialize};
@@ -16,9 +15,7 @@ pub struct EncodeQuery {
 }
 
 #[derive(Debug, Deserialize)]
-pub struct DecodeQuery {
-    pub dict: Option<String>,
-}
+pub struct DecodeQuery {}
 
 #[derive(Debug, Serialize)]
 pub struct EncodeResponse {
@@ -39,25 +36,6 @@ pub struct DecodeResponse {
     pub result: String,
 }
 
-#[derive(Debug, Serialize)]
-pub struct ErrorResponse {
-    pub error: String,
-}
-
-impl IntoResponse for ErrorResponse {
-    fn into_response(self) -> axum::response::Response {
-        (StatusCode::INTERNAL_SERVER_ERROR, Json(self)).into_response()
-    }
-}
-
-impl From<anyhow::Error> for ErrorResponse {
-    fn from(err: anyhow::Error) -> Self {
-        Self {
-            error: err.to_string(),
-        }
-    }
-}
-
 pub async fn encode_handler(
     State(state): State<Arc<AppState>>,
     Path(input): Path<String>,
diff --git a/apps/app_api/src/container.rs b/apps/app_api/src/container.rs
index 6f6be09..37b5972 100644
--- a/apps/app_api/src/container.rs
+++ b/apps/app_api/src/container.rs
@@ -1,6 +1,5 @@
 use std::sync::Arc;
 
-use applib::DictImporter;
 use applib::DictRepository;
 use applib::SqliteDictRepository;
 use applib::SystemDecoder;
@@ -15,11 +14,6 @@ impl Container {
         Ok(Self)
     }
 
-    pub async fn create_dict_importer(&self, dict_name: &str) -> anyhow::Result<DictImporter> {
-        let repo = self.create_dict_repo(dict_name).await?;
-        Ok(DictImporter::new(repo))
-    }
-
     pub async fn create_dict_repo(
         &self,
         dict_name: &str,