feat: API preview endpoint for import sessions

crates/presentation/src/handlers/import.rs

@@ -635,6 +635,70 @@ pub async fn api_put_mapping(
     }
 }
 
+pub async fn api_get_preview(
+    State(state): State<AppState>,
+    AuthenticatedUser(user_id): AuthenticatedUser,
+    Path(session_id_str): Path<String>,
+) -> impl IntoResponse {
+    let Ok(session_id) = session_id_str
+        .parse::<uuid::Uuid>()
+        .map(ImportSessionId::from_uuid)
+    else {
+        return (
+            StatusCode::BAD_REQUEST,
+            axum::Json(serde_json::json!({"error": "invalid session id"})),
+        )
+            .into_response();
+    };
+    match state
+        .app_ctx
+        .repos
+        .import_session
+        .get(&session_id, &user_id)
+        .await
+    {
+        Ok(Some(session)) => {
+            let annotated: Vec<domain::models::AnnotatedRow> =
+                session.row_results.unwrap_or_default();
+            let rows: Vec<serde_json::Value> = annotated
+                .iter()
+                .enumerate()
+                .map(|(i, a)| {
+                    use domain::models::import::RowResult;
+                    match &a.result {
+                        RowResult::Valid(row) => serde_json::json!({
+                            "index": i,
+                            "status": if a.is_duplicate { "duplicate" } else { "valid" },
+                            "title": row.title,
+                            "release_year": row.release_year,
+                            "director": row.director,
+                            "rating": row.rating,
+                            "watched_at": row.watched_at,
+                            "comment": row.comment,
+                        }),
+                        RowResult::Invalid { errors, .. } => serde_json::json!({
+                            "index": i,
+                            "status": "invalid",
+                            "errors": errors,
+                        }),
+                    }
+                })
+                .collect();
+            axum::Json(serde_json::json!({ "rows": rows })).into_response()
+        }
+        Ok(None) => (
+            StatusCode::NOT_FOUND,
+            axum::Json(serde_json::json!({"error": "session not found"})),
+        )
+            .into_response(),
+        Err(e) => (
+            StatusCode::INTERNAL_SERVER_ERROR,
+            axum::Json(serde_json::json!({"error": e.to_string()})),
+        )
+            .into_response(),
+    }
+}
+
 #[utoipa::path(
     post, path = "/api/v1/import/sessions/{id}/confirm",
     params(("id" = String, Path, description = "Import session UUID")),