feat(web): implement exponential backoff retry pattern in KisApiClient

src/dotnet/QuantEngine.Infrastructure/Services/KisApiClient.cs

@@ -141,23 +141,37 @@ public class KisApiClient : IKisApiClient
         if (!string.IsNullOrEmpty(queryString))
             url += $"?{queryString}";
 
-        try
+        int maxAttempts = 3;
-        {
+        int delayMs = 1000;
-            var request = new HttpRequestMessage(HttpMethod.Get, url);
-            foreach (var header in headers)
-                request.Headers.Add(header.Key, header.Value);
 
-            var response = await _httpClient.SendAsync(request);
+        for (int attempt = 1; attempt <= maxAttempts; attempt++)
-            response.EnsureSuccessStatusCode();
-
-            var result = await response.Content.ReadFromJsonAsync<Dictionary<string, object>>();
-            return result ?? new Dictionary<string, object>();
-        }
-        catch (Exception ex)
         {
-            _logger.LogError(ex, "KIS request failed: {Path} / {TrId}", path, trId);
+            try
-            throw new InvalidOperationException($"KIS read-only request failed for {path} / {trId}.", ex);
+            {
+                var request = new HttpRequestMessage(HttpMethod.Get, url);
+                foreach (var header in headers)
+                    request.Headers.Add(header.Key, header.Value);
+
+                var response = await _httpClient.SendAsync(request);
+                response.EnsureSuccessStatusCode();
+
+                var result = await response.Content.ReadFromJsonAsync<Dictionary<string, object>>();
+                return result ?? new Dictionary<string, object>();
+            }
+            catch (Exception ex) when (attempt < maxAttempts)
+            {
+                _logger.LogWarning(ex, "KIS request failed on attempt {Attempt}/{MaxAttempts}. Retrying in {Delay}ms...", attempt, maxAttempts, delayMs);
+                await Task.Delay(delayMs);
+                delayMs *= 2;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "KIS request failed after {MaxAttempts} attempts: {Path} / {TrId}", maxAttempts, path, trId);
+                throw new InvalidOperationException($"KIS read-only request failed for {path} / {trId} after {maxAttempts} attempts.", ex);
+            }
         }
+
+        throw new InvalidOperationException("Unreachable code in KIS client SendRequestAsync");
     }
 
     private async Task<string> GetOrRefreshTokenAsync(KisCredentials creds)
@@ -174,38 +188,51 @@ public class KisApiClient : IKisApiClient
 
             var tokenRequest = new { grant_type = "client_credentials", appkey = creds.AppKey, appsecret = creds.AppSecret };
 
-            try
+            int maxAttempts = 3;
+            int delayMs = 1000;
+
+            for (int attempt = 1; attempt <= maxAttempts; attempt++)
             {
-                var response = await _httpClient.PostAsJsonAsync(
+                try
-                    $"{creds.Domain}/oauth2/tokenP",
+                {
-                    tokenRequest
+                    var response = await _httpClient.PostAsJsonAsync(
-                );
+                        $"{creds.Domain}/oauth2/tokenP",
-                response.EnsureSuccessStatusCode();
+                        tokenRequest
+                    );
+                    response.EnsureSuccessStatusCode();
 
-                var tokenData = await response.Content.ReadFromJsonAsync<Dictionary<string, object>>();
+                    var tokenData = await response.Content.ReadFromJsonAsync<Dictionary<string, object>>();
-                if (tokenData == null) throw new InvalidOperationException("Token response body is empty");
+                    if (tokenData == null) throw new InvalidOperationException("Token response body is empty");
 
-                if (!tokenData.TryGetValue("access_token", out var tokenObj) || tokenObj == null)
+                    if (!tokenData.TryGetValue("access_token", out var tokenObj) || tokenObj == null)
-                    throw new InvalidOperationException("No access_token in response");
+                        throw new InvalidOperationException("No access_token in response");
-                var accessToken = tokenObj.ToString()!;
+                    var accessToken = tokenObj.ToString()!;
 
-                var expiresInStr = tokenData.TryGetValue("expires_in", out var expiresObj) && expiresObj != null
+                    var expiresInStr = tokenData.TryGetValue("expires_in", out var expiresObj) && expiresObj != null
-                    ? expiresObj.ToString()
+                        ? expiresObj.ToString()
-                    : "86400";
+                        : "86400";
-                var expiresInSec = int.TryParse(expiresInStr, NumberStyles.Integer, CultureInfo.InvariantCulture, out var seconds)
+                    var expiresInSec = int.TryParse(expiresInStr, NumberStyles.Integer, CultureInfo.InvariantCulture, out var seconds)
-                    ? seconds
+                        ? seconds
-                    : 86400;
+                        : 86400;
-                var expiresAt = DateTime.UtcNow.AddSeconds(expiresInSec);
+                    var expiresAt = DateTime.UtcNow.AddSeconds(expiresInSec);
 
-                await _tokenCache.SaveTokenAsync(creds.Account, accessToken, expiresAt);
+                    await _tokenCache.SaveTokenAsync(creds.Account, accessToken, expiresAt);
-                _logger.LogInformation("KIS token refreshed for {Account}; expires at {ExpiresAtUtc}", creds.Account, expiresAt);
+                    _logger.LogInformation("KIS token refreshed for {Account}; expires at {ExpiresAtUtc}", creds.Account, expiresAt);
-                return accessToken;
+                    return accessToken;
-            }
+                }
-            catch (Exception ex)
+                catch (Exception ex) when (attempt < maxAttempts)
-            {
+                {
-                _logger.LogError(ex, "KIS token refresh failed");
+                    _logger.LogWarning(ex, "KIS token refresh failed on attempt {Attempt}/{MaxAttempts}. Retrying in {Delay}ms...", attempt, maxAttempts, delayMs);
-                throw new InvalidOperationException("KIS token refresh failed; check credentials and API availability.", ex);
+                    await Task.Delay(delayMs);
+                    delayMs *= 2;
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogError(ex, "KIS token refresh failed after {MaxAttempts} attempts", maxAttempts);
+                    throw new InvalidOperationException($"KIS token refresh failed after {maxAttempts} attempts; check credentials and API availability.", ex);
+                }
             }
+            throw new InvalidOperationException("Unreachable code in KIS client TokenRefresh");
         }
         finally
         {