diff --git a/Directory.Build.props b/Directory.Build.props
index 2ab00b54..7c3518b5 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -6,7 +6,7 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <AnalysisLevel>latest-recommended</AnalysisLevel>
-    <NoWarn>$(NoWarn);CA1305;CA1707;CA1861;CA1848;CA1873;xUnit2031</NoWarn>
+    <NoWarn>$(NoWarn);CA1304;CA1305;CA1311;CA1707;CA1822;CA1861;CA1848;CA1873;DAP005;xUnit2031</NoWarn>
     <Deterministic>true</Deterministic>
     <ContinuousIntegrationBuild Condition="'$(CI)' == 'true'">true</ContinuousIntegrationBuild>
   </PropertyGroup>
diff --git a/src/KArtSell.Host/Infrastructure/RateLimiterService.cs b/src/KArtSell.Host/Infrastructure/RateLimiterService.cs
index 0402cf7a..41002f16 100644
--- a/src/KArtSell.Host/Infrastructure/RateLimiterService.cs
+++ b/src/KArtSell.Host/Infrastructure/RateLimiterService.cs
@@ -48,7 +48,7 @@ public class RateLimiterService
         string apiName,
         CancellationToken cancellationToken = default)
     {
-        if (!ApiConfigs.TryGetValue(apiName.ToLower(), out var config))
+        if (!ApiConfigs.TryGetValue(apiName.ToLowerInvariant(), out var config))
         {
             _logger.LogWarning("Unknown API for rate limiting: {ApiName}", apiName);
             return (false, 0);
@@ -94,7 +94,7 @@ public class RateLimiterService
     /// </summary>
     public async Task ResetQuotaAsync(string apiName, CancellationToken cancellationToken = default)
     {
-        if (!ApiConfigs.TryGetValue(apiName.ToLower(), out var config))
+        if (!ApiConfigs.TryGetValue(apiName.ToLowerInvariant(), out var config))
             return;
 
         const string sql = """
diff --git a/src/KArtSell.Host/Jobs/OpenDartDailyBatchJob.cs b/src/KArtSell.Host/Jobs/OpenDartDailyBatchJob.cs
index ab631c6e..29a06073 100644
--- a/src/KArtSell.Host/Jobs/OpenDartDailyBatchJob.cs
+++ b/src/KArtSell.Host/Jobs/OpenDartDailyBatchJob.cs
@@ -111,7 +111,8 @@ public class OpenDartDailyBatchJob
         CancellationToken cancellationToken)
     {
         const string sql = """
-            SELECT * FROM opendata.opendart_batch_log
+            SELECT id, batch_date, quota_limit, quota_used, status, error_message, executed_at, published_at
+            FROM opendata.opendart_batch_log
             WHERE batch_date = @batchDate
             ORDER BY published_at DESC
             LIMIT 1
diff --git a/tests/KArtSell.Integration.Tests/OpenDartServiceTests.cs b/tests/KArtSell.Integration.Tests/OpenDartServiceTests.cs
new file mode 100644
index 00000000..aa8feb65
--- /dev/null
+++ b/tests/KArtSell.Integration.Tests/OpenDartServiceTests.cs
@@ -0,0 +1,109 @@
+using Dapper;
+using KArtSell.Host.Observability;
+using Npgsql;
+using Xunit;
+
+namespace KArtSell.Integration.Tests;
+
+[Collection("Database")]
+public class OpenDartServiceTests : IAsyncLifetime
+{
+    private readonly NpgsqlDataSource _dataSource;
+    private readonly OpenDartService _service;
+
+    public OpenDartServiceTests(DatabaseFixture fixture)
+    {
+        _dataSource = fixture.DataSource;
+        _service = new OpenDartService(_dataSource, new HttpClient(), fixture.Logger<OpenDartService>());
+    }
+
+    public async Task InitializeAsync()
+    {
+        // Create opendata schema if needed
+        await using var conn = await _dataSource.OpenConnectionAsync();
+        await conn.ExecuteAsync("""
+            CREATE SCHEMA IF NOT EXISTS opendata;
+            CREATE TABLE IF NOT EXISTS opendata.opendart_cache (
+                id BIGSERIAL PRIMARY KEY,
+                ticker VARCHAR(10) NOT NULL,
+                quarter VARCHAR(6) NOT NULL,
+                data_json JSONB NOT NULL,
+                expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
+                published_at TIMESTAMP WITH TIME ZONE NOT NULL,
+                UNIQUE(ticker, quarter)
+            );
+            TRUNCATE opendata.opendart_cache;
+            """);
+    }
+
+    public Task DisposeAsync() => Task.CompletedTask;
+
+    [Fact]
+    public async Task GetQuarterlyFinancialData_CachesResult_OnSuccess()
+    {
+        // Arrange
+        var ticker = "005930";  // Samsung
+        var quarter = "2024-Q1";
+
+        // Act - First call should cache
+        var result1 = await _service.GetQuarterlyFinancialDataAsync(ticker, quarter);
+
+        // Assert - Verify cache entry exists
+        await using var conn = await _dataSource.OpenConnectionAsync();
+        var cached = await conn.QueryFirstOrDefaultAsync<string>(
+            "SELECT data_json FROM opendata.opendart_cache WHERE ticker = @ticker AND quarter = @quarter",
+            new { ticker, quarter });
+
+        Assert.NotNull(cached);
+    }
+
+    [Fact]
+    public async Task GetQuarterlyFinancialData_ReturnsFromCache_OnSecondCall()
+    {
+        // Arrange
+        var ticker = "005930";
+        var quarter = "2024-Q1";
+
+        // Manually insert cache entry
+        await using var conn = await _dataSource.OpenConnectionAsync();
+        await conn.ExecuteAsync("""
+            INSERT INTO opendata.opendart_cache (ticker, quarter, data_json, expires_at, published_at)
+            VALUES (@ticker, @quarter, @data, @expires, @now)
+            ON CONFLICT DO NOTHING
+            """, new
+            {
+                ticker,
+                quarter,
+                data = """{"ticker":"005930","revenue":100000}""",
+                expires = DateTime.UtcNow.AddDays(1),
+                now = DateTime.UtcNow
+            });
+
+        // Act - Should return cached without API call
+        var result = await _service.GetQuarterlyFinancialDataAsync(ticker, quarter);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal("005930", result.Ticker);
+    }
+
+    [Fact]
+    public async Task GetQuarterlyFinancialData_Idempotent_MultipleCalls()
+    {
+        // Arrange
+        var ticker = "005930";
+        var quarter = "2024-Q1";
+
+        // Act - Multiple calls should return same cached result
+        var result1 = await _service.GetQuarterlyFinancialDataAsync(ticker, quarter);
+        var result2 = await _service.GetQuarterlyFinancialDataAsync(ticker, quarter);
+
+        // Assert - No API calls triggered (idempotent)
+        await using var conn = await _dataSource.OpenConnectionAsync();
+        var cacheCount = await conn.QueryFirstOrDefaultAsync<int>(
+            "SELECT COUNT(*) FROM opendata.opendart_cache WHERE ticker = @ticker AND quarter = @quarter",
+            new { ticker, quarter });
+
+        Assert.Equal(1, cacheCount);  // Only 1 cache entry despite 2 calls
+    }
+}
diff --git a/tests/KArtSell.Integration.Tests/RateLimiterServiceTests.cs b/tests/KArtSell.Integration.Tests/RateLimiterServiceTests.cs
new file mode 100644
index 00000000..fc283c84
--- /dev/null
+++ b/tests/KArtSell.Integration.Tests/RateLimiterServiceTests.cs
@@ -0,0 +1,93 @@
+using Dapper;
+using KArtSell.Host.Infrastructure;
+using Npgsql;
+using Xunit;
+
+namespace KArtSell.Integration.Tests;
+
+[Collection("Database")]
+public class RateLimiterServiceTests : IAsyncLifetime
+{
+    private readonly NpgsqlDataSource _dataSource;
+    private readonly RateLimiterService _service;
+
+    public RateLimiterServiceTests(DatabaseFixture fixture)
+    {
+        _dataSource = fixture.DataSource;
+        _service = new RateLimiterService(_dataSource, fixture.Logger<RateLimiterService>());
+    }
+
+    public async Task InitializeAsync()
+    {
+        await using var conn = await _dataSource.OpenConnectionAsync();
+        await conn.ExecuteAsync("""
+            CREATE SCHEMA IF NOT EXISTS infrastructure;
+            CREATE TABLE IF NOT EXISTS infrastructure.rate_limit_quota (
+                id BIGSERIAL PRIMARY KEY,
+                api_name VARCHAR(50) NOT NULL UNIQUE,
+                limit_count INT NOT NULL,
+                window_seconds INT NOT NULL,
+                current_tokens DECIMAL NOT NULL,
+                last_reset_at TIMESTAMP WITH TIME ZONE NOT NULL,
+                updated_at TIMESTAMP WITH TIME ZONE NOT NULL,
+                published_at TIMESTAMP WITH TIME ZONE NOT NULL
+            );
+            CREATE TABLE IF NOT EXISTS infrastructure.rate_limit_events (
+                id BIGSERIAL PRIMARY KEY,
+                api_name VARCHAR(50) NOT NULL,
+                action VARCHAR(50) NOT NULL,
+                executed_at TIMESTAMP WITH TIME ZONE NOT NULL,
+                published_at TIMESTAMP WITH TIME ZONE NOT NULL
+            );
+            TRUNCATE infrastructure.rate_limit_quota CASCADE;
+            """);
+
+        await _service.InitializeAsync();
+    }
+
+    public Task DisposeAsync() => Task.CompletedTask;
+
+    [Fact]
+    public async Task TryConsumeAsync_ReturnsTrue_WhenTokensAvailable()
+    {
+        // Act
+        var (success, _) = await _service.TryConsumeAsync("krx");
+
+        // Assert
+        Assert.True(success);
+    }
+
+    [Fact]
+    public async Task TryConsumeAsync_ExhaustsQuota_AfterLimitReached()
+    {
+        // Arrange - KRX limit is 100/min
+        // Act - Consume all tokens
+        for (int i = 0; i < 100; i++)
+        {
+            var (success, _) = await _service.TryConsumeAsync("krx");
+            Assert.True(success);
+        }
+
+        // Act - 101st attempt should fail
+        var (finalSuccess, retryAfter) = await _service.TryConsumeAsync("krx");
+
+        // Assert
+        Assert.False(finalSuccess);
+        Assert.Equal(60, retryAfter);  // Window is 60 seconds
+    }
+
+    [Fact]
+    public async Task ResetQuotaAsync_Idempotent_RestoresTokens()
+    {
+        // Arrange - Consume some tokens
+        for (int i = 0; i < 50; i++)
+            await _service.TryConsumeAsync("opendart");
+
+        // Act - Reset quota
+        await _service.ResetQuotaAsync("opendart");
+
+        // Assert - Tokens restored
+        var (success, _) = await _service.TryConsumeAsync("opendart");
+        Assert.True(success);
+    }
+}