diff --git a/src/KArtSell.Host/Features/Observability/MetricsSql.cs b/src/KArtSell.Host/Features/Observability/MetricsSql.cs
deleted file mode 100644
index a2fef771..00000000
--- a/src/KArtSell.Host/Features/Observability/MetricsSql.cs
+++ /dev/null
@@ -1,98 +0,0 @@
-using Dapper;
-using Npgsql;
-
-namespace KArtSell.Host.Features.Observability;
-
-/// <summary>
-/// Data queries for observability metrics.
-/// All queries use PIT (point-in-time) pattern: published_at <= cutoff.
-/// Schema-qualified, explicit columns, no SELECT *.
-/// </summary>
-public class MetricsSql
-{
-    private readonly NpgsqlDataSource _dataSource;
-
-    public MetricsSql(NpgsqlDataSource dataSource)
-    {
-        _dataSource = dataSource;
-    }
-
-    public async Task<(int Total, int OnTime, TimeSpan AvgTime)?> GetBatchSlaAsync(CancellationToken cancellationToken = default)
-    {
-        const string sql = """
-            SELECT
-                COUNT(*) as total,
-                COUNT(CASE WHEN status = 'success' THEN 1 END) as on_time,
-                AVG(duration_seconds) as avg_seconds
-            FROM observability.batch_sla_metrics
-            WHERE published_at <= @now
-              AND completed_at >= @sevenDaysAgo
-            """;
-
-        await using var connection = await _dataSource.OpenConnectionAsync(cancellationToken);
-        var result = await connection.QueryFirstOrDefaultAsync<(int, int, double)?>(
-            sql,
-            new { now = DateTime.UtcNow, sevenDaysAgo = DateTime.UtcNow.AddDays(-7) },
-            commandTimeout: 5);
-
-        if (result == null || result.Value.Item1 == 0)
-            return null;
-
-        var (total, onTime, avgSec) = result.Value;
-        return (total, onTime, TimeSpan.FromSeconds(avgSec));
-    }
-
-    public async Task<(int Quarantined, int Total, List<string> Errors)?> GetDataQualityQuarantineAsync(CancellationToken cancellationToken = default)
-    {
-        const string sql = """
-            SELECT
-                COUNT(*) as total,
-                COUNT(CASE WHEN resolution_status IS NULL THEN 1 END) as quarantined,
-                STRING_AGG(DISTINCT reason, ', ') as errors
-            FROM observability.data_quality_quarantine
-            WHERE published_at <= @now
-              AND quarantined_at >= @sevenDaysAgo
-            """;
-
-        await using var connection = await _dataSource.OpenConnectionAsync(cancellationToken);
-        var result = await connection.QueryFirstOrDefaultAsync<(int Total, int Quarantined, string? Errors)?>(
-            sql,
-            new { now = DateTime.UtcNow, sevenDaysAgo = DateTime.UtcNow.AddDays(-7) },
-            commandTimeout: 5);
-
-        if (result == null || result.Value.Item1 == 0)
-            return null;
-
-        var (total, quarantined, errors) = result.Value;
-        var errorList = string.IsNullOrEmpty(errors) ? new List<string>() : errors.Split(',').Select(e => e.Trim()).Take(5).ToList();
-
-        return (quarantined, total, errorList);
-    }
-
-    public async Task<(int Detected, int Resolved, DateTime LastCheck)?> GetDuplicateDetectionAsync(CancellationToken cancellationToken = default)
-    {
-        // Placeholder: building_blocks.outbox_message table exists (0000_building_blocks.sql).
-        // Duplicate detection logging (via operation_audit_trail or dedicated table) not yet implemented.
-        // Returns null until OutboxPollerJob hooks duplicate tracking (see DEBT-014).
-        await Task.CompletedTask;  // Async compliance
-        return null;
-    }
-
-    public async Task<(int Detected, int Resolved, List<string> Pending)?> GetReconciliationBreaksAsync(CancellationToken cancellationToken = default)
-    {
-        // Placeholder: Reconciliation break detection requires outbox/inbox log correlation.
-        // Requires audit trail showing Evidence version mismatches. Not yet implemented.
-        // Returns null until operation_audit_trail is populated by job consumers (see DEBT-014).
-        await Task.CompletedTask;  // Async compliance
-        return null;
-    }
-
-    public async Task<(decimal Baseline, decimal Current)?> GetModelDriftAsync(CancellationToken cancellationToken = default)
-    {
-        // Placeholder: Model drift calculation requires baseline/current sharpe comparison from shadow_run results.
-        // Returns null until Gate 3 rehearsal populates model_operations.shadow_run with real metrics.
-        // Once shadow_run results exist, baseline/current sharpe can be calculated and compared (see DEBT-009).
-        await Task.CompletedTask;  // Async compliance
-        return null;
-    }
-}
diff --git a/tests/KArtSell.Integration.Tests/ObservabilityMetricsTests.cs b/tests/KArtSell.Integration.Tests/ObservabilityMetricsTests.cs
index 6268010e..afbb3295 100644
--- a/tests/KArtSell.Integration.Tests/ObservabilityMetricsTests.cs
+++ b/tests/KArtSell.Integration.Tests/ObservabilityMetricsTests.cs
@@ -1,4 +1,5 @@
 using Dapper;
+using KArtSell.BuildingBlocks.Observability;
 using KArtSell.Host.Features.Observability;
 using Npgsql;
 using Xunit;