diff --git a/scripts/sql/p1_historian.sql b/scripts/sql/p1_historian.sql
index 70ac2fb..4168050 100644
--- a/scripts/sql/p1_historian.sql
+++ b/scripts/sql/p1_historian.sql
@@ -33,3 +33,13 @@ WITH NO DATA;
 SELECT add_continuous_aggregate_policy('hc900.history_1min',
   start_offset => INTERVAL '3 hours', end_offset => INTERVAL '10 minutes',
   schedule_interval => INTERVAL '5 minutes', if_not_exists => TRUE);
+
+-- P1c: 메트릭엔진 드롭인 소스(bucket→recorded_at) + 온라인 KPI 누적 테이블
+CREATE OR REPLACE VIEW hc900.history_1min_src AS
+  SELECT tagname, bucket AS recorded_at, value, controller_id FROM hc900.history_1min;
+
+CREATE TABLE IF NOT EXISTS hc900.live_kpi (
+  column_id text NOT NULL, kpi text NOT NULL, window_start date NOT NULL,
+  value double precision, unit text, state text, excluded_min int, status text,
+  updated_at timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (column_id, kpi, window_start));
diff --git a/src/Hc900Crawler/Controllers/ReportController.cs b/src/Hc900Crawler/Controllers/ReportController.cs
index d9d0460..d35ab3f 100644
--- a/src/Hc900Crawler/Controllers/ReportController.cs
+++ b/src/Hc900Crawler/Controllers/ReportController.cs
@@ -1,7 +1,10 @@
+using System.Data;
 using Hc900Crawler.Core.Application.DTOs;
 using Hc900Crawler.Core.Application.Interfaces;
+using Hc900Crawler.Infrastructure.Database;
 using Hc900Crawler.Infrastructure.Reporting;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 
 namespace Hc900Crawler.Web.Controllers;
 
@@ -13,14 +16,42 @@ public class ReportController : ControllerBase
     private readonly ReportFillService _fill;
     private readonly IReportTemplateStore _store;
     private readonly ReportColumnMap _map;
+    private readonly Hc900DbContext _db;
 
     // 웹 대시보드 기본 메트릭 세트
     private static readonly string[] SUMMARY_METRICS =
         { "production_total", "yield_qv", "energy_intensity_qv", "mass_balance_closure", "control_residual" };
 
     public ReportController(IReportMetricService metrics, ReportFillService fill,
-        IReportTemplateStore store, ReportColumnMap map)
-    { _metrics = metrics; _fill = fill; _store = store; _map = map; }
+        IReportTemplateStore store, ReportColumnMap map, Hc900DbContext db)
+    { _metrics = metrics; _fill = fill; _store = store; _map = map; _db = db; }
+
+    /// <summary>온라인 KPI(live_kpi) 직독 — 누적기가 history_1s에서 갱신한 당일 실시간 값.</summary>
+    [HttpGet("live")]
+    public async Task<IActionResult> Live(string? column = null, CancellationToken ct = default)
+    {
+        var conn = _db.Database.GetDbConnection();
+        if (conn.State != ConnectionState.Open) await conn.OpenAsync(ct);
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = @"SELECT column_id, kpi, value, unit, state, excluded_min, status, window_start, updated_at
+                            FROM hc900.live_kpi" + (column == null ? "" : " WHERE column_id=@col") +
+                            " ORDER BY column_id, kpi";
+        if (column != null) { var p = cmd.CreateParameter(); p.ParameterName = "@col"; p.Value = column; cmd.Parameters.Add(p); }
+        var items = new List<object>();
+        await using var rd = await cmd.ExecuteReaderAsync(ct);
+        while (await rd.ReadAsync(ct))
+            items.Add(new {
+                Column = rd.GetString(0), Kpi = rd.GetString(1),
+                Value = rd.IsDBNull(2) ? (double?)null : rd.GetDouble(2),
+                Unit = rd.IsDBNull(3) ? null : rd.GetString(3),
+                State = rd.IsDBNull(4) ? null : rd.GetString(4),
+                ExcludedMin = rd.IsDBNull(5) ? (int?)null : rd.GetInt32(5),
+                Status = rd.IsDBNull(6) ? null : rd.GetString(6),
+                WindowStart = rd.GetFieldValue<DateTime>(7).ToString("yyyy-MM-dd"),
+                UpdatedAt = rd.GetFieldValue<DateTime>(8)
+            });
+        return Ok(new { Count = items.Count, Items = items });
+    }
 
     /// <summary>설정된 컬럼 목록(웹 UI 셀렉트용).</summary>
     [HttpGet("columns")]
diff --git a/src/Hc900Crawler/Program.cs b/src/Hc900Crawler/Program.cs
index ddaec0e..329d44d 100644
--- a/src/Hc900Crawler/Program.cs
+++ b/src/Hc900Crawler/Program.cs
@@ -177,6 +177,8 @@ builder.WebHost.UseUrls("http://0.0.0.0:5000");
 builder.Services.AddSingleton<Hc900Crawler.Infrastructure.Reporting.ReportColumnMap>();
 // P1a: 1초 링버퍼 히스토리안 (history_1s, 보존정책으로 디스크 상한 고정)
 builder.Services.AddHostedService<Hc900Crawler.Infrastructure.Hc900.Hc900FastHistoryService>();
+// P1c: 온라인 KPI 누적기 (history_1s → live_kpi)
+builder.Services.AddHostedService<Hc900Crawler.Infrastructure.Hc900.Hc900LiveKpiService>();
 builder.Services.AddScoped<Hc900Crawler.Core.Application.Interfaces.IReportMetricService,
                            Hc900Crawler.Infrastructure.Reporting.ReportMetricService>();
 builder.Services.AddScoped<Hc900Crawler.Infrastructure.Reporting.ReportFillService>();
diff --git a/src/Hc900Crawler/appsettings.json b/src/Hc900Crawler/appsettings.json
index 2156048..2423d3d 100644
--- a/src/Hc900Crawler/appsettings.json
+++ b/src/Hc900Crawler/appsettings.json
@@ -92,6 +92,11 @@
       "IntervalSeconds": 1,
       "RetentionDays": 14
     },
+    "LiveKpi": {
+      "Enabled": true,
+      "IntervalSeconds": 15,
+      "Source": "history_1s"
+    },
     "Cleaning": {
       "VacMax": 300,
       "ProductMin": 10,
diff --git a/src/Infrastructure/Hc900/Hc900FastHistoryService.cs b/src/Infrastructure/Hc900/Hc900FastHistoryService.cs
index 72007bb..b23cc5d 100644
--- a/src/Infrastructure/Hc900/Hc900FastHistoryService.cs
+++ b/src/Infrastructure/Hc900/Hc900FastHistoryService.cs
@@ -99,6 +99,9 @@ WHERE tagname = ANY(@tags)";
             @"SELECT add_continuous_aggregate_policy('hc900.history_1min',
                 start_offset => INTERVAL '3 hours', end_offset => INTERVAL '10 minutes',
                 schedule_interval => INTERVAL '5 minutes', if_not_exists => TRUE)",
+            // 메트릭엔진 드롭인 소스(bucket→recorded_at)
+            @"CREATE OR REPLACE VIEW hc900.history_1min_src AS
+                SELECT tagname, bucket AS recorded_at, value, controller_id FROM hc900.history_1min",
         };
         foreach (var s in stmts)
         {
diff --git a/src/Infrastructure/Hc900/Hc900LiveKpiService.cs b/src/Infrastructure/Hc900/Hc900LiveKpiService.cs
new file mode 100644
index 0000000..dbdcfdd
--- /dev/null
+++ b/src/Infrastructure/Hc900/Hc900LiveKpiService.cs
@@ -0,0 +1,117 @@
+using System.Data;
+using Hc900Crawler.Core.Application.DTOs;
+using Hc900Crawler.Core.Application.Interfaces;
+using Hc900Crawler.Infrastructure.Database;
+using Hc900Crawler.Infrastructure.Reporting;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Hc900Crawler.Infrastructure.Hc900;
+
+/// <summary>
+/// P1c 온라인 KPI 누적기. 매 N초 오늘(KST)의 컬럼별 KPI를 history_1s에서 재계산해 live_kpi에 upsert.
+/// 재계산 방식 = 러닝 상태의 stateless 동등판: 결과(T) ≡ 배치(당일 시작~now), causal 보장(상태 복구 불필요).
+/// </summary>
+public class Hc900LiveKpiService : BackgroundService
+{
+    private static readonly string[] KPIS = { "production_total", "yield_qv", "energy_intensity_qv", "mass_balance_closure" };
+
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly ILogger<Hc900LiveKpiService> _logger;
+    private readonly Hc900RealtimeService _realtime;
+    private readonly ReportColumnMap _map;
+    private readonly bool _enabled;
+    private readonly int _intervalSec;
+    private readonly string _source;
+
+    public Hc900LiveKpiService(IServiceScopeFactory scopeFactory, ILogger<Hc900LiveKpiService> logger,
+        Hc900RealtimeService realtime, ReportColumnMap map, IConfiguration config)
+    {
+        _scopeFactory = scopeFactory; _logger = logger; _realtime = realtime; _map = map;
+        _enabled     = config.GetValue("Report:LiveKpi:Enabled", true);
+        _intervalSec = Math.Max(5, config.GetValue("Report:LiveKpi:IntervalSeconds", 15));
+        _source      = config.GetValue("Report:LiveKpi:Source", "history_1s")!;   // 1초 버퍼 기본
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        if (!_enabled) { _logger.LogInformation("[LiveKpi] 비활성"); return; }
+        try { await EnsureSchemaAsync(stoppingToken); } catch (Exception ex) { _logger.LogError(ex, "[LiveKpi] live_kpi 준비 실패"); return; }
+        _logger.LogInformation("[LiveKpi] 시작 — 간격 {Int}s, 소스 {Src}", _intervalSec, _source);
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                await Task.Delay(TimeSpan.FromSeconds(_intervalSec), stoppingToken);
+                if (!_realtime.IsConnected) continue;
+
+                var todayKst = DateTime.UtcNow.AddHours(9).Date;
+                using var scope = _scopeFactory.CreateScope();
+                var metrics = scope.ServiceProvider.GetRequiredService<IReportMetricService>();
+                var ctx = scope.ServiceProvider.GetRequiredService<Hc900DbContext>();
+                var conn = ctx.Database.GetDbConnection();
+                if (conn.State != ConnectionState.Open) await conn.OpenAsync(stoppingToken);
+
+                int written = 0;
+                foreach (var col in _map.Columns())
+                {
+                    var results = new List<MetricResultDto>();
+                    foreach (var kpi in KPIS)
+                        results.Add(await metrics.ComputeAsync(new MetricRequestDto
+                        { Column = col, Metric = kpi, PeriodDateKst = todayKst, SourceTable = _source }, stoppingToken));
+
+                    // 컬럼 상태: error=계산오류, 생산>0=normal, 그 외(0·no_data)=idle(미가동)
+                    var prod = results.First(r => r.Metric == "production_total");
+                    string state = prod.Status == "error" ? "error"
+                                 : prod.Value is > 0 ? "normal" : "idle";
+
+                    foreach (var r in results)
+                    {
+                        int? excl = r.Extra.TryGetValue("excluded_min", out var e) && e is double ed ? (int)ed : null;
+                        await UpsertAsync(conn, col, r.Metric, todayKst, r.Value, r.Unit, state, excl, r.Status, stoppingToken);
+                        written++;
+                    }
+                }
+                _logger.LogDebug("[LiveKpi] {N}개 KPI 갱신 @ {Day}", written, todayKst);
+            }
+            catch (OperationCanceledException) { break; }
+            catch (Exception ex) { _logger.LogError(ex, "[LiveKpi] 갱신 실패"); }
+        }
+        _logger.LogInformation("[LiveKpi] 종료");
+    }
+
+    private static async Task UpsertAsync(System.Data.Common.DbConnection conn, string col, string kpi,
+        DateTime ws, double? val, string? unit, string state, int? excl, string status, CancellationToken ct)
+    {
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = @"
+INSERT INTO hc900.live_kpi (column_id, kpi, window_start, value, unit, state, excluded_min, status, updated_at)
+VALUES (@col,@kpi,@ws,@val,@unit,@state,@excl,@status, now())
+ON CONFLICT (column_id, kpi, window_start) DO UPDATE
+SET value=EXCLUDED.value, unit=EXCLUDED.unit, state=EXCLUDED.state,
+    excluded_min=EXCLUDED.excluded_min, status=EXCLUDED.status, updated_at=now()";
+        void P(string n, object? v) { var p = cmd.CreateParameter(); p.ParameterName = n; p.Value = v ?? DBNull.Value; cmd.Parameters.Add(p); }
+        P("@col", col); P("@kpi", kpi); P("@ws", ws.Date); P("@val", val);
+        P("@unit", unit); P("@state", state); P("@excl", excl); P("@status", status);
+        await cmd.ExecuteNonQueryAsync(ct);
+    }
+
+    private async Task EnsureSchemaAsync(CancellationToken ct)
+    {
+        using var scope = _scopeFactory.CreateScope();
+        var conn = scope.ServiceProvider.GetRequiredService<Hc900DbContext>().Database.GetDbConnection();
+        if (conn.State != ConnectionState.Open) await conn.OpenAsync(ct);
+        await using var cmd = conn.CreateCommand();
+        cmd.CommandText = @"
+CREATE TABLE IF NOT EXISTS hc900.live_kpi (
+  column_id text NOT NULL, kpi text NOT NULL, window_start date NOT NULL,
+  value double precision, unit text, state text, excluded_min int, status text,
+  updated_at timestamptz NOT NULL DEFAULT now(),
+  PRIMARY KEY (column_id, kpi, window_start))";
+        await cmd.ExecuteNonQueryAsync(ct);
+    }
+}
diff --git a/src/Infrastructure/Reporting/ReportMetricService.cs b/src/Infrastructure/Reporting/ReportMetricService.cs
index 98071f7..523e845 100644
--- a/src/Infrastructure/Reporting/ReportMetricService.cs
+++ b/src/Infrastructure/Reporting/ReportMetricService.cs
@@ -26,19 +26,25 @@ public sealed class ReportMetricService : IReportMetricService
     private static readonly HashSet<string> QV_METRICS =
         new() { "production_total", "yield_qv", "energy_intensity_qv", "mass_balance_closure" };
 
+    // recorded_at 윈도로 조회 가능한 시계열 소스(동일 long 포맷). history_1min_src=연속집계 호환뷰.
+    private static readonly HashSet<string> SERIES_SOURCES =
+        new() { "history_table", "history_1s", "history_1min_src" };
+
     public async Task<MetricResultDto> ComputeAsync(MetricRequestDto req, CancellationToken ct = default)
     {
         bool isFast = req.SourceTable == "fast_record";
+        // history_table(60s) | history_1s(1s 버퍼) | history_1min_src(연속집계) | fast_record. 미지정/미허용→history_table.
+        string tbl  = isFast ? "fast_record"
+                    : SERIES_SOURCES.Contains(req.SourceTable) ? req.SourceTable : "history_table";
         var res = new MetricResultDto
         {
             Metric = req.Metric, Column = req.Column,
-            Source = req.SourceTable, SamplingMs = isFast ? 0 : 60000
+            Source = tbl, SamplingMs = isFast ? 0 : (tbl == "history_1s" ? 1000 : 60000)
         };
 
         // KST 날짜 [00:00, +1d) → UTC (recorded_at은 UTC)
         var fromUtc = DateTime.SpecifyKind(req.PeriodDateKst.Date, DateTimeKind.Unspecified).AddHours(-9);
         var toUtc   = fromUtc.AddDays(1);
-        string tbl  = isFast ? "fast_record" : "history_table";
 
         try
         {