diff --git a/pecan/src/components/Constellation.tsx b/pecan/src/components/Constellation.tsx
index 7fbd2bb..aa68d9c 100644
--- a/pecan/src/components/Constellation.tsx
+++ b/pecan/src/components/Constellation.tsx
@@ -1,7 +1,8 @@
 import React, { useState, useEffect, useRef, useCallback } from 'react';
 import type { SensorStar } from '../hooks/useConstellationSignals';
 import { ConstellationSidebar } from './ConstellationSidebar';
-import { dataStore } from '../lib/DataStore';
+import { dataStore, type TelemetrySource } from '../lib/DataStore';
+import type { TimelineMode } from '../context/TimelineContext';
 import { calculateCorrelation, getCorrelationMeta, findStrongCorrelations } from '../utils/statistics';
 import { Zap, Share2, RefreshCw, Info } from 'lucide-react';
 
@@ -10,9 +11,27 @@ interface ConstellationCanvasProps {
   sensorValuesRef: React.RefObject<Record<string, number>>;
   telemetryHistoryRef: React.RefObject<Record<string, number[]>>;
   onExport: (constellationIds: string[]) => void;
+  /** Timeline cursor (epoch ms). When in replay or paused, "isLive" is evaluated at this time. */
+  cursorTimeMs?: number;
+  /** Active telemetry source — replay buffer is queried separately from live. */
+  source?: TelemetrySource;
+  /** Timeline mode — paused mode also pins the canvas to cursorTimeMs. */
+  mode?: TimelineMode;
 }
 
-export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetryHistoryRef, onExport }: ConstellationCanvasProps) {
+export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetryHistoryRef, onExport, cursorTimeMs, source = "live", mode = "live" }: ConstellationCanvasProps) {
+  // Mirror timeline state into refs so the rAF render loop can read fresh
+  // values without re-subscribing or restarting.
+  const cursorTimeMsRef = useRef<number>(cursorTimeMs ?? Date.now());
+  const sourceRef = useRef<TelemetrySource>(source);
+  const modeRef = useRef<TimelineMode>(mode);
+  useEffect(() => {
+    cursorTimeMsRef.current = cursorTimeMs ?? Date.now();
+    // Pinned-mode cursor moves rewrite history wholesale; drop cached correlations.
+    correlationCacheRef.current.clear();
+  }, [cursorTimeMs]);
+  useEffect(() => { sourceRef.current = source; correlationCacheRef.current.clear(); }, [source]);
+  useEffect(() => { modeRef.current = mode; }, [mode]);
   const canvasRef = useRef<HTMLCanvasElement>(null);
   const offscreenCanvasRef = useRef<HTMLCanvasElement | null>(null);
   
@@ -59,6 +78,10 @@ export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetr
   // --- RENDER ENGINE ---
   const timeRef = useRef(0);
   const bgStarsRef = useRef<{x: number, y: number, size: number, alpha: number}[]>([]);
+  // Correlation cache: pair-key -> { r, expiresAt }. History updates at most
+  // ~10Hz; recomputing Pearson per link per rAF (60Hz) is wasted work.
+  const correlationCacheRef = useRef<Map<string, { r: number, expiresAt: number }>>(new Map());
+  const CORRELATION_TTL_MS = 150;
 
   useEffect(() => {
     const canvas = canvasRef.current;
@@ -230,7 +253,11 @@ export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetr
         const sx = cx + x1 * scale;
         const sy = cy + y2 * scale;
         
-        const latest = dataStore.getLatest(s.msgID);
+        const activeSource = sourceRef.current;
+        const pinned = activeSource === "replay" || modeRef.current === "paused";
+        const latest = pinned
+          ? dataStore.getLatestAt(s.msgID, cursorTimeMsRef.current, activeSource)
+          : dataStore.getLatest(s.msgID, activeSource);
         const isLive = latest && !!latest.data[s.sigName];
         
         return { ...s, sx, sy, scale, zDepth: z2, isLive, behindCamera: scale <= 0 };
@@ -248,10 +275,17 @@ export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetr
         if (sNode && tNode && !sNode.behindCamera && !tNode.behindCamera) {
           const isSelected = selectedIds.includes(sNode.id) && selectedIds.includes(tNode.id);
           
-          // Calculate Correlation
-          const h1 = telemetryHistoryRef.current?.[sNode.id] || [];
-          const h2 = telemetryHistoryRef.current?.[tNode.id] || [];
-          const r = calculateCorrelation(h1, h2);
+          // Calculate Correlation (cached — TTL avoids per-frame Pearson recompute)
+          const cacheKey = sNode.id < tNode.id ? `${sNode.id}|${tNode.id}` : `${tNode.id}|${sNode.id}`;
+          const nowMs = performance.now();
+          let cached = correlationCacheRef.current.get(cacheKey);
+          if (!cached || cached.expiresAt <= nowMs) {
+            const h1 = telemetryHistoryRef.current?.[sNode.id] || [];
+            const h2 = telemetryHistoryRef.current?.[tNode.id] || [];
+            cached = { r: calculateCorrelation(h1, h2), expiresAt: nowMs + CORRELATION_TTL_MS };
+            correlationCacheRef.current.set(cacheKey, cached);
+          }
+          const r = cached.r;
           const meta = getCorrelationMeta(r);
           
           const alpha = (isSelected ? 0.9 : 0.25) * Math.min(sNode.scale, tNode.scale);
@@ -455,7 +489,7 @@ export default function ConstellationCanvas({ sensors, sensorValuesRef, telemetr
   };
 
   return (
-    <div className="relative w-full h-screen overflow-hidden select-none" style={{ background: '#020617' }}>
+    <div className="relative w-full h-full overflow-hidden select-none" style={{ background: '#020617' }}>
       <canvas
         ref={canvasRef}
         className="absolute inset-0 z-0"
diff --git a/pecan/src/hooks/useConstellationSignals.ts b/pecan/src/hooks/useConstellationSignals.ts
index 03b8fcb..b7331aa 100644
--- a/pecan/src/hooks/useConstellationSignals.ts
+++ b/pecan/src/hooks/useConstellationSignals.ts
@@ -36,10 +36,13 @@ function categoryHex(categoryName: string): string {
   return TAILWIND_HEX_MAP[cat.color] ?? DEFAULT_HEX;
 }
 
-export function useConstellationSignals(): SensorStar[] {
+export function useConstellationSignals(refreshKey?: string | number): SensorStar[] {
   const messages = useMemo(() => {
+    // refreshKey is referenced solely to invalidate the memo when the active
+    // DBC changes (e.g. after a .pecan replay import embeds a new DBC).
+    void refreshKey;
     return getLoadedDbcMessages();
-  }, []);
+  }, [refreshKey]);
 
   const sensors = useMemo(() => {
     // 1. Identify all unique categories and count their signal density
diff --git a/pecan/src/pages/Constellation.tsx b/pecan/src/pages/Constellation.tsx
index a598079..8d6a196 100644
--- a/pecan/src/pages/Constellation.tsx
+++ b/pecan/src/pages/Constellation.tsx
@@ -2,19 +2,40 @@ import { useRef, useState, useCallback, useEffect } from 'react';
 import ConstellationCanvas from '../components/Constellation';
 import { ConstellationExportModal } from '../components/ConstellationExportModal';
 import { useConstellationSignals } from '../hooks/useConstellationSignals';
-import { dataStore } from '../lib/DataStore';
+import { dataStore, type TelemetrySample } from '../lib/DataStore';
+import { useTimeline } from '../context/TimelineContext';
+import TimelineBar from '../components/TimelineBar';
 
 const HISTORY_LEN = 50;
 
 export default function ConstellationPage() {
-  const sensors = useConstellationSignals();
+  const { source, mode, selectedTimeMs, windowMs, replaySession } = useTimeline();
+
+  // Re-enumerate sensors when a new replay session loads (its embedded DBC may
+  // differ from the live DBC) so signals reflect the imported file.
+  const sensorsRefreshKey = source === "replay"
+    ? `replay:${replaySession?.loadedAtMs ?? 0}`
+    : "live";
+  const sensors = useConstellationSignals(sensorsRefreshKey);
+
   const sensorValuesRef = useRef<Record<string, number>>({});
   const telemetryHistoryRef = useRef<Record<string, number[]>>({});
   const [showExport, setShowExport] = useState(false);
   const [selectedForExport, setSelectedForExport] = useState<string[]>([]);
 
-  // Keep sensorValuesRef.current up-to-date with live data
+  // When pinned to a cursor (replay, or live in paused mode) we rebuild the
+  // sensor value/history refs from the cursor on every change so correlations
+  // and node colors reflect the historical moment, not the latest live frame.
+  const isPinnedToCursor = source === "replay" || mode === "paused";
+
+  // Live + live: subscribe to incoming frames and accumulate a rolling history.
+  // Wipe refs on entry so residual replay data doesn't bleed into correlations.
   useEffect(() => {
+    if (isPinnedToCursor) return;
+
+    sensorValuesRef.current = {};
+    telemetryHistoryRef.current = {};
+
     const unsub = dataStore.subscribe(() => {
       const allLatest = dataStore.getAllLatest();
       const vals: Record<string, number> = {};
@@ -22,7 +43,6 @@ export default function ConstellationPage() {
         for (const sigName in sample.data) {
           const key = `${sample.msgID}:${sigName}`;
           vals[key] = sample.data[sigName].sensorReading;
-          // update rolling history
           if (!telemetryHistoryRef.current[key]) {
             telemetryHistoryRef.current[key] = [];
           }
@@ -35,7 +55,44 @@ export default function ConstellationPage() {
       sensorValuesRef.current = vals;
     });
     return unsub;
-  }, []);
+  }, [isPinnedToCursor]);
+
+  // Pinned to cursor: rebuild values and rolling histories from the data
+  // store every time the cursor moves. This overwrites the refs entirely so
+  // there's no need to reset separately on source transitions.
+  useEffect(() => {
+    if (!isPinnedToCursor) return;
+
+    const allLatest = dataStore.getAllLatestAt(selectedTimeMs, source);
+
+    const vals: Record<string, number> = {};
+    const histories: Record<string, number[]> = {};
+    const windowCache = new Map<string, TelemetrySample[]>();
+
+    for (const s of sensors) {
+      const latest = allLatest.get(s.msgID);
+      const reading = latest?.data?.[s.sigName]?.sensorReading;
+      if (typeof reading === "number") {
+        vals[s.id] = reading;
+      }
+
+      let history = windowCache.get(s.msgID);
+      if (!history) {
+        history = dataStore.getHistoryAt(s.msgID, windowMs, selectedTimeMs, source);
+        windowCache.set(s.msgID, history);
+      }
+
+      const hist: number[] = [];
+      for (const sample of history) {
+        const v = sample.data?.[s.sigName]?.sensorReading;
+        if (typeof v === "number") hist.push(v);
+      }
+      histories[s.id] = hist.length > HISTORY_LEN ? hist.slice(-HISTORY_LEN) : hist;
+    }
+
+    sensorValuesRef.current = vals;
+    telemetryHistoryRef.current = histories;
+  }, [isPinnedToCursor, selectedTimeMs, source, windowMs, sensors]);
 
   const handleExport = useCallback((constellationIds: string[]) => {
     setSelectedForExport(constellationIds);
@@ -43,19 +100,27 @@ export default function ConstellationPage() {
   }, []);
 
   return (
-    <div className="w-full h-screen overflow-hidden">
-      <ConstellationCanvas
-        sensors={sensors}
-        sensorValuesRef={sensorValuesRef}
-        telemetryHistoryRef={telemetryHistoryRef}
-        onExport={handleExport}
-      />
-      {showExport && (
-        <ConstellationExportModal
-          signalIds={selectedForExport}
-          onClose={() => setShowExport(false)}
+    <div className="w-full h-screen overflow-hidden flex flex-col">
+      <div className="shrink-0 px-4 pt-2 z-30">
+        <TimelineBar />
+      </div>
+      <div className="flex-1 relative min-h-0">
+        <ConstellationCanvas
+          sensors={sensors}
+          sensorValuesRef={sensorValuesRef}
+          telemetryHistoryRef={telemetryHistoryRef}
+          onExport={handleExport}
+          cursorTimeMs={selectedTimeMs}
+          source={source}
+          mode={mode}
         />
-      )}
+        {showExport && (
+          <ConstellationExportModal
+            signalIds={selectedForExport}
+            onClose={() => setShowExport(false)}
+          />
+        )}
+      </div>
     </div>
   );
 }