diff --git a/apps/edge/src/edge.test.ts b/apps/edge/src/edge.test.ts
index b138ff2..09abc23 100644
--- a/apps/edge/src/edge.test.ts
+++ b/apps/edge/src/edge.test.ts
@@ -1,8 +1,8 @@
 import { describe, expect, it } from 'vitest';
 import { Wallet, TypedDataEncoder } from 'ethers';
 import { buildDeployAuthorizationTypedData } from '@apogee/core';
-import { buildEdgeServer, skillInvokeBootstrapComplete, skillInvokeCanRunAfterBootstrap } from './index.js';
-import type { BillingChainClient, StorageBoundary } from '@apogee/billing';
+import { buildEdgeServer, buildReceiptHeatmapCells, skillInvokeBootstrapComplete, skillInvokeCanRunAfterBootstrap } from './index.js';
+import type { BillingChainClient, ReceiptIndexRow, StorageBoundary } from '@apogee/billing';
 
 const address = '0x0000000000000000000000000000000000000001';
 const txHash = '0x'.padEnd(66, '1');
@@ -57,6 +57,20 @@ describe('edge API', () => {
     expect(skillInvokeCanRunAfterBootstrap('activating', false, 'active')).toBe(true);
   });
 
+  it('buckets receipt heatmap by UTC calendar day and hour', () => {
+    const now = Date.parse('2026-05-22T10:30:00.000Z');
+    const rows: ReceiptIndexRow[] = [
+      { receiptId: 'r1', agentId: '1', actionTag: 'text.summarize', payloadHash: '0x1', storageRoot: '0x2', valueWei: '0', txHash, status: 'minted', createdAt: '2026-05-21T23:15:00.000Z' },
+      { receiptId: 'r2', agentId: '1', actionTag: 'text.summarize', payloadHash: '0x3', storageRoot: '0x4', valueWei: '0', txHash, status: 'minted', createdAt: '2026-05-22T09:00:00.000Z' },
+      { receiptId: 'r3', agentId: '1', actionTag: 'text.summarize', payloadHash: '0x5', storageRoot: '0x6', valueWei: '0', txHash, status: 'minted', createdAt: '2026-05-15T23:59:00.000Z' },
+    ];
+
+    expect(buildReceiptHeatmapCells(rows, 7, now)).toEqual([
+      { day: 5, hour: 23, count: 1 },
+      { day: 6, hour: 9, count: 1 },
+    ]);
+  });
+
   it('serves health, docs, quote, settle, auth-gated agent, memory, receipt, and refund routes', async () => {
     const app = buildEdgeServer({ chainClient: new FakeChain(), storageClient: new FakeStorage(), signerKey, chainId: 16602, paymentRouterAddress: address, receiptBookAddress: address, jwtSecret: 'test-secret' });
     await app.ready();
diff --git a/apps/edge/src/index.ts b/apps/edge/src/index.ts
index 9df027d..4fd702d 100644
--- a/apps/edge/src/index.ts
+++ b/apps/edge/src/index.ts
@@ -539,6 +539,31 @@ const problem = (reply: FastifyReply, status: number, title: string, detail: str
 };
 const sameAddress = (a: string, b: string): boolean => a.toLowerCase() === b.toLowerCase();
 
+export function buildReceiptHeatmapCells(rows: ReceiptIndexRow[], days: number, nowMs = Date.now()): Array<{ day: number; hour: number; count: number }> {
+  const now = new Date(nowMs);
+  const todayUtc = Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate());
+  const dayIndexByDate = new Map<string, number>();
+  for (let dayIndex = 0; dayIndex < days; dayIndex += 1) {
+    const date = new Date(todayUtc - (days - 1 - dayIndex) * 86_400_000).toISOString().slice(0, 10);
+    dayIndexByDate.set(date, dayIndex);
+  }
+
+  const cells = new Map<string, { day: number; hour: number; count: number }>();
+  for (const receipt of rows) {
+    const created = new Date(receipt.createdAt);
+    if (!Number.isFinite(created.getTime())) continue;
+    const day = dayIndexByDate.get(created.toISOString().slice(0, 10));
+    if (day === undefined) continue;
+    const hour = created.getUTCHours();
+    const key = `${day}:${hour}`;
+    const cell = cells.get(key) ?? { day, hour, count: 0 };
+    cell.count += 1;
+    cells.set(key, cell);
+  }
+
+  return [...cells.values()].sort((a, b) => a.day - b.day || a.hour - b.hour);
+}
+
 async function requireAuth(request: FastifyRequest): Promise<AuthUser> {
   await request.jwtVerify();
   return { address: getAddress(request.user.address) };
@@ -1680,21 +1705,7 @@ export function buildEdgeServer(options: EdgeServerOptions): FastifyInstance {
       const ownedAgentIds = new Set([...store.agents.values()].filter((agent) => sameAddress(agent.owner, user.address)).map((agent) => agent.id));
       rows = rows.filter((receipt) => ownedAgentIds.has(receipt.agentId));
     }
-    const cells = new Map<string, { day: number; hour: number; count: number }>();
-    const now = Date.now();
-    for (const receipt of rows) {
-      const created = new Date(receipt.createdAt).getTime();
-      if (!Number.isFinite(created)) continue;
-      const ageDays = Math.floor((now - created) / 86_400_000);
-      if (ageDays < 0 || ageDays >= query.days) continue;
-      const day = query.days - 1 - ageDays;
-      const hour = new Date(receipt.createdAt).getHours();
-      const key = `${day}:${hour}`;
-      const cell = cells.get(key) ?? { day, hour, count: 0 };
-      cell.count += 1;
-      cells.set(key, cell);
-    }
-    return [...cells.values()].sort((a, b) => a.day - b.day || a.hour - b.hour);
+    return buildReceiptHeatmapCells(rows, query.days);
   });
 
   // ── Public proofs data (no auth, ISR-friendly) ────────────────────────────
diff --git a/apps/web/src/components/dashboard/DashboardHeatmap.tsx b/apps/web/src/components/dashboard/DashboardHeatmap.tsx
index 17ba126..6aa687d 100644
--- a/apps/web/src/components/dashboard/DashboardHeatmap.tsx
+++ b/apps/web/src/components/dashboard/DashboardHeatmap.tsx
@@ -1,17 +1,19 @@
+import React from 'react';
 import type { HeatmapCell } from '@/lib/types';
 
 const WEEKDAYS = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
 const HOURS = Array.from({ length: 24 }, (_, i) => i);
 
-// Edge returns day 0 = oldest, day 6 = today. Map each index to an actual date.
+// Edge returns UTC calendar day 0 = oldest, day 6 = today. Keep labels in
+// the same UTC frame as /v1/receipts/heatmap and /v1/proofs bucketing.
 function buildDayLabels(): { short: string; full: string }[] {
   const today = new Date();
+  const todayUtc = Date.UTC(today.getUTCFullYear(), today.getUTCMonth(), today.getUTCDate());
   return Array.from({ length: 7 }, (_, i) => {
-    const d = new Date(today);
-    d.setDate(today.getDate() - (6 - i));
+    const d = new Date(todayUtc - (6 - i) * 86_400_000);
     return {
-      short: `${WEEKDAYS[d.getDay()]} ${d.getDate()}`,
-      full: d.toDateString(),
+      short: `${WEEKDAYS[d.getUTCDay()]} ${d.getUTCDate()}`,
+      full: d.toISOString().slice(0, 10),
     };
   });
 }