diff --git a/Cargo.lock b/Cargo.lock
index 3cbdc3d219b..a18eb100617 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4164,7 +4164,7 @@ dependencies = [
 [[package]]
 name = "fc-api"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "async-trait",
  "fp-storage",
@@ -4176,7 +4176,7 @@ dependencies = [
 [[package]]
 name = "fc-consensus"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "async-trait",
  "fp-consensus",
@@ -4192,7 +4192,7 @@ dependencies = [
 [[package]]
 name = "fc-db"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "async-trait",
  "ethereum",
@@ -4222,7 +4222,7 @@ dependencies = [
 [[package]]
 name = "fc-mapping-sync"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fc-db",
  "fc-storage",
@@ -4245,7 +4245,7 @@ dependencies = [
 [[package]]
 name = "fc-rpc"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "ethereum-types",
@@ -4299,7 +4299,7 @@ dependencies = [
 [[package]]
 name = "fc-rpc-core"
 version = "1.1.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "ethereum-types",
@@ -4315,7 +4315,7 @@ dependencies = [
 [[package]]
 name = "fc-rpc-v2-api"
 version = "0.1.0"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum-types",
  "fc-rpc-v2-types",
@@ -4325,7 +4325,7 @@ dependencies = [
 [[package]]
 name = "fc-rpc-v2-types"
 version = "0.1.0"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "const-hex",
  "ethereum-types",
@@ -4336,7 +4336,7 @@ dependencies = [
 [[package]]
 name = "fc-storage"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "ethereum-types",
@@ -4529,7 +4529,7 @@ dependencies = [
 [[package]]
 name = "fp-account"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "hex",
  "impl-serde",
@@ -4547,7 +4547,7 @@ dependencies = [
 [[package]]
 name = "fp-consensus"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "parity-scale-codec",
@@ -4558,7 +4558,7 @@ dependencies = [
 [[package]]
 name = "fp-ethereum"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "ethereum-types",
@@ -4570,7 +4570,7 @@ dependencies = [
 [[package]]
 name = "fp-evm"
 version = "3.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "environmental",
  "evm",
@@ -4586,7 +4586,7 @@ dependencies = [
 [[package]]
 name = "fp-rpc"
 version = "3.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ethereum",
  "ethereum-types",
@@ -4602,7 +4602,7 @@ dependencies = [
 [[package]]
 name = "fp-self-contained"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "frame-support",
  "parity-scale-codec",
@@ -4614,7 +4614,7 @@ dependencies = [
 [[package]]
 name = "fp-storage"
 version = "2.0.0"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "parity-scale-codec",
  "serde",
@@ -9851,7 +9851,7 @@ dependencies = [
 [[package]]
 name = "pallet-ethereum"
 version = "4.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "environmental",
  "ethereum",
@@ -9906,7 +9906,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm"
 version = "6.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "cumulus-primitives-storage-weight-reclaim",
  "environmental",
@@ -9931,7 +9931,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-chain-id"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "frame-support",
  "frame-system",
@@ -10009,7 +10009,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-blake2"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fp-evm",
 ]
@@ -10017,7 +10017,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-bls12381"
 version = "1.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "ark-bls12-381 0.4.0",
  "ark-ec 0.4.2",
@@ -10029,7 +10029,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-bn128"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fp-evm",
  "sp-core",
@@ -10184,7 +10184,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-modexp"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fp-evm",
  "num",
@@ -10385,7 +10385,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-sha3fips"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fp-evm",
  "frame-support",
@@ -10396,7 +10396,7 @@ dependencies = [
 [[package]]
 name = "pallet-evm-precompile-simple"
 version = "2.0.0-dev"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "fp-evm",
  "ripemd",
@@ -13322,7 +13322,7 @@ dependencies = [
 [[package]]
 name = "precompile-utils"
 version = "0.1.0"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "derive_more 1.0.0",
  "environmental",
@@ -13351,7 +13351,7 @@ dependencies = [
 [[package]]
 name = "precompile-utils-macro"
 version = "0.1.0"
-source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#29be929e37829e5bb23a633b0afc3707b6483664"
+source = "git+https://github.com/moonbeam-foundation/frontier?branch=moonbeam-polkadot-stable2506#a6703ef38c16caf7f2974b036f0bd29fde628972"
 dependencies = [
  "case",
  "num_enum 0.7.3",
diff --git a/test/suites/smoke/test-eth-subscribe-newheads.ts b/test/suites/smoke/test-eth-subscribe-newheads.ts
new file mode 100644
index 00000000000..22b299136f9
--- /dev/null
+++ b/test/suites/smoke/test-eth-subscribe-newheads.ts
@@ -0,0 +1,155 @@
+import "@moonbeam-network/api-augment";
+import { describeSuite, beforeAll, expect } from "@moonwall/cli";
+import { type PublicClient, createPublicClient, webSocket } from "viem";
+
+// Configuration for the test
+const LISTEN_DURATION_MS = 60_000; // Listen for 60 seconds
+const MIN_BLOCKS_EXPECTED = 3; // Minimum blocks expected in the listen period
+
+describeSuite({
+  id: "S28",
+  title: "eth_subscribe newHeads - Block sequence continuity",
+  foundationMethods: "read_only",
+  testCases: ({ context, it, log }) => {
+    let client: PublicClient;
+    let wsEndpoint: string;
+
+    beforeAll(async () => {
+      // Get the WebSocket endpoint from the context
+      // viem transport URL might be http, convert to ws
+      const httpUrl = context.viem().transport.url;
+      wsEndpoint = httpUrl.replace("http://", "ws://").replace("https://", "wss://");
+      log(`Using WebSocket endpoint: ${wsEndpoint}`);
+    });
+
+    it({
+      id: "C100",
+      title: "should deliver continuous block headers with valid parent references",
+      timeout: LISTEN_DURATION_MS + 30_000, // Add buffer for setup/teardown
+      test: async function () {
+        const transport = webSocket(wsEndpoint);
+        client = createPublicClient({ transport });
+
+        const receivedBlocks: Array<{ number: bigint; hash: string; parentHash: string }> = [];
+        const receivedHashes = new Set<string>();
+        const skippedBlocks: Array<{ expected: bigint; received: bigint }> = [];
+        const missingParents: Array<{
+          blockNumber: bigint;
+          blockHash: string;
+          parentHash: string;
+        }> = [];
+
+        log(`Starting newHeads subscription for ${LISTEN_DURATION_MS / 1000} seconds...`);
+
+        await new Promise<void>((resolve, reject) => {
+          const timeoutId = setTimeout(() => {
+            unwatch();
+            resolve();
+          }, LISTEN_DURATION_MS);
+
+          const unwatch = client.watchBlocks({
+            onBlock: (block) => {
+              const blockInfo = {
+                number: block.number,
+                hash: block.hash,
+                parentHash: block.parentHash,
+              };
+              receivedBlocks.push(blockInfo);
+              log(`Received block #${block.number} (${block.hash.slice(0, 10)}...)`);
+
+              // Check for gaps with the previous block
+              if (receivedBlocks.length > 1) {
+                const prevBlock = receivedBlocks[receivedBlocks.length - 2];
+                const expectedNumber = prevBlock.number + 1n;
+
+                if (block.number !== expectedNumber) {
+                  skippedBlocks.push({
+                    expected: expectedNumber,
+                    received: block.number,
+                  });
+                  log(
+                    `⚠️  GAP DETECTED: Expected block #${expectedNumber}, ` +
+                      `received #${block.number} (skipped ${block.number - expectedNumber} blocks)`
+                  );
+                }
+
+                // Verify parent hash was delivered (skip for first block)
+                if (!receivedHashes.has(block.parentHash)) {
+                  missingParents.push({
+                    blockNumber: block.number,
+                    blockHash: block.hash,
+                    parentHash: block.parentHash,
+                  });
+                  log(
+                    `⚠️  MISSING PARENT at block #${block.number}: ` +
+                      `parent ${block.parentHash.slice(0, 10)}... was never delivered`
+                  );
+                }
+              }
+
+              receivedHashes.add(block.hash);
+            },
+            onError: (error) => {
+              clearTimeout(timeoutId);
+              reject(error);
+            },
+          });
+        });
+
+        log(`\nSubscription summary:`);
+        log(`  - Total blocks received: ${receivedBlocks.length}`);
+        log(`  - Unique block hashes: ${receivedHashes.size}`);
+        if (receivedBlocks.length > 0) {
+          log(`  - First block: #${receivedBlocks[0].number}`);
+          log(`  - Last block: #${receivedBlocks[receivedBlocks.length - 1].number}`);
+        }
+
+        // Verify we received enough blocks
+        expect(
+          receivedBlocks.length,
+          `Expected at least ${MIN_BLOCKS_EXPECTED} blocks, received ${receivedBlocks.length}`
+        ).toBeGreaterThanOrEqual(MIN_BLOCKS_EXPECTED);
+
+        // Check for skipped blocks
+        if (skippedBlocks.length > 0) {
+          log(`\n❌ SKIPPED BLOCKS DETECTED:`);
+          for (const skip of skippedBlocks) {
+            const gapSize = skip.received - skip.expected;
+            log(
+              `  - Gap at block #${skip.expected}: jumped to #${skip.received} (${gapSize} blocks missing)`
+            );
+          }
+        } else {
+          log(`\n✓ No gaps detected in block sequence`);
+        }
+
+        // Check for missing parent blocks
+        if (missingParents.length > 0) {
+          log(`\n❌ MISSING PARENT BLOCKS DETECTED:`);
+          for (const missing of missingParents) {
+            log(
+              `  - Block #${missing.blockNumber} (${missing.blockHash.slice(0, 10)}...): ` +
+                `parent ${missing.parentHash.slice(0, 18)}... was never delivered`
+            );
+          }
+        } else {
+          log(`\n✓ All parent hashes reference previously delivered blocks`);
+        }
+
+        // The test should fail if any blocks were skipped
+        expect(
+          skippedBlocks,
+          `newHeads subscription skipped blocks: ${skippedBlocks
+            .map((s) => `expected #${s.expected}, got #${s.received}`)
+            .join("; ")}`
+        ).toHaveLength(0);
+
+        // The test should fail if any parent blocks were never delivered
+        expect(
+          missingParents,
+          `Missing parent blocks detected: ${missingParents.length} blocks reference parents that were never delivered`
+        ).toHaveLength(0);
+      },
+    });
+  },
+});
diff --git a/test/suites/smoke/test-eth-subscribe-reorg.ts b/test/suites/smoke/test-eth-subscribe-reorg.ts
new file mode 100644
index 00000000000..709b1879769
--- /dev/null
+++ b/test/suites/smoke/test-eth-subscribe-reorg.ts
@@ -0,0 +1,505 @@
+import "@moonbeam-network/api-augment";
+import { describeSuite, beforeAll, expect } from "@moonwall/cli";
+import { type PublicClient, createPublicClient, webSocket } from "viem";
+import type { ApiPromise } from "@polkadot/api";
+
+// Configuration for the test
+// Longer duration increases the chance of observing a reorg on a live network
+const LISTEN_DURATION_MS = 5 * 60_000; // Listen for 5 minutes
+const MIN_BLOCKS_EXPECTED = 10; // Minimum blocks expected in the listen period
+
+interface BlockRecord {
+  number: bigint;
+  hash: string;
+  parentHash: string;
+  timestamp: number;
+}
+
+interface SubstrateBlockRecord {
+  number: number;
+  hash: string;
+  parentHash: string;
+  timestamp: number;
+}
+
+interface ReorgEvent {
+  type: "gap" | "chain_switch";
+  previousBlock: BlockRecord;
+  newBlock: BlockRecord;
+  skippedBlocks: bigint[];
+  timestamp: number;
+}
+
+// Per Ethereum spec (https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB):
+// "When a chain reorganization occurs, this subscription will emit an event
+// containing all new headers (blocks) for the new chain. This means that you
+// may see multiple headers emitted with the same height (block number)."
+//
+// This test verifies that newHeads behaves according to spec during reorgs.
+
+describeSuite({
+  id: "S29",
+  title: "eth_subscribe newHeads - Reorg detection and block delivery (per Ethereum spec)",
+  foundationMethods: "read_only",
+  testCases: ({ context, it, log }) => {
+    let viemClient: PublicClient;
+    let wsEndpoint: string;
+    let polkadotApi: ApiPromise;
+
+    beforeAll(async () => {
+      // Get the WebSocket endpoint from the context
+      const httpUrl = context.viem().transport.url;
+      wsEndpoint = httpUrl.replace("http://", "ws://").replace("https://", "wss://");
+      log(`Using WebSocket endpoint: ${wsEndpoint}`);
+
+      // Get the polkadotJs API for substrate-level block tracking
+      polkadotApi = context.polkadotJs();
+    });
+
+    it({
+      id: "C100",
+      title:
+        "should deliver all canonical block headers including those during reorgs (issue #3415)",
+      timeout: LISTEN_DURATION_MS + 60_000, // Add buffer for setup/teardown
+      test: async function () {
+        const transport = webSocket(wsEndpoint);
+        viemClient = createPublicClient({ transport });
+
+        // Track blocks from eth_subscribe newHeads
+        const ethBlocks: BlockRecord[] = [];
+        const ethHashes = new Set<string>();
+
+        // Track blocks from Substrate subscribeNewHeads
+        const substrateBlocks: SubstrateBlockRecord[] = [];
+        const substrateHashes = new Set<string>();
+
+        // Track anomalies
+        const skippedBlocks: Array<{ expected: bigint; received: bigint; gap: bigint }> = [];
+        const missingParents: Array<{
+          blockNumber: bigint;
+          blockHash: string;
+          parentHash: string;
+        }> = [];
+        const reorgEvents: ReorgEvent[] = [];
+        const blocksNotDeliveredByEth: SubstrateBlockRecord[] = [];
+
+        log(`Starting dual subscription test for ${LISTEN_DURATION_MS / 1000} seconds...`);
+        log(`Subscribing to both eth_subscribe(newHeads) and substrate newHead...`);
+
+        await new Promise<void>((resolve, reject) => {
+          const timeoutId = setTimeout(() => {
+            log("\nTest duration elapsed, cleaning up subscriptions...");
+            unwatch();
+            unsubscribeSubstrate?.();
+            resolve();
+          }, LISTEN_DURATION_MS);
+
+          // Subscribe to eth_subscribe newHeads via viem
+          const unwatch = viemClient.watchBlocks({
+            onBlock: (block) => {
+              const blockInfo: BlockRecord = {
+                number: block.number,
+                hash: block.hash,
+                parentHash: block.parentHash,
+                timestamp: Date.now(),
+              };
+              ethBlocks.push(blockInfo);
+
+              log(
+                `[ETH] Block #${block.number} hash=${block.hash.slice(0, 18)}... ` +
+                  `parent=${block.parentHash.slice(0, 18)}...`
+              );
+
+              // Check for issues with the previous block
+              if (ethBlocks.length > 1) {
+                const prevBlock = ethBlocks[ethBlocks.length - 2];
+                const expectedNumber = prevBlock.number + 1n;
+
+                // Check 1: Gap in block numbers (explicit skip)
+                if (block.number !== expectedNumber) {
+                  const gap = block.number - expectedNumber;
+                  skippedBlocks.push({
+                    expected: expectedNumber,
+                    received: block.number,
+                    gap,
+                  });
+
+                  const skippedNumbers: bigint[] = [];
+                  for (let i = expectedNumber; i < block.number; i++) {
+                    skippedNumbers.push(i);
+                  }
+
+                  reorgEvents.push({
+                    type: "gap",
+                    previousBlock: prevBlock,
+                    newBlock: blockInfo,
+                    skippedBlocks: skippedNumbers,
+                    timestamp: Date.now(),
+                  });
+
+                  log(
+                    `[ETH] ♻️  REORG (GAP): Expected #${expectedNumber}, ` +
+                      `received #${block.number} (${gap} blocks skipped: ${skippedNumbers.join(", ")})`
+                  );
+                }
+
+                // Check 2: Chain switch - parent hash doesn't match previous block's hash
+                // This is the key indicator of a reorg: we moved to a different fork
+                if (block.parentHash !== prevBlock.hash) {
+                  reorgEvents.push({
+                    type: "chain_switch",
+                    previousBlock: prevBlock,
+                    newBlock: blockInfo,
+                    skippedBlocks: [],
+                    timestamp: Date.now(),
+                  });
+
+                  log(`[ETH] ♻️  REORG (CHAIN SWITCH) at block #${block.number}:`);
+                  log(
+                    `[ETH]     Previous block #${prevBlock.number}: ${prevBlock.hash.slice(0, 18)}...`
+                  );
+                  log(
+                    `[ETH]     New block #${block.number} parent: ${block.parentHash.slice(0, 18)}...`
+                  );
+                  log(`[ETH]     ❌ Parent hash mismatch! Chain switched to different fork.`);
+                }
+
+                // Track missing parents for analysis (parent was never delivered to us)
+                if (!ethHashes.has(block.parentHash)) {
+                  missingParents.push({
+                    blockNumber: block.number,
+                    blockHash: block.hash,
+                    parentHash: block.parentHash,
+                  });
+                }
+              }
+
+              ethHashes.add(block.hash);
+            },
+            onError: (error) => {
+              log(`[ETH] Subscription error: ${error.message}`);
+              clearTimeout(timeoutId);
+              reject(error);
+            },
+          });
+
+          // Subscribe to Substrate newHead for comparison
+          let unsubscribeSubstrate: (() => void) | undefined;
+
+          polkadotApi.rpc.chain
+            .subscribeNewHeads((header) => {
+              const blockInfo: SubstrateBlockRecord = {
+                number: header.number.toNumber(),
+                hash: header.hash.toHex(),
+                parentHash: header.parentHash.toHex(),
+                timestamp: Date.now(),
+              };
+              substrateBlocks.push(blockInfo);
+              substrateHashes.add(header.hash.toHex());
+
+              log(
+                `[SUB] Block #${blockInfo.number} hash=${blockInfo.hash.slice(0, 18)}... ` +
+                  `parent=${blockInfo.parentHash.slice(0, 18)}...`
+              );
+            })
+            .then((unsub) => {
+              unsubscribeSubstrate = unsub;
+            })
+            .catch((error) => {
+              log(`[SUB] Subscription error: ${error.message}`);
+              // Don't fail the test, just log
+            });
+        });
+
+        // Analysis phase
+        log(`\n${"=".repeat(80)}`);
+        log(`SUBSCRIPTION ANALYSIS`);
+        log(`${"=".repeat(80)}`);
+
+        log(`\neth_subscribe(newHeads) summary:`);
+        log(`  - Total blocks received: ${ethBlocks.length}`);
+        log(`  - Unique block hashes: ${ethHashes.size}`);
+        if (ethBlocks.length > 0) {
+          log(`  - First block: #${ethBlocks[0].number}`);
+          log(`  - Last block: #${ethBlocks[ethBlocks.length - 1].number}`);
+          const range = ethBlocks[ethBlocks.length - 1].number - ethBlocks[0].number + 1n;
+          log(`  - Expected range: ${range} blocks`);
+          log(`  - Missing from range: ${range - BigInt(ethBlocks.length)} blocks`);
+        }
+
+        log(`\nSubstrate subscribeNewHeads summary:`);
+        log(`  - Total blocks received: ${substrateBlocks.length}`);
+        log(`  - Unique block hashes: ${substrateHashes.size}`);
+        if (substrateBlocks.length > 0) {
+          log(`  - First block: #${substrateBlocks[0].number}`);
+          log(`  - Last block: #${substrateBlocks[substrateBlocks.length - 1].number}`);
+        }
+
+        // Find blocks that Substrate reported but eth_subscribe missed
+        for (const subBlock of substrateBlocks) {
+          if (!ethHashes.has(subBlock.hash)) {
+            blocksNotDeliveredByEth.push(subBlock);
+          }
+        }
+
+        if (blocksNotDeliveredByEth.length > 0) {
+          log(`\n❌ BLOCKS REPORTED BY SUBSTRATE BUT NOT BY eth_subscribe:`);
+          for (const block of blocksNotDeliveredByEth) {
+            log(`  - Block #${block.number} (${block.hash.slice(0, 18)}...)`);
+          }
+        }
+
+        // Report skipped blocks
+        if (skippedBlocks.length > 0) {
+          log(`\n❌ SKIPPED BLOCKS DETECTED IN eth_subscribe:`);
+          for (const skip of skippedBlocks) {
+            log(
+              `  - Gap at block #${skip.expected}: jumped to #${skip.received} ` +
+                `(${skip.gap} blocks missing)`
+            );
+          }
+        } else {
+          log(`\n✓ No gaps detected in eth_subscribe block sequence`);
+        }
+
+        // Report reorg events
+        const chainSwitches = reorgEvents.filter((r) => r.type === "chain_switch");
+        const gaps = reorgEvents.filter((r) => r.type === "gap");
+
+        if (reorgEvents.length > 0) {
+          log(`\n♻️  REORG EVENTS DETECTED: ${reorgEvents.length} total`);
+          log(`    - Chain switches (parent mismatch): ${chainSwitches.length}`);
+          log(`    - Gaps (skipped block numbers): ${gaps.length}`);
+
+          if (chainSwitches.length > 0) {
+            log(`\n  CHAIN SWITCHES (issue #3415 - blocks skipped during reorg):`);
+            for (const reorg of chainSwitches) {
+              log(`    Block #${reorg.newBlock.number}:`);
+              log(
+                `      Previous delivered: #${reorg.previousBlock.number} (${reorg.previousBlock.hash.slice(0, 18)}...)`
+              );
+              log(`      New block parent:   ${reorg.newBlock.parentHash.slice(0, 18)}...`);
+              log(`      New block hash:     ${reorg.newBlock.hash.slice(0, 18)}...`);
+              log(
+                `      → The subscription jumped to a different fork without delivering intermediate blocks`
+              );
+            }
+          }
+
+          if (gaps.length > 0) {
+            log(`\n  GAPS (explicit block number skips):`);
+            for (const reorg of gaps) {
+              log(`    From #${reorg.previousBlock.number} to #${reorg.newBlock.number}`);
+              log(`      Skipped: ${reorg.skippedBlocks.join(", ")}`);
+            }
+          }
+        } else {
+          log(`\n✓ No reorg events detected`);
+        }
+
+        // Report missing parent blocks
+        if (missingParents.length > 0) {
+          log(`\n❌ MISSING PARENT BLOCKS:`);
+          for (const missing of missingParents) {
+            log(
+              `  - Block #${missing.blockNumber}: parent ${missing.parentHash.slice(0, 18)}... ` +
+                `was never delivered`
+            );
+          }
+        } else {
+          log(`\n✓ All parent hashes reference previously delivered blocks`);
+        }
+
+        // Assertions
+        log(`\n${"=".repeat(80)}`);
+        log(`TEST ASSERTIONS`);
+        log(`${"=".repeat(80)}`);
+
+        // Verify we received enough blocks
+        expect(
+          ethBlocks.length,
+          `Expected at least ${MIN_BLOCKS_EXPECTED} blocks from eth_subscribe, ` +
+            `received ${ethBlocks.length}`
+        ).toBeGreaterThanOrEqual(MIN_BLOCKS_EXPECTED);
+
+        // The core assertion for issue #3415: no blocks should be skipped
+        expect(
+          skippedBlocks,
+          `eth_subscribe(newHeads) skipped blocks during potential reorgs: ${skippedBlocks
+            .map((s) => `expected #${s.expected}, got #${s.received} (gap: ${s.gap})`)
+            .join("; ")}`
+        ).toHaveLength(0);
+
+        // All parent blocks should have been delivered
+        expect(
+          missingParents,
+          `Missing parent blocks detected: ${missingParents.length} blocks reference ` +
+            `parents that were never delivered`
+        ).toHaveLength(0);
+
+        // No chain switches should occur (issue #3415 - this is the main bug)
+        expect(
+          chainSwitches,
+          `Chain switch reorgs detected: ${chainSwitches.length} times the subscription ` +
+            `jumped to a different fork without delivering intermediate blocks`
+        ).toHaveLength(0);
+
+        // Every block Substrate reported should also be reported by eth_subscribe
+        // Note: This may have timing differences, so we log but don't fail on this
+        if (blocksNotDeliveredByEth.length > 0) {
+          log(
+            `\n⚠️  WARNING: ${blocksNotDeliveredByEth.length} blocks were reported by ` +
+              `Substrate but not by eth_subscribe. This may indicate the issue from #3415.`
+          );
+        }
+      },
+    });
+
+    it({
+      id: "C101",
+      title: "per Ethereum spec: reorgs should emit same block number with different hashes",
+      timeout: LISTEN_DURATION_MS + 60_000,
+      test: async function () {
+        // Per Ethereum spec: "When a chain reorganization occurs, this subscription
+        // will emit an event containing all new headers for the new chain. This means
+        // you may see multiple headers emitted with the same height (block number)."
+        //
+        // This test verifies that during reorgs, the subscription properly re-emits
+        // block headers for the new chain, resulting in the same block number
+        // appearing multiple times with different hashes.
+
+        const transport = webSocket(wsEndpoint);
+        viemClient = createPublicClient({ transport });
+
+        const blocks: BlockRecord[] = [];
+        const hashByNumber = new Map<bigint, Set<string>>();
+        const chainSwitches: Array<{
+          blockNumber: bigint;
+          prevHash: string;
+          newParentHash: string;
+        }> = [];
+        const duplicateNumbers: Array<{ number: bigint; hashes: string[] }> = [];
+
+        log(`Starting Ethereum spec compliance test for ${LISTEN_DURATION_MS / 1000} seconds...`);
+        log(`Per spec: reorgs should emit same block number with different hashes`);
+
+        await new Promise<void>((resolve, reject) => {
+          const timeoutId = setTimeout(() => {
+            unwatch();
+            resolve();
+          }, LISTEN_DURATION_MS);
+
+          const unwatch = viemClient.watchBlocks({
+            onBlock: (block) => {
+              const blockInfo: BlockRecord = {
+                number: block.number,
+                hash: block.hash,
+                parentHash: block.parentHash,
+                timestamp: Date.now(),
+              };
+
+              // Detect chain switches (reorgs where parent doesn't match)
+              if (blocks.length > 0) {
+                const prevBlock = blocks[blocks.length - 1];
+                if (block.number === prevBlock.number + 1n && block.parentHash !== prevBlock.hash) {
+                  chainSwitches.push({
+                    blockNumber: block.number,
+                    prevHash: prevBlock.hash,
+                    newParentHash: block.parentHash,
+                  });
+                  log(
+                    `[CHAIN SWITCH] Block #${block.number}: parent ${block.parentHash.slice(0, 12)}... ` +
+                      `!= prev hash ${prevBlock.hash.slice(0, 12)}...`
+                  );
+                }
+              }
+
+              blocks.push(blockInfo);
+
+              // Track all hashes seen for each block number
+              if (!hashByNumber.has(block.number)) {
+                hashByNumber.set(block.number, new Set());
+              }
+              const hashes = hashByNumber.get(block.number)!;
+              hashes.add(block.hash);
+
+              // Per spec, this SHOULD happen during reorgs
+              if (hashes.size > 1) {
+                log(
+                  `[SPEC COMPLIANT] Block #${block.number} re-emitted with new hash ` +
+                    `(${hashes.size} hashes seen): ${Array.from(hashes)
+                      .map((h) => h.slice(0, 12) + "...")
+                      .join(", ")}`
+                );
+              }
+            },
+            onError: (error) => {
+              clearTimeout(timeoutId);
+              reject(error);
+            },
+          });
+        });
+
+        // Find block numbers with multiple different hashes
+        for (const [number, hashes] of hashByNumber) {
+          if (hashes.size > 1) {
+            duplicateNumbers.push({
+              number,
+              hashes: Array.from(hashes),
+            });
+          }
+        }
+
+        log(`\n${"=".repeat(80)}`);
+        log(`ETHEREUM SPEC COMPLIANCE CHECK`);
+        log(`${"=".repeat(80)}`);
+        log(`\nSubscription summary:`);
+        log(`  - Total blocks received: ${blocks.length}`);
+        log(`  - Unique block numbers: ${hashByNumber.size}`);
+        log(`  - Chain switches detected (reorgs): ${chainSwitches.length}`);
+        log(`  - Block numbers with multiple hashes: ${duplicateNumbers.length}`);
+
+        if (chainSwitches.length > 0 && duplicateNumbers.length === 0) {
+          log(`\n❌ SPEC VIOLATION DETECTED:`);
+          log(`   ${chainSwitches.length} chain switches occurred but NO block numbers`);
+          log(`   were re-emitted with different hashes.`);
+          log(`\n   Per Ethereum spec, when a reorg occurs:`);
+          log(`   "this subscription will emit an event containing all new headers`);
+          log(`   for the new chain. This means that you may see multiple headers`);
+          log(`   emitted with the same height (block number)."`);
+          log(`\n   Current behavior: subscription jumps to new fork without`);
+          log(`   re-emitting headers for the new chain's blocks.`);
+        }
+
+        if (duplicateNumbers.length > 0) {
+          log(`\n✓ Spec-compliant reorg handling detected:`);
+          for (const dup of duplicateNumbers) {
+            log(`  - Block #${dup.number}: ${dup.hashes.length} different hashes`);
+            for (const hash of dup.hashes) {
+              log(`      ${hash}`);
+            }
+          }
+        }
+
+        expect(
+          blocks.length,
+          `Expected at least ${MIN_BLOCKS_EXPECTED} blocks`
+        ).toBeGreaterThanOrEqual(MIN_BLOCKS_EXPECTED);
+
+        // If we detected chain switches but no duplicate block numbers,
+        // the implementation is not following Ethereum spec
+        if (chainSwitches.length > 0) {
+          expect(
+            duplicateNumbers.length,
+            `Detected ${chainSwitches.length} chain switches (reorgs) but the subscription ` +
+              `did NOT re-emit block headers with the same number and different hashes. ` +
+              `Per Ethereum spec, reorgs should cause the same block number to be emitted ` +
+              `multiple times with different hashes.`
+          ).toBeGreaterThan(0);
+        }
+
+        log(`\n✓ Spec compliance check complete`);
+      },
+    });
+  },
+});