From 5d7a1e12a7c8c5bf67032399f4f8748c144a3054 Mon Sep 17 00:00:00 2001
From: Jan Nanista <jan@turnkey.io>
Date: Tue, 10 Nov 2026 10:56:36 -0700
Subject: [PATCH] chore: Warn user if they are not using a TurnkeySparkSigner

---
 .changeset/olive-worlds-deny.md             |  5 ++++
 packages/spark/src/__tests__/wallet.test.ts | 26 +++++++++++++++++++++
 packages/spark/src/signer.ts                |  4 ++++
 packages/spark/src/wallet.ts                |  8 +++++++
 4 files changed, 43 insertions(+)
 create mode 100644 .changeset/olive-worlds-deny.md

diff --git a/.changeset/olive-worlds-deny.md b/.changeset/olive-worlds-deny.md
new file mode 100644
index 000000000..f32922c12
--- /dev/null
+++ b/.changeset/olive-worlds-deny.md
@@ -0,0 +1,5 @@
+---
+"@turnkey/spark": patch
+---
+
+Warn users if they are not using TurnkeySparkSigner with TurnkeySparkWallet
diff --git a/packages/spark/src/__tests__/wallet.test.ts b/packages/spark/src/__tests__/wallet.test.ts
index 2121ff278..272a99437 100644
--- a/packages/spark/src/__tests__/wallet.test.ts
+++ b/packages/spark/src/__tests__/wallet.test.ts
@@ -468,6 +468,32 @@ At the moment, withdrawal requests are leaking test funds into the BTC wallet ${
     },
     TEST_TIMEOUT,
   );
+
+  describe("Signer warnings", () => {
+    let consoleWarnSpy: jest.SpyInstance;
+
+    beforeEach(() => {
+      consoleWarnSpy = jest.spyOn(console, "warn").mockImplementation();
+    });
+
+    afterEach(() => {
+      consoleWarnSpy.mockRestore();
+    });
+
+    it("should warn if the signer is not a TurnkeySparkSigner", async () => {
+      await createSparkWallet({} as TurnkeySparkSigner);
+
+      expect(consoleWarnSpy).toHaveBeenCalledWith(
+        "Warning: The provided signer is not a TurnkeySparkSigner.",
+      );
+    });
+
+    it("should not warn if the signer is a TurnkeySparkSigner", async () => {
+      await createSparkWallet(senderSigner);
+
+      expect(consoleWarnSpy).not.toHaveBeenCalled();
+    });
+  });
 });
 
 /**
diff --git a/packages/spark/src/signer.ts b/packages/spark/src/signer.ts
index fec6f56a8..eacc67697 100644
--- a/packages/spark/src/signer.ts
+++ b/packages/spark/src/signer.ts
@@ -373,6 +373,10 @@ export class TurnkeySparkSigner implements SparkSigner {
     }
   }
 
+  isTurnkeySparkSigner(): boolean {
+    return true;
+  }
+
   // ---------------------------------------------------------------------------
   // Identity key operations (already working)
   // ---------------------------------------------------------------------------
diff --git a/packages/spark/src/wallet.ts b/packages/spark/src/wallet.ts
index 2d1fad537..b9f7251d0 100644
--- a/packages/spark/src/wallet.ts
+++ b/packages/spark/src/wallet.ts
@@ -20,6 +20,8 @@ export class TurnkeySparkWallet extends SparkWallet {
   constructor(options?: ConfigOptions, signerArg?: SparkSigner) {
     super(options, signerArg);
 
+    warnIfNotTurnkeySigner(signerArg);
+
     this.transferService = new TurnkeyTransferService(
       this.config,
       this.connectionManager,
@@ -127,3 +129,9 @@ export class TurnkeySparkWallet extends SparkWallet {
     return (this as any).logging as LoggingService | undefined;
   }
 }
+
+const warnIfNotTurnkeySigner = (signer: SparkSigner | undefined) => {
+  if (!(signer as TurnkeySparkSigner)?.isTurnkeySparkSigner?.()) {
+    console.warn("Warning: The provided signer is not a TurnkeySparkSigner.");
+  }
+};