diff --git a/src/solana/stake.ts b/src/solana/stake.ts
index 0a4cb60..fe53d41 100644
--- a/src/solana/stake.ts
+++ b/src/solana/stake.ts
@@ -71,10 +71,13 @@ export function getStakeProgramId(network?: 'devnet' | 'mainnet'): PublicKey {
                 safeEnv('NETWORK')?.toLowerCase() ?? '';
       if (n === 'mainnet' || n === 'mainnet-beta') return 'mainnet' as const;
       if (n === 'devnet') return 'devnet' as const;
-      // In browser bundles, process.env is empty (env vars aren't inlined into
-      // third-party SDK code). Default to mainnet to match the app's fail-closed
-      // behavior — devnet must be opted into explicitly.
-      if (typeof window !== 'undefined') return 'mainnet' as const;
+      // SECURITY: previously defaulted to 'mainnet' in browser bundles (where
+      // process.env is empty — env vars aren't inlined into third-party SDK code),
+      // which could silently target the live mainnet stake program for any
+      // frontend caller that didn't pass an explicit network. Mirrors the same
+      // class of bug fixed in program-ids.ts getCurrentNetwork() (PERC-697): fail
+      // open to devnet, not mainnet. Mainnet must be opted into explicitly via an
+      // explicit `network` argument or the NETWORK/NEXT_PUBLIC_DEFAULT_NETWORK env var.
       return 'devnet' as const;
     })();
 
diff --git a/test/drift-check.test.ts b/test/drift-check.test.ts
index 71fe8b5..3b37ad9 100644
--- a/test/drift-check.test.ts
+++ b/test/drift-check.test.ts
@@ -608,6 +608,31 @@ describe("STAKE_PROGRAM_ID — address constants", () => {
     expect(STAKE_PROGRAM_IDS.devnet).toBe("6aJb1F9CDCVWCNYFwj8aQsVb696YnW6J1FznteHq4Q6k");
   });
 
+  it("getStakeProgramId() with no args, no env, in a browser context fails open to devnet (not mainnet)", () => {
+    // Mirrors the PERC-697 hardening in program-ids.ts getCurrentNetwork(): an
+    // unconfigured frontend caller must never be silently pointed at mainnet.
+    const savedStakeId = process.env.STAKE_PROGRAM_ID;
+    const savedNetwork = process.env.NETWORK;
+    const savedDefaultNetwork = process.env.NEXT_PUBLIC_DEFAULT_NETWORK;
+    delete process.env.STAKE_PROGRAM_ID;
+    delete process.env.NETWORK;
+    delete process.env.NEXT_PUBLIC_DEFAULT_NETWORK;
+    const hadWindow = "window" in globalThis;
+    const savedWindow = (globalThis as any).window;
+    (globalThis as any).window = {};
+    try {
+      const pk = getStakeProgramId();
+      expect(pk.toBase58()).toBe(STAKE_PROGRAM_IDS.devnet);
+      expect(pk.toBase58()).not.toBe(STAKE_PROGRAM_IDS.mainnet);
+    } finally {
+      if (hadWindow) (globalThis as any).window = savedWindow;
+      else delete (globalThis as any).window;
+      if (savedStakeId !== undefined) process.env.STAKE_PROGRAM_ID = savedStakeId;
+      if (savedNetwork !== undefined) process.env.NETWORK = savedNetwork;
+      if (savedDefaultNetwork !== undefined) process.env.NEXT_PUBLIC_DEFAULT_NETWORK = savedDefaultNetwork;
+    }
+  });
+
   it("mainnet and devnet addresses are different", () => {
     expect(STAKE_PROGRAM_IDS.mainnet).not.toBe(STAKE_PROGRAM_IDS.devnet);
   });