diff --git a/app.vue b/app.vue
index f876cbf..e68920e 100644
--- a/app.vue
+++ b/app.vue
@@ -52,8 +52,10 @@ onMounted(async () => {
       console.warn('Autonomi client init failed:', e)
     })
 
-    // Only bypass WalletConnect for local Anvil devnet, not Sepolia
-    if (!settingsStore.devnetIsSepolia) {
+    // Only bypass WalletConnect for local Anvil devnet. Sepolia / mainnet
+    // manifests expect the user to connect their own wallet via WalletConnect.
+    const { ANVIL_CHAIN_ID } = await import('~/utils/constants')
+    if (settingsStore.devnetChainId === ANVIL_CHAIN_ID) {
       const { initDevnetWallet } = await import('~/composables/useDevnetWallet')
       initDevnetWallet()
     }
diff --git a/components/AppSidebar.vue b/components/AppSidebar.vue
index 3748127..816a634 100644
--- a/components/AppSidebar.vue
+++ b/components/AppSidebar.vue
@@ -10,7 +10,7 @@
     <nav class="flex-1 px-2 py-2">
       <!-- Network mode indicator -->
       <div
-        v-if="settingsStore.devnetActive"
+        v-if="settingsStore.devnetActive && networkLabel"
         class="mb-2 rounded-md bg-amber-500/10 border border-amber-500/20 px-3 py-1.5 text-center text-xs font-medium text-amber-400"
       >
         {{ networkLabel }}
@@ -60,9 +60,11 @@
 </template>
 
 <script setup lang="ts">
+import { arbitrumSepolia } from 'viem/chains'
 import { useNodesStore } from '~/stores/nodes'
 import { useFilesStore } from '~/stores/files'
 import { useUpdaterStore } from '~/stores/updater'
+import { ANVIL_CHAIN_ID } from '~/utils/constants'
 
 const route = useRoute()
 const nodesStore = useNodesStore()
@@ -70,8 +72,12 @@ const filesStore = useFilesStore()
 const updaterStore = useUpdaterStore()
 const settingsStore = useSettingsStore()
 
-const networkLabel = computed(() => {
-  return settingsStore.devnetIsSepolia ? 'SEPOLIA TESTNET' : 'DEVNET'
+const networkLabel = computed<string | null>(() => {
+  switch (settingsStore.devnetChainId) {
+    case arbitrumSepolia.id: return 'SEPOLIA TESTNET'
+    case ANVIL_CHAIN_ID: return 'DEVNET'
+    default: return null  // mainnet or unset — no badge
+  }
 })
 
 const mainNav = computed(() => [
diff --git a/composables/useDevnetWallet.ts b/composables/useDevnetWallet.ts
index a5d16a1..0db1463 100644
--- a/composables/useDevnetWallet.ts
+++ b/composables/useDevnetWallet.ts
@@ -1,7 +1,7 @@
 import { createConfig, http } from '@wagmi/core'
 import { defineChain } from 'viem'
 import { privateKeyToAccount, type PrivateKeyAccount } from 'viem/accounts'
-import { arbitrumSepolia } from 'viem/chains'
+import { arbitrum, arbitrumSepolia } from 'viem/chains'
 import { useWalletStore } from '~/stores/wallet'
 import { useSettingsStore, getDevnetWalletKey } from '~/stores/settings'
 import { getTokenAddress, getActiveChainId } from '~/utils/wallet-config'
@@ -9,6 +9,10 @@ import { ANVIL_CHAIN_ID } from '~/utils/constants'
 import { formatEther, formatUnits, erc20Abi } from 'viem'
 import { getBalance, readContract } from '@wagmi/core'
 
+// Public Arbitrum One RPC fallback when no explicit URL is configured.
+const ARBITRUM_ONE_RPC = 'https://arb1.arbitrum.io/rpc'
+const ARBITRUM_SEPOLIA_RPC = 'https://sepolia-rollup.arbitrum.io/rpc'
+
 let devnetWagmiConfig: any = null
 let devnetAccount: PrivateKeyAccount | null = null
 
@@ -35,26 +39,46 @@ export function initDevnetWallet() {
 
   devnetAccount = privateKeyToAccount(key as `0x${string}`)
 
-  // Determine which chain to use
-  if (settings.devnetIsSepolia || (!settings.devnetRpcUrl && !settings.devnetActive)) {
-    // Sepolia mode or direct key import (no manifest) — use Arbitrum Sepolia
-    devnetWagmiConfig = createConfig({
-      chains: [arbitrumSepolia],
-      transports: {
-        [arbitrumSepolia.id]: http(settings.devnetRpcUrl ?? 'https://sepolia-rollup.arbitrum.io/rpc'),
-      },
-      connectors: [],
-    })
-  } else {
-    // Local Anvil devnet
-    const chain = buildAnvilChain(settings.devnetRpcUrl!)
-    devnetWagmiConfig = createConfig({
-      chains: [chain],
-      transports: {
-        [ANVIL_CHAIN_ID]: http(settings.devnetRpcUrl!),
-      },
-      connectors: [],
-    })
+  switch (settings.devnetChainId) {
+    case arbitrumSepolia.id:
+      devnetWagmiConfig = createConfig({
+        chains: [arbitrumSepolia],
+        transports: {
+          [arbitrumSepolia.id]: http(settings.devnetRpcUrl ?? ARBITRUM_SEPOLIA_RPC),
+        },
+        connectors: [],
+      })
+      break
+
+    case arbitrum.id:
+      devnetWagmiConfig = createConfig({
+        chains: [arbitrum],
+        transports: {
+          [arbitrum.id]: http(settings.devnetRpcUrl ?? ARBITRUM_ONE_RPC),
+        },
+        connectors: [],
+      })
+      break
+
+    case ANVIL_CHAIN_ID: {
+      if (!settings.devnetRpcUrl) {
+        console.error('Anvil devnet requires devnetRpcUrl')
+        return null
+      }
+      const chain = buildAnvilChain(settings.devnetRpcUrl)
+      devnetWagmiConfig = createConfig({
+        chains: [chain],
+        transports: {
+          [ANVIL_CHAIN_ID]: http(settings.devnetRpcUrl),
+        },
+        connectors: [],
+      })
+      break
+    }
+
+    default:
+      console.error('initDevnetWallet: unknown devnetChainId', settings.devnetChainId)
+      return null
   }
 
   walletStore.connected = true
diff --git a/pages/settings.vue b/pages/settings.vue
index 7e1cf03..7509872 100644
--- a/pages/settings.vue
+++ b/pages/settings.vue
@@ -377,6 +377,7 @@
 import { invoke } from '@tauri-apps/api/core'
 import { open } from '@tauri-apps/plugin-dialog'
 import { openUrl as tauriOpenUrl } from '@tauri-apps/plugin-opener'
+import { arbitrum, arbitrumSepolia } from 'viem/chains'
 import { setDevnetWalletKey } from '~/stores/settings'
 import { useSettingsStore } from '~/stores/settings'
 import { isValidEthAddress } from '~/utils/validators'
@@ -469,12 +470,14 @@ async function connectDirectWallet() {
     setDevnetWalletKey(key)
     settingsStore._devnetWalletKeySet = true
     settingsStore.devnetActive = true
-    settingsStore.devnetIsSepolia = isSepolia
     if (isSepolia) {
+      settingsStore.devnetChainId = arbitrumSepolia.id
       settingsStore.devnetRpcUrl = 'https://sepolia-rollup.arbitrum.io/rpc'
       settingsStore.devnetTokenAddress = '0x4bc1aCE0E66170375462cB4E6Af42Ad4D5EC689C'
       settingsStore.devnetVaultAddress = '0xd742E8CFEf27A9a884F3EFfA239Ee2F39c276522'
     } else {
+      // Arbitrum One mainnet — use mainnet token/vault defaults via wallet-config.
+      settingsStore.devnetChainId = arbitrum.id
       settingsStore.devnetRpcUrl = null
       settingsStore.devnetTokenAddress = null
       settingsStore.devnetVaultAddress = null
diff --git a/pages/wallet.vue b/pages/wallet.vue
index 688f11d..22bcfa5 100644
--- a/pages/wallet.vue
+++ b/pages/wallet.vue
@@ -95,7 +95,7 @@
             Connect Wallet
           </button>
           <p class="mt-2 text-xs text-autonomi-muted">
-            {{ settingsStore.devnetIsSepolia ? 'Arbitrum Sepolia testnet' : 'Arbitrum One network required' }}
+            {{ settingsStore.devnetChainId === arbitrumSepolia.id ? 'Arbitrum Sepolia testnet' : 'Arbitrum One network required' }}
           </p>
           <p class="mt-1 text-xs text-autonomi-muted">
             Or import a private key in <NuxtLink to="/settings" class="text-autonomi-blue hover:underline">Settings &gt; Advanced</NuxtLink>
@@ -136,6 +136,7 @@
 </template>
 
 <script setup lang="ts">
+import { arbitrumSepolia } from 'viem/chains'
 import { useWalletStore } from '~/stores/wallet'
 import { truncateAddress } from '~/utils/formatters'
 import { isValidEthAddress } from '~/utils/validators'
diff --git a/stores/settings.ts b/stores/settings.ts
index b5c29e2..158191d 100644
--- a/stores/settings.ts
+++ b/stores/settings.ts
@@ -1,5 +1,7 @@
 import { defineStore } from 'pinia'
 import { invoke } from '@tauri-apps/api/core'
+import { arbitrumSepolia } from 'viem/chains'
+import { ANVIL_CHAIN_ID } from '~/utils/constants'
 
 // Private key stored outside reactive state — not visible in Vue DevTools.
 let _walletKey: string | null = null
@@ -33,9 +35,14 @@ export const useSettingsStore = defineStore('settings', {
     indelibleUserEmail: null as string | null,
     themeMode: 'dark' as ThemeMode,
     loaded: false,
-    // Devnet/testnet mode (auto-detected from manifest file)
+    // Devnet/testnet/direct-key mode (set by manifest or settings form).
+    // devnetChainId picks the chain:
+    //   - null / not set   → production mainnet (WalletConnect)
+    //   - ANVIL_CHAIN_ID   → local Anvil devnet (manifest)
+    //   - arbitrumSepolia.id → Arbitrum Sepolia testnet
+    //   - arbitrum.id      → Arbitrum One mainnet via direct key
     devnetActive: false,
-    devnetIsSepolia: false,
+    devnetChainId: null as number | null,
     devnetRpcUrl: null as string | null,
     devnetTokenAddress: null as string | null,
     devnetVaultAddress: null as string | null,
@@ -154,7 +161,9 @@ export const useSettingsStore = defineStore('settings', {
         const result = await invoke<any>('load_devnet_manifest')
         if (result) {
           this.devnetActive = true
-          this.devnetIsSepolia = (result.rpc_url ?? '').includes('sepolia')
+          this.devnetChainId = (result.rpc_url ?? '').includes('sepolia')
+            ? arbitrumSepolia.id
+            : ANVIL_CHAIN_ID
           this.devnetRpcUrl = result.rpc_url
           this.devnetTokenAddress = result.payment_token_address
           this.devnetVaultAddress = result.payment_vault_address
@@ -163,7 +172,8 @@ export const useSettingsStore = defineStore('settings', {
             setDevnetWalletKey(result.wallet_private_key)
             this._devnetWalletKeySet = true
           }
-          console.info(`${this.devnetIsSepolia ? 'Sepolia' : 'Devnet'} mode active:`, result.rpc_url)
+          const modeLabel = this.devnetChainId === arbitrumSepolia.id ? 'Sepolia' : 'Devnet'
+          console.info(`${modeLabel} mode active:`, result.rpc_url)
         }
       } catch (e) {
         // No manifest or invalid — stay in production mode
diff --git a/tests/stores/settings.test.ts b/tests/stores/settings.test.ts
index f5579b5..a510432 100644
--- a/tests/stores/settings.test.ts
+++ b/tests/stores/settings.test.ts
@@ -66,7 +66,7 @@ describe('settings store', () => {
       await store.loadDevnetManifest()
 
       expect(store.devnetActive).toBe(true)
-      expect(store.devnetIsSepolia).toBe(false)
+      expect(store.devnetChainId).toBe(31337) // ANVIL_CHAIN_ID
       expect(store.devnetRpcUrl).toBe('http://127.0.0.1:8545')
       expect(store.devnetTokenAddress).toBe('0xtoken')
       expect(store.devnetVaultAddress).toBe('0xvault')
@@ -88,7 +88,7 @@ describe('settings store', () => {
       await store.loadDevnetManifest()
 
       expect(store.devnetActive).toBe(true)
-      expect(store.devnetIsSepolia).toBe(true)
+      expect(store.devnetChainId).toBe(421614) // arbitrumSepolia.id
     })
 
     it('stays in production mode when no manifest', async () => {
diff --git a/tests/utils/wallet-config.test.ts b/tests/utils/wallet-config.test.ts
index ddeedb1..5c998d7 100644
--- a/tests/utils/wallet-config.test.ts
+++ b/tests/utils/wallet-config.test.ts
@@ -49,18 +49,32 @@ describe('wallet-config', () => {
       expect(getActiveChainId()).toBe(42161)
     })
 
+    it('returns Arbitrum mainnet (42161) when direct-key targets mainnet', () => {
+      settings.devnetActive = true
+      settings.devnetChainId = 42161
+
+      expect(getActiveChainId()).toBe(42161)
+    })
+
     it('returns Anvil (31337) in local devnet', () => {
       settings.devnetActive = true
-      settings.devnetIsSepolia = false
+      settings.devnetChainId = 31337
 
       expect(getActiveChainId()).toBe(31337)
     })
 
     it('returns Sepolia (421614) in Sepolia mode', () => {
       settings.devnetActive = true
-      settings.devnetIsSepolia = true
+      settings.devnetChainId = 421614
 
       expect(getActiveChainId()).toBe(421614)
     })
+
+    it('falls back to mainnet when devnetActive but chainId is null', () => {
+      settings.devnetActive = true
+      settings.devnetChainId = null
+
+      expect(getActiveChainId()).toBe(42161)
+    })
   })
 })
diff --git a/utils/wallet-config.ts b/utils/wallet-config.ts
index 1fb12ba..4db5071 100644
--- a/utils/wallet-config.ts
+++ b/utils/wallet-config.ts
@@ -1,5 +1,4 @@
-import { arbitrum, arbitrumSepolia } from '@reown/appkit/networks'
-import { ANVIL_CHAIN_ID } from '~/utils/constants'
+import { arbitrum } from '@reown/appkit/networks'
 import { useSettingsStore } from '~/stores/settings'
 
 // Project ID from cloud.reown.com (shared with project-dave)
@@ -36,10 +35,11 @@ export function getVaultAddress(): `0x${string}` {
   return PAYMENT_VAULT_ADDRESS
 }
 
-/** Active chain ID — Anvil (31337) in local devnet, Sepolia (421614) in Sepolia mode, Arbitrum (42161) in production. */
+/** Active chain ID — uses devnetChainId when set, falls back to Arbitrum One mainnet. */
 export function getActiveChainId(): number {
   const settings = useSettingsStore()
-  if (settings.devnetActive && settings.devnetIsSepolia) return arbitrumSepolia.id as number
-  if (settings.devnetActive) return ANVIL_CHAIN_ID
+  if (settings.devnetActive && settings.devnetChainId !== null) {
+    return settings.devnetChainId
+  }
   return arbitrum.id
 }