fix: transaction screens name a token from the tokens of the transaction's network (closes #629)

decodeCalldata() looked a token's symbol and decimals up in the active
network's tracked tokens and balances, whatever chain id it was given, so
TransactionDetail and TxApproval showed a token tracked on another network
by address only, with its amount in base units. The lookup now uses what the
wallet knows of the tokens on the transaction's network: the active
network's tracked tokens and balances, or for another network the tokens
tracked on it and no balances. TxApproval's token labels, the symbol it
hands the wait, success and error screens, and SuccessTx's decoded token
label use the same lookup.

Model: opus-5-5

src/popup/views/helpers.js

@@ -1,7 +1,7 @@
 // Helpers the views in this directory share: showing a view and going back,
 // error and flash lines and the warning banners, formatting of amounts, fees,
-// balances, addresses and dates, the RPC and Blockscout URLs and node of the
-// network a chain id names, explorer links, and click-to-copy.
+// balances, addresses and dates, the RPC and Blockscout URLs, node and tokens
+// of the network a chain id names, explorer links, and click-to-copy.
 //
 // Escaping rule for every view in this directory, since they all build
 // markup by concatenation: any VALUE interpolated into an innerHTML string
@@ -300,15 +300,30 @@ function nativeCurrency() {
     return currentNetwork().nativeCurrency;
 }
 
-// The symbol shown for a token line, resolved from the bundled list, the
-// tokens the user tracks, and the explorer's report — the same chain the
-// amount line's scale comes from. Null when no source names one, so the token
-// lines keep saying `Unknown token` for a token nothing knows.
-function tokenLabel(address) {
-    return resolveTokenSymbol(address, {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    });
+// What the wallet knows of the tokens on the network with this chain id, or
+// on the active network when no chain id is given, as the `sources` that
+// resolveTokenSymbol() and resolveTokenDecimals() take. A contract address
+// names a token on one network only, and every token balance held is the
+// active network's, so another network gets the tokens tracked on it
+// (state.networkTrackedTokens, see applyChainSwitchFields()) and no balances.
+function tokenSourcesByChainId(chainId) {
+    const net = chainId ? networkByChainId(chainId) : currentNetwork();
+    if (net && net.id === state.networkId) {
+        return { trackedTokens: state.trackedTokens, wallets: state.wallets };
+    }
+    return {
+        trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
+        wallets: [],
+    };
+}
+
+// The symbol shown for a token line on the network with `chainId`, or on the
+// active network when none is given: from the bundled list, the tokens the
+// user tracks, and the explorer's report, the sources the amount line's scale
+// comes from. Null when no source names one, so the token lines keep saying
+// `Unknown token` for a token nothing knows.
+function tokenLabel(address, chainId) {
+    return resolveTokenSymbol(address, tokenSourcesByChainId(chainId));
 }
 
 // A network fee in wei as the confirmation and approval screens both show it:
@@ -775,6 +790,7 @@ module.exports = {
     keyMaterialName,
     unknownableAmount,
     nativeCurrency,
+    tokenSourcesByChainId,
     tokenLabel,
     formatFee,
     addressDotHtml,