fix: a network switch in Settings keeps another page's token on the network it was added on (closes #692)

A network switch in Settings filed under the new network a token or fraud contract that another page stored since this page's last save, because the switch's save writes only the fields this page changed. Before the switch, onChainSwitch() now takes the stored tracked tokens into the page's own list with takeStoredTrackedTokens(), matched by contract address, so a token either page added or removed stays as that page left it. The switch then files that list under the previous network. When the stored record is on another network, no tokens are taken. Fraud contracts are cleared on every switch, as before.

Model: opus-5-5

src/shared/chainSwitch.js

@@ -53,18 +53,31 @@ function clearPopupCaches() {
 // change. So the switch also resets these fields in the stored record:
 //
 // - every address's balance and token balances;
-// - the time of the last balance refresh.
+// - the time of the last balance refresh;
+// - the fraud contracts.
 //
-// A balance that the background or another page stored since this page's last
-// save is then not kept under the new network
-// (https://git.eeqj.de/sneak/AutistMask/issues/653).
+// A balance or a fraud contract that the background or another page stored
+// since this page's last save is then not kept under the new network
+// (https://git.eeqj.de/sneak/AutistMask/issues/653,
+// https://git.eeqj.de/sneak/AutistMask/issues/692).
+//
+// Before the switch, `state` takes the tracked tokens that another page stored
+// since this page's last save (takeStoredTrackedTokens() in state.js). The
+// switch then puts them away under the previous network, the network they were
+// added on. When the stored record is on another network, a switch saved
+// elsewhere has not reached this page yet. The stored record's tokens are then
+// that network's, and none are taken.
 async function onChainSwitch(newNetworkId) {
-    const { state, saveState } = require("./state");
+    const { state, saveState, takeStoredTrackedTokens } = require("./state");
     let net = null;
     await saveState((stored) => {
         if (state.networkId === newNetworkId) return false;
+        if (stored.networkId === state.networkId) {
+            takeStoredTrackedTokens(stored);
+        }
         net = applyChainSwitchFields(state, newNetworkId);
         stored.lastBalanceRefresh = 0;
+        stored.fraudContracts = [];
         for (const wallet of stored.wallets) {
             for (const addr of wallet.addresses) {
                 addr.balance = "0";