fix: eth_sign's warning and the README say what it signs (closes #409)

eth_sign is signed as an EIP-191 personal message over its data, which is
what the Ethereum JSON-RPC specification defines it to return. Its warning
on the signature prompt said the site was asking to sign a raw hash that
could drain funds, and the README said the same; neither was true. The
warning now says the site used the older eth_sign method and that the data
will be signed as a personal message, and the README's SignApproval section
says so too. A test pins that eth_sign is read address first and data
second, and that the page receives the personal message signature over the
data.

Model: opus-5-5

README.md

@@ -422,11 +422,12 @@ captured at `eth_sendRawTransaction` rather than against anything the extension
 reported, rejecting each prompt is required to return a rejection to the page
 rather than hang or resolve, a network switch request is required to leave the
 stored network unchanged and send no `chainChanged` until it is approved, a
-prompt raised while another approval window has focus is required to open a
-window of its own, and the password is required to be absent from every message
-the approval window sends to the background — with the message that would carry
-it required to be present, so that check cannot pass by observing nothing. That
-last one is the standing floor under
+network switch in Settings is required to send the page `chainChanged` with the
+new chain id, a prompt raised while another approval window has focus is
+required to open a window of its own, and the password is required to be absent
+from every message the approval window sends to the background — with the
+message that would carry it required to be present, so that check cannot pass by
+observing nothing. That last one is the standing floor under
 [#157](https://git.eeqj.de/sneak/AutistMask/issues/157).
 
 The limits of that coverage and of the rest of the Chrome suite, none of them
@@ -1789,7 +1790,8 @@ view would leave a wallet one click from deletion.
       network changes only here, or when the user approves a site's request on
       **NetworkApproval**; either way, switching restores the RPC and Blockscout
       endpoints last used on that network, or that network's defaults if it has
-      none
+      none, and sends `chainChanged` with the new chain id to every open tab.
+      Choosing the network already active changes nothing and sends nothing
     - Ethereum RPC: endpoint URL input + "Save" button (validated against
       `eth_chainId` before being saved)
     - Blockscout API: endpoint URL input + "Save" button (validated against
@@ -2122,7 +2124,12 @@ view would leave a wallet one click from deletion.
       blocklist)
     - Site origin (bold, scheme and port included) + "wants you to sign a
       message"
-    - Danger warning box (shown for `eth_sign`, which signs a raw hash)
+    - Warning box, shown for `eth_sign`: "This site used the older eth_sign
+      method. The data will be signed as a personal message." An `eth_sign`
+      request names the address first and the data second. Its data is signed
+      exactly as a `personal_sign` message is, as an EIP-191 personal message,
+      which is what the Ethereum JSON-RPC specification defines `eth_sign` to
+      return.
     - Type: "Personal message" or "Typed data (EIP-712)"
     - From: color dot + full address + etherscan link
     - Message: for `personal_sign` and `eth_sign`, the text the message's bytes

TODO.md

@@ -2,10 +2,9 @@
 
 - `git pull` `next` and cut a branch from it — one branch per issue, named
   `issue-<N>-<slug>`. Never branch from `main`.
-- Do the work as one commit whose title ends with ` (closes #N)`, with the
-  `TODO.md` update in that same commit.
-- Move Next Step to the top of Completed Steps; move the top item of Future
-  Steps into Next Step.
+- Do the work as one commit whose title ends with ` (closes #N)`.
+- Add no entry to Completed Steps. What landed is recorded on the tracker and in
+  `git log`, where each commit title names the issue it closes.
 - Run `make fmt`, then `make check`. A feature branch may be red; `next` and
   `main` may not.
 - Rebase onto current `next` immediately before pushing — other branches land on
@@ -54,6 +53,15 @@ then continue tagging as milestones land.
   anything around it to carry the `hidden` class that `showView()` puts on every
   view but the current one. No caller changed.
 
+- 2026-10-08: Switching the network in Settings now tells open pages
+  ([#500](https://git.eeqj.de/sneak/AutistMask/issues/500)). Once the switch is
+  saved, Settings asks the background to send `chainChanged` with the new chain
+  id to every open tab, through the same function an approved site request uses.
+  Choosing the network already active changes nothing and sends nothing. Only
+  the extension's own pages can ask for this. `tests/chainSwitchGate.test.js`
+  drives the real Settings view against the background, and the Chrome suite
+  checks that the test page hears both switches.
+
 - 2026-10-07: A site can no longer switch the wallet's network by itself
   ([#408](https://git.eeqj.de/sneak/AutistMask/issues/408)). A connected site's
   `wallet_switchEthereumChain` request for the other supported network opens a

src/background/index.js

@@ -984,9 +984,8 @@ async function handleRpc(method, params, origin) {
 
         if (method === "eth_sign") {
             signParams.dangerWarning =
-                "\u26a0\ufe0f DANGER: This site is requesting to sign a raw hash. " +
-                "This can be used to sign transactions that drain your funds. " +
-                "Only proceed if you fully understand what you are signing.";
+                "This site used the older eth_sign method. " +
+                "The data will be signed as a personal message.";
         }
 
         if (findPendingApproval(origin, "sign")) {
@@ -1471,6 +1470,7 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         "AUTISTMASK_ADDRESSES_REMOVED",
         "AUTISTMASK_GET_CONNECTED_SITES",
         "AUTISTMASK_REMOVE_SITE",
+        "AUTISTMASK_NETWORK_CHANGED",
     ];
     if (POPUP_ONLY_TYPES.includes(msg.type) && !isExtensionSender(sender)) {
         sendResponse({ error: "Unauthorized sender" });
@@ -1854,6 +1854,13 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         broadcastSiteRemoved(msg.origin);
         return false;
     }
+
+    // Settings switched the network and has saved it. Open tabs are told the
+    // new chain id the same way as after a site's approved switch request.
+    if (msg.type === "AUTISTMASK_NETWORK_CHANGED") {
+        broadcastChainChanged(msg.chainId);
+        return false;
+    }
 });
 
 module.exports = { PROXY_METHODS };

src/popup/index.html

@@ -7,9 +7,10 @@
         <link rel="stylesheet" href="styles.css" />
     </head>
     <!-- Chrome gives extension pages a stylesheet of its own that sets the
-         font on body, and a Tailwind class beats it only when marked
-         important: hence font-mono! rather than font-mono. -->
-    <body class="bg-bg text-fg font-mono! text-sm">
+         font and its size on body, and a Tailwind class beats it only when
+         marked important: hence font-mono! and text-sm! rather than
+         font-mono and text-sm. -->
+    <body class="bg-bg text-fg font-mono! text-sm!">
         <div id="app" class="p-2 pr-5 overflow-x-hidden">
             <!-- ============ GLOBAL TITLE BAR ============ -->
             <div
@@ -87,11 +88,14 @@
 
                 <!-- Mnemonic form section -->
                 <div id="add-wallet-section-mnemonic">
-                    <p class="mb-2">
-                        Enter your 12 or 24 word recovery phrase below, or click
-                        the button to roll the die for a new one.
-                    </p>
-                    <div class="mb-1 flex justify-end">
+                    <!-- The die button shares the instruction's row: on a row
+                         of its own it pushes Import below the fold at
+                         360x600. -->
+                    <div class="mb-2 flex justify-between items-start gap-2">
+                        <p>
+                            Enter your 12 or 24 word recovery phrase below, or
+                            click the button to roll the die for a new one.
+                        </p>
                         <button
                             id="btn-generate-phrase"
                             class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer text-xs"

src/popup/views/approval.js

@@ -721,7 +721,7 @@ function showSignApproval(details) {
             "This message is plain text, not hex, so it cannot be signed.";
     }
 
-    // Display danger warning for eth_sign (raw hash signing)
+    // The warning the background attaches to an eth_sign request.
     const warningEl = $("approve-sign-danger-warning");
     if (warningEl) {
         if (sp.dangerWarning) {

src/popup/views/settings.js

@@ -316,7 +316,11 @@ function init(ctx) {
     const networkSelect = $("settings-network");
     networkSelect.addEventListener("change", async () => {
         const newId = networkSelect.value;
+        if (newId === state.networkId) return;
         const net = await onChainSwitch(newId);
+        // Open pages are told by the background, as after a site's approved
+        // switch request.
+        notify({ type: "AUTISTMASK_NETWORK_CHANGED", chainId: net.chainId });
         $("settings-rpc").value = state.rpcUrl;
         $("settings-blockscout").value = state.blockscoutUrl;
         showFlash("Switched to " + net.name + ".");

tests/backgroundApproval.test.js

@@ -1551,6 +1551,53 @@ describe("what the approval is verified against", () => {
     });
 });
 
+// eth_sign names the address first and the data second, the reverse of
+// personal_sign, and is answered as the JSON-RPC specification defines it:
+// with an EIP-191 personal message signature over the data, the same
+// signature personal_sign returns
+// (https://git.eeqj.de/sneak/AutistMask/issues/409).
+describe("eth_sign", () => {
+    test("is read address first, and returns a personal message signature over the data", async () => {
+        const bg = loadBackground();
+        const page = bg.send(
+            {
+                type: "AUTISTMASK_RPC",
+                method: "eth_sign",
+                params: [signer.address, MESSAGE],
+            },
+            { origin: ORIGIN },
+        );
+        await settle();
+        const id = approvalIdIn(bg.created.map((c) => c.url));
+
+        const details = bg.send(
+            { type: "AUTISTMASK_GET_APPROVAL", id },
+            { url: bg.fromPopup.url },
+        );
+        const { signParams } = details.sendResponse.mock.calls[0][0];
+        expect(signParams).toMatchObject({
+            method: "eth_sign",
+            message: MESSAGE,
+            from: signer.address,
+        });
+        expect(signParams.dangerWarning).toBe(
+            "This site used the older eth_sign method. " +
+                "The data will be signed as a personal message.",
+        );
+
+        const signature = await signer.signMessage(
+            Buffer.from(MESSAGE.slice(2), "hex"),
+        );
+        bg.send(
+            { type: "AUTISTMASK_SIGN_RESPONSE", id, approved: true, signature },
+            { url: bg.fromPopup.url },
+        );
+        await settle();
+
+        expect(page.sendResponse).toHaveBeenCalledWith({ result: signature });
+    });
+});
+
 // The interlock must not cost the retry the approval exists to allow.
 describe("the interlock releases a failed attempt", () => {
     test("a retryable failure before the broadcast leaves the approval usable", async () => {

tests/chainSwitchGate.test.js

@@ -16,7 +16,9 @@
 //
 // The endpoint half of #308 lives in tests/networkEndpoints.test.js, which
 // covers the popup's chain switch; this file covers the background's, which
-// goes through storage rather than the shared state singleton.
+// goes through storage rather than the shared state singleton. The last block
+// covers what the background tells open tabs when the user switches the
+// network in Settings.
 
 const { networkById } = require("../src/shared/networks");
 const { makeStorageStub } = require("./support/storageStub");
@@ -225,6 +227,14 @@ function loadBackground() {
         answerPrompt,
         closePrompt,
         opened,
+        // A message to the background from `sender`, and its answer.
+        send: (msg, sender) => {
+            let reply = null;
+            messageListener(msg, sender, (r) => {
+                reply = r;
+            });
+            return reply;
+        },
         walletState: () => storage.read("autistmask"),
         chainChangedEvents: () =>
             toTabs.filter((m) => m.eventName === "chainChanged"),
@@ -390,3 +400,109 @@ describe("only the user switches the network", () => {
         expect(bg.walletState().rpcUrl).toBe(CUSTOM_RPC);
     });
 });
+
+// Switching the network in Settings tells open pages, as an approved site
+// request does (https://git.eeqj.de/sneak/AutistMask/issues/500). These drive
+// the real Settings view over the background's storage, with what it sends
+// delivered to the background from the extension's own page.
+describe("switching the network in Settings tells every open tab", () => {
+    const POPUP = { url: EXT_URL + "src/popup/index.html" };
+
+    // A stand-in for one DOM node: enough of an element for init() to set
+    // properties on it and hang listeners off it.
+    function fakeElement() {
+        return {
+            value: "",
+            checked: false,
+            textContent: "",
+            style: {},
+            dataset: {},
+            classList: { add() {}, remove() {} },
+            listeners: {},
+            addEventListener(event, handler) {
+                this.listeners[event] = handler;
+            },
+            querySelectorAll: () => [],
+        };
+    }
+
+    // Settings, opened the way the popup opens it. Returns its network
+    // selector.
+    async function openSettings(bg) {
+        const elements = {};
+        const element = (id) => (elements[id] ||= fakeElement());
+        jest.doMock("../src/popup/views/helpers", () => ({
+            $: element,
+            showView: () => {},
+            updateDebugBanner: () => {},
+            showFlash: () => {},
+            escapeHtml: (s) => s,
+            flashCopyFeedback: () => {},
+            goBack: () => {},
+            pushCurrentView: () => {},
+            onViewLeave: () => {},
+            VIEWS: [],
+        }));
+        global.chrome.runtime.sendMessage = (msg) => {
+            bg.send(msg, POPUP);
+        };
+        await require("../src/shared/state").loadState();
+        require("../src/popup/views/settings").init({
+            pageClosed: new AbortController().signal,
+        });
+        const select = element("settings-network");
+        select.value = "mainnet";
+        return select;
+    }
+
+    // The user picks `networkId` in the selector.
+    async function choose(select, networkId) {
+        select.value = networkId;
+        await select.listeners.change();
+        await settle();
+    }
+
+    afterEach(() => {
+        jest.dontMock("../src/popup/views/helpers");
+    });
+
+    test("switching to the other network sends chainChanged once, with its chain id", async () => {
+        const bg = loadBackground();
+        const select = await openSettings(bg);
+
+        await choose(select, "sepolia");
+
+        expect(bg.walletState().networkId).toBe("sepolia");
+        expect(bg.chainChangedEvents()).toEqual([
+            {
+                type: "AUTISTMASK_EVENT",
+                eventName: "chainChanged",
+                data: SEPOLIA.chainId,
+            },
+        ]);
+    });
+
+    test("choosing the network already active changes nothing and sends nothing", async () => {
+        const bg = loadBackground();
+        const select = await openSettings(bg);
+        const before = bg.walletState();
+
+        await choose(select, "mainnet");
+
+        expect(bg.walletState()).toEqual(before);
+        expect(bg.chainChangedEvents()).toEqual([]);
+    });
+
+    test("a page cannot make the background send chainChanged", async () => {
+        const bg = loadBackground();
+
+        const reply = bg.send(
+            { type: "AUTISTMASK_NETWORK_CHANGED", chainId: SEPOLIA.chainId },
+            { url: CONNECTED_ORIGIN + "/" },
+        );
+        await settle();
+
+        expect(reply).toEqual({ error: "Unauthorized sender" });
+        expect(bg.chainChangedEvents()).toEqual([]);
+    });
+});

tests/e2e/firefox/driver.js

@@ -290,6 +290,7 @@ class Driver {
             `const el = document.querySelector(arguments[0]);
              if (document.readyState !== "complete" || !el) return false;
              if (el.closest(".hidden")) return false;
+             if (getComputedStyle(el).visibility !== "visible") return false;
              const r = el.getBoundingClientRect();
              return r.width > 0 && r.height > 0;`,
             [selector],

tests/e2e/firefox/run.js

@@ -128,6 +128,18 @@ step("the popup is drawn in the monospace font it declares", async (env) => {
     );
 });
 
+// The same check as the Chrome suite's (#456), so both browsers are held to
+// the same size.
+step("the popup's text is drawn at the 14px text-sm declares", async (env) => {
+    const size = await env.driver.execute(
+        "return getComputedStyle(document.body).fontSize;",
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The recovery screen (#361): the Chrome suite's four cases, run before any
 // wallet exists for the same reason. With no wallet nothing saves on a timer,
 // so no save can write a good record over the unreadable one. The last of them

tests/e2e/harness.js

@@ -348,6 +348,7 @@ async function visible(page, selector, timeout = 15000) {
                 const el = document.querySelector(sel);
                 if (document.readyState !== "complete" || !el) return false;
                 if (el.closest(".hidden")) return false;
+                if (getComputedStyle(el).visibility !== "visible") return false;
                 const r = el.getBoundingClientRect();
                 return r.width > 0 && r.height > 0;
             },

tests/e2e/run.js

@@ -113,6 +113,18 @@ test("the popup is drawn in the monospace font it declares (#418)", async (env)
     );
 });
 
+// The same stylesheet sets the size on body to 75%, which would draw the
+// popup at 12px.
+test("the popup's text is drawn at the 14px text-sm declares (#456)", async (env) => {
+    const size = await env.page.evaluate(
+        () => getComputedStyle(document.body).fontSize,
+    );
+    assert(
+        size === "14px",
+        "the popup's text is drawn at " + size + ", not at the 14px of text-sm",
+    );
+});
+
 // The empirical half of #182. The manifest change is only a claim about
 // what the CSP permits; this is the observation. Two things have to hold
 // together, and the run covers both: the popup realm compiles WASM (here),
@@ -4538,6 +4550,42 @@ test("a site's network switch changes nothing until the user approves it (#408)"
     );
 });
 
+// Switching the network in Settings tells the page too, as an approved site
+// request does (https://git.eeqj.de/sneak/AutistMask/issues/500). The wallet
+// goes back to mainnet the same way at the end.
+test("a network switch in Settings tells the page (#500)", async (env) => {
+    const { mainnet, sepolia } = NETWORKS;
+    const before = await storedNetwork(env.page);
+    assert(
+        before.networkId === "mainnet",
+        "this test starts on mainnet, not on " + before.networkId,
+    );
+    const eventsBefore = (await chainChangedEvents(env.dapp)).length;
+    await openSettings(env.page);
+
+    await env.page.selectOption("#settings-network", "sepolia");
+    let events = await chainChangedEvents(env.dapp, eventsBefore + 1);
+    assert(
+        events.length === eventsBefore + 1 &&
+            events[events.length - 1].data === sepolia.chainId,
+        "the page was not told of the switch to Sepolia: " +
+            JSON.stringify(events),
+    );
+
+    await env.page.selectOption("#settings-network", "mainnet");
+    events = await chainChangedEvents(env.dapp, eventsBefore + 2);
+    assert(
+        events.length === eventsBefore + 2 &&
+            events[events.length - 1].data === mainnet.chainId,
+        "the page was not told of the switch back to mainnet: " +
+            JSON.stringify(events),
+    );
+    assert(
+        isDeepStrictEqual(await storedNetwork(env.page), before),
+        "switching back did not restore the mainnet network and endpoints",
+    );
+});
+
 // The closing pass over both boundaries at once. Every message the section
 // put on either channel is re-read here and required to be free of the
 // password — and required to be there at all, method by method, so the