Implement personal_sign and eth_signTypedData_v4 message signing

Replace stub error handlers with full approval flow for personal_sign,
eth_sign, eth_signTypedData_v4, and eth_signTypedData. Uses toolbar
popup only (no fallback window) and keeps sign approvals pending across
popup close/reopen cycles so the user can respond via the toolbar icon.

src/background/index.js

@@ -6,6 +6,7 @@ const {
     ETHEREUM_MAINNET_CHAIN_ID,
     DEFAULT_RPC_URL,
 } = require("../shared/constants");
+const { getBytes } = require("ethers");
 const { state, loadState, saveState } = require("../shared/state");
 const { refreshBalances, getProvider } = require("../shared/balances");
 const { debugFetch } = require("../shared/log");
@@ -177,13 +178,51 @@ function requestTxApproval(origin, hostname, txParams) {
     });
 }
 
-// Detect when an approval popup (browser-action) closes without a response
+// Open a sign-approval popup and return a promise that resolves with { signature } or { error }.
+// Uses the toolbar popup only — no fallback window.  If openPopup() fails the
+// popup URL is still set, so the user can click the toolbar icon to respond.
+function requestSignApproval(origin, hostname, signParams) {
+    return new Promise((resolve) => {
+        const id = nextApprovalId++;
+        pendingApprovals[id] = {
+            origin,
+            hostname,
+            signParams,
+            resolve,
+            type: "sign",
+        };
+
+        if (actionApi && typeof actionApi.setPopup === "function") {
+            actionApi.setPopup({
+                popup: "src/popup/index.html?approval=" + id,
+            });
+        }
+        if (actionApi && typeof actionApi.openPopup === "function") {
+            try {
+                const result = actionApi.openPopup();
+                if (result && typeof result.catch === "function") {
+                    result.catch(() => {});
+                }
+            } catch {
+                // openPopup unsupported — user clicks toolbar icon
+            }
+        }
+    });
+}
+
+// Detect when an approval popup (browser-action) closes without a response.
+// Sign approvals are NOT auto-rejected on disconnect because toolbar popups
+// naturally close on focus loss and the user can reopen them.
 runtime.onConnect.addListener((port) => {
     if (port.name.startsWith("approval:")) {
         const id = parseInt(port.name.split(":")[1], 10);
         port.onDisconnect.addListener(() => {
             const approval = pendingApprovals[id];
             if (approval) {
+                if (approval.type === "sign") {
+                    // Keep pending — user can reopen the toolbar popup
+                    return;
+                }
                 if (approval.type === "tx") {
                     approval.resolve({
                         error: {
@@ -390,18 +429,59 @@ async function handleRpc(method, params, origin) {
     }
 
     if (method === "personal_sign" || method === "eth_sign") {
-        return {
-            error: { message: "Signing not yet implemented in AutistMask." },
-        };
+        const s = await getState();
+        const activeAddress = await getActiveAddress();
+        if (!activeAddress)
+            return { error: { message: "No accounts available" } };
+
+        const hostname = extractHostname(origin);
+        const allowed = s.allowedSites[activeAddress] || [];
+        if (
+            !allowed.includes(hostname) &&
+            !connectedSites[origin + ":" + activeAddress]
+        ) {
+            return { error: { code: 4100, message: "Unauthorized" } };
+        }
+
+        // personal_sign: params[0]=message, params[1]=address
+        // eth_sign:      params[0]=address, params[1]=message
+        const signParams =
+            method === "personal_sign"
+                ? { method, message: params[0], from: params[1] }
+                : { method, message: params[1], from: params[0] };
+
+        const decision = await requestSignApproval(
+            origin,
+            hostname,
+            signParams,
+        );
+        if (decision.error) return { error: decision.error };
+        return { result: decision.signature };
     }
 
     if (method === "eth_signTypedData_v4" || method === "eth_signTypedData") {
-        return {
-            error: {
-                message:
-                    "Typed data signing not yet implemented in AutistMask.",
-            },
-        };
+        const s = await getState();
+        const activeAddress = await getActiveAddress();
+        if (!activeAddress)
+            return { error: { message: "No accounts available" } };
+
+        const hostname = extractHostname(origin);
+        const allowed = s.allowedSites[activeAddress] || [];
+        if (
+            !allowed.includes(hostname) &&
+            !connectedSites[origin + ":" + activeAddress]
+        ) {
+            return { error: { code: 4100, message: "Unauthorized" } };
+        }
+
+        const signParams = { method, typedData: params[1], from: params[0] };
+        const decision = await requestSignApproval(
+            origin,
+            hostname,
+            signParams,
+        );
+        if (decision.error) return { error: decision.error };
+        return { result: decision.signature };
     }
 
     if (method === "eth_sendTransaction") {
@@ -514,7 +594,7 @@ if (windowsApi && windowsApi.onRemoved) {
     windowsApi.onRemoved.addListener((windowId) => {
         for (const [id, approval] of Object.entries(pendingApprovals)) {
             if (approval.windowId === windowId) {
-                if (approval.type === "tx") {
+                if (approval.type === "tx" || approval.type === "sign") {
                     approval.resolve({
                         error: {
                             code: 4001,
@@ -550,6 +630,10 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
                 resp.type = "tx";
                 resp.txParams = approval.txParams;
             }
+            if (approval.type === "sign") {
+                resp.type = "sign";
+                resp.signParams = approval.signParams;
+            }
             sendResponse(resp);
         } else {
             sendResponse(null);
@@ -624,6 +708,76 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
         return true;
     }
 
+    if (msg.type === "AUTISTMASK_SIGN_RESPONSE") {
+        const approval = pendingApprovals[msg.id];
+        if (!approval) return false;
+        delete pendingApprovals[msg.id];
+        resetPopupUrl();
+
+        if (!msg.approved) {
+            approval.resolve({
+                error: { code: 4001, message: "User rejected the request." },
+            });
+            return true;
+        }
+
+        (async () => {
+            try {
+                await loadState();
+                const activeAddress = await getActiveAddress();
+                let wallet, addrIndex;
+                for (const w of state.wallets) {
+                    for (let i = 0; i < w.addresses.length; i++) {
+                        if (w.addresses[i].address === activeAddress) {
+                            wallet = w;
+                            addrIndex = i;
+                            break;
+                        }
+                    }
+                    if (wallet) break;
+                }
+                if (!wallet) throw new Error("Wallet not found");
+                const decrypted = await decryptWithPassword(
+                    wallet.encryptedSecret,
+                    msg.password,
+                );
+                const signer = getSignerForAddress(
+                    wallet,
+                    addrIndex,
+                    decrypted,
+                );
+
+                const sp = approval.signParams;
+                let signature;
+
+                if (sp.method === "personal_sign" || sp.method === "eth_sign") {
+                    signature = await signer.signMessage(getBytes(sp.message));
+                } else {
+                    // eth_signTypedData_v4 / eth_signTypedData
+                    const typedData = JSON.parse(sp.typedData);
+                    const { domain, types, message } = typedData;
+                    // ethers handles EIP712Domain internally
+                    delete types.EIP712Domain;
+                    signature = await signer.signTypedData(
+                        domain,
+                        types,
+                        message,
+                    );
+                }
+
+                approval.resolve({ signature });
+                sendResponse({ signature });
+            } catch (e) {
+                const errMsg = e.shortMessage || e.message;
+                approval.resolve({
+                    error: { message: errMsg },
+                });
+                sendResponse({ error: errMsg });
+            }
+        })();
+        return true;
+    }
+
     if (msg.type === "AUTISTMASK_ACTIVE_CHANGED") {
         broadcastAccountsChanged();
         return false;

src/popup/index.html

@@ -917,6 +917,58 @@
                 </div>
             </div>
 
+            <!-- ============ SIGNATURE APPROVAL ============ -->
+            <div id="view-approve-sign" class="view hidden">
+                <h2 class="font-bold mb-2">Signature Request</h2>
+                <p class="mb-2">
+                    <span id="approve-sign-hostname" class="font-bold"></span>
+                    wants you to sign a message.
+                </p>
+
+                <div class="mb-3">
+                    <div class="text-xs text-muted mb-1">Type</div>
+                    <div id="approve-sign-type" class="text-xs font-bold"></div>
+                </div>
+
+                <div class="mb-3">
+                    <div class="text-xs text-muted mb-1">From</div>
+                    <div id="approve-sign-from" class="text-xs break-all"></div>
+                </div>
+
+                <div class="mb-3">
+                    <div class="text-xs text-muted mb-1">Message</div>
+                    <div
+                        id="approve-sign-message"
+                        class="text-xs break-all"
+                        style="max-height: 12rem; overflow-y: auto"
+                    ></div>
+                </div>
+
+                <div class="mb-2">
+                    <label class="block mb-1 text-xs">Password</label>
+                    <input
+                        type="password"
+                        id="approve-sign-password"
+                        class="border border-border p-1 w-full font-mono text-sm bg-bg text-fg"
+                    />
+                </div>
+                <div id="approve-sign-error" class="text-xs hidden mb-2"></div>
+                <div class="flex justify-between">
+                    <button
+                        id="btn-approve-sign"
+                        class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer"
+                    >
+                        Sign
+                    </button>
+                    <button
+                        id="btn-reject-sign"
+                        class="border border-border px-2 py-1 hover:bg-fg hover:text-bg cursor-pointer"
+                    >
+                        Reject
+                    </button>
+                </div>
+            </div>
+
             <!-- ============ SITE APPROVAL ============ -->
             <div id="view-approve-site" class="view hidden">
                 <h2 class="font-bold mb-2">Connection Request</h2>

src/popup/views/approval.js

@@ -1,6 +1,6 @@
 const { $, addressDotHtml, escapeHtml, showView } = require("./helpers");
 const { state, saveState } = require("../../shared/state");
-const { formatEther, formatUnits, Interface } = require("ethers");
+const { formatEther, formatUnits, Interface, toUtf8String } = require("ethers");
 const { ERC20_ABI } = require("../../shared/constants");
 const { TOKEN_BY_ADDRESS } = require("../../shared/tokenList");
 const txStatus = require("./txStatus");
@@ -212,6 +212,86 @@ function showTxApproval(details) {
     showView("approve-tx");
 }
 
+function decodeHexMessage(hex) {
+    try {
+        const bytes = Uint8Array.from(
+            hex
+                .slice(2)
+                .match(/.{1,2}/g)
+                .map((b) => parseInt(b, 16)),
+        );
+        return toUtf8String(bytes);
+    } catch {
+        return null;
+    }
+}
+
+function formatTypedDataHtml(jsonStr) {
+    try {
+        const data = JSON.parse(jsonStr);
+        let html = "";
+
+        if (data.domain) {
+            html += `<div class="mb-2"><div class="text-muted">Domain</div>`;
+            for (const [key, val] of Object.entries(data.domain)) {
+                html += `<div><span class="text-muted">${escapeHtml(key)}:</span> ${escapeHtml(String(val))}</div>`;
+            }
+            html += `</div>`;
+        }
+
+        if (data.primaryType) {
+            html += `<div class="mb-2"><div class="text-muted">Primary type</div>`;
+            html += `<div class="font-bold">${escapeHtml(data.primaryType)}</div></div>`;
+        }
+
+        if (data.message) {
+            html += `<div class="mb-2"><div class="text-muted">Message</div>`;
+            for (const [key, val] of Object.entries(data.message)) {
+                const display =
+                    typeof val === "object" ? JSON.stringify(val) : String(val);
+                html += `<div><span class="text-muted">${escapeHtml(key)}:</span> <span class="break-all">${escapeHtml(display)}</span></div>`;
+            }
+            html += `</div>`;
+        }
+
+        return html;
+    } catch {
+        return `<div class="break-all">${escapeHtml(jsonStr)}</div>`;
+    }
+}
+
+function showSignApproval(details) {
+    const sp = details.signParams;
+
+    $("approve-sign-hostname").textContent = details.hostname;
+    $("approve-sign-from").innerHTML = approvalAddressHtml(sp.from);
+
+    const isTyped =
+        sp.method === "eth_signTypedData_v4" ||
+        sp.method === "eth_signTypedData";
+    $("approve-sign-type").textContent = isTyped
+        ? "Typed data (EIP-712)"
+        : "Personal message";
+
+    if (isTyped) {
+        $("approve-sign-message").innerHTML = formatTypedDataHtml(sp.typedData);
+    } else {
+        const decoded = decodeHexMessage(sp.message);
+        if (decoded !== null) {
+            $("approve-sign-message").textContent = decoded;
+        } else {
+            $("approve-sign-message").textContent = sp.message;
+        }
+    }
+
+    $("approve-sign-password").value = "";
+    $("approve-sign-error").classList.add("hidden");
+    $("btn-approve-sign").disabled = false;
+    $("btn-approve-sign").classList.remove("text-muted");
+
+    showView("approve-sign");
+}
+
 function show(id) {
     approvalId = id;
     runtime.connect({ name: "approval:" + id });
@@ -224,6 +304,10 @@ function show(id) {
             showTxApproval(details);
             return;
         }
+        if (details.type === "sign") {
+            showSignApproval(details);
+            return;
+        }
         $("approve-hostname").textContent = details.hostname;
         $("approve-address").innerHTML = approvalAddressHtml(
             state.activeAddress,
@@ -301,6 +385,48 @@ function init(ctx) {
         });
         window.close();
     });
+
+    $("btn-approve-sign").addEventListener("click", () => {
+        const password = $("approve-sign-password").value;
+        if (!password) {
+            $("approve-sign-error").textContent = "Please enter your password.";
+            $("approve-sign-error").classList.remove("hidden");
+            return;
+        }
+        $("approve-sign-error").classList.add("hidden");
+        $("btn-approve-sign").disabled = true;
+        $("btn-approve-sign").classList.add("text-muted");
+
+        runtime.sendMessage(
+            {
+                type: "AUTISTMASK_SIGN_RESPONSE",
+                id: approvalId,
+                approved: true,
+                password: password,
+            },
+            (response) => {
+                if (response && response.signature) {
+                    window.close();
+                } else {
+                    const msg =
+                        (response && response.error) || "Signing failed.";
+                    $("approve-sign-error").textContent = msg;
+                    $("approve-sign-error").classList.remove("hidden");
+                    $("btn-approve-sign").disabled = false;
+                    $("btn-approve-sign").classList.remove("text-muted");
+                }
+            },
+        );
+    });
+
+    $("btn-reject-sign").addEventListener("click", () => {
+        runtime.sendMessage({
+            type: "AUTISTMASK_SIGN_RESPONSE",
+            id: approvalId,
+            approved: false,
+        });
+        window.close();
+    });
 }
 
 module.exports = { init, show };

src/popup/views/helpers.js

@@ -26,6 +26,7 @@ const VIEWS = [
     "transaction",
     "approve-site",
     "approve-tx",
+    "approve-sign",
 ];
 
 function $(id) {