fix: wipe the exported private key from the DOM on leaving the screen (closes #221)

The export screen registered no view-leave cleanup, so leaving it by any
route other than its own Back button — the settings gear, for instance —
left the decrypted private key in #export-privkey-value inside the hidden
view for the rest of the popup's life. The reveal path had the same
post-await hole the recovery phrase screen had: the write landed after
the wipe, with nothing scheduled to wipe it again.

The screen moves out of addressDetail.js into its own module shaped like
showPhrase.js: onViewLeave() cleanup that wipes the value node, the
password input and the closure state, and a revealGeneration liveness
guard captured before the decrypt. The guard sits in front of the key
derivation, so a decrypt that resolves after the screen was left does not
even derive the key.

The audit for the same bug class covered every other screen holding
secret material in the DOM. AddWallet (a generated or pasted recovery
phrase, an imported private key or extended private key, and the
password) and the password inputs on ConfirmTx, DeleteWallet, ApproveTx
and ApproveSign were all cleared on entry only, so each survived in its
hidden view after the screen navigated on. All five now register the same
cleanup. None of them writes a secret after an await, so none needs a
generation guard.

The load-bearing test leaves the screen mid-decrypt and asserts the key
never lands in the DOM, and that it still does not land once the user has
returned to the screen — which the generation counter catches and a
current-view check alone would not.

README.md

@@ -486,6 +486,14 @@ ExportPrivKey and ShowRecoveryPhrase — are deliberately absent from that list,
 so the popup can never reopen onto one of them with no password prompt in front
 of it.
 
+Every screen that holds secret material in the page registers a cleanup with
+`onViewLeave()` (`src/popup/views/helpers.js`), which `showView()` runs on every
+exit from that screen rather than only on its "Back" button, so nothing secret
+survives in a hidden view once the user has navigated away by any route. That
+covers the revealed private key and recovery phrase, the recovery phrase,
+private key or extended private key entered on AddWallet, and the password typed
+on ConfirmTx, DeleteWallet, ApproveTx and ApproveSign.
+
 #### Welcome (`welcome`)
 
 - **When**: No wallets exist yet (`state.hasWallet` is false). This is the root
@@ -596,10 +604,15 @@ of it.
     - "Reveal" (correct password) → decrypts the wallet secret, derives this
       address's key, hides the password input and shows the key (no screen
       change)
-    - "Reveal" (wrong password) → "Wrong password." on the error line, nothing
-      revealed
-    - "Back" → clears the key and password from the DOM, then → previous screen
-      (AddressDetail)
+    - "Reveal" (wrong password) → full-sentence error on the error line, nothing
+      revealed (no screen change)
+    - "Back" → previous screen (AddressDetail)
+- **Secret handling**: nothing is decrypted, no key is derived, and nothing is
+  written into the page until the password is accepted; the key is never stored
+  in state, and it is wiped from the page whenever the screen is left by any
+  route, including the Settings gear. A decrypt still running when the screen is
+  left is discarded rather than written. The screen is not restorable, so
+  reopening the popup lands on Home rather than back on the key.
 
 #### AddressToken (`address-token`)
 

TODO.md

@@ -44,6 +44,12 @@ undefined identifiers, which is how
 
 # Completed Steps
 
+- 2026-08-12: The private key export screen now wipes the key from the page
+  whenever it is left by any route, and a decrypt still in flight when the
+  screen is left is discarded instead of written; the same `onViewLeave()`
+  cleanup was extended to every other screen holding secret material in the DOM
+  (AddWallet, ConfirmTx, DeleteWallet, ApproveTx, ApproveSign)
+  ([#221](https://git.eeqj.de/sneak/AutistMask/issues/221)).
 - 2026-08-12: Bundled token list documentation no longer states a count. The
   four "top 250" claims in `README.md` and the "roughly 500" claim in
   `docs/README.md` are replaced with a description of how the list is actually

src/popup/views/addWallet.js

@@ -1,4 +1,11 @@
-const { $, showView, showFlash, goBack, clearViewStack } = require("./helpers");
+const {
+    $,
+    showView,
+    showFlash,
+    goBack,
+    clearViewStack,
+    onViewLeave,
+} = require("./helpers");
 const {
     generateMnemonic,
     hdWalletFromMnemonic,
@@ -66,13 +73,23 @@ function switchMode(mode) {
     $("add-wallet-password-hint").textContent = PASSWORD_HINTS[mode];
 }
 
-function show() {
+// Wipe the secret material this screen holds in the DOM: a generated or
+// pasted recovery phrase, an imported private key or extended private key,
+// and the password that would encrypt them. Registered as the view-leave
+// handler as well as run on entry, so none of it survives in the hidden
+// view after the user navigates away by any route, including the Settings
+// gear and the import itself.
+function clear() {
     $("wallet-mnemonic").value = "";
     $("import-private-key").value = "";
     $("import-xprv-key").value = "";
     $("add-wallet-password").value = "";
     $("add-wallet-password-confirm").value = "";
     $("add-wallet-phrase-warning").style.visibility = "hidden";
+}
+
+function show() {
+    clear();
     switchMode("mnemonic");
     showView("add-wallet");
 }
@@ -288,6 +305,8 @@ async function importXprvKey(ctx) {
 }
 
 function init(ctx) {
+    onViewLeave("add-wallet", clear);
+
     // Tab click handlers
     $("tab-mnemonic").addEventListener("click", () => switchMode("mnemonic"));
     $("tab-privkey").addEventListener("click", () => switchMode("privkey"));

src/popup/views/addressDetail.js

@@ -2,7 +2,6 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
     balanceLinesForAddress,
     addressDotHtml,
     addressTitle,
@@ -27,8 +26,7 @@ const {
 } = require("./send");
 const { log } = require("../../shared/log");
 const makeBlockie = require("ethereum-blockies-base64");
-const { decryptWithPassword } = require("../../shared/vault");
-const { getSignerForAddress } = require("../../shared/wallet");
+const exportPrivkey = require("./exportPrivkey");
 
 let ctx;
 
@@ -298,81 +296,12 @@ function init(_ctx) {
     $("btn-export-privkey").addEventListener("click", () => {
         moreDropdown.classList.add("hidden");
         moreBtn.classList.remove("bg-fg", "text-bg");
-        pushCurrentView();
-        const wallet = state.wallets[state.selectedWallet];
-        const addr = wallet.addresses[state.selectedAddress];
-        const blockieEl = $("export-privkey-jazzicon");
-        blockieEl.innerHTML = "";
-        const bImg = document.createElement("img");
-        bImg.src = makeBlockie(addr.address);
-        bImg.width = 48;
-        bImg.height = 48;
-        bImg.style.imageRendering = "pixelated";
-        bImg.style.borderRadius = "50%";
-        blockieEl.appendChild(bImg);
-        $("export-privkey-title").textContent =
-            wallet.name + " \u2014 Address " + (state.selectedAddress + 1);
-        const exportAddrContainer = $("export-privkey-dot").parentElement;
-        exportAddrContainer.innerHTML = renderAddressHtml(addr.address);
-        attachCopyHandlers(exportAddrContainer);
-        $("export-privkey-password").value = "";
-        $("export-privkey-flash").textContent = "";
-        $("export-privkey-flash").style.visibility = "hidden";
-        $("export-privkey-password-section").classList.remove("hidden");
-        $("export-privkey-result").classList.add("hidden");
-        $("export-privkey-value").textContent = "";
-        showView("export-privkey");
+        // No pushCurrentView() here: exportPrivkey.show() can return
+        // without navigating, so it does its own push.
+        exportPrivkey.show(state.selectedWallet, state.selectedAddress);
     });
 
-    $("btn-export-privkey-confirm").addEventListener("click", async () => {
-        const password = $("export-privkey-password").value;
-        if (!password) {
-            $("export-privkey-flash").textContent = "Password is required.";
-            $("export-privkey-flash").style.visibility = "visible";
-            return;
-        }
-        const btn = $("btn-export-privkey-confirm");
-        btn.disabled = true;
-        btn.classList.add("text-muted");
-        const wallet = state.wallets[state.selectedWallet];
-        try {
-            const secret = await decryptWithPassword(
-                wallet.encryptedSecret,
-                password,
-            );
-            const signer = getSignerForAddress(
-                wallet,
-                state.selectedAddress,
-                secret,
-            );
-            const privateKey = signer.privateKey;
-            $("export-privkey-password-section").classList.add("hidden");
-            $("export-privkey-value").textContent = privateKey;
-            $("export-privkey-result").classList.remove("hidden");
-            $("export-privkey-flash").style.visibility = "hidden";
-        } catch {
-            $("export-privkey-flash").textContent = "Wrong password.";
-            $("export-privkey-flash").style.visibility = "visible";
-        } finally {
-            btn.disabled = false;
-            btn.classList.remove("text-muted");
-        }
-    });
-
-    $("export-privkey-value").addEventListener("click", () => {
-        const key = $("export-privkey-value").textContent;
-        if (key) {
-            navigator.clipboard.writeText(key);
-            showFlash("Copied!");
-            flashCopyFeedback($("export-privkey-value"));
-        }
-    });
-
-    $("btn-export-privkey-back").addEventListener("click", () => {
-        $("export-privkey-value").textContent = "";
-        $("export-privkey-password").value = "";
-        goBack();
-    });
+    exportPrivkey.init();
 }
 
 module.exports = { init, show };

src/popup/views/approval.js

@@ -7,6 +7,7 @@ const {
     hideError,
     renderAddressHtml,
     attachCopyHandlers,
+    onViewLeave,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const {
@@ -444,7 +445,24 @@ function findActiveWallet() {
     return null;
 }
 
+// Drop the password from the DOM when either approval screen is left. The
+// approval window navigates on after a signature — approve-tx goes to the
+// wait screen — and the password must not sit in the hidden view for the
+// life of that window.
+function clearTxPassword() {
+    $("approve-tx-password").value = "";
+    hideError("approve-tx-error");
+}
+
+function clearSignPassword() {
+    $("approve-sign-password").value = "";
+    hideError("approve-sign-error");
+}
+
 function init(ctx) {
+    onViewLeave("approve-tx", clearTxPassword);
+    onViewLeave("approve-sign", clearSignPassword);
+
     $("approve-remember").addEventListener("change", async () => {
         state.rememberSiteChoice = $("approve-remember").checked;
         await saveState();

src/popup/views/confirmTx.js

@@ -21,6 +21,7 @@ const {
     renderAddressHtml,
     attachCopyHandlers,
     goBack,
+    onViewLeave,
 } = require("./helpers");
 const { state, currentNetwork } = require("../../shared/state");
 const { getSignerForAddress } = require("../../shared/wallet");
@@ -390,7 +391,17 @@ async function checkRecipientHistory(txInfo) {
     }
 }
 
+// Drop the password from the DOM. Registered as the view-leave handler so
+// it does not sit in the hidden view once the screen navigates on — to the
+// wait screen after a send, or anywhere else the user goes.
+function clearPassword() {
+    $("confirm-tx-password").value = "";
+    hideError("confirm-tx-password-error");
+}
+
 function init(ctx) {
+    onViewLeave("confirm-tx", clearPassword);
+
     $("btn-confirm-send").addEventListener("click", async () => {
         const password = $("confirm-tx-password").value;
         if (!password) {

src/popup/views/deleteWallet.js

@@ -1,4 +1,11 @@
-const { $, showView, showFlash, goBack, clearViewStack } = require("./helpers");
+const {
+    $,
+    showView,
+    showFlash,
+    goBack,
+    clearViewStack,
+    onViewLeave,
+} = require("./helpers");
 const { state, saveState } = require("../../shared/state");
 const { decryptWithPassword } = require("../../shared/vault");
 const {
@@ -9,22 +16,34 @@ const {
 let deleteWalletIndex = null;
 let ctx = null;
 
+// Drop the password from the DOM and the wallet selection from the
+// closure. Registered as the view-leave handler as well as run on entry,
+// so the typed password does not sit in the hidden view after the user
+// navigates away by any route, including the Settings gear.
+function clear() {
+    deleteWalletIndex = null;
+    $("delete-wallet-password").value = "";
+    $("delete-wallet-flash").textContent = "";
+    $("delete-wallet-flash").style.visibility = "hidden";
+}
+
 function show(walletIdx) {
+    clear();
     deleteWalletIndex = walletIdx;
     const wallet = state.wallets[walletIdx];
     $("delete-wallet-name").textContent =
         wallet.name || "Wallet " + (walletIdx + 1);
-    $("delete-wallet-password").value = "";
-    $("delete-wallet-flash").textContent = "";
-    $("delete-wallet-flash").style.visibility = "hidden";
     showView("delete-wallet-confirm");
 }
 
 function init(_ctx) {
     ctx = _ctx;
 
+    onViewLeave("delete-wallet-confirm", clear);
+
+    // No wipe here: goBack() routes through showView(), which runs the
+    // leave hook.
     $("btn-delete-wallet-back").addEventListener("click", () => {
-        deleteWalletIndex = null;
         goBack();
     });
 

src/popup/views/exportPrivkey.js

@@ -0,0 +1,174 @@
+// Private key export for a single address.
+//
+// The key controls the address outright — anyone holding it can move every
+// token in it, from any device, forever — so this screen is handled under
+// the same rules as the recovery phrase screen (./showPhrase.js):
+//
+//   1. Nothing is decrypted, no key is derived, and nothing is written into
+//      the DOM until decryptWithPassword has accepted the password.
+//   2. Leaving the screen by any path wipes it, via the onViewLeave hook,
+//      and a decrypt still in flight when that happens is discarded
+//      instead of written (revealGeneration).
+//   3. The key never reaches the logger. This module deliberately does not
+//      import src/shared/log.js.
+//
+// The key is also never assigned to `state`, so it cannot be persisted to
+// extension storage, and "export-privkey" is excluded from RESTORABLE_VIEWS
+// so the popup can never reopen onto it.
+
+const {
+    $,
+    showView,
+    showFlash,
+    flashCopyFeedback,
+    goBack,
+    onViewLeave,
+    pushCurrentView,
+    renderAddressHtml,
+    attachCopyHandlers,
+} = require("./helpers");
+const { state } = require("../../shared/state");
+const { decryptWithPassword } = require("../../shared/vault");
+const { getSignerForAddress } = require("../../shared/wallet");
+const makeBlockie = require("ethereum-blockies-base64");
+
+const VIEW = "export-privkey";
+
+let walletIndex = null;
+let addressIndex = null;
+
+// Bumped by every clear(), which is what leaving the screen runs. reveal()
+// captures it before awaiting the decrypt and refuses to touch the DOM if
+// it has moved: a decrypt still in flight when the screen is left would
+// otherwise write the key *after* the wipe, with nothing scheduled to wipe
+// it again, leaving it in the hidden view for the life of the popup.
+let revealGeneration = 0;
+
+// True only if the reveal that captured `generation` is still the live one:
+// the screen has not been left, cleared, or re-entered for another address
+// since it started.
+function isCurrentReveal(generation) {
+    return (
+        generation === revealGeneration &&
+        walletIndex !== null &&
+        addressIndex !== null &&
+        state.currentView === VIEW
+    );
+}
+
+function fail(message) {
+    $("export-privkey-flash").textContent = message;
+    $("export-privkey-flash").style.visibility = "visible";
+}
+
+// Wipe every trace of the key and drop the address selection. Safe to call
+// when nothing was ever revealed, and safe to call twice.
+function clear() {
+    walletIndex = null;
+    addressIndex = null;
+    revealGeneration += 1;
+    $("export-privkey-value").textContent = "";
+    $("export-privkey-password").value = "";
+    $("export-privkey-result").classList.add("hidden");
+    $("export-privkey-password-section").classList.remove("hidden");
+    $("export-privkey-flash").textContent = "";
+    $("export-privkey-flash").style.visibility = "hidden";
+}
+
+function show(walletIdx, addrIdx) {
+    const wallet = state.wallets[walletIdx];
+    const addr = wallet && wallet.addresses[addrIdx];
+    if (!addr) {
+        showFlash("That address is no longer available.");
+        return;
+    }
+    clear();
+    walletIndex = walletIdx;
+    addressIndex = addrIdx;
+
+    const blockieEl = $("export-privkey-jazzicon");
+    blockieEl.innerHTML = "";
+    const img = document.createElement("img");
+    img.src = makeBlockie(addr.address);
+    img.width = 48;
+    img.height = 48;
+    img.style.imageRendering = "pixelated";
+    img.style.borderRadius = "50%";
+    blockieEl.appendChild(img);
+
+    $("export-privkey-title").textContent =
+        wallet.name + " — Address " + (addrIdx + 1);
+    const addrContainer = $("export-privkey-dot").parentElement;
+    addrContainer.innerHTML = renderAddressHtml(addr.address);
+    attachCopyHandlers(addrContainer);
+
+    // Pushed here rather than by the caller: this function can return
+    // without navigating, and a push that happened anyway would leave an
+    // entry on the stack that no screen transition matches.
+    pushCurrentView();
+    showView(VIEW);
+}
+
+async function reveal() {
+    const password = $("export-privkey-password").value;
+    if (!password) {
+        fail("Password is required.");
+        return;
+    }
+    if (walletIndex === null) {
+        fail("No address is selected.");
+        return;
+    }
+    const wallet = state.wallets[walletIndex];
+
+    const btn = $("btn-export-privkey-confirm");
+    btn.disabled = true;
+    btn.classList.add("text-muted");
+    const generation = revealGeneration;
+    try {
+        const secret = await decryptWithPassword(
+            wallet.encryptedSecret,
+            password,
+        );
+        // The only suspension point in this view, and the gate on the only
+        // place a secret is written: if the screen was left while the
+        // decrypt ran, the wipe has already happened, so the key is not
+        // even derived, let alone written.
+        if (!isCurrentReveal(generation)) return;
+        const signer = getSignerForAddress(wallet, addressIndex, secret);
+        $("export-privkey-password").value = "";
+        $("export-privkey-password-section").classList.add("hidden");
+        $("export-privkey-value").textContent = signer.privateKey;
+        $("export-privkey-result").classList.remove("hidden");
+        $("export-privkey-flash").textContent = "";
+        $("export-privkey-flash").style.visibility = "hidden";
+    } catch {
+        if (!isCurrentReveal(generation)) return;
+        fail("That password is not correct. Please try again.");
+    } finally {
+        btn.disabled = false;
+        btn.classList.remove("text-muted");
+    }
+}
+
+function init() {
+    onViewLeave(VIEW, clear);
+
+    // No wipe here: goBack() routes through showView(), which runs the
+    // leave hook. A per-button wipe would only cover this one path.
+    $("btn-export-privkey-back").addEventListener("click", () => {
+        goBack();
+    });
+
+    $("btn-export-privkey-confirm").addEventListener("click", reveal);
+
+    $("export-privkey-value").addEventListener("click", () => {
+        const key = $("export-privkey-value").textContent;
+        if (!key) return;
+        navigator.clipboard.writeText(key);
+        showFlash("Copied!");
+        flashCopyFeedback($("export-privkey-value"));
+    });
+}
+
+module.exports = { init, show };

tests/exportPrivkey.test.js

@@ -0,0 +1,331 @@
+// Tests for the private key export screen (issue #221).
+//
+// The screen holds the one secret that owns an address outright, so what is
+// pinned here is disposal: the key is wiped from the DOM whenever the screen
+// is left by any route, and a decrypt still in flight when the screen is
+// left never writes at all. That last case is the one a per-button wipe and
+// a naive leave hook both miss — the write lands after the wipe, with
+// nothing scheduled to wipe it again.
+//
+// The view is driven against a minimal DOM stub rather than a real browser:
+// the module is deliberately shaped like src/popup/views/showPhrase.js, with
+// no dependency that needs a document beyond the nodes it reads and writes.
+
+const mockPrivateKey = "0x" + "ab".repeat(32);
+
+jest.mock("ethereum-blockies-base64", () => () => "data:image/png;base64,x");
+jest.mock("../src/shared/vault", () => ({
+    decryptWithPassword: jest.fn(),
+}));
+jest.mock("../src/shared/wallet", () => ({
+    getSignerForAddress: jest.fn(() => ({ privateKey: mockPrivateKey })),
+}));
+
+const { RESTORABLE_VIEWS } = require("../src/popup/restorableViews");
+
+const VIEW = "export-privkey";
+const PASSWORD = "correct horse battery";
+
+// ------------------------------------------------------------ DOM stub
+
+function makeElement(id, withParent) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        listeners: {},
+        classList: {
+            add: (...names) => names.forEach((n) => classes.add(n)),
+            remove: (...names) => names.forEach((n) => classes.delete(n)),
+            contains: (n) => classes.has(n),
+            toggle: (n, force) => {
+                const on = force === undefined ? !classes.has(n) : force;
+                if (on) classes.add(n);
+                else classes.delete(n);
+                return on;
+            },
+        },
+        addEventListener: (name, fn) => {
+            el.listeners[name] = el.listeners[name] || [];
+            el.listeners[name].push(fn);
+        },
+        appendChild: () => {},
+        remove: () => {},
+        querySelectorAll: () => [],
+    };
+    el.parentElement = withParent ? makeElement(id + "-parent", false) : null;
+    return el;
+}
+
+function makeDocument() {
+    const els = new Map();
+    return {
+        getElementById(id) {
+            // The debug banner is created on demand by helpers.js; absent
+            // is the state a non-debug, non-testnet popup is in.
+            if (id === "debug-banner") return null;
+            if (!els.has(id)) els.set(id, makeElement(id, true));
+            return els.get(id);
+        },
+        createElement: () => makeElement("created", false),
+        addEventListener: () => {},
+        body: { prepend: () => {} },
+    };
+}
+
+// ------------------------------------------------------------ harness
+
+function load() {
+    jest.resetModules();
+    globalThis.chrome = {
+        storage: { local: { get: async () => ({}), set: async () => {} } },
+    };
+    globalThis.document = makeDocument();
+
+    const helpers = require("../src/popup/views/helpers");
+    const { state } = require("../src/shared/state");
+    const vault = require("../src/shared/vault");
+    const wallet = require("../src/shared/wallet");
+    const exportPrivkey = require("../src/popup/views/exportPrivkey");
+
+    state.wallets = [
+        {
+            name: "Wallet 1",
+            type: "key",
+            encryptedSecret: "ciphertext",
+            addresses: [
+                {
+                    address: "0x" + "11".repeat(20),
+                    balance: "0.0000",
+                    tokenBalances: [],
+                },
+                {
+                    address: "0x" + "22".repeat(20),
+                    balance: "0.0000",
+                    tokenBalances: [],
+                },
+            ],
+        },
+    ];
+    state.viewStack = [];
+    state.currentView = "address";
+
+    exportPrivkey.init();
+    return { helpers, state, vault, wallet, exportPrivkey };
+}
+
+function click(id) {
+    const el = globalThis.document.getElementById(id);
+    return Promise.all((el.listeners.click || []).map((fn) => fn()));
+}
+
+function node(id) {
+    return globalThis.document.getElementById(id);
+}
+
+// Start a reveal and hand back both the promise it returns and the resolver
+// for the decrypt it is waiting on, so a test can navigate away mid-flight.
+function startReveal(vault) {
+    let resolveDecrypt;
+    let rejectDecrypt;
+    vault.decryptWithPassword.mockImplementation(
+        () =>
+            new Promise((resolve, reject) => {
+                resolveDecrypt = resolve;
+                rejectDecrypt = reject;
+            }),
+    );
+    node("export-privkey-password").value = PASSWORD;
+    const pending = click("btn-export-privkey-confirm");
+    return {
+        pending,
+        resolve: (v) => resolveDecrypt(v),
+        reject: (e) => rejectDecrypt(e),
+    };
+}
+
+// ------------------------------------------------------------ tests
+
+describe("a decrypt still running when the screen is left", () => {
+    // The load-bearing case. Without the liveness guard in reveal(), the
+    // write lands after the leave hook has already wiped, and the key sits
+    // in the hidden view for the life of the popup.
+    test("never writes the key into the DOM", async () => {
+        const { helpers, vault, wallet, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const reveal = startReveal(vault);
+        // The settings gear, mid-decrypt.
+        helpers.showView("settings");
+        reveal.resolve("wallet secret");
+        await reveal.pending;
+
+        expect(node("export-privkey-value").textContent).toBe("");
+        // Nothing was even derived: the guard sits in front of the
+        // derivation, not just in front of the write.
+        expect(wallet.getSignerForAddress).not.toHaveBeenCalled();
+    });
+
+    // The generation counter, not merely the current-view check: by the time
+    // the stale decrypt resolves the user is back on the screen, so a guard
+    // that only asked "is this view showing?" would let the write through.
+    test("never writes it after the screen is re-entered", async () => {
+        const { helpers, vault, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const stale = startReveal(vault);
+        helpers.showView("settings");
+        exportPrivkey.show(0, 1);
+        expect(node("export-privkey-value").textContent).toBe("");
+
+        stale.resolve("wallet secret");
+        await stale.pending;
+
+        expect(node("export-privkey-value").textContent).toBe("");
+        expect(node("export-privkey-result").classList.contains("hidden")).toBe(
+            true,
+        );
+    });
+
+    // Same hole on the failure path: a wrong-password error written after
+    // the wipe would restore the flash line on a screen the user has left.
+    test("never writes the failure message either", async () => {
+        const { helpers, vault, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const reveal = startReveal(vault);
+        helpers.showView("settings");
+        reveal.reject(new Error("decryption failed"));
+        await reveal.pending;
+
+        expect(node("export-privkey-flash").textContent).toBe("");
+        expect(node("export-privkey-flash").style.visibility).toBe("hidden");
+    });
+});
+
+describe("a reveal that is not interrupted", () => {
+    // Guards the guard: a liveness check that rejected every write would
+    // pass every test above and ship a screen that reveals nothing.
+    test("puts the key on screen", async () => {
+        const { vault, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const reveal = startReveal(vault);
+        reveal.resolve("wallet secret");
+        await reveal.pending;
+
+        expect(node("export-privkey-value").textContent).toBe(mockPrivateKey);
+        expect(node("export-privkey-result").classList.contains("hidden")).toBe(
+            false,
+        );
+        // The password is dropped as soon as it has been spent.
+        expect(node("export-privkey-password").value).toBe("");
+    });
+
+    test("writes nothing before the password is accepted", async () => {
+        const { vault, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const reveal = startReveal(vault);
+        expect(node("export-privkey-value").textContent).toBe("");
+        reveal.resolve("wallet secret");
+        await reveal.pending;
+    });
+
+    test("reveals nothing when the password is wrong", async () => {
+        const { vault, exportPrivkey } = load();
+        exportPrivkey.show(0, 0);
+
+        const reveal = startReveal(vault);
+        reveal.reject(new Error("decryption failed"));
+        await reveal.pending;
+
+        expect(node("export-privkey-value").textContent).toBe("");
+        expect(node("export-privkey-flash").textContent).toBe(
+            "That password is not correct. Please try again.",
+        );
+    });
+});
+
+describe("leaving the screen after the key is on it", () => {
+    async function revealed() {
+        const loaded = load();
+        loaded.exportPrivkey.show(0, 0);
+        const reveal = startReveal(loaded.vault);
+        reveal.resolve("wallet secret");
+        await reveal.pending;
+        expect(node("export-privkey-value").textContent).toBe(mockPrivateKey);
+        return loaded;
+    }
+
+    test("the Back button clears the key", async () => {
+        await revealed();
+        await click("btn-export-privkey-back");
+
+        expect(node("export-privkey-value").textContent).toBe("");
+        expect(node("export-privkey-password").value).toBe("");
+    });
+
+    test("the settings gear clears the key", async () => {
+        const { helpers } = await revealed();
+        helpers.showView("settings");
+
+        expect(node("export-privkey-value").textContent).toBe("");
+        expect(node("export-privkey-password").value).toBe("");
+        // And the screen is back to its password prompt, not to a result
+        // panel that would flash an empty well on the next visit.
+        expect(node("export-privkey-result").classList.contains("hidden")).toBe(
+            true,
+        );
+        expect(
+            node("export-privkey-password-section").classList.contains(
+                "hidden",
+            ),
+        ).toBe(false);
+    });
+
+    // Any other navigation: the same hook covers routes that do not exist
+    // yet, which is the point of registering it on the view rather than on
+    // the controls that leave it.
+    test("any other navigation clears the key", async () => {
+        const { helpers } = await revealed();
+        helpers.showView("main");
+
+        expect(node("export-privkey-value").textContent).toBe("");
+    });
+});
+
+describe("views the popup may reopen onto", () => {
+    // Restoring onto this screen would put a private key on display with no
+    // password prompt in front of it, on a popup reopened by accident.
+    test("the private key export screen is not restorable", () => {
+        expect(RESTORABLE_VIEWS.has(VIEW)).toBe(false);
+    });
+
+    test("it is still a registered view", () => {
+        const { helpers } = load();
+        expect(helpers.VIEWS).toContain(VIEW);
+    });
+});
+
+describe("the key cannot reach the logger", () => {
+    const fs = require("fs");
+    const path = require("path");
+    const source = fs.readFileSync(
+        path.join(__dirname, "..", "src", "popup", "views", "exportPrivkey.js"),
+        "utf8",
+    );
+
+    test("the view does not import src/shared/log.js", () => {
+        expect(source).not.toMatch(/require\(["'][^"']*shared\/log["']\)/);
+    });
+
+    test("the view calls no logger method", () => {
+        expect(source).not.toMatch(/\blog\.(debugf|infof|warnf|errorf)\b/);
+    });
+});