test: known-answer coverage for HD derivation and the vault (closes #159 )

wallet.js and vault.js — the two modules that hold user funds — had no derivation or encryption tests. Add them, pinned to published vectors rather than to whatever the implementation returns today. wallet.js: hdWalletFromMnemonic, hdWalletFromXprv, deriveAddressFromXpub and getSignerForAddress are pinned to the standard development recovery phrase's first three accounts at m/44'/60'/0'/0/n and to the BIP-39 all-zero-entropy phrase's first address; addressFromPrivateKey is pinned to the published key/address pairs, so the HD path and the bare-key path must meet at the same address from two directions. isValidMnemonic and isValidXprv cover bad checksum, wrong word count, wrong key type and empty/garbage input. The absolute-vs-relative path asymmetry between hdWalletFromMnemonic and hdWalletFromXprv is proven harmless: for the same master key both reach the same xpub and the same addresses. vault.js: round trip (including non-ASCII and an empty password), wrong password rejected as a rejected promise with no partial plaintext, tampered ciphertext / auth tag / nonce / salt rejected, truncated and spliced blobs rejected, missing fields rejected, fresh salt and nonce per encryption, the documented { salt, nonce, ciphertext } shape, and no trace of the plaintext or password anywhere in the serialized blob. The Argon2id cost parameters are pinned three ways — the INTERACTIVE constants still mean 2 passes over 64 MiB, a key independently derived at that cost opens the vault, and both encrypt and decrypt are observed calling crypto_pwhash with those constants — because the KDF cost is the vault's only defence against offline attack on a stolen blob and nothing else in the suite would notice it being lowered. The tamper cases share one encrypted fixture to stay inside script/test's 30-second budget. One test is skipped: isValidXprv accepts an extended private key with a one-character typo, because ethers skips base58 checksum verification for the usual 82-byte payload. That defect is tracked separately and is not fixed here; the skipped test asserts the correct behaviour and cites the issue.
docs: correct three README claims contradicted by the code (closes #213 )
2026-08-11 12:48:38 +00:00 · 2026-08-11 14:41:16 +02:00 · 2026-08-11 14:31:45 +02:00
4 changed files with 995 additions and 137 deletions
--- a/README.md
+++ b/README.md
@@ -271,10 +271,10 @@ on a different table knows exactly tf I am talking about.

 Every interactive element must visually indicate that it is clickable. Buttons
 use a visible border, padding, and a hover state (invert to white-on-black).
-Text that triggers an action (e.g. "Import private key") uses an underline. No
-invisible hit targets, no bare text that happens to have a click handler. If it
-does something when you click it, it must look like it does something when you
-click it.
+Text that triggers an action (e.g. "Add additional wallet...") uses an
+underline. No invisible hit targets, no bare text that happens to have a click
+handler. If it does something when you click it, it must look like it does
+something when you click it.

 #### Display Consistency

@@ -334,115 +334,181 @@ attack.

 The core hierarchy is **Wallets → Addresses**:

- A **wallet** is either:
-    - An **HD wallet** (recovery phrase): generates multiple addresses from a
-      single 12/24 word recovery phrase using BIP-39/BIP-44 derivation. The user
-      can add more addresses with a "+" button.
-    - A **key wallet** (private key): a single address imported directly from a
-      private key. No "+" button since there is only one address.
- An **address** holds ETH and any user-added ERC-20 tokens.
+- A **wallet** is one of three types:
+    - An **HD wallet** (`type: "hd"`, recovery phrase): generates multiple
+      addresses from a single 12/24 word recovery phrase using BIP-39/BIP-44
+      derivation. The user can add more addresses with a "+" button.
+    - A **key wallet** (`type: "key"`, private key): a single address imported
+      directly from a private key. No "+" button since there is only one
+      address.
+    - An **xprv wallet** (`type: "xprv"`, extended private key): the same
+      multi-address behavior as an HD wallet, including the "+" button and the
+      address scan on import, but imported from an extended private key rather
+      than a recovery phrase. It therefore has no recovery phrase to display or
+      back up.
+- An **address** holds ETH and ERC-20 tokens.
 - The user can have multiple wallets, each with multiple addresses (HD) or a
  single address (key).

+Which tokens an address shows is decided by `fetchTokenBalances()` in
+`src/shared/balances.js`, from the Blockscout `token-balances` response, so
+tokens do appear without the user adding them. An ERC-20 is shown when its
+balance is nonzero and it is in the bundled top-250 token list, is tracked by
+the user, or has 1,000 or more holders; a token claiming a symbol from the
+bundled list from any other contract address is always dropped. That filter is
+unconditional — the "Hide tokens with fewer than 1,000 holders" setting governs
+the transaction history and the send-screen token selector, not this list.
+Tracked tokens with a zero balance are listed as well while "Show tracked tokens
+with zero balance" is on.
+
 #### Navigation

 The main view shows all addresses grouped by wallet, with ETH balances inline.
 The user taps an address to see its detail view (full address, balance, tokens,
-send/receive). Navigation is flat — every view has a "Back" or "Cancel" button
-that returns to the previous context. No deep nesting, no tabs, no hamburger
-menus.
+send/receive). Navigation is a stack: each forward action pushes the current
+screen, and every view has a "Back" or "Cancel" button that pops back to it (see
+the Screen Map below). There is no hamburger menu and no persistent tab bar; the
+Settings gear in the title bar is the only global control. Two screens carry an
+in-screen control beyond that: AddWallet uses three tabs to select the import
+mode, and AddressDetail keeps its one rarely-used action ("Export Private Key")
+behind a "···" menu.

 ### Screen Map

-Navigation uses a stack model (like iOS): each action pushes a screen onto the
-stack, and "Back" pops it. The root screen is either Welcome (no wallets) or
-Home (has wallets). Screens are listed below with their elements and
-transitions.
+Navigation uses a stack model (like iOS): each forward action pushes the current
+screen onto `state.viewStack`, and "Back" pops it (`pushCurrentView()` and
+`goBack()` in `src/popup/views/helpers.js`). The root screen is either Welcome
+(no wallets) or Home (has wallets). Each screen below gives its view id in
+parentheses; the registry of view ids is the `VIEWS` array in
+`src/popup/views/helpers.js`, and the markup for a screen is the element with id
+`view-` plus that view id in `src/popup/index.html`.

-#### Welcome
+Three elements sit outside the screens and are present on all of them: the title
+bar ("AutistMask by @sneak" plus the Settings gear), the flash message line
+under it, and the red banner at the very top that appears on a debug build, when
+runtime debug mode is on, or when the active network is a testnet. They are not
+repeated in the element lists below.

- **When**: No wallets exist yet.
- **Elements**: "AutistMask" heading, brief intro text, "Add wallet" button.
+Closing and reopening the popup returns to the screen the user was last on only
+for the views listed in `RESTORABLE_VIEWS` (`src/popup/index.js`). Every other
+screen, including ExportPrivKey, falls back to Home.
+
+#### Welcome (`welcome`)
+
+- **When**: No wallets exist yet (`state.hasWallet` is false). This is the root
+  screen in that case.
+- **Elements**:
+    - "Welcome! To get started, add a wallet." text
+    - "Add wallet" button
 - **Transitions**:
    - "Add wallet" → **AddWallet**

-#### Home
+#### Home (`main`)

 - **When**: At least one wallet exists. This is the root screen.
 - **Elements**:
-    - Header: "AutistMask", Settings gear button
-    - Active address ETH balance (large) + USD value (inline parentheses)
-    - Total USD value across all tokens (small text)
+    - Active address ETH balance (large) + USD value in parentheses
+    - "Total:" USD value across ETH and every token shown for the active address
    - Active address (color dot, full address, etherscan link, tap to copy)
-    - Send / Receive quick-action buttons
+    - Send / Receive quick-action buttons, both acting on the active address
    - ETH/USD price display
-    - Wallet list: each wallet shows name (tap to rename), "+" button (HD only),
-      and its addresses with color dots, balances, and `[info]` buttons
-    - Recent transactions across all addresses (merged, deduplicated, filtered)
+    - Wallet list: each wallet shows its name (tap to rename inline) and a "+"
+      button for HD and xprv wallets, then one block per address with "Address
+      N" (bold when active), the ENS name if resolved, the full address, an
+      `[info]` button, the address USD total, and a balance line for ETH and for
+      each token shown for that address
+    - "Recent Transactions": up to 25 transactions merged across every address
+      of every wallet, deduplicated by hash and filtered
    - "Add additional wallet..." link at bottom
 - **Transitions**:
-    - Tap address row → sets active address (no screen change)
+    - Tap address row → sets the active address and broadcasts
+      `AUTISTMASK_ACTIVE_CHANGED` (no screen change)
+    - Tap wallet name → inline rename field (no screen change)
+    - "+" on wallet → derives the next address inline (no screen change)
    - `[info]` on address → **AddressDetail**
-    - "Send" → **Send** (selects active address)
+    - "Send" → **Send** (refuses with a flash message on a zero balance)
    - "Receive" → **Receive** (shows active address QR)
-    - "+" on wallet → derives next address inline
+    - Tap home tx row → **TransactionDetail**
    - "Add additional wallet..." → **AddWallet**
    - Settings gear → **Settings** (toggles; tap again to return)
-    - Tap home tx row → **AddressDetail** (for the address involved)

-#### AddWallet
+#### AddWallet (`add-wallet`)

- **When**: User wants to add a new wallet (from Home, Welcome, or Settings).
+- **When**: User wants to add a new wallet (from Welcome, Home, or Settings).
+  This one screen covers all three import modes; there is no separate import
+  screen.
 - **Elements**:
-    - "Add Wallet" heading, "Back" button
-    - Instruction text
-    - Die button `[die]` (generates random recovery phrase)
-    - Recovery phrase textarea
-    - Backup warning box (shown after die is clicked)
-    - Password + confirm password inputs
-    - "Add" button
-    - "Have a private key instead?" link
- **Transitions**:
-    - "Add" (valid phrase + password) → **Home**
-    - "Back" → previous screen (Home or Welcome)
-    - "Have a private key instead?" → **ImportKey**
-
-#### ImportKey
-
- **When**: User wants to import a single private key.
- **Elements**:
-    - "Import Private Key" heading, "Back" button
-    - Instruction text
-    - Private key input (password-masked)
-    - Password + confirm password inputs
+    - "Back" button, "Add Wallet" heading
+    - Three tabs — "From Phrase" (`tab-mnemonic`), "From Key" (`tab-privkey`),
+      "From xprv" (`tab-xprv`) — each showing its own form section:
+        - **From Phrase**: instruction text, a die button that generates a
+          random recovery phrase, a recovery phrase textarea, and a backup
+          warning box that becomes visible once the die button has been used
+        - **From Key**: instruction text and a masked private key input
+        - **From xprv**: instruction text and a masked extended private key
+          input
+    - Password + confirm password inputs, with a hint line whose wording depends
+      on the selected tab
    - "Import" button
 - **Transitions**:
-    - "Import" (valid key + password) → **Home**
-    - "Back" → **AddWallet**
+    - "Import" with a valid entry and a matching password of at least 12
+      characters → creates the wallet, clears the navigation stack, and →
+      **Home**. The phrase and xprv modes then scan for further used addresses
+      and report the count as a flash message.
+    - "Import" with an invalid entry, a duplicate wallet or address, or a short
+      or mismatched password → flash message, no screen change
+    - "Back" → previous screen (Welcome, Home, or Settings)

-#### AddressDetail
+#### AddressDetail (`address`)

 - **When**: User tapped `[info]` on an address from Home.
 - **Elements**:
    - "Back" button
    - Blockie identicon (48px, centered)
    - Title: "Wallet Name — Address N"
-    - ENS name (if resolved, bold with color dot)
+    - ENS name (if resolved, bold above the address)
    - Full address (color dot, etherscan link, tap to copy)
    - USD total for address
-    - Balance list: ETH + tracked ERC-20 tokens (4 decimal places, USD inline).
-      Each balance row is clickable → **AddressToken**
-    - Send / Receive / + Token buttons
+    - Balance list: ETH + the ERC-20 tokens shown for this address (4 decimal
+      places, USD inline). Each balance row is clickable → **AddressToken**
+    - Send / Receive / + Token buttons and a "···" menu button
+    - "···" dropdown containing a single "Export Private Key" entry
    - Transaction list (with ENS resolution for counterparties)
 - **Transitions**:
    - Tap balance row → **AddressToken** (for that token)
-    - "Send" → **Send**
+    - "Send" → **Send** (refuses with a flash message on a zero balance)
    - "Receive" → **Receive**
    - "+ Token" → **AddToken**
+    - "···" → "Export Private Key" → **ExportPrivKey**
    - Tap transaction row → **TransactionDetail**
-    - "Back" → **Home**
+    - "Back" → previous screen (Home)

-#### AddressToken
+#### ExportPrivKey (`export-privkey`)
+
+- **When**: User chose "Export Private Key" from the "···" menu on
+  AddressDetail. This screen discloses secret material.
+- **Elements**:
+    - "Back" button
+    - Blockie identicon (48px, centered)
+    - "Export Private Key" heading
+    - "Wallet Name — Address N" and the full address (etherscan link, tap to
+      copy)
+    - Warning that anyone holding the private key can transfer all funds from
+      the address
+    - Error line
+    - Password input and "Reveal" button, shown until the key is revealed
+    - The private key on a highlighted background, tap to copy, shown only after
+      the password has been accepted
+- **Transitions**:
+    - "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)
+
+#### AddressToken (`address-token`)

 - **When**: User clicked a specific token balance on AddressDetail.
 - **Elements**:
@@ -453,49 +519,64 @@ transitions.
    - USD total for this token
    - Single token balance line (4 decimal places)
    - Send / Receive buttons
+    - Token contract well (ERC-20 only): full contract address (tap to copy,
+      etherscan link) plus name, symbol, decimals, holder count and project
+      website where known
    - Token-filtered transaction list (only this token's transfers)
 - **Transitions**:
-    - "Send" → **Send** (token pre-selected and locked in dropdown)
+    - "Send" → **Send** (token locked: the dropdown is replaced by a static
+      symbol and contract address)
    - "Receive" → **Receive** (ERC-20 warning shown for non-ETH tokens)
    - Tap transaction row → **TransactionDetail**
-    - "Back" → **AddressDetail**
+    - "Back" → previous screen (AddressDetail)

-#### Send
+#### Send (`send`)

- **When**: User wants to send ETH or a token from this address.
+- **When**: User wants to send ETH or a token, from Home, AddressDetail, or
+  AddressToken.
 - **Elements**:
-    - "Send" heading, "Back" button
+    - "Back" button, "Send" heading
    - From: address with color dot + etherscan link
    - What to send: token dropdown (or static display with contract address when
      locked from AddressToken)
-    - To: address or ENS name input
+    - To: address or ENS name input, with an inline validation message
    - Amount input with current balance display
-    - "Review" button
+    - "Review" button, disabled until the recipient validates
 - **Transitions**:
    - "Review" (valid inputs, ENS resolved) → **ConfirmTx**
-    - "Back" → **AddressToken** (if came from token view) or **AddressDetail**
+    - "Review" with an unresolvable ENS name or an invalid amount → flash
+      message, no screen change
+    - "Back" → previous screen (Home, AddressDetail, or AddressToken)

-#### ConfirmTx
+#### ConfirmTx (`confirm-tx`)

 - **When**: User reviewed send details and is ready to authorize.
 - **Elements**:
-    - "Confirm Transaction" heading, "Back" button
+    - "Back" button, "Confirm Transaction" heading
    - Type: "Native ETH transfer" or "ERC-20 token transfer (SYMBOL)"
    - Token contract: full address + etherscan link (ERC-20 only)
    - From: blockie + color dot + full address + etherscan link + wallet title
    - To: blockie + color dot + full address + etherscan link + ENS name
    - Amount: value + symbol (USD in parentheses)
    - Your balance: value + symbol (USD in parentheses)
-    - Estimated network fee: ETH amount (USD in parentheses), fetched async
-    - Warnings (scam address, self-send)
+    - Estimated network fee: "Estimating..." then the ETH amount (USD in
+      parentheses) or "Unable to estimate", fetched async
+    - Warnings: inline warnings from the local checks (scam address, self-send)
+      plus four reserved warning boxes made visible by the async checks —
+      recipient with no transaction history, recipient is a contract, burn
+      address, and an Etherscan phishing/scam label
    - Errors (insufficient balance)
-    - "Send" button (disabled if errors)
+    - Password: an inline field on this screen, not a modal, with its own error
+      line
+    - "Sign & Send" button (disabled if errors)
 - **Transitions**:
-    - "Send" → password modal → broadcast tx → **WaitTx**
-    - "Send" → password modal → broadcast fails → **ErrorTx**
+    - "Sign & Send" (correct password) → broadcast tx → **WaitTx**
+    - "Sign & Send" (correct password) → broadcast fails → **ErrorTx**
+    - "Sign & Send" (wrong password) → "Wrong password." on the password error
+      line, no screen change
    - "Back" → **Send**

-#### WaitTx
+#### WaitTx (`wait-tx`)

 - **When**: Transaction has been broadcast, waiting for on-chain confirmation.
 - **Elements**:
@@ -509,20 +590,24 @@ transitions.
    - Receipt found → **SuccessTx**
    - 60 seconds without confirmation → **ErrorTx** (timeout message)

-#### SuccessTx
+#### SuccessTx (`success-tx`)

 - **When**: Transaction confirmed on-chain.
 - **Elements**:
    - "Transaction Confirmed" heading
+    - Decoded action well (shown when the transaction carried recognized
+      calldata; the top-level Amount and To are hidden in that case)
    - Amount + symbol
    - To: color dot + full address + etherscan link
    - Block number
    - Transaction hash: full hash (tap to copy) + etherscan link
    - "Done" button
 - **Transitions**:
-    - "Done" → **AddressToken** (if `selectedToken` set) or **AddressDetail**
+    - "Done" in the approval popup → closes the popup window
+    - "Done" otherwise → resets the navigation stack, then → **AddressToken**
+      (if `selectedToken` set) or **AddressDetail**

-#### ErrorTx
+#### ErrorTx (`error-tx`)

 - **When**: Transaction broadcast failed, or timed out waiting for confirmation.
 - **Elements**:
@@ -534,24 +619,28 @@ transitions.
      full hash (tap to copy) + etherscan link
    - "Done" button
 - **Transitions**:
-    - "Done" → **AddressToken** (if `selectedToken` set) or **AddressDetail**
+    - "Done" in the approval popup → closes the popup window
+    - "Done" otherwise → resets the navigation stack, then → **AddressToken**
+      (if `selectedToken` set) or **AddressDetail**

-#### Receive
+#### Receive (`receive`)

- **When**: User wants to receive funds at this address.
+- **When**: User wants to receive funds at this address, from Home,
+  AddressDetail, or AddressToken.
 - **Elements**:
-    - "Receive" heading, "Back" button
+    - "Back" button, "Receive" heading
    - Instruction text
    - QR code encoding the address
    - Full address (color dot, selectable, etherscan link)
    - "Copy address" button
    - ERC-20 warning (shown when navigating from AddressToken for non-ETH token)
 - **Transitions**:
-    - "Back" → **AddressToken** (if `selectedToken` set) or **AddressDetail**
+    - "Back" → previous screen (Home, AddressDetail, or AddressToken)

-#### TransactionDetail
+#### TransactionDetail (`transaction`)

- **When**: User tapped a transaction row from AddressDetail or AddressToken.
+- **When**: User tapped a transaction row on Home, AddressDetail, or
+  AddressToken.
 - **Elements** (grouped into logical blocks using light well containers; field
  labels are self-explanatory so groups have no headings):
    - "Transaction" heading, "Back" button
@@ -576,91 +665,182 @@ transitions.
    - Raw data (shown when calldata is present): full calldata in monospace
      dashed border
 - **Transitions**:
-    - "Back" → **AddressToken** (if `selectedToken` set) or **AddressDetail**
+    - "Back" → previous screen (Home, AddressDetail, or AddressToken)

-#### AddToken
+#### AddToken (`add-token`)

- **When**: User wants to track an ERC-20 token on this address.
+- **When**: User wants to track an ERC-20 token, reached from "+ Token" on
+  AddressDetail.
 - **Elements**:
-    - "Add Token" heading, "Back" button
+    - "Back" button, "Add Token" heading
    - Instruction text (find contract address on Etherscan)
    - Contract address input
-    - Token info preview (name, symbol — fetched from contract)
-    - Common token quick-pick buttons
+    - Status line ("Looking up token...", cleared or replaced on failure)
+    - Common token quick-pick buttons (top 25 by market cap), which fill the
+      contract address input
    - "Add" button
 - **Transitions**:
-    - "Add" (valid contract) → **AddressDetail**
-    - "Back" → **AddressDetail**
+    - "Add" (valid contract) → tracks the token, pops the stack, and re-renders
+      **AddressDetail**
+    - "Add" with a token already tracked, a scam-listed address, or a failed
+      contract lookup → flash message, no screen change
+    - "Back" → previous screen (AddressDetail)

-#### Settings
+#### Settings (`settings`)

- **When**: User tapped Settings gear from Home.
+- **When**: User tapped the Settings gear.
 - **Elements**:
-    - "Settings" heading, "Back" button
-    - Wallets: "+ Add wallet" button
-    - Display: "Show tracked tokens with zero balance" checkbox
-    - Ethereum RPC: endpoint URL input + "Save" button
-    - Blockscout API: endpoint URL input + "Save" button
+    - "Back" button, "Settings" heading
+    - Wallets: one row per wallet with its name (tap to rename inline) and an
+      `[x]` delete button, plus a "+ Add wallet" button
+    - Tracked Tokens: one row per tracked token with an `[x]` remove button,
+      plus a "+ Add token" button
+    - Display: "Show tracked tokens with zero balance" checkbox and a Theme
+      selector (System / Light / Dark)
+    - Network: network selector (Ethereum Mainnet / Sepolia Testnet); switching
+      resets the RPC and Blockscout endpoints to that network's defaults
+    - Ethereum RPC: endpoint URL input + "Save" button (validated against
+      `eth_chainId` before being saved)
+    - Blockscout API: endpoint URL input + "Save" button (validated against
+      `/stats` before being saved)
    - Token Spam Protection:
        - "Hide tokens with fewer than 1,000 holders" checkbox
        - "Hide transactions from detected fraud contracts" checkbox
        - "Hide dust transactions below N gwei" checkbox + threshold input
+        - "UTC Timestamps" checkbox
    - Allowed Sites: list with remove buttons
    - Denied Sites: list with remove buttons
+    - About: project link, license, author, version, release date, and the
+      commit, which links to the commit in the repository
+    - Debug: hidden until revealed, then an "Enable debug mode" checkbox that
+      turns on the red banner and verbose logging
 - **Transitions**:
    - "+ Add wallet" → **AddWallet**
-    - "Back" (or Settings gear again) → **Home**
+    - "+ Add token" → **SettingsAddToken**
+    - `[x]` on a wallet → **DeleteWallet**
+    - Tap wallet name → inline rename field (no screen change)
+    - `[x]` on a tracked token or a site → removes it in place (no screen
+      change)
+    - Ten clicks on the version → reveals the Debug well (no screen change)
+    - "Back" (or Settings gear again) → previous screen (Home)

-#### SiteApproval
+#### DeleteWallet (`delete-wallet-confirm`)

- **When**: A website requests wallet access via `eth_requestAccounts`. Opened
-  in a separate popup by the background script.
+- **When**: User tapped the `[x]` next to a wallet in Settings.
+- **Elements**:
+    - "Back" button, "Delete Wallet" heading
+    - Warning naming the wallet and stating that deletion is permanent and any
+      funds are unrecoverable without the recovery phrase
+    - Error line
+    - Password input
+    - "Confirm Delete" button
+- **Transitions**:
+    - "Confirm Delete" (correct password, other wallets remain) → deletes the
+      wallet and its site permissions, then → **Settings** with a "Wallet
+      deleted." flash message
+    - "Confirm Delete" (correct password, last wallet) → deletes the wallet,
+      clears the selection and the navigation stack, then → **Welcome**
+    - Either way, the active address moves only if it belonged to the deleted
+      wallet, and `AUTISTMASK_ACTIVE_CHANGED` is broadcast when it does
+      (`src/shared/walletDelete.js`)
+    - "Confirm Delete" (wrong password) → "Wrong password." on the error line,
+      nothing deleted
+    - "Back" → previous screen (Settings)
+
+#### SettingsAddToken (`settings-addtoken`)
+
+- **When**: User tapped "+ Add token" in Settings. Tokens added here are tracked
+  across every address, unlike AddToken which is reached from one address.
+- **Elements**:
+    - "Back" button, "Add Token" heading
+    - Instruction text
+    - "Top tokens:" quick-pick buttons (top 10 by market cap; already-tracked
+      tokens are disabled)
+    - "Or pick from top 100:" dropdown (already-tracked tokens are disabled) +
+      "Add selected" button
+    - "Or enter contract address:" input, a status line, and an "Add" button
+- **Transitions**:
+    - Any of the three add paths, on success → adds the token and shows an
+      "Added SYMBOL" flash message (no screen change)
+    - A duplicate, a scam-listed address, or a failed contract lookup → flash
+      message, no screen change
+    - "Back" → previous screen (Settings)
+
+#### SiteApproval (`approve-site`)
+
+- **When**: A website requests wallet access via `eth_requestAccounts` or
+  `wallet_requestPermissions` and is on neither the allowed nor the denied list.
+  The background script prefers the toolbar popup (`action.openPopup()`) and
+  falls back to a separate popup window (`src/background/index.js`,
+  `requestApproval()`).
 - **Elements**:
    - "Connection Request" heading
-    - Site hostname (bold)
+    - Phishing warning banner (shown when the hostname is on the phishing
+      blocklist)
+    - Site hostname (bold) + "wants to connect to your wallet"
    - Address that will be shared (color dot + full address + etherscan link)
    - "Remember my choice for this site" checkbox
    - "Allow" / "Deny" buttons
 - **Transitions**:
-    - "Allow" / "Deny" → closes popup (returns result to background script)
+    - "Allow" / "Deny" → closes popup (returns result to background script; the
+      choice is persisted to the allowed or denied list when "Remember" is
+      checked)
+    - Popup closed without answering → treated as a denial

-#### TxApproval
+#### TxApproval (`approve-tx`)

 - **When**: A connected website requests a transaction via
-  `eth_sendTransaction`. Opened via the toolbar popup by the background script.
+  `eth_sendTransaction`. Always opened in a separate popup window by the
+  background script (`windows.create()`), because the request is triggered
+  programmatically rather than by a user gesture.
 - **Elements**:
    - "Transaction Request" heading
+    - Phishing warning banner (shown when the hostname is on the phishing
+      blocklist)
    - Site hostname (bold) + "wants to send a transaction"
    - Decoded action (if calldata is recognized): action name, token details,
      amounts, steps, deadline (see Transaction Decoding)
    - From: color dot + full address + etherscan link
-    - To/Contract: color dot + full address + etherscan link (or "contract
+    - Contract: color dot + full address + etherscan link (or "contract
      creation"), token symbol label if known
-    - Value: amount in ETH (4 decimal places)
+    - Value: amount in ETH (4 decimal places, USD in parentheses)
    - Raw data: full calldata displayed inline (shown if present)
-    - Password input
+    - Password input and an error line
    - "Confirm" / "Reject" buttons
 - **Transitions**:
-    - "Confirm" (with password) → closes popup (returns result to background)
+    - "Confirm" (correct password) → decrypts and signs in the popup, hands the
+      signed transaction to the background to broadcast, then → **WaitTx** in
+      the same popup window
+    - "Confirm" (wrong password) → error line, no screen change
    - "Reject" → closes popup (returns rejection to background)
+    - Popup window closed without answering → the request is rejected with
+      EIP-1193 code 4001

-#### SignApproval
+#### SignApproval (`approve-sign`)

 - **When**: A connected website requests a message signature via
-  `personal_sign`, `eth_sign`, or `eth_signTypedData_v4`. Opened via the toolbar
-  popup by the background script.
+  `personal_sign`, `eth_sign`, or `eth_signTypedData_v4`. Opened the same way as
+  TxApproval, in a separate popup window.
 - **Elements**:
    - "Signature Request" heading
+    - Phishing warning banner (shown when the hostname is on the phishing
+      blocklist)
    - Site hostname (bold) + "wants you to sign a message"
+    - Danger warning box (shown for `eth_sign`, which signs a raw hash)
    - Type: "Personal message" or "Typed data (EIP-712)"
    - From: color dot + full address + etherscan link
    - Message: decoded UTF-8 text (personal_sign) or formatted domain/type/
      message fields (EIP-712 typed data)
-    - Password input
+    - Password input and an error line
    - "Sign" / "Reject" buttons
 - **Transitions**:
-    - "Sign" (with password) → signs locally → closes popup (returns signature)
+    - "Sign" (correct password) → signs locally → closes popup (returns
+      signature)
+    - "Sign" (wrong password, or a signing failure) → error line, no screen
+      change
    - "Reject" → closes popup (returns rejection to background)
+    - Popup window closed without answering → the request is rejected with
+      EIP-1193 code 4001

 ### External Services

@@ -696,7 +876,7 @@ communicates with three external services to function as a wallet:
 What the extension does NOT do:

 - No analytics or telemetry services
- No token list APIs (user adds tokens manually by contract address)
+- No token list APIs (the top-250 token list is bundled at build time)
 - No Infura/Alchemy dependency (any JSON-RPC endpoint works)
 - No backend servers operated by the developer

@@ -815,10 +995,12 @@ hardcoded test phrase.
 - Create new HD wallet (generates 12-word recovery phrase)
 - Import HD wallet from existing 12 or 24 word recovery phrase
 - Import single-address wallet from private key
+- Import multi-address wallet from an extended private key (`xprv`)
 - Add multiple addresses within an HD wallet
 - Manage multiple wallets simultaneously
 - View ETH balance per address
- View ERC-20 token balances (user adds token by contract address)
+- View ERC-20 token balances (bundled top-250 tokens, tokens with 1,000 or more
+  holders, and tokens the user adds by contract address)
 - Send ETH to an address
 - Send ERC-20 tokens to an address
 - Receive ETH/tokens (display address, copy to clipboard, QR code)
@@ -964,7 +1146,8 @@ Currently supported:
 - Built in token swaps (use a DEX in the browser)
 - Analytics, telemetry, or tracking of any kind
 - Advertisements or promotions
- Obscure token list auto-discovery (user adds tokens manually)
+- Obscure token list auto-discovery — nothing outside the bundled list, the
+  1,000-holder floor, and the tokens the user added by contract address
    - We detect common/popular ERC20s in the basic case
 - Fiat on/off ramps
 - Extensive transaction decoding/parsing
@@ -986,12 +1169,12 @@ Currently supported:

 ### Transactions

- [ ] Gas estimation and fee display before confirming
+- [x] Gas estimation and fee display before confirming

 ### Testing

- [ ] Tests for mnemonic generation and address derivation
- [ ] Tests for xpub derivation and child address generation
+- [x] Tests for mnemonic generation and address derivation
+- [x] Tests for xpub derivation and child address generation
 - [ ] Test on Firefox (Manifest V2)

 ### Scam List
@@ -1021,14 +1204,18 @@ This repository includes data files from third-party projects that are not
 covered by the GPL-3.0 license above. These files, their copyright holders, and
 their licenses are:

-| File                                                       | Source                                                                                                                    | Copyright                         | License                                                        |
-| ---------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | --------------------------------- | -------------------------------------------------------------- |
-| `src/shared/phishingBlocklist.json`                        | [eth-phishing-detect](https://github.com/AugurProject/eth-phishing-detect) community-maintained phishing domain blocklist | Copyright (c) 2018 kumavis        | [DBAD (Don't Be a Dick)](https://github.com/philsturgeon/dbad) |
-| `src/shared/scamlist.js` (address data from MyEtherWallet) | [ethereum-lists](https://github.com/MyEtherWallet/ethereum-lists) `addresses-darklist.json`                               | Copyright (c) 2020 MyEtherWallet  | MIT                                                            |
-| `src/shared/scamlist.js` (address data from EtherScamDB)   | [EtherScamDB](https://github.com/MrLuit/EtherScamDB) `scams.yaml`                                                         | Copyright (c) 2018 Luit Hollander | MIT                                                            |
+| File                                                       | Source                                                                                                    | Copyright                         | License                                                        |
+| ---------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | --------------------------------- | -------------------------------------------------------------- |
+| `src/shared/phishingBlocklist.json`                        | `eth-phishing-detect` community-maintained phishing domain blocklist, vendored from its `src/config.json` | Copyright (c) 2018 kumavis        | [DBAD (Don't Be a Dick)](https://github.com/philsturgeon/dbad) |
+| `src/shared/scamlist.js` (address data from MyEtherWallet) | [ethereum-lists](https://github.com/MyEtherWallet/ethereum-lists) `addresses-darklist.json`               | Copyright (c) 2020 MyEtherWallet  | MIT                                                            |
+| `src/shared/scamlist.js` (address data from EtherScamDB)   | [EtherScamDB](https://github.com/MrLuit/EtherScamDB) `scams.yaml`                                         | Copyright (c) 2018 Luit Hollander | MIT                                                            |

 The full license texts for these third-party files are included in the
-[LICENSE](LICENSE) file.
+[LICENSE](LICENSE) file. The `eth-phishing-detect` row carries no repository
+link because the upstream is hosted under a competitor's organization name,
+which project policy keeps out of code and documentation; the vendored copy and
+the runtime refresh both come from that upstream, whose URL is the
+`BLOCKLIST_URL` constant in `src/shared/phishingDomains.js`.

 ## Author

--- a/TODO.md
+++ b/TODO.md
@@ -44,6 +44,15 @@ undefined identifiers, which is how

 # Completed Steps

+- 2026-08-11: Known-answer test coverage for the crypto core — BIP-39/BIP-32
+  derivation in `wallet.js` and the Argon2id vault in `vault.js`
+  ([#159](https://git.eeqj.de/sneak/AutistMask/issues/159)).
+- 2026-08-11: Three `README.md` claims corrected against the code — blocklist
+  attribution, token-display rule, navigation model
+  ([#213](https://git.eeqj.de/sneak/AutistMask/issues/213)).
+- 2026-08-11: README Screen Map rebuilt from the code — every screen, element
+  and transition re-verified against `src/popup/`
+  ([#164](https://git.eeqj.de/sneak/AutistMask/issues/164)).
 - 2026-08-11: `docs/README.md` rewritten against the code: no competitor names,
  all five network destinations documented, password/Settings/Add Wallet
  sections corrected ([#163](https://git.eeqj.de/sneak/AutistMask/issues/163)).
--- a/tests/vault.test.js
+++ b/tests/vault.test.js
@@ -0,0 +1,346 @@
+// Tests for src/shared/vault.js: the Argon2id + XSalsa20-Poly1305 encryption
+// that protects recovery phrases and private keys at rest.
+//
+// The properties that matter here are the ones whose failure is silent. A
+// vault that decrypts under the wrong password, that hands back plaintext from
+// a ciphertext an attacker edited, that reuses a nonce, or that leaves the
+// recovery phrase readable somewhere in the stored blob all look exactly like
+// a working vault from the UI. So each test below asserts a negative: the
+// thing that must not happen.
+//
+// Cost: every encrypt and decrypt runs one Argon2id pwhash at the production
+// interactive parameters, which the module hardcodes. The parameters are not
+// weakened or overridden anywhere in this file — they are pinned by the "key
+// derivation cost" tests, since they are the vault's only defence against an
+// offline attack on a stolen blob. The suite is kept inside script/test's
+// 30-second budget by sharing one encrypted fixture across the tamper cases
+// instead of re-encrypting per test.
+
+const sodium = require("libsodium-wrappers-sumo");
+const {
+    encryptWithPassword,
+    decryptWithPassword,
+} = require("../src/shared/vault");
+
+// A publicly known development phrase. Never fund it.
+const SECRET = "test test test test test test test test test test test junk";
+const PASSWORD = "correct horse battery staple";
+const WRONG_PASSWORD = "correct horse battery stapl";
+
+const SALT_BYTES = 16;
+const NONCE_BYTES = 24;
+const POLY1305_TAG_BYTES = 16;
+
+const BASE64 = /^[A-Za-z0-9+/_-]+={0,2}$/;
+
+function b64decode(s) {
+    return sodium.from_base64(s);
+}
+
+// A shallow copy with one field replaced, so the shared fixture is never
+// mutated by a tamper test.
+function withField(blob, field, value) {
+    return { ...blob, [field]: value };
+}
+
+// Flip the low bit of one byte of a base64-encoded field.
+function flipByte(b64, index) {
+    const bytes = b64decode(b64);
+    bytes[index] ^= 0x01;
+    return sodium.to_base64(bytes);
+}
+
+let vault;
+
+beforeAll(async () => {
+    await sodium.ready;
+    vault = await encryptWithPassword(SECRET, PASSWORD);
+});
+
+describe("stored blob shape", () => {
+    test("is exactly the documented { salt, nonce, ciphertext }", () => {
+        expect(Object.keys(vault).sort()).toEqual([
+            "ciphertext",
+            "nonce",
+            "salt",
+        ]);
+    });
+
+    test("every field is a base64 string", () => {
+        for (const field of ["salt", "nonce", "ciphertext"]) {
+            expect(typeof vault[field]).toBe("string");
+            expect(vault[field]).toMatch(BASE64);
+        }
+    });
+
+    test("salt and nonce are full length", () => {
+        expect(b64decode(vault.salt)).toHaveLength(SALT_BYTES);
+        expect(b64decode(vault.nonce)).toHaveLength(NONCE_BYTES);
+    });
+
+    test("ciphertext carries a Poly1305 authentication tag", () => {
+        expect(b64decode(vault.ciphertext)).toHaveLength(
+            SECRET.length + POLY1305_TAG_BYTES,
+        );
+    });
+
+    test("the blob survives JSON storage unchanged", async () => {
+        const stored = JSON.parse(JSON.stringify(vault));
+
+        await expect(decryptWithPassword(stored, PASSWORD)).resolves.toBe(
+            SECRET,
+        );
+    });
+});
+
+describe("no plaintext leakage", () => {
+    test("the secret does not appear in the serialized vault", () => {
+        const serialized = JSON.stringify(vault);
+
+        expect(serialized).not.toContain(SECRET);
+        for (const word of new Set(SECRET.split(" "))) {
+            expect(serialized).not.toContain(word);
+        }
+    });
+
+    test("the ciphertext bytes do not contain the secret bytes", () => {
+        const bytes = Buffer.from(b64decode(vault.ciphertext));
+
+        expect(bytes.includes(Buffer.from(SECRET, "utf8"))).toBe(false);
+        // Not even the first word, which would betray an unencrypted prefix.
+        expect(bytes.includes(Buffer.from("test test", "utf8"))).toBe(false);
+    });
+
+    test("the password does not appear in the serialized vault", () => {
+        expect(JSON.stringify(vault)).not.toContain(PASSWORD);
+    });
+});
+
+describe("round trip", () => {
+    test("decrypts back to the original secret", async () => {
+        await expect(decryptWithPassword(vault, PASSWORD)).resolves.toBe(
+            SECRET,
+        );
+    });
+
+    test("survives a non-ASCII plaintext byte for byte", async () => {
+        const unicode = "recovery phrase é中文\u{1f600}";
+
+        const blob = await encryptWithPassword(unicode, PASSWORD);
+
+        await expect(decryptWithPassword(blob, PASSWORD)).resolves.toBe(
+            unicode,
+        );
+    });
+
+    test("an empty password still round-trips and is not a bypass", async () => {
+        const blob = await encryptWithPassword(SECRET, "");
+
+        await expect(decryptWithPassword(blob, "")).resolves.toBe(SECRET);
+        // An empty password must not act as a skeleton key on other vaults,
+        // nor may a real password open an empty-password vault.
+        await expect(decryptWithPassword(vault, "")).rejects.toThrow();
+        await expect(decryptWithPassword(blob, PASSWORD)).rejects.toThrow();
+    });
+});
+
+describe("fresh salt and nonce", () => {
+    test("two encryptions of the same plaintext differ in all three fields", async () => {
+        const second = await encryptWithPassword(SECRET, PASSWORD);
+
+        expect(second.salt).not.toBe(vault.salt);
+        expect(second.nonce).not.toBe(vault.nonce);
+        expect(second.ciphertext).not.toBe(vault.ciphertext);
+        await expect(decryptWithPassword(second, PASSWORD)).resolves.toBe(
+            SECRET,
+        );
+    });
+});
+
+describe("key derivation cost", () => {
+    // Argon2id's opslimit and memlimit are the whole of the vault's resistance
+    // to an offline attack on a stolen blob, and lowering them breaks nothing
+    // any other test here can see — the suite merely runs faster. So pin them
+    // directly, both to libsodium's INTERACTIVE constants and to the absolute
+    // values those constants must keep meaning.
+    const INTERACTIVE_OPSLIMIT = 2;
+    const INTERACTIVE_MEMLIMIT = 64 * 1024 * 1024;
+
+    test("the interactive constants still mean 2 passes over 64 MiB", () => {
+        expect(sodium.crypto_pwhash_OPSLIMIT_INTERACTIVE).toBe(
+            INTERACTIVE_OPSLIMIT,
+        );
+        expect(sodium.crypto_pwhash_MEMLIMIT_INTERACTIVE).toBe(
+            INTERACTIVE_MEMLIMIT,
+        );
+        // The floor these must never quietly be swapped for: _MIN is one pass
+        // over 8 KiB, an 8192x reduction in memory cost.
+        expect(sodium.crypto_pwhash_OPSLIMIT_MIN).toBeLessThan(
+            INTERACTIVE_OPSLIMIT,
+        );
+        expect(sodium.crypto_pwhash_MEMLIMIT_MIN).toBeLessThan(
+            INTERACTIVE_MEMLIMIT,
+        );
+    });
+
+    test("a key derived at the interactive parameters opens the vault", () => {
+        // Independent of any spy, and of the module's own code path: derive
+        // the key here from the vault's published salt at the interactive cost
+        // and open its ciphertext directly. A vault whose key came from any
+        // other opslimit, memlimit or Argon2id variant yields a different key
+        // and cannot be opened this way.
+        const key = sodium.crypto_pwhash(
+            sodium.crypto_secretbox_KEYBYTES,
+            PASSWORD,
+            b64decode(vault.salt),
+            INTERACTIVE_OPSLIMIT,
+            INTERACTIVE_MEMLIMIT,
+            sodium.crypto_pwhash_ALG_ARGON2ID13,
+        );
+        const opened = sodium.crypto_secretbox_open_easy(
+            b64decode(vault.ciphertext),
+            b64decode(vault.nonce),
+            key,
+        );
+
+        expect(sodium.to_string(opened)).toBe(SECRET);
+    });
+
+    test.each([
+        [
+            "encrypt",
+            async () => {
+                await encryptWithPassword(SECRET, PASSWORD);
+            },
+        ],
+        [
+            "decrypt",
+            async () => {
+                await decryptWithPassword(vault, PASSWORD);
+            },
+        ],
+    ])("%s derives exactly one key at the interactive cost", async (_, run) => {
+        const spy = jest.spyOn(sodium, "crypto_pwhash");
+        try {
+            await run();
+
+            expect(spy).toHaveBeenCalledTimes(1);
+            const [keyBytes, , salt, opslimit, memlimit, alg] =
+                spy.mock.calls[0];
+            expect(keyBytes).toBe(sodium.crypto_secretbox_KEYBYTES);
+            expect(salt).toHaveLength(SALT_BYTES);
+            expect(opslimit).toBe(sodium.crypto_pwhash_OPSLIMIT_INTERACTIVE);
+            expect(memlimit).toBe(sodium.crypto_pwhash_MEMLIMIT_INTERACTIVE);
+            expect(alg).toBe(sodium.crypto_pwhash_ALG_ARGON2ID13);
+        } finally {
+            spy.mockRestore();
+        }
+    });
+});
+
+describe("wrong password", () => {
+    test("is rejected, and rejects cleanly", async () => {
+        // rejects.toThrow asserts a rejected promise, not a synchronous throw
+        // and not an unhandled rejection: the caller can catch this.
+        await expect(
+            decryptWithPassword(vault, WRONG_PASSWORD),
+        ).rejects.toThrow();
+    });
+
+    test("returns no plaintext, not even partially", async () => {
+        const result = await decryptWithPassword(vault, WRONG_PASSWORD).catch(
+            (err) => err,
+        );
+
+        expect(result).toBeInstanceOf(Error);
+        expect(String(result)).not.toContain("test");
+    });
+
+    test("the empty password is rejected on a password-protected vault", async () => {
+        await expect(decryptWithPassword(vault, "")).rejects.toThrow();
+    });
+});
+
+describe("tampering", () => {
+    test("a flipped ciphertext bit is rejected by the auth tag", async () => {
+        const tampered = withField(
+            vault,
+            "ciphertext",
+            flipByte(vault.ciphertext, 0),
+        );
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a flipped bit in the authentication tag itself is rejected", async () => {
+        const tagStart = b64decode(vault.ciphertext).length - 1;
+        const tampered = withField(
+            vault,
+            "ciphertext",
+            flipByte(vault.ciphertext, tagStart),
+        );
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a flipped nonce bit is rejected", async () => {
+        const tampered = withField(vault, "nonce", flipByte(vault.nonce, 0));
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a flipped salt bit is rejected", async () => {
+        const tampered = withField(vault, "salt", flipByte(vault.salt, 0));
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a truncated ciphertext is rejected", async () => {
+        const bytes = b64decode(vault.ciphertext);
+        const tampered = withField(
+            vault,
+            "ciphertext",
+            sodium.to_base64(bytes.slice(0, bytes.length - 4)),
+        );
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a ciphertext shorter than the auth tag is rejected", async () => {
+        const tampered = withField(
+            vault,
+            "ciphertext",
+            sodium.to_base64(b64decode(vault.ciphertext).slice(0, 4)),
+        );
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a truncated nonce is rejected", async () => {
+        const tampered = withField(
+            vault,
+            "nonce",
+            sodium.to_base64(b64decode(vault.nonce).slice(0, NONCE_BYTES - 1)),
+        );
+
+        await expect(decryptWithPassword(tampered, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a ciphertext from another vault is rejected", async () => {
+        const other = await encryptWithPassword("a different secret", PASSWORD);
+        const spliced = withField(vault, "ciphertext", other.ciphertext);
+
+        await expect(decryptWithPassword(spliced, PASSWORD)).rejects.toThrow();
+    });
+
+    test("a missing field is rejected rather than decrypted", async () => {
+        for (const field of ["salt", "nonce", "ciphertext"]) {
+            const broken = { ...vault };
+            delete broken[field];
+
+            await expect(
+                decryptWithPassword(broken, PASSWORD),
+            ).rejects.toThrow();
+        }
+    });
+});
--- a/tests/wallet.test.js
+++ b/tests/wallet.test.js
@@ -1,4 +1,6 @@
-// Tests for the DEBUG build flag as it gates mnemonic generation.
+// Tests for src/shared/wallet.js: the DEBUG build flag as it gates mnemonic
+// generation (first two describes), and HD key derivation against published
+// known-answer vectors (rest of the file).
 //
 // The modules read the __BUILD_DEBUG__ global that esbuild replaces at bundle
 // time. Under jest the global is absent, which is exactly the release-build
@@ -92,3 +94,317 @@ describe("generateMnemonic in a debug build", () => {
        );
    });
 });
+
+// ---------------------------------------------------------------------------
+// Key derivation.
+//
+// Every address below is a published constant, not something this codebase
+// produced. Asserting against what the implementation happens to return today
+// would pass just as happily with the wrong coin type, the wrong path depth or
+// a non-empty seed passphrase, all of which silently send funds to addresses
+// no other wallet can recover.
+//
+// Vector sources:
+//
+//   VECTOR_PHRASE / VECTOR_ADDRESSES / VECTOR_PRIVATE_KEYS — the standard
+//   development recovery phrase and the first three accounts it yields at
+//   m/44'/60'/0'/0/n with an empty seed passphrase, as published in the
+//   Hardhat and Ganache documentation. Publicly known; never fund it.
+//
+//   ZERO_ENTROPY_PHRASE / ZERO_ENTROPY_ADDRESS — the BIP-39 all-zero-entropy
+//   phrase (Trezor's official BIP-39 vector set, first entry) and its
+//   m/44'/60'/0'/0/0 Ethereum address with an empty seed passphrase. A second,
+//   independently published phrase so the pin is not one vector deep.
+//
+//   BIP32_VECTOR_1_XPRV — the master key of BIP-32 test vector 1
+//   (seed 000102030405060708090a0b0c0d0e0f).
+//
+// The two Hardhat facts cross-check each other: VECTOR_PRIVATE_KEYS[n] is the
+// published key for VECTOR_ADDRESSES[n], so addressFromPrivateKey and the HD
+// path must meet at the same address from two different directions.
+
+const { HDNodeWallet, Mnemonic, verifyMessage } = require("ethers");
+const wallet = require("../src/shared/wallet");
+const { BIP44_ETH_PATH } = require("../src/shared/constants");
+
+const VECTOR_PHRASE =
+    "test test test test test test test test test test test junk";
+
+const VECTOR_ADDRESSES = [
+    "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
+    "0x70997970C51812dc3A010C7d01b50e0d17dc79C8",
+    "0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC",
+];
+
+const VECTOR_PRIVATE_KEYS = [
+    "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80",
+    "0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d",
+    "0x5de4111afa1a4b94908f83103eb1f1706367c2e68ca870fc3fb9a804cdab365a",
+];
+
+const ZERO_ENTROPY_PHRASE =
+    "abandon abandon abandon abandon abandon abandon " +
+    "abandon abandon abandon abandon abandon about";
+const ZERO_ENTROPY_ADDRESS = "0x9858EfFD232B4033E47d90003D41EC34EcaEda94";
+
+const BIP32_VECTOR_1_XPRV =
+    "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqji" +
+    "ChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi";
+
+// The master (depth-0) extended private key for a phrase, which is what the
+// import-an-xprv flow is handed. Built with ethers rather than with the module
+// under test, so hdWalletFromXprv is not being checked against itself.
+function masterXprv(phrase, passphrase = "") {
+    return HDNodeWallet.fromSeed(
+        Mnemonic.fromPhrase(phrase, passphrase).computeSeed(),
+    ).extendedKey;
+}
+
+describe("hdWalletFromMnemonic", () => {
+    test("first address matches the published vector for m/44'/60'/0'/0/0", () => {
+        expect(wallet.hdWalletFromMnemonic(VECTOR_PHRASE).firstAddress).toBe(
+            VECTOR_ADDRESSES[0],
+        );
+    });
+
+    test("second published phrase derives its published address", () => {
+        expect(
+            wallet.hdWalletFromMnemonic(ZERO_ENTROPY_PHRASE).firstAddress,
+        ).toBe(ZERO_ENTROPY_ADDRESS);
+    });
+
+    test("returns the account-level xpub, which is watch-only", () => {
+        const { xpub } = wallet.hdWalletFromMnemonic(VECTOR_PHRASE);
+
+        expect(xpub.startsWith("xpub")).toBe(true);
+        // A neutered ethers node exposes no private key at all, so accept
+        // either absent or null rather than pinning which.
+        expect(
+            HDNodeWallet.fromExtendedKey(xpub).privateKey ?? null,
+        ).toBeNull();
+        expect(wallet.isValidXprv(xpub)).toBe(false);
+    });
+
+    test("the account path is the documented BIP-44 Ethereum path", () => {
+        expect(BIP44_ETH_PATH).toBe("m/44'/60'/0'/0");
+    });
+
+    test("rejects an invalid recovery phrase rather than deriving from it", () => {
+        expect(() => wallet.hdWalletFromMnemonic("not a phrase")).toThrow();
+    });
+});
+
+describe("deriveAddressFromXpub", () => {
+    const { xpub } = wallet.hdWalletFromMnemonic(VECTOR_PHRASE);
+
+    test.each([0, 1, 2])(
+        "child %i matches the published vector address",
+        (index) => {
+            expect(wallet.deriveAddressFromXpub(xpub, index)).toBe(
+                VECTOR_ADDRESSES[index],
+            );
+        },
+    );
+
+    test("agrees with hdWalletFromMnemonic at index 0", () => {
+        expect(wallet.deriveAddressFromXpub(xpub, 0)).toBe(
+            wallet.hdWalletFromMnemonic(VECTOR_PHRASE).firstAddress,
+        );
+    });
+
+    test("rejects garbage instead of returning an address", () => {
+        expect(() =>
+            wallet.deriveAddressFromXpub("xpub-nonsense", 0),
+        ).toThrow();
+    });
+});
+
+describe("hdWalletFromMnemonic seed passphrase handling", () => {
+    // The vectors above are only reproducible with an empty BIP-39 seed
+    // passphrase. This pins that the empty string reaching
+    // HDNodeWallet.fromPhrase is load-bearing: with any passphrase applied the
+    // published address is unreachable, and a wallet derived that way could
+    // not be restored anywhere else from the phrase alone.
+    test("a non-empty seed passphrase would yield a different address", () => {
+        const withPassphrase = HDNodeWallet.fromPhrase(
+            VECTOR_PHRASE,
+            "TREZOR",
+            BIP44_ETH_PATH,
+        ).deriveChild(0).address;
+
+        expect(withPassphrase).not.toBe(VECTOR_ADDRESSES[0]);
+    });
+});
+
+describe("hdWalletFromXprv", () => {
+    // hdWalletFromMnemonic derives the absolute path "m/44'/60'/0'/0" while
+    // hdWalletFromXprv derives the relative path "44'/60'/0'/0". For a
+    // depth-0 master key the two are the same derivation; these tests pin that
+    // equivalence to a published address rather than assuming it.
+    test("master xprv for the vector phrase yields the vector address", () => {
+        expect(
+            wallet.hdWalletFromXprv(masterXprv(VECTOR_PHRASE)).firstAddress,
+        ).toBe(VECTOR_ADDRESSES[0]);
+    });
+
+    test("agrees with hdWalletFromMnemonic on xpub and address", () => {
+        const fromPhrase = wallet.hdWalletFromMnemonic(VECTOR_PHRASE);
+        const fromXprv = wallet.hdWalletFromXprv(masterXprv(VECTOR_PHRASE));
+
+        expect(fromXprv).toEqual(fromPhrase);
+    });
+
+    test("derived xpub generates the same child addresses", () => {
+        const { xpub } = wallet.hdWalletFromXprv(masterXprv(VECTOR_PHRASE));
+
+        expect(
+            [0, 1, 2].map((i) => wallet.deriveAddressFromXpub(xpub, i)),
+        ).toEqual(VECTOR_ADDRESSES);
+    });
+
+    test("accepts the BIP-32 test vector 1 master key", () => {
+        const { xpub, firstAddress } =
+            wallet.hdWalletFromXprv(BIP32_VECTOR_1_XPRV);
+
+        expect(xpub.startsWith("xpub")).toBe(true);
+        expect(firstAddress).toMatch(/^0x[0-9a-fA-F]{40}$/);
+    });
+
+    test("rejects a watch-only xpub", () => {
+        const { xpub } = wallet.hdWalletFromMnemonic(VECTOR_PHRASE);
+
+        expect(() => wallet.hdWalletFromXprv(xpub)).toThrow();
+    });
+
+    test("rejects garbage", () => {
+        expect(() => wallet.hdWalletFromXprv("nonsense")).toThrow();
+    });
+});
+
+describe("isValidXprv", () => {
+    test.each([
+        ["BIP-32 test vector 1 master key", BIP32_VECTOR_1_XPRV, true],
+        ["the empty string", "", false],
+        ["garbage", "not-a-key", false],
+        ["a bare private key", VECTOR_PRIVATE_KEYS[0], false],
+        ["a truncated xprv", BIP32_VECTOR_1_XPRV.slice(0, -6), false],
+        ["an xprv with an extra character", BIP32_VECTOR_1_XPRV + "a", false],
+    ])("%s -> %s", (_name, key, expected) => {
+        expect(wallet.isValidXprv(key)).toBe(expected);
+    });
+
+    test("a watch-only xpub is not an xprv", () => {
+        const { xpub } = wallet.hdWalletFromMnemonic(VECTOR_PHRASE);
+
+        expect(wallet.isValidXprv(xpub)).toBe(false);
+    });
+
+    // Skipped: this asserts the correct behaviour, which the code does not
+    // currently have. isValidXprv gates the paste-your-extended-private-key
+    // import in src/popup/views/addWallet.js:215, and it accepts a key with a
+    // one-character typo: ethers' HDNodeWallet.fromExtendedKey skips base58
+    // checksum verification whenever the decoded payload is the usual 82
+    // bytes, which is the whole point of that checksum. Measured on this
+    // vector: changing any one of the last 14 characters passes validation,
+    // and for 9 of those 14 positions the import silently yields a *different*
+    // wallet (e.g. 0x3F334f0a356d6B46B1d70B590E7437D77100d28D instead of
+    // 0x022b971dFF0C43305e691DEd7a14367AF19D6407) with no error shown.
+    // Tracked as https://git.eeqj.de/sneak/AutistMask/issues/210; out of scope
+    // here, which is tests only. Unskip when it is fixed.
+    test.skip("rejects an extended key with a one-character typo", () => {
+        const index = BIP32_VECTOR_1_XPRV.length - 8;
+        const typo =
+            BIP32_VECTOR_1_XPRV.slice(0, index) +
+            (BIP32_VECTOR_1_XPRV[index] === "a" ? "b" : "a") +
+            BIP32_VECTOR_1_XPRV.slice(index + 1);
+
+        expect(wallet.isValidXprv(typo)).toBe(false);
+    });
+});
+
+describe("isValidMnemonic", () => {
+    test.each([
+        ["the vector phrase", VECTOR_PHRASE, true],
+        ["the BIP-39 zero-entropy phrase", ZERO_ENTROPY_PHRASE, true],
+        [
+            "a 12-word phrase with a bad checksum",
+            "abandon abandon abandon abandon abandon abandon " +
+                "abandon abandon abandon abandon abandon abandon",
+            false,
+        ],
+        ["an 11-word phrase", "abandon ".repeat(10) + "about", false],
+        ["a word outside the wordlist", VECTOR_PHRASE + " zzzzzz", false],
+        ["the empty string", "", false],
+        ["garbage", "correct horse battery staple", false],
+    ])("%s -> %s", (_name, phrase, expected) => {
+        expect(wallet.isValidMnemonic(phrase)).toBe(expected);
+    });
+});
+
+describe("addressFromPrivateKey", () => {
+    test.each([0, 1, 2])(
+        "published key %i yields its published address",
+        (index) => {
+            expect(
+                wallet.addressFromPrivateKey(VECTOR_PRIVATE_KEYS[index]),
+            ).toBe(VECTOR_ADDRESSES[index]);
+        },
+    );
+
+    test("rejects a key of the wrong length", () => {
+        expect(() => wallet.addressFromPrivateKey("0xdeadbeef")).toThrow();
+    });
+
+    test("rejects the empty string", () => {
+        expect(() => wallet.addressFromPrivateKey("")).toThrow();
+    });
+});
+
+describe("getSignerForAddress", () => {
+    test.each([0, 1, 2])("hd wallet, address index %i", (index) => {
+        const signer = wallet.getSignerForAddress(
+            { type: "hd" },
+            index,
+            VECTOR_PHRASE,
+        );
+
+        expect(signer.address).toBe(VECTOR_ADDRESSES[index]);
+        expect(signer.privateKey).toBe(VECTOR_PRIVATE_KEYS[index]);
+    });
+
+    test.each([0, 1, 2])("xprv wallet, address index %i", (index) => {
+        const signer = wallet.getSignerForAddress(
+            { type: "xprv" },
+            index,
+            masterXprv(VECTOR_PHRASE),
+        );
+
+        expect(signer.address).toBe(VECTOR_ADDRESSES[index]);
+        expect(signer.privateKey).toBe(VECTOR_PRIVATE_KEYS[index]);
+    });
+
+    test("single private key ignores the address index", () => {
+        for (const index of [0, 1, 2]) {
+            const signer = wallet.getSignerForAddress(
+                { type: "privkey" },
+                index,
+                VECTOR_PRIVATE_KEYS[1],
+            );
+
+            expect(signer.address).toBe(VECTOR_ADDRESSES[1]);
+        }
+    });
+
+    test("the returned signer signs recoverably as the expected address", async () => {
+        const signer = wallet.getSignerForAddress(
+            { type: "hd" },
+            1,
+            VECTOR_PHRASE,
+        );
+        const message = "AutistMask derivation test";
+
+        const signature = await signer.signMessage(message);
+
+        expect(verifyMessage(message, signature)).toBe(VECTOR_ADDRESSES[1]);
+    });
+});