Add interactive seed word prompt

src/tests/test_seed_prompt.py

@@ -28,3 +28,31 @@ def test_masked_input_windows_space(monkeypatch, capsys):
     out = capsys.readouterr().out
     assert out.startswith("Password: ")
     assert out.count("*") == 4
+
+
+def test_prompt_seed_words_valid(monkeypatch):
+    from mnemonic import Mnemonic
+
+    m = Mnemonic("english")
+    phrase = m.generate(strength=128)
+    words = phrase.split()
+
+    inputs = iter(words + ["y"] * len(words))
+    monkeypatch.setattr("builtins.input", lambda *_: next(inputs))
+
+    result = seed_prompt.prompt_seed_words(len(words))
+    assert result == phrase
+
+
+def test_prompt_seed_words_invalid_word(monkeypatch):
+    from mnemonic import Mnemonic
+
+    m = Mnemonic("english")
+    phrase = m.generate(strength=128)
+    words = phrase.split()
+    # Insert an invalid word for the first entry then the correct one
+    inputs = iter(["invalid"] + [words[0]] + words[1:] + ["y"] * len(words))
+    monkeypatch.setattr("builtins.input", lambda *_: next(inputs))
+
+    result = seed_prompt.prompt_seed_words(len(words))
+    assert result == phrase

src/utils/__init__.py

@@ -25,7 +25,7 @@ try:
         update_checksum_file,
     )
     from .password_prompt import prompt_for_password
-    from .seed_prompt import masked_input
+    from .seed_prompt import masked_input, prompt_seed_words
     from .input_utils import timed_input
     from .memory_protection import InMemorySecret
     from .clipboard import copy_to_clipboard
@@ -60,6 +60,7 @@ __all__ = [
     "shared_lock",
     "prompt_for_password",
     "masked_input",
+    "prompt_seed_words",
     "timed_input",
     "InMemorySecret",
     "copy_to_clipboard",

src/utils/seed_prompt.py

@@ -71,3 +71,71 @@ def masked_input(prompt: str) -> str:
     if sys.platform == "win32":
         return _masked_input_windows(prompt)
     return _masked_input_posix(prompt)
+
+
+def prompt_seed_words(count: int = 12) -> str:
+    """Prompt the user for a BIP-39 seed phrase.
+
+    The user is asked for each word one at a time. A numbered list is
+    displayed showing ``*`` for entered words and ``_`` for words yet to be
+    provided. After all words are entered the user is asked to confirm each
+    word individually. If the user answers ``no`` to a confirmation prompt the
+    word can be re-entered.
+
+    Parameters
+    ----------
+    count:
+        Number of words to prompt for. Defaults to ``12``.
+
+    Returns
+    -------
+    str
+        The complete seed phrase.
+
+    Raises
+    ------
+    ValueError
+        If the resulting phrase fails ``Mnemonic.check`` validation.
+    """
+
+    from mnemonic import Mnemonic
+
+    m = Mnemonic("english")
+    words: list[str] = [""] * count
+
+    idx = 0
+    while idx < count:
+        progress = [f"{i+1}: {'*' if w else '_'}" for i, w in enumerate(words)]
+        print("\n".join(progress))
+        entered = input(f"Enter word number {idx+1}: ").strip().lower()
+        if entered not in m.wordlist:
+            print("Invalid word, try again.")
+            continue
+        words[idx] = entered
+        idx += 1
+
+    for i in range(count):
+        while True:
+            response = (
+                input(f"Is this the correct word for number {i+1}? {words[i]} (Y/N): ")
+                .strip()
+                .lower()
+            )
+            if response in ("y", "yes"):
+                break
+            if response in ("n", "no"):
+                while True:
+                    new_word = input(f"Re-enter word number {i+1}: ").strip().lower()
+                    if new_word in m.wordlist:
+                        words[i] = new_word
+                        break
+                    print("Invalid word, try again.")
+                # Ask for confirmation again with the new word
+            else:
+                print("Please respond with 'Y' or 'N'.")
+                continue
+
+    phrase = " ".join(words)
+    if not m.check(phrase):
+        raise ValueError("Invalid BIP-39 seed phrase")
+    return phrase