Add /addword command to add missing Wordle answers

Some real Wordle answers aren't in the bundled answers.txt list. This
adds a REPL command to append a word to answers.txt and remove it from
guesses.txt if present there, since the two lists are meant to be
disjoint.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_cli.py

@@ -1,7 +1,12 @@
+import argparse
+
 import pytest
 
-from wordle_solver.game import Clue
-from wordle_solver.cli import parse_line, hard_mode_violation
+from wordle_solver import cli
+from wordle_solver.game import Clue, score_guess
+from wordle_solver.cli import handle_slash_command, parse_line, hard_mode_violation
+from wordle_solver.solver import Solver
+from wordle_solver.wager import Wager
 
 G = Clue.GREEN
 Y = Clue.YELLOW
@@ -82,3 +87,69 @@ class TestHardModeViolation:
     def test_empty_constraints_always_none(self):
         from collections import Counter
         assert hard_mode_violation("crane", {}, Counter()) is None
+
+
+class TestAddWordCommand:
+    def _solver(self):
+        return Solver(answers=["crane", "trace"], extra_guesses=["about", "zesty"])
+
+    def _opts(self):
+        return argparse.Namespace(top=10, position_weight=1.0, presence_weight=1.0)
+
+    def test_rejects_wrong_arg_count(self, capsys):
+        solver = self._solver()
+        handle_slash_command("/addword", solver, Wager(), {}, solver.answers, self._opts())
+        assert "Usage" in capsys.readouterr().out
+        assert solver.answers == ["crane", "trace"]
+
+    def test_rejects_non_alpha_or_wrong_length(self, capsys):
+        solver = self._solver()
+        handle_slash_command("/addword abc12", solver, Wager(), {}, solver.answers, self._opts())
+        assert "5 letters" in capsys.readouterr().out
+        assert solver.answers == ["crane", "trace"]
+
+    def test_already_in_answers_short_circuits(self, capsys, monkeypatch):
+        solver = self._solver()
+        called = False
+
+        def fake_add(word):
+            nonlocal called
+            called = True
+            return {"added": False, "removed_from_guesses": False}
+
+        monkeypatch.setattr(cli, "add_answer_word", fake_add)
+        handle_slash_command("/addword crane", solver, Wager(), {}, solver.answers, self._opts())
+
+        assert "already" in capsys.readouterr().out
+        assert not called
+        assert solver.answers == ["crane", "trace"]
+
+    def test_adds_word_and_removes_from_guesses(self, capsys, monkeypatch):
+        solver = self._solver()
+        monkeypatch.setattr(
+            cli, "add_answer_word",
+            lambda word: {"added": True, "removed_from_guesses": True},
+        )
+
+        handle_slash_command("/addword zesty", solver, Wager(), {}, solver.answers, self._opts())
+
+        out = capsys.readouterr().out
+        assert "Added ZESTY" in out
+        assert "removed it from guesses.txt" in out
+        assert solver.answers == ["crane", "trace", "zesty"]
+        assert "zesty" not in solver.extra_guesses
+
+    def test_new_candidate_consistent_with_history_is_added(self, capsys, monkeypatch):
+        solver = self._solver()
+        # Derive the pattern "trace" would actually produce against "chase",
+        # so the new word is consistent with history by construction.
+        pattern = score_guess("trace", "chase")
+        solver.apply("trace", pattern)
+        monkeypatch.setattr(
+            cli, "add_answer_word",
+            lambda word: {"added": True, "removed_from_guesses": False},
+        )
+
+        handle_slash_command("/addword chase", solver, Wager(), {}, solver.answers, self._opts())
+
+        assert "chase" in solver.candidates