Daily Word: grow the hopeful answer pool + lock it with a validation test

Per Codex. Pool grown 51/44 → 115/104 hopeful answers (5/6 letter) via the
agreed workflow: LLM proposes themed candidates → code filters to the bundled
guess dictionary (length/alpha/dedup) → human spot-check prunes tone-drift
("growl", "plain", "color"…). ~3.5-month runway before repeats per variant.

test_wordpool.py locks the invariant in CI: every answer must be lowercase
alpha, correct length, unique, and present in words-5/6.json — so no future
addition can become an unguessable puzzle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_wordpool.py

@@ -0,0 +1,20 @@
+import json
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+
+
+def test_wordpool_answers_are_valid_and_guessable():
+    """Every daily-word answer must be lowercase alpha, the right length, unique,
+    and present in the bundled guess dictionary — so no answer is ever unguessable.
+    Locks the 'code disposes' invariant against future pool additions."""
+    pool = json.loads((ROOT / "goodnews" / "data" / "wordpool.json").read_text())
+    for variant, n in (("5", 5), ("6", 6)):
+        dictwords = set(json.loads((ROOT / "frontend" / "static" / f"words-{n}.json").read_text()))
+        answers = pool[variant]
+        assert answers, f"{variant}-letter pool is empty"
+        assert len(answers) == len(set(answers)), f"{variant}-letter pool has duplicates"
+        for w in answers:
+            assert isinstance(w, str) and w.isalpha() and w.islower(), f"bad token: {w!r}"
+            assert len(w) == n, f"{w!r} is not {n} letters"
+            assert w in dictwords, f"{w!r} not in the guess dictionary → would be unguessable"