feat(notion-search): add query expansion via Claude Haiku

Generates up to 5 query variants (synonyms + cross-language KR↔EN) so
later Notion API search can union over them. Permissive failure modes:
LLM error or non-JSON response falls back to [original] with stderr
warning. Dedupes and caps variants.

4 tests: variants list, dedup+cap, JSON-parse fallback, exception
fallback. 12 passing total.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

custom-skills/31-notion-organizer/code/scripts/test_notion_search.py

@@ -122,6 +122,47 @@ def test_cache_handles_corrupted_file():
         _assert(result is None, "corrupted cache file returns None")
 
 
+def test_expand_query_returns_variants_with_original_first():
+    """LLM mock returns variants; expansion includes original verbatim as first item."""
+    import notion_search
+
+    fake_llm = lambda prompt, **kw: '["AI agents", "multi-agent systems", "autonomous LLMs"]'
+    variants = notion_search.expand_query("AI agents", llm_caller=fake_llm)
+    _assert(variants[0] == "AI agents", "original query is first variant")
+    _assert(len(variants) >= 2, "at least 2 variants returned")
+    _assert("multi-agent systems" in variants, "LLM-suggested variant included")
+
+
+def test_expand_query_dedupes_and_caps():
+    """Duplicates removed; total ≤ max_variants."""
+    import notion_search
+
+    fake_llm = lambda prompt, **kw: '["AI", "AI", "agents", "agents", "systems", "tools", "models"]'
+    variants = notion_search.expand_query("AI", llm_caller=fake_llm, max_variants=3)
+    _assert(len(variants) <= 3, "capped at max_variants=3")
+    _assert(len(variants) == len(set(variants)), "no duplicates in result")
+
+
+def test_expand_query_falls_back_on_invalid_json():
+    """LLM returns prose instead of JSON → fall back to [original]."""
+    import notion_search
+
+    fake_llm = lambda prompt, **kw: "I'm sorry, I can't help with that."
+    variants = notion_search.expand_query("AI agents", llm_caller=fake_llm)
+    _assert(variants == ["AI agents"], "non-JSON response falls back to original only")
+
+
+def test_expand_query_falls_back_on_llm_exception():
+    """LLM raises → fall back to [original]."""
+    import notion_search
+
+    def boom(prompt, **kw):
+        raise RuntimeError("API error")
+
+    variants = notion_search.expand_query("AI agents", llm_caller=boom)
+    _assert(variants == ["AI agents"], "LLM exception falls back to original only")
+
+
 def run_all():
     tests = [
         test_call_claude_dispatches_to_sdk_when_available,
@@ -132,6 +173,10 @@ def run_all():
         test_cache_miss_on_different_candidates,
         test_cache_miss_after_ttl_expires,
         test_cache_handles_corrupted_file,
+        test_expand_query_returns_variants_with_original_first,
+        test_expand_query_dedupes_and_caps,
+        test_expand_query_falls_back_on_invalid_json,
+        test_expand_query_falls_back_on_llm_exception,
     ]
     for t in tests:
         print(f"\n{t.__name__}")