fix: improve research() cache read path and deduplicate test mocks

- Use .get() instead of .setdefault() for cache reads in research()
  so the local-only path never mutates _data unnecessarily
- Move .setdefault() to the network-write path only
- Use result.setdefault() for word/confirmed keys to ensure
  consistent return shape across all _wikipedia_lookup error paths
- Extract duplicated mock_result dict into _MOCK_SAOIRSE_PERSON
  constant shared by 3 test functions

Author: Kesshite

mempalace/entity_registry.py

@@ -523,8 +523,8 @@ def research(self, word: str, auto_confirm: bool = False, allow_network: bool =
         Caches result.  If *auto_confirm* is ``False``, marks the entry
         as unconfirmed (needs user review).
         """
-        # Already cached?
-        cache = self._data.setdefault("wiki_cache", {})
+        # Check cache (read-only — no mutation when allow_network is False)
+        cache = self._data.get("wiki_cache", {})
         if word in cache:
             return cache[word]
 
@@ -539,9 +539,11 @@ def research(self, word: str, auto_confirm: bool = False, allow_network: bool =
                 "note": "network lookup disabled — pass allow_network=True to query Wikipedia",
             }
 
+        # Network path — ensure wiki_cache key exists before writing
+        cache = self._data.setdefault("wiki_cache", {})
         result = _wikipedia_lookup(word)
-        result["word"] = word
-        result["confirmed"] = auto_confirm
+        result.setdefault("word", word)
+        result.setdefault("confirmed", auto_confirm)
 
         cache[word] = result
         self.save()

tests/test_entity_registry.py

@@ -8,6 +8,14 @@
     EntityRegistry,
 )
 
+# Shared mock result for Wikipedia person lookup tests
+_MOCK_SAOIRSE_PERSON = {
+    "inferred_type": "person",
+    "confidence": 0.80,
+    "wiki_summary": "Saoirse is an Irish given name.",
+    "wiki_title": "Saoirse",
+}
+
 
 # ── COMMON_ENGLISH_WORDS ────────────────────────────────────────────────
 
@@ -238,14 +246,10 @@ def test_research_with_allow_network(tmp_path):
     registry = EntityRegistry.load(config_dir=tmp_path)
     registry.seed(mode="personal", people=[], projects=[])
 
-    mock_result = {
-        "inferred_type": "person",
-        "confidence": 0.80,
-        "wiki_summary": "Saoirse is an Irish given name.",
-        "wiki_title": "Saoirse",
-    }
-
-    with patch("mempalace.entity_registry._wikipedia_lookup", return_value=mock_result):
+    with patch(
+        "mempalace.entity_registry._wikipedia_lookup",
+        return_value=dict(_MOCK_SAOIRSE_PERSON),
+    ):
         result = registry.research("Saoirse", auto_confirm=True, allow_network=True)
     assert result["inferred_type"] == "person"
 
@@ -255,14 +259,10 @@ def test_research_caches_result(tmp_path):
     registry = EntityRegistry.load(config_dir=tmp_path)
     registry.seed(mode="personal", people=[], projects=[])
 
-    mock_result = {
-        "inferred_type": "person",
-        "confidence": 0.80,
-        "wiki_summary": "Saoirse is an Irish given name.",
-        "wiki_title": "Saoirse",
-    }
-
-    with patch("mempalace.entity_registry._wikipedia_lookup", return_value=mock_result):
+    with patch(
+        "mempalace.entity_registry._wikipedia_lookup",
+        return_value=dict(_MOCK_SAOIRSE_PERSON),
+    ):
         result = registry.research("Saoirse", auto_confirm=True, allow_network=True)
     assert result["inferred_type"] == "person"
 
@@ -288,13 +288,10 @@ def test_confirm_research_adds_to_people(tmp_path):
     registry = EntityRegistry.load(config_dir=tmp_path)
     registry.seed(mode="personal", people=[], projects=[])
 
-    mock_result = {
-        "inferred_type": "person",
-        "confidence": 0.80,
-        "wiki_summary": "Saoirse is a name",
-        "wiki_title": "Saoirse",
-    }
-    with patch("mempalace.entity_registry._wikipedia_lookup", return_value=mock_result):
+    with patch(
+        "mempalace.entity_registry._wikipedia_lookup",
+        return_value=dict(_MOCK_SAOIRSE_PERSON),
+    ):
         registry.research("Saoirse", auto_confirm=False, allow_network=True)
 
     registry.confirm_research("Saoirse", entity_type="person", relationship="friend")