fix(mcp): case-insensitive agent name in diary_write/diary_read (#1243)

`tool_diary_write` stored the `agent` metadata verbatim after `sanitize_name`
(which preserves case), while `tool_diary_read` filtered by exact match —
so writing as "Claude" and reading as "claude" silently returned zero rows.

Both endpoints now lowercase `agent_name` immediately after sanitization.
The default per-agent wing slug is also stable across casings since it's
derived from the same normalized form.

Behavior change: entries written prior to this fix under mixed-case agent
names will not match the new lowercase filter; documented under v3.3.5
in CHANGELOG with a `mempalace repair` pointer.

Adds a regression test (`test_diary_read_case_insensitive_agent`) and
updates the existing `test_diary_write_and_read` to assert the new
lowercase agent identity.

Closes #1243

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

tests/test_mcp_server.py

@@ -476,9 +476,9 @@ class TestWriteTools:
 
         assert result1["success"] is True
         assert result2["success"] is True
-        assert (
-            result1["drawer_id"] != result2["drawer_id"]
-        ), "Documents with shared header but different content must have distinct drawer IDs"
+        assert result1["drawer_id"] != result2["drawer_id"], (
+            "Documents with shared header but different content must have distinct drawer IDs"
+        )
 
     def test_delete_drawer(self, monkeypatch, config, palace_path, seeded_collection, kg):
         _patch_mcp_server(monkeypatch, config, kg)
@@ -682,7 +682,8 @@ class TestDiaryTools:
             topic="architecture",
         )
         assert w["success"] is True
-        assert w["agent"] == "TestAgent"
+        # agent_name is normalized to lowercase on write (#1243).
+        assert w["agent"] == "testagent"
 
         r = tool_diary_read(agent_name="TestAgent")
         assert r["total"] == 1
@@ -774,6 +775,50 @@ class TestDiaryTools:
         assert r_scoped["total"] == 1
         assert r_scoped["entries"][0]["content"] == "project-wing entry"
 
+    def test_diary_read_case_insensitive_agent(self, monkeypatch, config, palace_path, kg):
+        """Regression for #1243: diary_read must be case-insensitive over
+        agent_name. Writing as "Claude" and reading as "claude" (or vice
+        versa) must surface the same entries — sanitize_name preserved
+        case, which silently dropped reads when the agent name's casing
+        differed from the write."""
+        _patch_mcp_server(monkeypatch, config, kg)
+        _client, _col = _get_collection(palace_path, create=True)
+        del _client
+        from mempalace.mcp_server import tool_diary_read, tool_diary_write
+
+        # Write as "Claude" → read as "claude" should match.
+        w1 = tool_diary_write(
+            agent_name="Claude",
+            entry="entry written as Claude",
+            topic="general",
+        )
+        assert w1["success"]
+
+        r1 = tool_diary_read(agent_name="claude")
+        assert "entries" in r1, r1
+        contents1 = {e["content"] for e in r1["entries"]}
+        assert "entry written as Claude" in contents1
+
+        # Write as "CLAUDE" → read as "Claude" should also match the
+        # same agent. After normalization both writes target the same
+        # lowercase agent identity, so both entries are returned.
+        w2 = tool_diary_write(
+            agent_name="CLAUDE",
+            entry="entry written as CLAUDE",
+            topic="general",
+        )
+        assert w2["success"]
+
+        r2 = tool_diary_read(agent_name="Claude")
+        contents2 = {e["content"] for e in r2["entries"]}
+        assert "entry written as Claude" in contents2
+        assert "entry written as CLAUDE" in contents2
+
+        # The stored agent metadata is the lowercase form, and the
+        # default wing is derived from that lowercase form too.
+        assert w1["agent"] == "claude"
+        assert w2["agent"] == "claude"
+
 
 # ── Cache Invalidation (inode/mtime) ──────────────────────────────────
 
@@ -960,9 +1005,9 @@ class TestCacheInvalidation:
         all_calls = captured["get"] + captured["create"]
         assert all_calls, "expected get_collection or create_collection to be called"
         for kwargs in all_calls:
-            assert (
-                "embedding_function" in kwargs
-            ), f"missing embedding_function= in chromadb call: {kwargs}"
+            assert "embedding_function" in kwargs, (
+                f"missing embedding_function= in chromadb call: {kwargs}"
+            )
             assert kwargs["embedding_function"] is not None
 
         # Same expectation on the create=False (cache-miss) reopen path.