diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41dfaac..d3982fe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ---
 
+## [3.3.5] — unreleased
+
+### Bug Fixes
+
+- **`mempalace_diary_read` silently dropped entries on agent-name case mismatch.** `tool_diary_write` stored the `agent` metadata verbatim after `sanitize_name`, which preserves case, while `tool_diary_read` filtered by exact match. Writing as `"Claude"` and reading as `"claude"` (or vice-versa) returned zero rows. Both endpoints now lowercase `agent_name` immediately after sanitization, so reads are case-insensitive and the default per-agent wing slug is stable across casings. **Behavior change:** entries written prior to this fix under mixed-case agent names will not match the new lowercase filter; run `mempalace repair` if you need to migrate legacy diary metadata. (#1243)
+
+---
+
 ## [3.3.4] — unreleased
 
 ### Added
diff --git a/mempalace/mcp_server.py b/mempalace/mcp_server.py
index 13654f6..7269376 100644
--- a/mempalace/mcp_server.py
+++ b/mempalace/mcp_server.py
@@ -677,7 +677,7 @@ def tool_check_duplicate(content: str, threshold: float = 0.9):
             "vector_disabled": True,
             "vector_disabled_reason": _vector_disabled_reason,
             "hint": (
-                "duplicate detection requires vector search; run " "`mempalace repair` to restore"
+                "duplicate detection requires vector search; run `mempalace repair` to restore"
             ),
         }
     try:
@@ -1133,9 +1133,13 @@ def tool_diary_write(agent_name: str, entry: str, topic: str = "general", wing:
 
     This is the agent's personal journal — observations, thoughts,
     what it worked on, what it noticed, what it thinks matters.
+
+    Note: ``agent_name`` is normalized to lowercase before storage so
+    that diary reads are case-insensitive (see #1243). "Claude",
+    "claude", and "CLAUDE" all resolve to the same agent.
     """
     try:
-        agent_name = sanitize_name(agent_name, "agent_name")
+        agent_name = sanitize_name(agent_name, "agent_name").lower()
         entry = sanitize_content(entry)
         topic = sanitize_name(topic, "topic")
     except ValueError as e:
@@ -1144,7 +1148,7 @@ def tool_diary_write(agent_name: str, entry: str, topic: str = "general", wing:
     if wing:
         wing = sanitize_name(wing)
     else:
-        wing = f"wing_{agent_name.lower().replace(' ', '_')}"
+        wing = f"wing_{agent_name.replace(' ', '_')}"
     room = "diary"
     col = _get_collection(create=True)
     if not col:
@@ -1209,9 +1213,14 @@ def tool_diary_read(agent_name: str, last_n: int = 10, wing: str = ""):
     written to. Diary writes from hooks land in project-derived wings
     (``wing_<project>``), so requiring a specific wing on read would
     silo those entries from agent-initiated reads.
+
+    Note: ``agent_name`` is normalized to lowercase before filtering so
+    that reads are case-insensitive (see #1243). Entries written under
+    pre-fix mixed-case agent names will not match the lowercase filter;
+    use ``mempalace repair`` to migrate legacy data if needed.
     """
     try:
-        agent_name = sanitize_name(agent_name, "agent_name")
+        agent_name = sanitize_name(agent_name, "agent_name").lower()
         if wing:
             wing = sanitize_name(wing)
     except ValueError as e:
diff --git a/tests/test_mcp_server.py b/tests/test_mcp_server.py
index f8148af..16dad6d 100644
--- a/tests/test_mcp_server.py
+++ b/tests/test_mcp_server.py
@@ -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) ──────────────────────────────────