diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3d8aa945..74cbf6ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@
 
 ### Added
 
-- Add a read-only Third-party notes drawer to the Memory panel that lists configured note/knowledge MCP sources such as Joplin, Obsidian, Notion, and llm-wiki, while explicitly leaving automatic session recall unchanged.
+- Add a default-off, read-only Third-party notes drawer to the Memory panel that lists configured note/knowledge MCP sources such as Joplin, Obsidian, Notion, and llm-wiki when explicitly enabled with `webui_external_notes_sources` or `HERMES_WEBUI_EXTERNAL_NOTES_SOURCES=1`, while leaving automatic session recall unchanged.
 
 ## [v0.51.115] — 2026-05-22 — Release CM (stage-pr2731 — 1-PR — clarify prompt collapse/expand with chevron-icon polish)
 
diff --git a/api/routes.py b/api/routes.py
index d53f90c0..ef4a16d6 100644
--- a/api/routes.py
+++ b/api/routes.py
@@ -7878,6 +7878,7 @@ def _handle_memory_read(handler):
             "memory_mtime": mem_file.stat().st_mtime if mem_file.exists() else None,
             "user_mtime": user_file.stat().st_mtime if user_file.exists() else None,
             "soul_mtime": soul_file.stat().st_mtime if soul_file.exists() else None,
+            "external_notes_enabled": _external_notes_sources_enabled(),
         },
     )
 
@@ -11558,6 +11559,29 @@ def _handle_mcp_tools_list(handler):
     })
 
 
+def _webui_truthy(value) -> bool:
+    return str(value or "").strip().lower() in {"1", "true", "yes", "on"}
+
+
+def _external_notes_sources_enabled(config_data: dict | None = None) -> bool:
+    """Return whether the third-party notes drawer is explicitly enabled.
+
+    The Memory panel is a primary surface, so this power-user drawer stays
+    default-off unless a deployment opts in through config or environment.
+    """
+    env_value = os.getenv("HERMES_WEBUI_EXTERNAL_NOTES_SOURCES", "")
+    if env_value:
+        return _webui_truthy(env_value)
+    cfg = config_data if isinstance(config_data, dict) else get_config()
+    if not isinstance(cfg, dict):
+        return False
+    return _webui_truthy(
+        cfg.get("webui_external_notes_sources")
+        or cfg.get("external_notes_sources")
+        or cfg.get("notes_sources_drawer")
+    )
+
+
 _NOTES_SOURCE_SERVER_HINTS = {
     "joplin", "obsidian", "notion", "llm-wiki", "llmwiki", "wiki",
     "notes", "note", "knowledge", "kb", "readwise", "logseq",
@@ -11707,6 +11731,16 @@ def _notes_sources_from_mcp_inventory(server_summaries: dict, tools: list[dict])
 def _handle_notes_sources_list(handler):
     """List note/knowledge MCP sources for the WebUI Notes drawer."""
     cfg = get_config()
+    if not _external_notes_sources_enabled(cfg):
+        return j(handler, {
+            "enabled": False,
+            "sources": [],
+            "source": "disabled",
+            "inventory_scope": "disabled_by_default",
+            "attach_supported": False,
+            "automatic_recall_unchanged": True,
+            "recent_ai_notes": [],
+        })
     servers = cfg.get("mcp_servers", {})
     if not isinstance(servers, dict):
         servers = {}
@@ -11721,6 +11755,7 @@ def _handle_notes_sources_list(handler):
         tools = _mcp_tools_from_registry(server_summaries)
         source = "tool_registry" if tools else "none"
     return j(handler, {
+        "enabled": True,
         "sources": _notes_sources_from_mcp_inventory(server_summaries, tools),
         "source": source,
         "inventory_scope": "already_known_runtime_only",
@@ -11936,6 +11971,8 @@ def _joplin_recent_ai_notes(*, limit: int = 6) -> list[dict]:
 
 
 def _handle_notes_search(handler, parsed):
+    if not _external_notes_sources_enabled():
+        return j(handler, {"source": "disabled", "results": [], "error": "External notes sources are disabled."}, status=404)
     query = parse_qs(parsed.query or "")
     source = str(query.get("source", ["joplin"])[0] or "joplin").strip().lower()
     q = str(query.get("q", [""])[0] or "").strip()
@@ -11952,6 +11989,8 @@ def _handle_notes_search(handler, parsed):
 
 
 def _handle_notes_item(handler, parsed):
+    if not _external_notes_sources_enabled():
+        return j(handler, {"source": "disabled", "error": "External notes sources are disabled."}, status=404)
     query = parse_qs(parsed.query or "")
     source = str(query.get("source", ["joplin"])[0] or "joplin").strip().lower()
     note_id = str(query.get("id", [""])[0] or "").strip()
diff --git a/static/panels.js b/static/panels.js
index 1b2adf1f..dbada1b3 100644
--- a/static/panels.js
+++ b/static/panels.js
@@ -3837,6 +3837,7 @@ async function previewExternalNote(source, id) {
 }
 
 async function openMemorySection(section, el) {
+  if (section === 'external_notes' && _memoryData && !_memoryData.external_notes_enabled) return;
   _currentMemorySection = section;
   document.querySelectorAll('#memoryPanel .side-menu-item').forEach(e => e.classList.remove('active'));
   if (el) el.classList.add('active');
@@ -5228,12 +5229,16 @@ async function loadMemory(force) {
   try {
     const data = await api('/api/memory');
     _memoryData = data;
+    if (_currentMemorySection === 'external_notes' && !data.external_notes_enabled) {
+      _currentMemorySection = null;
+    }
     if (_currentMemorySection === 'external_notes') {
       await loadNotesSources(!!force);
     }
     if (panel) {
       panel.innerHTML = '';
       for (const s of MEMORY_SECTIONS) {
+        if (s.key === 'external_notes' && !_memoryData.external_notes_enabled) continue;
         const el = document.createElement('button');
         el.type = 'button';
         el.className = 'side-menu-item';
diff --git a/tests/test_webui_notes_sources.py b/tests/test_webui_notes_sources.py
index 7c1b5174..bcf8c8fe 100644
--- a/tests/test_webui_notes_sources.py
+++ b/tests/test_webui_notes_sources.py
@@ -60,6 +60,26 @@ def test_notes_sources_shows_configured_note_servers_without_tool_inventory():
     assert sources[0]["status"] == "configured"
 
 
+def test_external_notes_sources_drawer_is_default_off(monkeypatch):
+    from api import routes
+
+    monkeypatch.delenv("HERMES_WEBUI_EXTERNAL_NOTES_SOURCES", raising=False)
+
+    assert routes._external_notes_sources_enabled({}) is False
+    assert routes._external_notes_sources_enabled({"webui_external_notes_sources": False}) is False
+
+
+def test_external_notes_sources_drawer_can_be_enabled_by_config_or_env(monkeypatch):
+    from api import routes
+
+    monkeypatch.delenv("HERMES_WEBUI_EXTERNAL_NOTES_SOURCES", raising=False)
+    assert routes._external_notes_sources_enabled({"webui_external_notes_sources": True}) is True
+    assert routes._external_notes_sources_enabled({"external_notes_sources": "yes"}) is True
+
+    monkeypatch.setenv("HERMES_WEBUI_EXTERNAL_NOTES_SOURCES", "1")
+    assert routes._external_notes_sources_enabled({}) is True
+
+
 def test_joplin_search_notes_returns_safe_snippets(monkeypatch):
     from api import routes
 
@@ -162,6 +182,14 @@ def test_external_notes_ui_uses_minimal_lucide_icons_for_ai_recent_notes():
     assert "📚" not in notes_block
 
 
+def test_external_notes_menu_item_is_default_off_from_memory_payload():
+    from pathlib import Path
+
+    panels = Path("static/panels.js").read_text(encoding="utf-8")
+    assert "external_notes_enabled" in panels
+    assert "if (s.key === 'external_notes' && !_memoryData.external_notes_enabled) continue;" in panels
+
+
 def test_external_notes_search_button_matches_minimal_dark_controls():
     from pathlib import Path