diff --git a/tests/test_tui_gateway_server.py b/tests/test_tui_gateway_server.py
index d29f5b12a..47c476b01 100644
--- a/tests/test_tui_gateway_server.py
+++ b/tests/test_tui_gateway_server.py
@@ -847,6 +847,41 @@ def test_history_to_messages_preserves_tool_calls_for_resume_display():
     ]
 
 
+def test_history_to_messages_keeps_reasoning_only_assistant_turn():
+    # A thinking-only assistant turn (reasoning present, no visible text) is
+    # persisted and recallable, but was dropped from the resumed session view
+    # as "empty" -- so it vanished while the agent could still recall it from
+    # the transcript. Keep it (with reasoning) so the desktop "Thinking…"
+    # disclosure renders. (#44022)
+    history = [
+        {"role": "user", "content": "think about this"},
+        {"role": "assistant", "content": "", "reasoning": "step-by-step thoughts"},
+        {"role": "assistant", "content": "here is the answer"},
+    ]
+
+    assert server._history_to_messages(history) == [
+        {"role": "user", "text": "think about this"},
+        {"role": "assistant", "text": "", "reasoning": "step-by-step thoughts"},
+        {"role": "assistant", "text": "here is the answer"},
+    ]
+
+
+def test_history_to_messages_still_drops_empty_assistant_without_reasoning():
+    # A genuinely empty assistant turn (no text, no reasoning, no tool calls)
+    # remains filtered out -- the fix only spares reasoning-bearing turns.
+    history = [
+        {"role": "user", "content": "hi"},
+        {"role": "assistant", "content": "", "reasoning": ""},
+        {"role": "assistant", "content": "   "},
+        {"role": "assistant", "content": "real reply"},
+    ]
+
+    assert server._history_to_messages(history) == [
+        {"role": "user", "text": "hi"},
+        {"role": "assistant", "text": "real reply"},
+    ]
+
+
 def test_history_to_messages_renders_multimodal_content():
     # bb/gui preserves image URLs in the resume payload so the desktop
     # renderer's extractEmbeddedImages can pull them back out and display
diff --git a/tui_gateway/server.py b/tui_gateway/server.py
index a54453aea..774deb89f 100644
--- a/tui_gateway/server.py
+++ b/tui_gateway/server.py
@@ -3708,16 +3708,27 @@ def _history_to_messages(history: list[dict]) -> list[dict]:
                 {"role": "tool", "name": name, "context": _tool_ctx(name, args)}
             )
             continue
-        if not content_text.strip():
+        # An assistant turn may carry only reasoning/thinking content with no
+        # visible text (extended-thinking turns, thinking-only recovery
+        # responses). Such a turn is persisted with its reasoning fields and is
+        # recallable from the transcript, but dropping it here as "empty" makes
+        # it vanish from the resumed/reloaded session view while the desktop's
+        # reasoning disclosure has nothing to render. Keep it when it carries
+        # reasoning so the "Thinking…" block still shows. (#44022)
+        reasoning_keys = (
+            "reasoning",
+            "reasoning_content",
+            "reasoning_details",
+            "codex_reasoning_items",
+        )
+        has_reasoning = role == "assistant" and any(
+            m.get(key) for key in reasoning_keys
+        )
+        if not content_text.strip() and not has_reasoning:
             continue
         msg = {"role": role, "text": content_text}
         if role == "assistant":
-            for key in (
-                "reasoning",
-                "reasoning_content",
-                "reasoning_details",
-                "codex_reasoning_items",
-            ):
+            for key in reasoning_keys:
                 if key in m and m.get(key) is not None:
                     msg[key] = m.get(key)
         messages.append(msg)