fix(#4146): accept text-only gateway thinking previews

api/gateway_chat.py

@@ -142,6 +142,18 @@ def _gateway_stream_usage(payload: dict) -> dict:
     }
 
 
+def _gateway_reasoning_delta(payload: dict) -> str:
+    if not isinstance(payload, dict):
+        return ""
+    return str(
+        payload.get("text")
+        or payload.get("preview")
+        or payload.get("delta")
+        or payload.get("content")
+        or ""
+    ).strip()
+
+
 def _gateway_tool_progress_event(payload: dict) -> tuple[str, dict] | None:
     """Translate Hermes Gateway tool-progress SSE payloads to WebUI events."""
     if not isinstance(payload, dict):
@@ -150,7 +162,7 @@ def _gateway_tool_progress_event(payload: dict) -> tuple[str, dict] | None:
     if not name:
         return None
     if name == "_thinking":
-        reason_delta = str(payload.get("preview") or payload.get("delta") or "").strip()
+        reason_delta = _gateway_reasoning_delta(payload)
         if not reason_delta:
             return None
         return "reasoning", {"text": reason_delta}
@@ -388,14 +400,7 @@ def _run_gateway_chat_streaming(
                     sse_event = "message"
                     continue
                 if sse_event == "reasoning.available":
-                    reason_delta = (
-                        payload.get("text")
-                        or payload.get("preview")
-                        or payload.get("delta")
-                        or payload.get("content")
-                        or ""
-                    )
-                    reason_delta = str(reason_delta).strip()
+                    reason_delta = _gateway_reasoning_delta(payload)
                     if reason_delta:
                         if stream_id in STREAM_REASONING_TEXT:
                             STREAM_REASONING_TEXT[stream_id] += reason_delta

tests/test_webui_gateway_chat_backend.py

@@ -138,6 +138,14 @@ def test_gateway_tool_progress_event_translates_gateway_lifecycle_payloads():
             "text": "Thinking...",
         },
     )
+    assert _gateway_tool_progress_event(
+        {"tool": "_thinking", "status": "running", "text": "Thinking from text..."}
+    ) == (
+        "reasoning",
+        {
+            "text": "Thinking from text...",
+        },
+    )
     assert _gateway_tool_progress_event({"tool": "_thinking", "status": "running"}) is None
 
 
@@ -242,6 +250,8 @@ def test_gateway_chat_worker_translates_sse_and_persists_session(tmp_path, monke
             yield b'event: hermes.tool.progress\n'
             yield b'data: {"tool":"terminal","label":"terminal: pytest","toolCallId":"call-1","status":"running"}\n\n'
             yield b'data: {"choices":[{"delta":{"content":"hel"}}]}\n\n'
+            yield b'event: hermes.tool.progress\n'
+            yield b'data: {"tool":"_thinking","text":"Thinking from tool progress"}\n\n'
             yield b'event: reasoning.available\n'
             yield b'data: {"text":"Reasoning preview", "preview":"Reasoning preview"}\n\n'
             yield b'event: hermes.tool.progress\n'
@@ -334,6 +344,7 @@ def test_gateway_chat_worker_translates_sse_and_persists_session(tmp_path, monke
         "is_error": False,
         "tid": "call-1",
     }) in event_pairs
+    assert ("reasoning", {"text": "Thinking from tool progress"}) in event_pairs
     assert ("reasoning", {"text": "Reasoning preview"}) in event_pairs
     assert ("tool_complete", {
         "event_type": "tool.completed",