fix: token usage dropped when it rides on a non-empty finish delta (#1703)

src/llm_core.py

@@ -1323,7 +1323,19 @@ async def stream_llm(url: str, model: str, messages: List[Dict], temperature: fl
                                 # Usage chunk (from stream_options)
                                 _choices = j.get("choices") or []
                                 _delta0 = _choices[0].get("delta") if _choices else None
-                                if "usage" in j and _delta0 in (None, {}, {"content": None}):
+                                # Capture usage whenever the chunk carries it and
+                                # the delta has no actual output. Some gateways /
+                                # local servers attach usage to the FINAL delta,
+                                # which also carries role/finish_reason (so it is
+                                # not exactly None/{}/{"content": None}); gating on
+                                # those exact shapes discarded their token counts.
+                                _delta_has_output = isinstance(_delta0, dict) and (
+                                    _delta0.get("content")
+                                    or _delta0.get("reasoning_content")
+                                    or _delta0.get("reasoning")
+                                    or _delta0.get("tool_calls")
+                                )
+                                if "usage" in j and not _delta_has_output:
                                     u = j["usage"]
                                     _usage_data = {"input_tokens": u.get("prompt_tokens", 0), "output_tokens": u.get("completion_tokens", 0)}
                                     # llama.cpp puts a `timings` block alongside `usage` with the