diff --git a/agent/chat_completion_helpers.py b/agent/chat_completion_helpers.py
index 0175469ed6..e24c71e52d 100644
--- a/agent/chat_completion_helpers.py
+++ b/agent/chat_completion_helpers.py
@@ -4309,7 +4309,9 @@ def interruptible_streaming_api_call(agent, api_kwargs: dict, *, on_first_delta=
                     extra = getattr(chunk, "model_extra", None)
                     if isinstance(extra, dict):
                         last_one = extra.get("lastOne")
-                if last_one is True and finish_reason is None:
+                # Integer/string-truthy sentinels included — relabelled
+                # upstreams have been seen sending 1 / "true".
+                if last_one in (True, 1, "true") and finish_reason is None:
                     finish_reason = "stop"
                 continue
 
diff --git a/contributors/emails/jon@cromulent.dk b/contributors/emails/jon@cromulent.dk
new file mode 100644
index 0000000000..aab1990bb0
--- /dev/null
+++ b/contributors/emails/jon@cromulent.dk
@@ -0,0 +1 @@
+jon-nielsen
diff --git a/hermes_cli/proxy/server.py b/hermes_cli/proxy/server.py
index 5f8968df4b..880ac4830a 100644
--- a/hermes_cli/proxy/server.py
+++ b/hermes_cli/proxy/server.py
@@ -248,8 +248,11 @@ def create_app(adapter: UpstreamAdapter) -> "web.Application":
                         done_tracker.feed(chunk)
                     await resp.write(chunk)
             if done_tracker is not None and done_tracker.should_append_done():
-                await resp.write(DONE_SSE_FRAME)
-        except (aiohttp.ClientError, asyncio.CancelledError) as exc:
+                try:
+                    await resp.write(DONE_SSE_FRAME)
+                except Exception as exc:  # client hung up at EOF — harmless
+                    logger.debug("proxy: DONE append skipped: %s", exc)
+        except (aiohttp.ClientError, asyncio.CancelledError, OSError) as exc:
             if done_tracker is not None:
                 done_tracker.mark_interrupted()
             logger.warning("proxy: streaming interrupted: %s", exc)
diff --git a/hermes_cli/proxy/sse_done.py b/hermes_cli/proxy/sse_done.py
index 2a5ed9a72e..bf2f69e832 100644
--- a/hermes_cli/proxy/sse_done.py
+++ b/hermes_cli/proxy/sse_done.py
@@ -41,6 +41,7 @@ class SseDoneTracker:
     saw_malformed_event: bool = False
     interrupted: bool = False
     _buf: bytearray = field(default_factory=bytearray, repr=False)
+    _data_lines: list = field(default_factory=list, repr=False)
 
     def feed(self, chunk: bytes) -> None:
         """Observe a forwarded chunk (bytes are not modified)."""
@@ -68,10 +69,12 @@ class SseDoneTracker:
             or self.saw_malformed_event
         ):
             return False
-        # Flush any trailing line without a final newline (rare but valid).
+        # Flush any trailing line without a final newline (rare but valid),
+        # then dispatch a final event that never saw its blank-line boundary.
         if self._buf:
             self._consume_line(bytes(self._buf))
             self._buf.clear()
+        self._dispatch_event()
         if self.saw_done or self.saw_error_event or self.saw_malformed_event:
             return False
         return self.saw_terminal_finish or self.saw_last_one
@@ -80,9 +83,24 @@ class SseDoneTracker:
         # Strip CR from CRLF-delimited SSE.
         if line.endswith(b"\r"):
             line = line[:-1]
+        if not line:
+            # Blank line = SSE event boundary: dispatch accumulated data.
+            self._dispatch_event()
+            return
         if not line.startswith(b"data:"):
             return
-        payload = line[5:].strip()
+        # Per the SSE spec one event may span several consecutive ``data:``
+        # lines whose payloads are joined with "\n" at dispatch time.
+        # Parsing each line independently would misread a split JSON event
+        # as two malformed fragments.
+        self._data_lines.append(line[5:].strip())
+
+    def _dispatch_event(self) -> None:
+        if not self._data_lines:
+            return
+        payload = b"\n".join(self._data_lines)
+        self._data_lines = []
+        payload = payload.strip()
         if payload == b"[DONE]":
             self.saw_done = True
             return
@@ -103,7 +121,9 @@ class SseDoneTracker:
         if event.get("error") is not None:
             self.saw_error_event = True
             return
-        if event.get("lastOne") is True:
+        # Accept integer-truthy sentinels too — relabelled upstreams have
+        # been observed sending ``"lastOne": 1`` / ``"true"``.
+        if event.get("lastOne") in (True, 1, "true"):
             self.saw_last_one = True
         for choice in event.get("choices") or []:
             if not isinstance(choice, dict):