fix: tolerate non-utf8 worker output

src/kimi_cli/web/runner/process.py

@@ -51,6 +51,10 @@
 JSONRPCOutMessageAdapter = TypeAdapter[JSONRPCOutMessage](JSONRPCOutMessage)
 
 
+def _decode_worker_output(data: bytes) -> str:
+    return data.decode("utf-8", errors="replace")
+
+
 class SessionProcess:
     """Manages a single session's KimiCLI subprocess.
 
@@ -306,6 +310,7 @@ async def _read_loop(self) -> None:
                         stderr = await self._process.stderr.read()
                         if not stderr:
                             stderr = b"No stderr"
+                        stderr_text = _decode_worker_output(stderr)
                         # Clear in-flight IDs before broadcasting so that
                         # is_busy is already False when the frontend reacts
                         # to the error and sends a new prompt.
@@ -315,24 +320,23 @@ async def _read_loop(self) -> None:
                                 id=str(uuid4()),
                                 error=JSONRPCErrorObject(
                                     code=self._process.returncode or -1,
-                                    message=stderr.decode("utf-8"),
+                                    message=stderr_text,
                                 ),
                             ).model_dump_json()
                         )
                         logger.warning(
-                            f"Process exited with {self._process.returncode}: "
-                            f"{stderr.decode('utf-8')}"
+                            f"Process exited with {self._process.returncode}: {stderr_text}"
                         )
                         await self._emit_status(
                             "error",
                             reason="process_exit",
-                            detail=stderr.decode("utf-8"),
+                            detail=stderr_text,
                         )
                         break
                     else:
                         continue
 
-                await self._broadcast(line.decode("utf-8").rstrip("\n"))
+                await self._broadcast(_decode_worker_output(line).rstrip("\n"))
 
                 # Handle out message
                 try:

tests/web/test_session_error_recovery.py

@@ -129,6 +129,39 @@ async def tracking_broadcast(msg: str) -> None:
     assert sp.status.state == "error"
 
 
+@pytest.mark.asyncio
+async def test_read_loop_eof_handles_non_utf8_stderr() -> None:
+    sp = SessionProcess(uuid4())
+    messages: list[str] = []
+
+    async def capture_broadcast(msg: str) -> None:
+        messages.append(msg)
+
+    sp._broadcast = capture_broadcast  # type: ignore[assignment]
+
+    mock_stdout = asyncio.StreamReader()
+    mock_stdout.feed_eof()
+
+    mock_stderr = asyncio.StreamReader()
+    mock_stderr.feed_data(b"windows dash: \x97")
+    mock_stderr.feed_eof()
+
+    mock_process = MagicMock()
+    mock_process.stdout = mock_stdout
+    mock_process.stderr = mock_stderr
+    mock_process.returncode = 1
+
+    sp._process = mock_process
+    sp._expecting_exit = False
+
+    await sp._read_loop()
+
+    assert messages
+    assert "windows dash: �" in messages[0]
+    assert sp.status.reason == "process_exit"
+    assert sp.status.detail == "windows dash: �"
+
+
 # ---------------------------------------------------------------------------
 # Tests: error state allows recovery with new prompt
 # ---------------------------------------------------------------------------