Keep UTF-8 terminal output intact across packets

app.py

@@ -10,6 +10,7 @@ import termios
 import asyncio
 import json
 import base64
+import codecs
 from collections import deque
 import logging
 import uuid
@@ -923,6 +924,7 @@ class TerminalSession:
         self.buffer = deque()  # 有界輸出回放區，保留序號供重連補播
         self.buffer_size = 0
         self.output_seq = 0
+        self.utf8_decoder = codecs.getincrementaldecoder("utf-8")(errors="replace")
         self.subscribers: dict[int, asyncio.Queue] = {}
         self._next_sub_id = 0
         self.cleanup_task: asyncio.Task | None = None
@@ -952,16 +954,20 @@ class TerminalSession:
             await kill_session(self.id, loop, only_if_idle=True)
 
     def feed(self, data: bytes):
+        text = self.utf8_decoder.decode(data, final=False)
+        if not text:
+            return
         self.output_seq += 1
-        self.buffer.append((self.output_seq, data))
-        self.buffer_size += len(data)
+        encoded = text.encode("utf-8")
+        self.buffer.append((self.output_seq, encoded))
+        self.buffer_size += len(encoded)
         while self.buffer_size > SESSION_BUFFER_MAX and self.buffer:
             _seq, old_data = self.buffer.pop(0)
             self.buffer_size -= len(old_data)
         dead = []
         for sid, q in self.subscribers.items():
             try:
-                q.put_nowait((self.output_seq, data))
+                q.put_nowait((self.output_seq, text))
             except Exception:
                 dead.append(sid)
         for sid in dead:
@@ -1150,12 +1156,12 @@ async def terminal_ws(websocket: WebSocket):
                 except Exception:
                     pass
                 break
-            seq, chunk = item
+            seq, text = item
             try:
                 await websocket.send_text(
                     json.dumps({
                         "type": "output", "seq": seq,
-                        "data": chunk.decode("utf-8", errors="replace"),
+                        "data": text,
                     })
                 )
             except Exception:
@@ -1173,7 +1179,7 @@ async def terminal_ws(websocket: WebSocket):
                     continue
                 await websocket.send_text(json.dumps({
                     "type": "output", "seq": seq,
-                    "data": chunk.decode("utf-8", errors="replace"),
+                    "data": chunk.decode("utf-8", errors="strict"),
                 }))
             await websocket.send_text(json.dumps({
                 "type": "system",