feat(voice): buffer a lone connective and merge with the next utterance

Instead of immediately discarding a fragment like "그러면", hold it briefly
(WSAI_FRAGMENT_MERGE_MS, default 5s). If the next utterance arrives in time,
merge it in front and answer the whole thing ("그러면" + "뭐 먹지"); if nothing
follows within the window, it's silently dropped. Also redeployed the wsai-bot
container so the sustained (700ms) barge-in bot.mjs is now live.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

wsai/dashboard.py

@@ -17,8 +17,10 @@ from __future__ import annotations
 
 import json
 import logging
+import os
 import queue
 import threading
+import time
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 
 from .monitor import Monitor
@@ -491,6 +493,10 @@ class Dashboard:
         self.bot = BotControl()  # dashboard <-> Discord bot control plane
         self._history: list[tuple[str, str]] = []
         self._history_turns = history_turns
+        # A lone connective ("그러면") is held here to see if the next utterance
+        # continues it; merged if it arrives within the window, else dropped.
+        self._pending_fragment: dict | None = None
+        self._fragment_window = float(os.environ.get("WSAI_FRAGMENT_MERGE_MS", "5000")) / 1000.0
         self._server: ThreadingHTTPServer | None = None
         self._thread: threading.Thread | None = None
         self._loop = None
@@ -755,13 +761,25 @@ class Dashboard:
                 turn.replied("[잡음]")
                 turn.finish()
                 return {"heard": heard, "reply": "[잡음]", "wav": b""}
+            now = time.monotonic()
+            pending = self._pending_fragment
+            if pending and (now - pending["ts"]) > self._fragment_window:
+                pending = self._pending_fragment = None  # too old — give up on it
             if _is_fragment(heard):
-                # A lone connective ("그러면") — no answerable intent yet. Discard
-                # rather than reply to a fragment.
-                turn.thought("불완전한 말(연결어) — 대답하지 않고 폐기")
+                # A lone connective ("그러면") — hold it and wait for the next
+                # utterance to continue it. If nothing follows within the window
+                # it's silently dropped (never answered).
+                self._pending_fragment = {"text": heard, "ts": now}
+                turn.thought("불완전한 말(연결어) — 이어질 말 대기 (없으면 폐기)")
                 turn.replied("[대기]")
                 turn.finish()
                 return {"heard": heard, "reply": "[대기]", "wav": b""}
+            if pending:
+                # A real utterance arrived in time — merge the held fragment in
+                # front and answer the whole thing ("그러면" + "뭐 먹지").
+                heard = (pending["text"].rstrip(" .,!?…~") + " " + heard).strip()
+                self._pending_fragment = None
+                turn.heard(heard)
             t_llm = time.monotonic()
             reply_text = self._think(heard)
             self._step(turn, "LLM" if self.brain else "echo", (time.monotonic() - t_llm) * 1000)