feat(webui): support image uploads in composer and message bubbles

nanobot/agent/loop.py

@@ -858,15 +858,17 @@ class AgentLoop:
                 )
             )
 
-        # Persist the triggering user message immediately, before running the
-        # agent loop. If the process is killed mid-turn (OOM, SIGKILL, self-
-        # restart, etc.), the existing runtime_checkpoint preserves the
-        # in-flight assistant/tool state but NOT the user message itself, so
-        # the user's prompt is silently lost on recovery. Saving it up front
-        # makes recovery possible from the session log alone.
+        # Persist the triggering user message up front so a mid-turn crash
+        # doesn't silently lose the prompt on recovery. ``media`` rides along
+        # as raw on-disk paths — sanitized image blocks are stripped from
+        # JSONL, and webui replay needs the paths to mint signed URLs.
         user_persisted_early = False
-        if isinstance(msg.content, str) and msg.content.strip():
-            session.add_message("user", msg.content)
+        media_paths = [p for p in (msg.media or []) if isinstance(p, str) and p]
+        has_text = isinstance(msg.content, str) and msg.content.strip()
+        if has_text or media_paths:
+            extra: dict[str, Any] = {"media": list(media_paths)} if media_paths else {}
+            text = msg.content if isinstance(msg.content, str) else ""
+            session.add_message("user", text, **extra)
             self._mark_pending_user_turn(session)
             self.sessions.save(session)
             user_persisted_early = True