Revert "refactor(history_message): migrate HistoryMessage consumers to direct dict access (Phase 4)"

This reverts commit 2ba0aaae3c.

src/gui_2.py

@@ -7791,11 +7791,7 @@ def _handle_history_logic_result(app: "App") -> Result[bool]:
   )
 
   if not changed and len(current.disc_entries) > 0:
-   last_curr = current.disc_entries[-1]
-   last_prev = app._last_ui_snapshot.disc_entries[-1]
-   curr_content = last_curr['content'] if 'content' in last_curr else ''
-   prev_content = last_prev['content'] if 'content' in last_prev else ''
-   if curr_content != prev_content:
+   if current.disc_entries[-1].get('content') != app._last_ui_snapshot.disc_entries[-1].get('content'):
     changed = True
 
   if changed:

src/synthesis_formatter.py

@@ -21,7 +21,7 @@ def format_takes_diff(takes: dict[str, list[dict]]) -> str:
  shared_lines = []
  for i in range(common_prefix_len):
   msg = histories[0][i]
-  shared_lines.append(f"{msg['role'] if 'role' in msg else 'unknown'}: {msg['content'] if 'content' in msg else ''}")
+  shared_lines.append(f"{msg.get('role', 'unknown')}: {msg.get('content', '')}")
  
  shared_text = "=== Shared History ==="
  if shared_lines:
@@ -34,7 +34,7 @@ def format_takes_diff(takes: dict[str, list[dict]]) -> str:
     variation_lines.append(f"[{take_name}]")
     for i in range(common_prefix_len, len(history)):
      msg = history[i]
-     variation_lines.append(f"{msg['role'] if 'role' in msg else 'unknown'}: {msg['content'] if 'content' in msg else ''}")
+     variation_lines.append(f"{msg.get('role', 'unknown')}: {msg.get('content', '')}")
     variation_lines.append("")
  else:
   # Single take case