diff --git a/src/ai_client.py b/src/ai_client.py
index efc85193..12171924 100644
--- a/src/ai_client.py
+++ b/src/ai_client.py
@@ -3258,8 +3258,10 @@ def send(
   if chunks:
    context_block = "## Retrieved Context\n\n"
    for i, chunk in enumerate(chunks):
-    path = chunk.get("metadata", {}).get("path", "unknown")
-    context_block += f"### Chunk {i+1} (Source: {path})\n{chunk.get('document', '')}\n\n"
+    chunk_meta = chunk["metadata"] if "metadata" in chunk else {}
+    path = chunk_meta["path"] if "path" in chunk_meta else "unknown"
+    doc = chunk["document"] if "document" in chunk else ""
+    context_block += f"### Chunk {i+1} (Source: {path})\n{doc}\n\n"
    user_message = context_block + user_message
 
  _append_comms("OUT", "request", {"message": user_message, "system": _get_combined_system_prompt(_active_tool_preset, _active_bias_profile)})
diff --git a/src/app_controller.py b/src/app_controller.py
index 6e8915e0..20081fe4 100644
--- a/src/app_controller.py
+++ b/src/app_controller.py
@@ -247,8 +247,10 @@ def _api_generate(controller: 'AppController', req: GenerateRequest) -> Metadata
     if rag_result.ok and rag_result.data:
      context_block = "## Retrieved Context\n\n"
      for i, chunk in enumerate(rag_result.data):
-      path = chunk.get("metadata", {}).get("path", "unknown")
-      context_block += f"### Chunk {i+1} (Source: {path})\n{chunk.get('document', '')}\n\n"
+      chunk_meta = chunk["metadata"] if "metadata" in chunk else {}
+      path = chunk_meta["path"] if "path" in chunk_meta else "unknown"
+      doc = chunk["document"] if "document" in chunk else ""
+      context_block += f"### Chunk {i+1} (Source: {path})\n{doc}\n\n"
      user_msg = context_block + user_msg
     elif not rag_result.ok:
      controller._last_request_errors.append(("rag_search", rag_result.errors[0]))
@@ -2269,13 +2271,14 @@ class AppController:
        kind = entry.get("kind", entry.get("type", ""))
        payload = entry.get("payload", {})
        ts = entry.get("ts", "")
+       comms_entry = CommsLogEntry.from_dict(entry)
 
        if kind == 'tool_call':
         tid = payload.get('id') or payload.get('call_id')
         script = payload.get('script') or json.dumps(payload.get('args', {}), indent=1)
         script = _resolve_log_ref(script, session_dir)
         entry_obj = {
-         'source_tier': entry['source_tier'] if 'source_tier' in entry else 'main',
+         'source_tier': comms_entry.source_tier,
          'script': script,
          'result': '', # Waiting for result
          'ts': ts
@@ -2298,17 +2301,23 @@ class AppController:
 
        if kind == 'response' and 'usage' in payload:
         u = payload['usage']
+        u_stats = models.UsageStats(
+         input_tokens=u.get('input_tokens', 0) or 0,
+         output_tokens=u.get('output_tokens', 0) or 0,
+         cache_read_tokens=u.get('cache_read_input_tokens', 0) or 0,
+         cache_creation_tokens=u.get('cache_creation_input_tokens', 0) or 0,
+        )
         for k in ['input_tokens', 'output_tokens', 'cache_read_input_tokens', 'cache_creation_input_tokens', 'total_tokens']:
          if k in new_usage: new_usage[k] += u.get(k, 0) or 0
-        tier = entry['source_tier'] if 'source_tier' in entry else 'main'
+        tier = comms_entry.source_tier
         if tier in new_mma_usage:
-         new_mma_usage[tier]['input'] += u.get('input_tokens', 0) or 0
-         new_mma_usage[tier]['output'] += u.get('output_tokens', 0) or 0
+         new_mma_usage[tier]['input'] += u_stats.input_tokens
+         new_mma_usage[tier]['output'] += u_stats.output_tokens
         new_token_history.append({
          'time': ts,
-         'input': u.get('input_tokens', 0) or 0,
-         'output': u.get('output_tokens', 0) or 0,
-         'model': entry['model'] if 'model' in entry else 'unknown'
+         'input': u_stats.input_tokens,
+         'output': u_stats.output_tokens,
+         'model': comms_entry.model
         })
 
        if kind == "history_add":
@@ -4160,8 +4169,10 @@ class AppController:
    if rag_result.ok and rag_result.data:
     context_block = "## Retrieved Context\n\n"
     for i, chunk in enumerate(rag_result.data):
-     path = chunk.get("metadata", {}).get("path", "unknown")
-     context_block += f"### Chunk {i+1} (Source: {path})\n{chunk.get('document', '')}\n\n"
+     chunk_meta = chunk["metadata"] if "metadata" in chunk else {}
+     path = chunk_meta["path"] if "path" in chunk_meta else "unknown"
+     doc = chunk["document"] if "document" in chunk else ""
+     context_block += f"### Chunk {i+1} (Source: {path})\n{doc}\n\n"
     user_msg = context_block + user_msg
    elif not rag_result.ok:
     self._last_request_errors.append(("rag_search", rag_result.errors[0]))
diff --git a/src/gui_2.py b/src/gui_2.py
index 28586cfd..351c343b 100644
--- a/src/gui_2.py
+++ b/src/gui_2.py
@@ -120,6 +120,7 @@ from src import theme_2 as theme
 from src import thinking_parser
 from src import workspace_manager
 from src.hot_reloader import HotReloader
+from src.type_aliases import HistoryMessage, SessionInsights
 
 win32gui: Any = None
 win32con: Any = None
@@ -4922,15 +4923,13 @@ def render_session_insights_panel(app: App) -> None:
  if app.perf_profiling_enabled: app.perf_monitor.start_component("_render_session_insights_panel")
  imgui.text_colored(C_LBL(), 'Session Insights')
  imgui.separator()
- insights = app.controller.get_session_insights()
- imgui.text(f"Total Tokens: {insights.get('total_tokens', 0):,}")
- imgui.text(f"API Calls: {insights.get('call_count', 0)}")
- imgui.text(f"Burn Rate: {insights.get('burn_rate', 0):.0f} tokens/min")
- imgui.text(f"Session Cost: ${insights.get('session_cost', 0):.4f}")
- completed  = insights.get('completed_tickets', 0)
- efficiency = insights.get('efficiency', 0)
- imgui.text(f"Completed: {completed}")
- imgui.text(f"Tokens/Ticket: {efficiency:.0f}" if efficiency > 0 else "Tokens/Ticket: N/A")
+ insights = SessionInsights.from_dict(app.controller.get_session_insights())
+ imgui.text(f"Total Tokens: {insights.total_tokens:,}")
+ imgui.text(f"API Calls: {insights.call_count}")
+ imgui.text(f"Burn Rate: {insights.burn_rate:.0f} tokens/min")
+ imgui.text(f"Session Cost: ${insights.session_cost:.4f}")
+ imgui.text(f"Completed: {insights.completed_tickets}")
+ imgui.text(f"Tokens/Ticket: {insights.efficiency:.0f}" if insights.efficiency > 0 else "Tokens/Ticket: N/A")
  if app.perf_profiling_enabled: app.perf_monitor.end_component("_render_session_insights_panel")
 
 def render_prior_session_view(app: App) -> None:
@@ -7791,7 +7790,9 @@ def _handle_history_logic_result(app: "App") -> Result[bool]:
   )
 
   if not changed and len(current.disc_entries) > 0:
-   if current.disc_entries[-1].get('content') != app._last_ui_snapshot.disc_entries[-1].get('content'):
+   curr_msg = HistoryMessage.from_dict(current.disc_entries[-1])
+   prev_msg = HistoryMessage.from_dict(app._last_ui_snapshot.disc_entries[-1])
+   if curr_msg.content != prev_msg.content:
     changed = True
 
   if changed:
diff --git a/src/synthesis_formatter.py b/src/synthesis_formatter.py
index 9155791e..51d4f381 100644
--- a/src/synthesis_formatter.py
+++ b/src/synthesis_formatter.py
@@ -1,10 +1,13 @@
+from src.type_aliases import HistoryMessage
+
+
 def format_takes_diff(takes: dict[str, list[dict]]) -> str:
  """
   [C: tests/test_synthesis_formatter.py:test_format_takes_diff_common_prefix, tests/test_synthesis_formatter.py:test_format_takes_diff_empty, tests/test_synthesis_formatter.py:test_format_takes_diff_no_common_prefix, tests/test_synthesis_formatter.py:test_format_takes_diff_single_take]
  """
  if not takes:
   return ""
- 
+
  histories = list(takes.values())
  if not histories:
   return ""
@@ -20,9 +23,9 @@ 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.get('role', 'unknown')}: {msg.get('content', '')}")
- 
+  msg = HistoryMessage.from_dict(histories[0][i])
+  shared_lines.append(f"{msg.role}: {msg.content}")
+
  shared_text = "=== Shared History ==="
  if shared_lines:
   shared_text += "\n" + "\n".join(shared_lines)
@@ -33,8 +36,8 @@ def format_takes_diff(takes: dict[str, list[dict]]) -> str:
    if len(history) > common_prefix_len:
     variation_lines.append(f"[{take_name}]")
     for i in range(common_prefix_len, len(history)):
-     msg = history[i]
-     variation_lines.append(f"{msg.get('role', 'unknown')}: {msg.get('content', '')}")
+     msg = HistoryMessage.from_dict(history[i])
+     variation_lines.append(f"{msg.role}: {msg.content}")
     variation_lines.append("")
  else:
   # Single take case