refactor: inline base64 image stripping in _save_turn

nanobot/agent/loop.py

@@ -463,15 +463,20 @@ class AgentLoop:
     def _save_turn(self, session: Session, messages: list[dict], skip: int) -> None:
         """Save new-turn messages into session, truncating large tool results."""
         from datetime import datetime
-        from nanobot.utils import helpers
         for m in messages[skip:]:
             entry = {k: v for k, v in m.items() if k != "reasoning_content"}
             if entry.get("role") == "tool" and isinstance(entry.get("content"), str):
                 content = entry["content"]
                 if len(content) > self._TOOL_RESULT_MAX_CHARS:
-                    entry["content"] = content[: self._TOOL_RESULT_MAX_CHARS] + "\n... (truncated)"
-            if entry.get("role") == "user":
-                entry["content"] = helpers.strip_base64_images(entry["content"])
+                    entry["content"] = content[:self._TOOL_RESULT_MAX_CHARS] + "\n... (truncated)"
+            if entry.get("role") == "user" and isinstance(entry.get("content"), list):
+                entry["content"] = [
+                    {"type": "text", "text": "[image]"} if (
+                        c.get("type") == "image_url"
+                        and c.get("image_url", {}).get("url", "").startswith("data:image/")
+                    ) else c
+                    for c in entry["content"]
+                ]
             entry.setdefault("timestamp", datetime.now().isoformat())
             session.messages.append(entry)
         session.updated_at = datetime.now()

nanobot/utils/helpers.py

@@ -2,8 +2,6 @@
 
 from pathlib import Path
 from datetime import datetime
-from typing import Any
-
 
 def ensure_dir(path: Path) -> Path:
     """Ensure a directory exists, creating it if necessary."""
@@ -78,29 +76,4 @@ def parse_session_key(key: str) -> tuple[str, str]:
     parts = key.split(":", 1)
     if len(parts) != 2:
         raise ValueError(f"Invalid session key: {key}")
-    return parts[0], parts[1]
-
-def strip_base64_images(content: str | list[dict[str, Any]]) -> str | list[dict[str, Any]]:
-    """Strip base64 image data from message content, replacing with text placeholder."""
-    if not isinstance(content, list):
-        return content
-
-    new_content = []
-    for item in content:
-        if not isinstance(item, dict):
-            new_content.append(item)
-            continue
-
-        if item.get("type") == "image_url":
-            url = item.get("image_url", {}).get("url", "")
-            if url.startswith("data:image/") and ";base64," in url:
-                new_content.append({"type": "text", "text": "[image]"})
-                continue
-        new_content.append(item)
-
-    text_parts = [c["text"] for c in new_content if isinstance(c, dict) and c.get("type") == "text"]
-    if len(new_content) == 1 and not text_parts:
-        return new_content[0] if new_content else ""
-    if text_parts and len(new_content) == len(text_parts):
-        return "\n".join(text_parts)
-    return new_content
+    return parts[0], parts[1]