Fix type errors from adding FileMessagePart to MessagePart union

Adding FileMessagePart widened the non-text branch in several consumers that
assumed non-text parts are always images. Fix logFormatter, Gemini, console
Message, and countTokensAsync to handle file parts, and keep constructMessages
narrowing intact when sanitizing file parts (preserve discriminated union).

Author: Admin

core/llm/countTokens.ts

@@ -102,6 +102,9 @@ async function countTokensAsync(
       if (part.type === "imageUrl") {
         return countImageTokens(part);
       }
+      if (part.type === "file") {
+        return (await encoding.encode(`[Attachment: ${part.name}]`)).length;
+      }
       return (await encoding.encode(part.text ?? "")).length;
     });
     return (await Promise.all(promises)).reduce((sum, val) => sum + val, 0);

core/llm/llms/Gemini.ts

@@ -210,6 +210,12 @@ class Gemini extends BaseLLM {
       };
     }
 
+    if (part.type === "file") {
+      return {
+        text: `[Attachment: ${part.name}]`,
+      };
+    }
+
     let data = "";
     if (part.imageUrl?.url) {
       const extracted = extractBase64FromDataUrl(part.imageUrl.url);

core/llm/logFormatter.ts

@@ -276,8 +276,10 @@ export class LLMLogFormatter {
       for (const part of message.content) {
         if (part.type === "text") {
           this.logMessageText(item, part.text);
-        } else {
+        } else if (part.type === "imageUrl") {
           this.logLines(item, `Image: ${part.imageUrl.url}`);
+        } else if (part.type === "file") {
+          this.logLines(item, `Attachment: ${part.name}`);
         }
       }
     }

gui/src/components/console/Message.tsx

@@ -33,9 +33,12 @@ function renderMessageContent(
     return message.content.map((part) => {
       if (part.type == "text") {
         return renderMessageText(part.text);
-      } else {
+      } else if (part.type == "imageUrl") {
         return <div>Image: {part.imageUrl.url}</div>;
+      } else if (part.type == "file") {
+        return <div>Attachment: {part.name}</div>;
       }
+      return null;
     });
   }
 }

gui/src/redux/util/constructMessages.ts

@@ -34,25 +34,6 @@ interface MessageWithContextItems {
   ctxItems: ContextItemWithId[];
   message: ChatMessage;
 }
-
-/**
- * File attachments are rendered in the UI (via editorState) but are not sent
- * to LLM providers, which do not understand the `file` part type. Convert them
- * to a text placeholder so every provider receives a safe, valid message.
- */
-function sanitizeFilePartsForLLM(content: ChatMessage["content"]): ChatMessage["content"] {
-  if (!Array.isArray(content)) {
-    return content;
-  }
-  if (!content.some((part) => part.type === "file")) {
-    return content;
-  }
-  return content.map((part) =>
-    part.type === "file"
-      ? { type: "text" as const, text: `[Attachment: ${part.name}]` }
-      : part,
-  );
-}
 export function constructMessages(
   history: ChatHistoryItem[],
   baseSystemMessage: string | undefined,
@@ -240,10 +221,31 @@ export function constructMessages(
     });
   }
 
-  const messages = msgs.map((m) => ({
-    ...m.message,
-    content: sanitizeFilePartsForLLM(m.message.content),
-  }));
+  // File attachments are rendered in the UI (via editorState) but are not sent
+  // to LLM providers, which do not understand the `file` part type. Convert them
+  // to a text placeholder so every provider receives a safe, valid message.
+  const messages = msgs.map((m) => {
+    const { message } = m;
+    if (
+      message.role !== "user" &&
+      message.role !== "assistant" &&
+      message.role !== "thinking"
+    ) {
+      return message;
+    }
+    if (
+      typeof message.content === "string" ||
+      !message.content.some((part) => part.type === "file")
+    ) {
+      return message;
+    }
+    const content = message.content.map((part) =>
+      part.type === "file"
+        ? { type: "text" as const, text: `[Attachment: ${part.name}]` }
+        : part,
+    );
+    return { ...message, content };
+  });
   return {
     messages,
     appliedRules,