fix: filter empty text content blocks to prevent LLM API 400 errors

core/llm/countTokens.ts

@@ -9,7 +9,7 @@ import {
 } from "../index.js";
 import { autodetectTemplateType } from "./autodetect.js";
 import {
-  addSpaceToAnyEmptyMessages,
+  stripEmptyContentParts,
   chatMessageIsEmpty,
   isUserOrToolMsg,
   messageHasToolCallId,
@@ -446,7 +446,7 @@ function compileChatMessages({
   // Remove any empty messages or non-user/tool trailing messages
   msgsCopy = msgsCopy.filter((msg) => !chatMessageIsEmpty(msg));
 
-  msgsCopy = addSpaceToAnyEmptyMessages(msgsCopy);
+  msgsCopy = stripEmptyContentParts(msgsCopy);
 
   // Extract the tool sequence from the end of the message array
   const toolSequence = extractToolSequence(msgsCopy);

core/llm/llms/Bedrock.ts

@@ -538,11 +538,15 @@ class Bedrock extends BaseLLM {
   ): ContentBlock[] {
     const blocks: ContentBlock[] = [];
     if (typeof content === "string") {
-      blocks.push({ text: content });
+      if (content.trim()) {
+        blocks.push({ text: content });
+      }
     } else {
       for (const part of content) {
         if (part.type === "text") {
-          blocks.push({ text: part.text });
+          if (part.text?.trim()) {
+            blocks.push({ text: part.text });
+          }
         } else if (part.type === "imageUrl" && part.imageUrl) {
           const parsed = parseDataUrl(part.imageUrl.url);
           if (parsed) {

core/llm/messages.ts

@@ -4,25 +4,36 @@ export function messageHasToolCalls(msg: ChatMessage): boolean {
   return msg.role === "assistant" && !!msg.toolCalls;
 }
 
-export function messageIsEmpty(message: ChatMessage): boolean {
-  if (typeof message.content === "string") {
-    return message.content.trim() === "";
+function contentIsEmpty(content: ChatMessage["content"]): boolean {
+  if (typeof content === "string") {
+    return content.trim() === "";
   }
-  if (Array.isArray(message.content)) {
-    return message.content.every(
-      (item) => item.type === "text" && item.text?.trim() === "",
+  if (Array.isArray(content)) {
+    return content.every(
+      (item) => item.type === "text" && (!item.text || item.text.trim() === ""),
     );
   }
-  return false;
+  return !content;
+}
+
+export function messageIsEmpty(message: ChatMessage): boolean {
+  return contentIsEmpty(message.content);
 }
 
-// some providers don't support empty messages
-export function addSpaceToAnyEmptyMessages(
-  messages: ChatMessage[],
-): ChatMessage[] {
+/** Strip empty text parts from array content. */
+export function stripEmptyContentParts(messages: ChatMessage[]): ChatMessage[] {
   return messages.map((message) => {
-    if (messageIsEmpty(message)) {
-      message.content = " ";
+    if (Array.isArray(message.content)) {
+      message.content = message.content.filter(
+        (part) =>
+          part.type !== "text" ||
+          (part.text !== null &&
+            part.text !== undefined &&
+            part.text.trim() !== ""),
+      );
+      if (message.content.length === 0) {
+        message.content = "";
+      }
     }
     return message;
   });
@@ -57,15 +68,9 @@ export function chatMessageIsEmpty(message: ChatMessage): boolean {
   switch (message.role) {
     case "system":
     case "user":
-      return (
-        typeof message.content === "string" && message.content.trim() === ""
-      );
+      return contentIsEmpty(message.content);
     case "assistant":
-      return (
-        typeof message.content === "string" &&
-        message.content.trim() === "" &&
-        !message.toolCalls
-      );
+      return contentIsEmpty(message.content) && !message.toolCalls;
     case "thinking":
     case "tool":
       return false;

core/llm/openaiTypeConverters.ts

@@ -106,6 +106,18 @@ function appendReasoningFieldsIfSupported(
   }
 }
 
+function toAssistantContent(
+  content: ChatMessage["content"],
+): string | TextMessagePart[] {
+  if (typeof content === "string") {
+    return content || " "; // LM Studio (and other providers) don't accept empty content
+  }
+  const parts = content
+    .filter((p) => p.type === "text" && p.text?.trim())
+    .map((p) => p as TextMessagePart);
+  return parts.length > 0 ? parts : " ";
+}
+
 export function toChatMessage(
   message: ChatMessage,
   options: CompletionOptions,
@@ -145,12 +157,7 @@ export function toChatMessage(
       }[];
     } = {
       role: "assistant",
-      content:
-        typeof message.content === "string"
-          ? message.content || " " // LM Studio (and other providers) don't accept empty content
-          : message.content
-              .filter((part) => part.type === "text")
-              .map((part) => part as TextMessagePart),
+      content: toAssistantContent(message.content),
     };
 
     // Add tool calls if present
@@ -178,31 +185,45 @@ export function toChatMessage(
     if (typeof message.content === "string") {
       return {
         role: "user",
-        content: message.content ?? " ", // LM Studio (and other providers) don't accept empty content
+        content: message.content || " ",
       };
     }
 
     // If no multi-media is in the message, just send as text
     // for compatibility with OpenAI-"compatible" servers
     // that don't support multi-media format
+    const hasNonText = message.content.some((item) => item.type !== "text");
+    if (hasNonText) {
+      // Filter out empty text parts when there's non-text content (images)
+      const filteredContent = message.content
+        .filter(
+          (part) =>
+            part.type !== "text" || (part.text && part.text.trim() !== ""),
+        )
+        .map((part) => {
+          if (part.type === "imageUrl") {
+            return {
+              type: "image_url" as const,
+              image_url: {
+                url: part.imageUrl.url,
+                detail: "auto" as const,
+              },
+            };
+          }
+          return part;
+        });
+      return {
+        role: "user",
+        content: filteredContent,
+      };
+    }
+
     return {
       role: "user",
-      content: message.content.some((item) => item.type !== "text")
-        ? message.content.map((part) => {
-            if (part.type === "imageUrl") {
-              return {
-                type: "image_url" as const,
-                image_url: {
-                  url: part.imageUrl.url,
-                  detail: "auto" as const,
-                },
-              };
-            }
-            return part;
-          })
-        : message.content
-            .map((item) => (item as TextMessagePart).text)
-            .join("") || " ",
+      content:
+        message.content
+          .map((item) => (item as TextMessagePart).text)
+          .join("") || "...",
     };
   }
 }

packages/openai-adapters/src/apis/Bedrock.ts

@@ -203,9 +203,15 @@ export class BedrockApi implements BaseLlmApi {
           const content = message.content;
           if (content) {
             if (typeof content === "string") {
-              currentBlocks.push({ text: content });
+              if (content.trim()) {
+                currentBlocks.push({ text: content });
+              }
             } else {
               content.forEach((part) => {
+                // Skip empty text parts
+                if (part.type === "text" && !part.text?.trim()) {
+                  return;
+                }
                 currentBlocks.push(this._oaiPartToBedrockPart(part));
               });
             }