@@ -74,13 +74,14 @@ describe("presentAssistantMessage - Image Handling in Native Tool Calling", () =
 				return false
 			}
 			mockTask.userMessageContent.push(toolResult)
-			const images = mockTask.userMessageContent.filter((block: UserContentBlock) => block.type === "image")
-			if (images.length > 0) {
-				const withoutImages = mockTask.userMessageContent.filter(
-					(block: UserContentBlock) => block.type !== "image",
+			const results = mockTask.userMessageContent.filter(
+				(block: UserContentBlock) => block.type === "tool_result",
+			)
+			if (results.length !== mockTask.userMessageContent.length) {
+				const others = mockTask.userMessageContent.filter(
+					(block: UserContentBlock) => block.type !== "tool_result",
 				)
-				withoutImages.push(...images)
-				mockTask.userMessageContent.splice(0, mockTask.userMessageContent.length, ...withoutImages)
+				mockTask.userMessageContent.splice(0, mockTask.userMessageContent.length, ...results, ...others)
 			}
 			return true
 		})
 
@@ -469,11 +469,12 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 	 * Push a tool_result block to userMessageContent, preventing duplicates.
 	 * Duplicate tool_use_ids cause API errors.
 	 *
-	 * Keeps all tool_result blocks contiguous, as the Anthropic API requires:
-	 * image blocks attached to earlier tool results must not sit between two
-	 * tool_results ("tool_use ids were found without tool_result blocks
-	 * immediately after"), so any images preceding the new result are moved
-	 * after it.
+	 * Keeps all tool_result blocks first and contiguous, as the Anthropic API
+	 * requires: a user message responding to tool_use blocks must begin with
+	 * the tool_result blocks, and any other content (images, text) between or
+	 * ahead of them is rejected ("tool_use ids were found without tool_result
+	 * blocks immediately after"). All tool_result blocks are therefore kept
+	 * ahead of other content in this array.
 	 *
 	 * @param toolResult - The tool_result block to add
 	 * @returns true if added, false if duplicate was skipped
@@ -491,15 +492,15 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		}
 		this.userMessageContent.push(toolResult)
 
-		// The new result is always appended at the end, so every image block
-		// currently in the array precedes it and would split the tool_result
-		// run once another result arrives. Move them after the new result.
-		const images = this.userMessageContent.filter(
-			(block): block is Anthropic.ImageBlockParam => block.type === "image",
+		// Partition into [tool_results, other blocks], preserving order within
+		// each group, so results stay first and contiguous regardless of what
+		// other content (images, text) arrived between pushes.
+		const results = this.userMessageContent.filter(
+			(block): block is Anthropic.ToolResultBlockParam => block.type === "tool_result",
 		)
-		if (images.length > 0) {
-			const withoutImages = this.userMessageContent.filter((block) => block.type !== "image")
-			this.userMessageContent.splice(0, this.userMessageContent.length, ...withoutImages, ...images)
+		if (results.length !== this.userMessageContent.length) {
+			const others = this.userMessageContent.filter((block) => block.type !== "tool_result")
+			this.userMessageContent.splice(0, this.userMessageContent.length, ...results, ...others)
 		}
 
 		return true
 
@@ -6295,10 +6295,11 @@ describe("pushToolResultToUserContent", () => {
 
 		expect(added).toBe(true)
 		expect(task.userMessageContent).toHaveLength(3)
-		// The image must not sit between two tool_results, so it moves after
-		// the new result; other blocks keep their relative order.
-		expect(task.userMessageContent[0].type).toBe("text")
-		expect(task.userMessageContent[1]).toEqual(toolResult)
+		// Results must lead the message (Anthropic rejects other content ahead
+		// of or between tool_results), so the pre-existing text and image move
+		// after the result; blocks keep their relative order within each group.
+		expect(task.userMessageContent[0]).toEqual(toolResult)
+		expect(task.userMessageContent[1].type).toBe("text")
 		expect(task.userMessageContent[2]).toEqual(image)
 	})