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fix: prevent duplicate tool_result blocks in native tool protocol #9248

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merged 1 commit into from
Nov 15, 2025
Merged

fix: prevent duplicate tool_result blocks in native tool protocol #9248

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13 changes: 13 additions & 0 deletions src/core/assistant-message/presentAssistantMessage.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -277,6 +277,9 @@ export async function presentAssistantMessage(cline: Task) {
break
}

// Track if we've already pushed a tool result for this tool call (native protocol only)
let hasToolResult = false

const pushToolResult = (content: ToolResponse) => {
// Check if we're using native tool protocol
const toolProtocol = vscode.workspace
Expand All @@ -288,6 +291,14 @@ export async function presentAssistantMessage(cline: Task) {
const toolCallId = (block as any).id

if (isNative && toolCallId) {
// For native protocol, only allow ONE tool_result per tool call
if (hasToolResult) {
console.warn(
`[presentAssistantMessage] Skipping duplicate tool_result for tool_use_id: ${toolCallId}`,
)
return
}

// For native protocol, add as tool_result block
let resultContent: string
if (typeof content === "string") {
Expand All @@ -312,6 +323,8 @@ export async function presentAssistantMessage(cline: Task) {
tool_use_id: toolCallId,
content: resultContent,
} as Anthropic.ToolResultBlockParam)

hasToolResult = true
} else {
// For XML protocol, add as text blocks (legacy behavior)
cline.userMessageContent.push({ type: "text", text: `${toolDescription()} Result:` })
Expand Down