From 810399c27e97e184d4d77cca6ac5a530a9a60683 Mon Sep 17 00:00:00 2001
From: oyi77 <oyi77@users.noreply.github.com>
Date: Sat, 6 Jun 2026 03:54:31 +0700
Subject: [PATCH] feat(duckduckgo-web): add tool-call translation via webTools
 prompt injection

DuckDuckGo AI Chat has no native function calling. Serialize OpenAI tools[] into system prompt instructions (webTools.ts), parse <tool>{...}</tool> blocks from response text back into OpenAI tool_calls.

Pattern: same as deepseek-web (#2820) and qwen-web (#3252). When tools requested, buffers full response for tool-call parsing. When no tools, standard streaming passthrough.
---
 open-sse/executors/duckduckgo-web.ts | 41 +++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/open-sse/executors/duckduckgo-web.ts b/open-sse/executors/duckduckgo-web.ts
index 0cea817dec44..e03d32fff211 100644
--- a/open-sse/executors/duckduckgo-web.ts
+++ b/open-sse/executors/duckduckgo-web.ts
@@ -1,5 +1,6 @@
 import { BaseExecutor, type ExecuteInput } from "./base.ts";
 import { FETCH_TIMEOUT_MS } from "../config/constants.ts";
+import { serializeToolsToPrompt, parseToolCallsFromText } from "../translator/webTools.ts";
 
 export const DUCKDUCKGO_BASE = "https://duckduckgo.com";
 const STATUS_URL = `${DUCKDUCKGO_BASE}/duckchat/v1/status`;
@@ -64,7 +65,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
   }
 
   async execute(input: ExecuteInput) {
-    const { model, messages, stream, signal, upstreamHeaders } = input;
+    const { model, messages, stream, signal, upstreamHeaders, body } = input;
 
     if (!messages || messages.length === 0) {
       return new Response(
@@ -73,6 +74,14 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
       );
     }
 
+    const bodyObj = (body || {}) as Record<string, unknown>;
+    const requestedTools = bodyObj.tools;
+    const hasTools = Array.isArray(requestedTools) && requestedTools.length > 0;
+    const toolSystemPrompt = hasTools ? serializeToolsToPrompt(requestedTools) : "";
+    const effectiveMessages = toolSystemPrompt
+      ? [{ role: "system", content: toolSystemPrompt }, ...messages]
+      : messages;
+
     // Acquire session from pool for fingerprint rotation
     const pool = this.getPool();
     let session;
@@ -117,7 +126,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
         },
         body: JSON.stringify({
           model,
-          messages,
+          messages: effectiveMessages,
           stream: stream !== false,
         }),
         signal: mergedSignal,
@@ -145,13 +154,13 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
             },
             body: JSON.stringify({
               model,
-              messages,
+              messages: effectiveMessages,
               stream: stream !== false,
             }),
             signal: mergedSignal,
           });
 
-          return this.processResponse(retryResponse, stream !== false);
+          return this.processResponse(retryResponse, stream !== false, hasTools, requestedTools);
         }
         return new Response(
           JSON.stringify({ error: { message: "Service unavailable" } }),
@@ -167,7 +176,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
         );
       }
 
-      const result = this.processResponse(chatResponse, stream !== false);
+      const result = this.processResponse(chatResponse, stream !== false, hasTools, requestedTools);
 
       // Report pool status based on response
       if (pool && session) {
@@ -222,7 +231,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
     }
   }
 
-  private async processResponse(response: Response, streaming: boolean): Promise<Response> {
+  private async processResponse(response: Response, streaming: boolean, hasTools?: boolean, requestedTools?: unknown): Promise<Response> {
     if (!response.ok) {
       const body = await response.text();
       return new Response(body, {
@@ -231,7 +240,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
       });
     }
 
-    if (streaming) {
+    if (streaming && !hasTools) {
       const reader = response.body?.getReader();
       if (!reader) {
         return new Response(
@@ -304,6 +313,24 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
         }
       }
 
+      if (hasTools) {
+        const { content: cleanedContent, toolCalls } = parseToolCallsFromText(
+          fullContent, `call-${Date.now()}`, requestedTools
+        );
+        const choice: Record<string, unknown> = {
+          index: 0,
+          message: { role: "assistant", content: cleanedContent },
+          finish_reason: toolCalls ? "tool_calls" : "stop",
+        };
+        if (toolCalls) {
+          (choice.message as Record<string, unknown>).tool_calls = toolCalls;
+          (choice.message as Record<string, unknown>).content = null;
+        }
+        return new Response(JSON.stringify({ choices: [choice] }), {
+          headers: { "Content-Type": "application/json" },
+        });
+      }
+
       const openaiResponse = {
         choices: [
           {