fix: reset tool call state between separate tool blocks to ensure unique IDs across stream segments

internal/js/chat-stream/index.js

@@ -18,6 +18,7 @@ const {
   normalizePreparedToolNames,
   boolDefaultTrue,
   filterIncrementalToolCallDeltasByAllowed,
+  resetStreamToolCallState,
 } = require('./toolcall_policy');
 const {
   estimateTokens,
@@ -115,6 +116,7 @@ module.exports.__test = {
   normalizePreparedToolNames,
   boolDefaultTrue,
   filterIncrementalToolCallDeltasByAllowed,
+  resetStreamToolCallState,
   estimateTokens,
   buildUsage,
   filterLeakedContentFilterParts,

internal/js/chat-stream/toolcall_policy.js

@@ -98,6 +98,15 @@ function filterIncrementalToolCallDeltasByAllowed(deltas, allowedNames, seenName
   return out;
 }
 
+function resetStreamToolCallState(idStore, seenNames) {
+  if (idStore instanceof Map) {
+    idStore.clear();
+  }
+  if (seenNames instanceof Map) {
+    seenNames.clear();
+  }
+}
+
 function ensureStreamToolCallID(idStore, index) {
   const key = Number.isInteger(index) ? index : 0;
   const existing = idStore.get(key);
@@ -135,4 +144,5 @@ module.exports = {
   boolDefaultTrue,
   formatIncrementalToolCallDeltas,
   filterIncrementalToolCallDeltasByAllowed,
+  resetStreamToolCallState,
 };

internal/js/chat-stream/vercel_stream_impl.js

@@ -18,6 +18,7 @@ const {
   formatIncrementalToolCallDeltas,
   filterIncrementalToolCallDeltasByAllowed,
   boolDefaultTrue,
+  resetStreamToolCallState,
 } = require('./toolcall_policy');
 const { createChatCompletionEmitter } = require('./stream_emitter');
 const {
@@ -161,6 +162,7 @@ async function handleVercelStream(req, res, rawBody, payload) {
           if (evt.type === 'tool_calls' && Array.isArray(evt.calls) && evt.calls.length > 0) {
             toolCallsEmitted = true;
             sendDeltaFrame({ tool_calls: formatOpenAIStreamToolCalls(evt.calls, streamToolCallIDs) });
+            resetStreamToolCallState(streamToolCallIDs, streamToolNames);
             continue;
           }
           if (evt.text) {
@@ -283,6 +285,7 @@ async function handleVercelStream(req, res, rawBody, payload) {
                 if (evt.type === 'tool_calls') {
                   toolCallsEmitted = true;
                   sendDeltaFrame({ tool_calls: formatOpenAIStreamToolCalls(evt.calls, streamToolCallIDs) });
+                  resetStreamToolCallState(streamToolCallIDs, streamToolNames);
                   continue;
                 }
                 if (evt.text) {