diff --git a/internal/js/chat-stream/vercel_stream.js b/internal/js/chat-stream/vercel_stream.js
index 439edb8..4b1d6f3 100644
--- a/internal/js/chat-stream/vercel_stream.js
+++ b/internal/js/chat-stream/vercel_stream.js
@@ -1,33 +1,22 @@
 'use strict';
 
 const {
-  extractToolNames,
   createToolSieveState,
   processToolSieveChunk,
   flushToolSieve,
   parseStandaloneToolCalls,
   formatOpenAIStreamToolCalls,
 } = require('../helpers/stream-tool-sieve');
-const {
-  BASE_HEADERS,
-} = require('../shared/deepseek-constants');
-
-const {
-  writeOpenAIError,
-} = require('./error_shape');
-const {
-  parseChunkForContent,
-  isCitation,
-} = require('./sse_parse');
-const {
-  buildUsage,
-} = require('./token_usage');
+const { BASE_HEADERS } = require('../shared/deepseek-constants');
+const { writeOpenAIError } = require('./error_shape');
+const { parseChunkForContent, isCitation } = require('./sse_parse');
+const { buildUsage } = require('./token_usage');
 const {
   resolveToolcallPolicy,
+  formatIncrementalToolCallDeltas,
+  filterIncrementalToolCallDeltasByAllowed,
 } = require('./toolcall_policy');
-const {
-  createChatCompletionEmitter,
-} = require('./stream_emitter');
+const { createChatCompletionEmitter } = require('./stream_emitter');
 const {
   asString,
   isAbortError,
@@ -57,6 +46,7 @@ async function handleVercelStream(req, res, rawBody, payload) {
   const searchEnabled = toBool(prep.body.search_enabled);
   const toolPolicy = resolveToolcallPolicy(prep.body, payload.tools);
   const toolNames = toolPolicy.toolNames;
+  const emitEarlyToolDeltas = toolPolicy.emitEarlyToolDeltas;
 
   if (!model || !leaseID || !deepseekToken || !powHeader || !completionPayload) {
     writeOpenAIError(res, 500, 'invalid vercel prepare response');
@@ -132,6 +122,7 @@ async function handleVercelStream(req, res, rawBody, payload) {
     const toolSieveState = createToolSieveState();
     let toolCallsEmitted = false;
     const streamToolCallIDs = new Map();
+    const streamToolNames = new Map();
     const decoder = new TextDecoder();
     reader = completionRes.body.getReader();
     let buffered = '';
@@ -255,6 +246,18 @@ async function handleVercelStream(req, res, rawBody, payload) {
               }
               const events = processToolSieveChunk(toolSieveState, p.text, toolNames);
               for (const evt of events) {
+                if (evt.type === 'tool_call_deltas') {
+                  if (!emitEarlyToolDeltas) {
+                    continue;
+                  }
+                  const filtered = filterIncrementalToolCallDeltasByAllowed(evt.deltas, toolNames, streamToolNames);
+                  const formatted = formatIncrementalToolCallDeltas(filtered, streamToolCallIDs);
+                  if (formatted.length > 0) {
+                    toolCallsEmitted = true;
+                    sendDeltaFrame({ tool_calls: formatted });
+                  }
+                  continue;
+                }
                 if (evt.type === 'tool_calls') {
                   toolCallsEmitted = true;
                   sendDeltaFrame({ tool_calls: formatOpenAIStreamToolCalls(evt.calls, streamToolCallIDs) });