feat: Improve tool sieve to correctly preserve trailing text within the same chunk as a tool call.

api/helpers/stream-tool-sieve.js

@@ -220,7 +220,7 @@ function consumeToolCapture(state, toolNames) {
   }
   const prefixPart = captured.slice(0, start);
   const suffixPart = captured.slice(obj.end);
-  if (!state.toolNameSent && (hasMeaningfulText(prefixPart) || hasMeaningfulText(suffixPart) || looksLikeToolExampleContext(state.recentTextTail))) {
+  if (!state.toolNameSent && (hasMeaningfulText(prefixPart) || looksLikeToolExampleContext(state.recentTextTail) || looksLikeToolExampleContext(suffixPart))) {
     return {
       ready: true,
       prefix: captured,

api/helpers/stream-tool-sieve.test.js

@@ -183,3 +183,15 @@ test('sieve still intercepts tool call after leading plain text without suffix',
   assert.equal(leakedText.includes('我将调用工具。'), true);
   assert.equal(leakedText.toLowerCase().includes('tool_calls'), false);
 });
+
+test('sieve intercepts tool call and preserves trailing same-chunk text', () => {
+  const events = runSieve(
+    ['{"tool_calls":[{"name":"read_file","input":{"path":"README.MD"}}]}然后继续解释。'],
+    ['read_file'],
+  );
+  const hasTool = events.some((evt) => (evt.type === 'tool_calls' && evt.calls?.length > 0) || (evt.type === 'tool_call_deltas' && evt.deltas?.length > 0));
+  const leakedText = collectText(events);
+  assert.equal(hasTool, true);
+  assert.equal(leakedText.includes('然后继续解释。'), true);
+  assert.equal(leakedText.toLowerCase().includes('tool_calls'), false);
+});

internal/adapter/openai/handler_toolcall_test.go

@@ -539,6 +539,47 @@ func TestHandleStreamToolCallAfterLeadingTextStillIntercepted(t *testing.T) {
 	}
 }
 
+func TestHandleStreamToolCallWithSameChunkTrailingTextStillIntercepted(t *testing.T) {
+	h := &Handler{}
+	resp := makeSSEHTTPResponse(
+		`data: {"p":"response/content","v":"{\"tool_calls\":[{\"name\":\"search\",\"input\":{\"q\":\"go\"}}]}接下来我会继续说明。"}`,
+		`data: [DONE]`,
+	)
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/v1/chat/completions", nil)
+
+	h.handleStream(rec, req, resp, "cid7c", "deepseek-chat", "prompt", false, false, []string{"search"})
+
+	frames, done := parseSSEDataFrames(t, rec.Body.String())
+	if !done {
+		t.Fatalf("expected [DONE], body=%s", rec.Body.String())
+	}
+	if !streamHasToolCallsDelta(frames) {
+		t.Fatalf("expected tool_calls delta, body=%s", rec.Body.String())
+	}
+	content := strings.Builder{}
+	for _, frame := range frames {
+		choices, _ := frame["choices"].([]any)
+		for _, item := range choices {
+			choice, _ := item.(map[string]any)
+			delta, _ := choice["delta"].(map[string]any)
+			if c, ok := delta["content"].(string); ok {
+				content.WriteString(c)
+			}
+		}
+	}
+	got := content.String()
+	if !strings.Contains(got, "接下来我会继续说明。") {
+		t.Fatalf("expected trailing plain text to be preserved, got=%q", got)
+	}
+	if strings.Contains(strings.ToLower(got), "tool_calls") {
+		t.Fatalf("unexpected raw tool json leak, got=%q", got)
+	}
+	if streamFinishReason(frames) != "tool_calls" {
+		t.Fatalf("expected finish_reason=tool_calls, body=%s", rec.Body.String())
+	}
+}
+
 func TestHandleStreamToolCallKeyAppearsLateStillNoPrefixLeak(t *testing.T) {
 	h := &Handler{}
 	spaces := strings.Repeat(" ", 200)

internal/adapter/openai/tool_sieve.go

@@ -227,7 +227,7 @@ func consumeToolCapture(state *toolStreamSieveState, toolNames []string) (prefix
 	}
 	prefixPart := captured[:start]
 	suffixPart := captured[end:]
-	if !state.toolNameSent && (strings.TrimSpace(prefixPart) != "" || strings.TrimSpace(suffixPart) != "" || looksLikeToolExampleContext(state.recentTextTail)) {
+	if !state.toolNameSent && (strings.TrimSpace(prefixPart) != "" || looksLikeToolExampleContext(state.recentTextTail) || looksLikeToolExampleContext(suffixPart)) {
 		return captured, nil, "", true
 	}
 	parsed := util.ParseStandaloneToolCalls(obj, toolNames)