fix: strip empty WorkBuddy chat-stream deltas

CHANGELOG.md

@@ -7,8 +7,12 @@ Write each change in both `### English` and `### 中文` under `## Unreleased`.
 
 ### English
 
+- Strip empty WorkBuddy chat-stream deltas so clients do not render a flood of blank thinking chunks
+
 ### 中文
 
+- WorkBuddy 的 chat 流式不再带上空的 `content` / `reasoning_content`，避免客户端刷出空白思考
+
 ## 0.3.3 - 2026-09-07
 
 ### English

internal/providers/workbuddy/client.go

@@ -441,7 +441,7 @@ func (c *Client) ChatStream(ctx context.Context, accountID string, req translate
 		resp.Body.Close()
 		return nil, classifiedError(resp.StatusCode, body)
 	}
-	return resp, nil
+	return rewriteChatStream(resp), nil
 }
 
 func outcomeFromAggregate(aggregate map[string]any) (providers.ChatOutcome, error) {

internal/providers/workbuddy/client_test.go

@@ -504,6 +504,73 @@ func TestErrorMapping(t *testing.T) {
 	}
 }
 
+func TestCopySanitizedSSEDropsEmptyThinkingDeltas(t *testing.T) {
+	input := strings.Join([]string{
+		`data: {"id":"c1","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"role":"assistant","content":"","reasoning_content":"think","function_call":null,"refusal":"","tool_calls":[],"extra_fields":null},"logprobs":null,"finish_reason":""}]}`,
+		`data: {"id":"c1","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"role":"assistant","content":"OK","reasoning_content":"","function_call":null,"refusal":"","tool_calls":[],"extra_fields":null},"logprobs":null,"finish_reason":""}]}`,
+		`data: {"id":"c1","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"role":"assistant","content":"","reasoning_content":"","function_call":{"name":"","arguments":""},"refusal":"","tool_calls":[],"extra_fields":null},"logprobs":null,"finish_reason":"stop"}],"usage":{"prompt_tokens":16,"completion_tokens":2}}`,
+		`data: [DONE]`,
+		"",
+	}, "\n\n")
+	var out strings.Builder
+	if err := copySanitizedSSE(strings.NewReader(input), &out); err != nil {
+		t.Fatal(err)
+	}
+	text := out.String()
+	if strings.Contains(text, `"content":""`) || strings.Contains(text, `"reasoning_content":""`) || strings.Contains(text, `"function_call"`) {
+		t.Fatalf("empty delta fields leaked: %s", text)
+	}
+	if !strings.Contains(text, `"reasoning_content":"think"`) || !strings.Contains(text, `"content":"OK"`) {
+		t.Fatalf("real deltas dropped: %s", text)
+	}
+	if strings.Count(text, `"role":"assistant"`) != 1 {
+		t.Fatalf("role should appear once, got %s", text)
+	}
+	if !strings.Contains(text, `"finish_reason":"stop"`) || !strings.Contains(text, `"prompt_tokens":16`) || !strings.Contains(text, "data: [DONE]") {
+		t.Fatalf("terminal chunk missing: %s", text)
+	}
+}
+
+func TestChatStreamStripsEmptyWorkBuddyDeltas(t *testing.T) {
+	payload, _ := Credential{AccessToken: "at", UID: "u1", Domain: "codebuddy.cn", ExpiresAt: 4102444800}.Encode()
+	store := &memStore{items: map[string][]byte{"acc1": payload}}
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == pathModelsCN {
+			_ = json.NewEncoder(w).Encode(map[string]any{"code": 0, "data": map[string]any{
+				"models": []map[string]any{{"id": "glm-5.3-flash", "name": "GLM"}},
+				"agents": []map[string]any{{"name": "cli", "models": []string{"glm-5.3-flash"}}},
+			}})
+			return
+		}
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = w.Write([]byte(
+			`data: {"choices":[{"delta":{"role":"assistant","content":"","reasoning_content":"think","function_call":null,"refusal":"","tool_calls":[]},"finish_reason":""}]}` + "\n\n" +
+				`data: {"choices":[{"delta":{"role":"assistant","content":"OK","reasoning_content":"","function_call":null},"finish_reason":""}]}` + "\n\n" +
+				`data: {"choices":[{"delta":{"content":"","reasoning_content":"","function_call":{"name":"","arguments":""}},"finish_reason":"stop"}],"usage":{"prompt_tokens":1,"completion_tokens":1}}` + "\n\n" +
+				"data: [DONE]\n\n",
+		))
+	}))
+	defer server.Close()
+	client := NewClient(store)
+	client.http = server.Client()
+	client.http.Transport = rewriteTransport{server: server.URL, round: server.Client().Transport}
+	resp, err := client.ChatStream(context.Background(), "acc1", translate.ChatRequest{
+		Model: "glm-5.3-flash", Messages: []translate.ChatMessage{{Role: "user", Content: "hi"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	body, _ := io.ReadAll(resp.Body)
+	text := string(body)
+	if strings.Contains(text, `"content":""`) || strings.Contains(text, `"reasoning_content":""`) {
+		t.Fatalf("empty thinking leaked: %s", text)
+	}
+	if !strings.Contains(text, `"reasoning_content":"think"`) || !strings.Contains(text, `"content":"OK"`) || !strings.Contains(text, "data: [DONE]") {
+		t.Fatalf("stream=%s", text)
+	}
+}
+
 func TestPrepareBodyForcesStreamAndStringToolChoice(t *testing.T) {
 	out := PrepareBody([]byte(`{"model":"m","stream":false,"tool_choice":{"type":"function","function":{"name":"get_time"}}}`))
 	var body map[string]any

internal/providers/workbuddy/sse.go

@@ -2,9 +2,11 @@ package workbuddy
 
 import (
 	"bufio"
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/http"
 	"sort"
 	"strings"
 	"time"
@@ -163,3 +165,142 @@ func mergeToolCalls(merged map[int]map[string]any, order *[]int, raw json.RawMes
 		}
 	}
 }
+
+// rewriteChatStream strips empty WorkBuddy delta fields. Upstream chat chunks
+// always include content:"", reasoning_content:"", refusal:"", tool_calls:[],
+// and a dummy function_call; OpenAI-compatible clients then render a flood of
+// blank thinking events.
+func rewriteChatStream(resp *http.Response) *http.Response {
+	pr, pw := io.Pipe()
+	go func() {
+		defer resp.Body.Close()
+		defer pw.Close()
+		if err := copySanitizedSSE(resp.Body, pw); err != nil {
+			_ = pw.CloseWithError(err)
+		}
+	}()
+	out := *resp
+	out.Body = pr
+	out.ContentLength = -1
+	header := resp.Header.Clone()
+	header.Del("Content-Length")
+	out.Header = header
+	return &out
+}
+
+func copySanitizedSSE(src io.Reader, dst io.Writer) error {
+	scanner := bufio.NewScanner(src)
+	scanner.Buffer(make([]byte, 0, 64*1024), 16*1024*1024)
+	sentRole := false
+	for scanner.Scan() {
+		line := strings.TrimSuffix(scanner.Text(), "\r")
+		if line == "" {
+			continue
+		}
+		if !strings.HasPrefix(line, "data:") {
+			if _, err := fmt.Fprintf(dst, "%s\n", line); err != nil {
+				return err
+			}
+			continue
+		}
+		payload := strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+		if payload == "" {
+			continue
+		}
+		cleaned, ok := sanitizeSSEPayload(payload, &sentRole)
+		if !ok {
+			continue
+		}
+		if _, err := fmt.Fprintf(dst, "data: %s\n\n", cleaned); err != nil {
+			return err
+		}
+	}
+	return scanner.Err()
+}
+
+func sanitizeSSEPayload(payload string, sentRole *bool) (string, bool) {
+	if payload == "[DONE]" {
+		return payload, true
+	}
+	decoder := json.NewDecoder(bytes.NewReader([]byte(payload)))
+	decoder.UseNumber()
+	var chunk map[string]any
+	if err := decoder.Decode(&chunk); err != nil {
+		return payload, true
+	}
+	keep := chunk["usage"] != nil
+	if choices, ok := chunk["choices"].([]any); ok {
+		for _, raw := range choices {
+			choice, _ := raw.(map[string]any)
+			if choice == nil {
+				continue
+			}
+			if delta, ok := choice["delta"].(map[string]any); ok {
+				sanitizeDelta(delta)
+				if sentRole != nil {
+					if _, hasRole := delta["role"]; hasRole && *sentRole {
+						delete(delta, "role")
+					}
+				}
+				if len(delta) > 0 {
+					keep = true
+					if sentRole != nil {
+						if _, hasRole := delta["role"]; hasRole {
+							*sentRole = true
+						}
+					}
+				}
+			}
+			switch finish := choice["finish_reason"].(type) {
+			case string:
+				if finish == "" {
+					delete(choice, "finish_reason")
+				} else {
+					keep = true
+				}
+			case nil:
+				delete(choice, "finish_reason")
+			}
+		}
+	}
+	if !keep {
+		return "", false
+	}
+	encoded, err := json.Marshal(chunk)
+	if err != nil {
+		return payload, true
+	}
+	return string(encoded), true
+}
+
+func sanitizeDelta(delta map[string]any) {
+	dropEmptyString(delta, "content")
+	dropEmptyString(delta, "reasoning_content")
+	dropEmptyString(delta, "refusal")
+	if extra, ok := delta["extra_fields"]; ok && extra == nil {
+		delete(delta, "extra_fields")
+	}
+	if calls, ok := delta["tool_calls"].([]any); ok && len(calls) == 0 {
+		delete(delta, "tool_calls")
+	}
+	if delta["tool_calls"] == nil {
+		delete(delta, "tool_calls")
+	}
+	switch call := delta["function_call"].(type) {
+	case nil:
+		delete(delta, "function_call")
+	case map[string]any:
+		name, _ := call["name"].(string)
+		args, _ := call["arguments"].(string)
+		if name == "" && args == "" {
+			delete(delta, "function_call")
+		}
+	}
+}
+
+func dropEmptyString(delta map[string]any, key string) {
+	value, ok := delta[key].(string)
+	if ok && value == "" {
+		delete(delta, key)
+	}
+}