refactor: centralize assistant turn semantics and stream accumulation into new assistantturn and completionruntime packages

VERSION

@@ -1 +1 @@
-4.3.1
+4.4.0

docs/ARCHITECTURE.en.md

@@ -25,6 +25,8 @@ ds2api/
 │   ├── chathistory/                      # Server-side conversation history storage/query
 │   ├── claudeconv/                       # Claude message conversion helpers
 │   ├── compat/                           # Compatibility and regression helpers
+│   ├── assistantturn/                    # Upstream output to canonical assistant turn / stream event semantics
+│   ├── completionruntime/                # Shared Go DeepSeek completion startup, non-stream collection, and retry
 │   ├── config/                           # Config loading/validation/hot reload
 │   ├── deepseek/                         # DeepSeek upstream client/protocol/transport
 │   │   ├── client/                       # Login/session/completion/upload/delete calls
@@ -171,6 +173,8 @@ flowchart LR
 - `internal/httpapi/openai/*`: OpenAI HTTP surface split into chat, responses, files, embeddings, history, and shared packages; chat/responses share the promptcompat, stream, and toolcall semantics.
 - `internal/httpapi/{claude,gemini}`: protocol wrappers that normalize into the same prompt compatibility semantics without duplicating upstream execution.
 - `internal/promptcompat`: compatibility core for turning OpenAI/Claude/Gemini requests into DeepSeek web-chat plain-text context.
+- `internal/assistantturn`: Go output-side canonical semantics, converting DeepSeek SSE collection results and stream finalization state into assistant turns and centralizing thinking, tool call, citation, usage, stop/error behavior.
+- `internal/completionruntime`: shared Go completion execution helpers for DeepSeek session/PoW/call startup, non-stream collection, and empty-output retry; streaming paths use it to start upstream requests, continue to use `internal/stream` for real-time consumption, and use `assistantturn` during finalization.
 - `internal/translatorcliproxy`: structure translation between Claude/Gemini and OpenAI.
 - `internal/deepseek/{client,protocol,transport}`: upstream requests, sessions, PoW adaptation, protocol constants, and transport details.
 - `internal/js/chat-stream` + `api/chat-stream.js`: Vercel Node streaming bridge; Go prepare/release owns auth, account lease, and completion payload assembly, while Node relays real-time SSE with Go-aligned finalization and tool sieve semantics.

docs/ARCHITECTURE.md

@@ -25,6 +25,8 @@ ds2api/
 │   ├── chathistory/                      # 服务器端对话记录存储与查询
 │   ├── claudeconv/                       # Claude 消息格式转换工具
 │   ├── compat/                           # 兼容性辅助与回归支持
+│   ├── assistantturn/                    # 上游输出到统一 assistant turn / stream event 的语义层
+│   ├── completionruntime/                # Go 主路径共享 DeepSeek completion 启动、非流式收集与 retry
 │   ├── config/                           # 配置加载、校验、热更新
 │   ├── deepseek/                         # DeepSeek 上游 client/protocol/transport
 │   │   ├── client/                       # 登录、会话、completion、上传/删除等上游调用
@@ -171,6 +173,8 @@ flowchart LR
 - `internal/httpapi/openai/*`：OpenAI HTTP surface，按 chat、responses、files、embeddings、history、shared 拆分；chat/responses 共享 promptcompat、stream、toolcall 等核心语义。
 - `internal/httpapi/{claude,gemini}`：协议输入输出适配，归一到同一套 prompt compatibility 语义，不重复实现上游调用逻辑。
 - `internal/promptcompat`：OpenAI/Claude/Gemini 请求到 DeepSeek 网页纯文本上下文的兼容内核。
+- `internal/assistantturn`：Go 输出侧统一语义层，把 DeepSeek SSE 收集结果和流式收尾状态归一成 assistant turn，集中处理 thinking、tool call、citation、usage、stop/error 语义。
+- `internal/completionruntime`：Go surface 共享的 completion 执行辅助，负责 DeepSeek session/PoW/call 启动、非流式 collect 和 empty-output retry；流式路径复用它启动上游请求，继续用 `internal/stream` 做实时消费，并在最终收尾阶段接入 `assistantturn`。
 - `internal/translatorcliproxy`：Claude/Gemini 与 OpenAI 结构互转。
 - `internal/deepseek/{client,protocol,transport}`：上游请求、会话、PoW 适配、协议常量与传输层。
 - `internal/js/chat-stream` + `api/chat-stream.js`：Vercel Node 流式桥；Go prepare/release 管理鉴权、账号租约和 completion payload，Node 侧负责实时 SSE 转发并保持 Go 对齐的终结态和 tool sieve 语义。

docs/prompt-compatibility.md

@@ -48,6 +48,8 @@ DS2API 当前的核心思路，不是把客户端传来的 `messages`、`tools`
   -> 文件收集 / inline 上传 / current input file（OpenAI 链路）
   -> completion payload
   -> 下游网页对话接口
+  -> assistantturn 输出语义归一（Go 非流式 + 流式收尾）
+  -> 各协议 renderer（OpenAI / Responses / Claude / Gemini）
 ```
 
 对应的关键代码入口：
@@ -72,6 +74,10 @@ DS2API 当前的核心思路，不是把客户端传来的 `messages`、`tools`
   [internal/promptcompat/thinking_injection.go](../internal/promptcompat/thinking_injection.go)
 - completion payload：
   [internal/promptcompat/standard_request.go](../internal/promptcompat/standard_request.go)
+- Go 输出侧 assistant turn：
+  [internal/assistantturn/turn.go](../internal/assistantturn/turn.go)
+- Go completion runtime：
+  [internal/completionruntime/nonstream.go](../internal/completionruntime/nonstream.go)
 
 ## 4. 下游真正收到的东西
 
@@ -101,7 +107,8 @@ DS2API 当前的核心思路，不是把客户端传来的 `messages`、`tools`
 - 对外返回给客户端的 `prompt_tokens` / `input_tokens` / `promptTokenCount` 不再按“最后一条消息”或字符粗估近似返回，而是基于**完整上下文 prompt**做 tokenizer 计数；为了避免上下文实际超限但客户端误以为还能塞下，请求侧上下文 token 会额外保守上浮一点，宁可略大也不低估。
 - 当前 `/v1/chat/completions` 业务路径仍是“每次请求新建一个远端 `chat_session_id`，并默认发送 `parent_message_id: null`”；因此 DS2API 对外默认表现为“新会话 + prompt 拼历史”，而不是复用 DeepSeek 原生会话树。
 - 但 DeepSeek 远端本身支持同一 `chat_session_id` 的跨轮次持续对话。2026-04-27 已用项目内现有 DeepSeek client 做过一次不改业务代码的双轮实测：同一 `chat_session_id` 下，第 1 轮返回 `request_message_id=1` / `response_message_id=2` / 文本 `SESSION_TEST_ONE`；第 2 轮重新获取一次 PoW，并发送 `parent_message_id=2` 后，成功返回 `request_message_id=3` / `response_message_id=4` / 文本 `SESSION_TEST_TWO`。这说明“同远端会话持续聊天”能力存在，且每轮需要携带正确的 parent/message 链接信息，同时重新获取对应轮次可用的 PoW。
-- OpenAI Chat / Responses 原生走统一 OpenAI 标准化与 DeepSeek payload 组装；Claude / Gemini 会尽量复用 OpenAI prompt/tool 语义，其中 Gemini 直接复用 `promptcompat.BuildOpenAIPromptForAdapter`，Claude 消息接口在可代理场景会转换为 OpenAI chat 形态再执行。
+- OpenAI Chat / Responses 原生走统一 OpenAI 标准化与 DeepSeek payload 组装；Claude / Gemini 会尽量复用 OpenAI prompt/tool 语义，其中 Gemini 直接复用 `promptcompat.BuildOpenAIPromptForAdapter`。Go 主服务新增 `completionruntime` 启动层，统一执行 DeepSeek session/PoW/call；输出侧新增 `assistantturn` 语义层：非流式 OpenAI Chat / Responses / Claude / Gemini 会把 DeepSeek SSE 收集结果先归一成同一份 assistant turn，再分别渲染成各协议原生外形；流式 OpenAI Chat / Responses / Claude / Gemini 继续保持各协议实时 SSE framing，但最终收尾的 tool fallback、schema 归一、usage、empty-output / content-filter 错误语义同样由 `assistantturn` 判定。Claude / Gemini 的常规 Go 主路径不再依赖内部 `httptest` 转发到 OpenAI handler；`translatorcliproxy` 仍保留用于 Vercel bridge、兼容工具和回归测试。
+- Vercel Node 流式路径本轮不迁移，仍使用现有 Node bridge / stream-tool-sieve 实现；后续若变更 Node 流式语义，需要按 `assistantturn` 的 Go canonical 输出语义同步对齐。
 - 客户端传入的 thinking / reasoning 开关会被归一到下游 `thinking_enabled`。Gemini `generationConfig.thinkingConfig.thinkingBudget` 会翻译成同一套 thinking 开关；关闭时即使上游返回 `response/thinking_content`，兼容层也不会把它当作可见正文输出。若最终解析出的模型名带 `-nothinking` 后缀，则会无条件强制关闭 thinking，优先级高于请求体中的 `thinking` / `reasoning` / `reasoning_effort`。Claude surface 在流式请求且未显式声明 `thinking` 时，仍按 Anthropic 语义默认关闭；但在非流式代理场景，兼容层会内部开启一次下游 thinking，用于捕获“正文为空、工具调用落在 thinking 里”的情况，随后在回包前剥离用户不可见的 thinking block。
 - 对 OpenAI Chat / Responses 的非流式收尾，如果最终可见正文为空，兼容层会优先尝试把思维链中的独立 DSML / XML 工具块当作真实工具调用解析出来。流式链路也会在收尾阶段做同样的 fallback 检测，但不会因为思维链内容去中途拦截或改写流式输出；真正的工具识别始终基于原始上游文本，而不是基于“已经做过可见输出清洗”的版本，因此即使最终可见层会剥离完整 leaked DSML / XML `tool_calls` wrapper、并抑制全空参数或无效 wrapper 块，也不会影响真实工具调用转成结构化 `tool_calls` / `function_call`。补发结果会作为本轮 assistant 的结构化 `tool_calls` / `function_call` 输出返回，而不是塞进 `content` 文本；如果客户端没有开启 thinking / reasoning，思维链只用于检测，不会作为 `reasoning_content` 或可见正文暴露。只有正文为空且思维链里也没有可执行工具调用时，才继续按空回复错误处理。
 - OpenAI Chat / Responses 的空回复错误处理之前会默认做一次内部补偿重试：第一次上游完整结束后，如果最终可见正文为空、没有解析到工具调用、也没有已经向客户端流式发出工具调用，并且终止原因不是 `content_filter`，兼容层会复用同一个 `chat_session_id`、账号、token 与工具策略，把原始 completion `prompt` 追加固定后缀 `Previous reply had no visible output. Please regenerate the visible final answer or tool call now.` 后重新提交一次。重试遵循 DeepSeek 多轮对话协议：从第一次上游 SSE 流中提取 `response_message_id`，并在重试 payload 中设置 `parent_message_id` 为该值，使重试成为同一会话的后续轮次而非断裂的根消息；同时重新获取一次 PoW（若 PoW 获取失败则回退到原始 PoW）。该重试不会重新标准化消息、不会新建 session、不会切换账号，也不会向流式客户端插入重试标记；第二次 thinking / reasoning 会按正常增量直接接到第一次之后，并继续使用 overlap trim 去重。若第二次仍为空，终端错误码仍保持现有 `upstream_empty_output`；若任一尝试触发空 `content_filter`，不做补偿重试并保持 `content_filter` 错误。JS Vercel 运行时同样设置 `parent_message_id`，但因无法直接调用 PoW API 而复用原始 PoW。

internal/assistantturn/stream.go

@@ -0,0 +1,64 @@
+package assistantturn
+
+import (
+	"ds2api/internal/httpapi/openai/shared"
+	"ds2api/internal/sse"
+)
+
+type StreamEventType string
+
+const (
+	StreamEventTextDelta     StreamEventType = "text_delta"
+	StreamEventThinkingDelta StreamEventType = "thinking_delta"
+	StreamEventToolCall      StreamEventType = "tool_call"
+	StreamEventDone          StreamEventType = "done"
+	StreamEventError         StreamEventType = "error"
+	StreamEventPing          StreamEventType = "ping"
+)
+
+type StreamEvent struct {
+	Type     StreamEventType
+	Text     string
+	Thinking string
+	ToolCall any
+	Error    *OutputError
+	Usage    *Usage
+}
+
+type Accumulator struct {
+	inner shared.StreamAccumulator
+}
+
+type AccumulatorOptions struct {
+	ThinkingEnabled       bool
+	SearchEnabled         bool
+	StripReferenceMarkers bool
+}
+
+func NewAccumulator(opts AccumulatorOptions) *Accumulator {
+	return &Accumulator{
+		inner: shared.StreamAccumulator{
+			ThinkingEnabled:       opts.ThinkingEnabled,
+			SearchEnabled:         opts.SearchEnabled,
+			StripReferenceMarkers: opts.StripReferenceMarkers,
+		},
+	}
+}
+
+func (a *Accumulator) Apply(parsed sse.LineResult) shared.StreamAccumulatorResult {
+	if a == nil {
+		return shared.StreamAccumulatorResult{}
+	}
+	return a.inner.Apply(parsed)
+}
+
+func (a *Accumulator) Snapshot() (rawText, text, rawThinking, thinking, detectionThinking string) {
+	if a == nil {
+		return "", "", "", "", ""
+	}
+	return a.inner.RawText.String(),
+		a.inner.Text.String(),
+		a.inner.RawThinking.String(),
+		a.inner.Thinking.String(),
+		a.inner.ToolDetectionThinking.String()
+}

internal/assistantturn/turn.go

@@ -0,0 +1,227 @@
+package assistantturn
+
+import (
+	"net/http"
+	"strings"
+
+	"ds2api/internal/httpapi/openai/shared"
+	"ds2api/internal/promptcompat"
+	"ds2api/internal/sse"
+	"ds2api/internal/toolcall"
+	"ds2api/internal/util"
+)
+
+type StopReason string
+
+const (
+	StopReasonStop          StopReason = "stop"
+	StopReasonToolCalls     StopReason = "tool_calls"
+	StopReasonContentFilter StopReason = "content_filter"
+	StopReasonError         StopReason = "error"
+)
+
+type Usage struct {
+	InputTokens     int
+	OutputTokens    int
+	ReasoningTokens int
+	TotalTokens     int
+}
+
+type OutputError struct {
+	Status  int
+	Message string
+	Code    string
+}
+
+type Turn struct {
+	Model             string
+	Prompt            string
+	RawText           string
+	RawThinking       string
+	DetectionThinking string
+	Text              string
+	Thinking          string
+	ToolCalls         []toolcall.ParsedToolCall
+	ParsedToolCalls   toolcall.ToolCallParseResult
+	CitationLinks     map[int]string
+	ContentFilter     bool
+	ResponseMessageID int
+	StopReason        StopReason
+	Usage             Usage
+	Error             *OutputError
+}
+
+type BuildOptions struct {
+	Model                 string
+	Prompt                string
+	RefFileTokens         int
+	SearchEnabled         bool
+	StripReferenceMarkers bool
+	ToolNames             []string
+	ToolsRaw              any
+	ToolChoice            promptcompat.ToolChoicePolicy
+}
+
+type StreamSnapshot struct {
+	RawText               string
+	VisibleText           string
+	RawThinking           string
+	VisibleThinking       string
+	DetectionThinking     string
+	ContentFilter         bool
+	CitationLinks         map[int]string
+	ResponseMessageID     int
+	AlreadyEmittedCalls   bool
+	AdditionalToolCalls   []toolcall.ParsedToolCall
+	AlreadyEmittedToolRaw bool
+}
+
+func BuildTurnFromCollected(result sse.CollectResult, opts BuildOptions) Turn {
+	thinking := shared.CleanVisibleOutput(result.Thinking, opts.StripReferenceMarkers)
+	text := shared.CleanVisibleOutput(result.Text, opts.StripReferenceMarkers)
+	if opts.SearchEnabled {
+		text = shared.ReplaceCitationMarkersWithLinks(text, result.CitationLinks)
+	}
+
+	parsed := shared.DetectAssistantToolCalls(result.Text, text, result.Thinking, result.ToolDetectionThinking, opts.ToolNames)
+	calls := toolcall.NormalizeParsedToolCallsForSchemas(parsed.Calls, opts.ToolsRaw)
+	parsed.Calls = calls
+
+	stopReason := StopReasonStop
+	if result.ContentFilter {
+		stopReason = StopReasonContentFilter
+	}
+	if len(calls) > 0 {
+		stopReason = StopReasonToolCalls
+	}
+
+	turn := Turn{
+		Model:             opts.Model,
+		Prompt:            opts.Prompt,
+		RawText:           result.Text,
+		RawThinking:       result.Thinking,
+		DetectionThinking: result.ToolDetectionThinking,
+		Text:              text,
+		Thinking:          thinking,
+		ToolCalls:         calls,
+		ParsedToolCalls:   parsed,
+		CitationLinks:     result.CitationLinks,
+		ContentFilter:     result.ContentFilter,
+		ResponseMessageID: result.ResponseMessageID,
+		StopReason:        stopReason,
+	}
+	turn.Usage = BuildUsage(opts.Model, opts.Prompt, thinking, text, opts.RefFileTokens)
+	turn.Error = ValidateTurn(turn, opts.ToolChoice)
+	if turn.Error != nil {
+		turn.StopReason = StopReasonError
+	}
+	return turn
+}
+
+func BuildTurnFromStreamSnapshot(snapshot StreamSnapshot, opts BuildOptions) Turn {
+	thinking := shared.CleanVisibleOutput(snapshot.VisibleThinking, opts.StripReferenceMarkers)
+	text := shared.CleanVisibleOutput(snapshot.VisibleText, opts.StripReferenceMarkers)
+	if opts.SearchEnabled {
+		text = shared.ReplaceCitationMarkersWithLinks(text, snapshot.CitationLinks)
+	}
+
+	parsed := shared.DetectAssistantToolCalls(snapshot.RawText, text, snapshot.RawThinking, snapshot.DetectionThinking, opts.ToolNames)
+	calls := parsed.Calls
+	if len(calls) == 0 && len(snapshot.AdditionalToolCalls) > 0 {
+		calls = snapshot.AdditionalToolCalls
+	}
+	calls = toolcall.NormalizeParsedToolCallsForSchemas(calls, opts.ToolsRaw)
+	parsed.Calls = calls
+
+	stopReason := StopReasonStop
+	if snapshot.ContentFilter {
+		stopReason = StopReasonContentFilter
+	}
+	if len(calls) > 0 || snapshot.AlreadyEmittedCalls || snapshot.AlreadyEmittedToolRaw {
+		stopReason = StopReasonToolCalls
+	}
+
+	turn := Turn{
+		Model:             opts.Model,
+		Prompt:            opts.Prompt,
+		RawText:           snapshot.RawText,
+		RawThinking:       snapshot.RawThinking,
+		DetectionThinking: snapshot.DetectionThinking,
+		Text:              text,
+		Thinking:          thinking,
+		ToolCalls:         calls,
+		ParsedToolCalls:   parsed,
+		CitationLinks:     snapshot.CitationLinks,
+		ContentFilter:     snapshot.ContentFilter,
+		ResponseMessageID: snapshot.ResponseMessageID,
+		StopReason:        stopReason,
+	}
+	turn.Usage = BuildUsage(opts.Model, opts.Prompt, thinking, text, opts.RefFileTokens)
+	if !snapshot.AlreadyEmittedCalls && !snapshot.AlreadyEmittedToolRaw {
+		turn.Error = ValidateTurn(turn, opts.ToolChoice)
+	}
+	if turn.Error != nil && len(calls) == 0 {
+		turn.StopReason = StopReasonError
+	}
+	return turn
+}
+
+func BuildUsage(model, prompt, thinking, text string, refFileTokens int) Usage {
+	inputTokens := util.CountPromptTokens(prompt, model) + refFileTokens
+	reasoningTokens := util.CountOutputTokens(thinking, model)
+	outputTokens := reasoningTokens + util.CountOutputTokens(text, model)
+	return Usage{
+		InputTokens:     inputTokens,
+		OutputTokens:    outputTokens,
+		ReasoningTokens: reasoningTokens,
+		TotalTokens:     inputTokens + outputTokens,
+	}
+}
+
+func ValidateTurn(turn Turn, policy promptcompat.ToolChoicePolicy) *OutputError {
+	if policy.IsRequired() && len(turn.ToolCalls) == 0 {
+		return &OutputError{
+			Status:  http.StatusUnprocessableEntity,
+			Message: "tool_choice requires at least one valid tool call.",
+			Code:    "tool_choice_violation",
+		}
+	}
+	if len(turn.ToolCalls) > 0 {
+		return nil
+	}
+	if strings.TrimSpace(turn.Text) != "" {
+		return nil
+	}
+	status, message, code := UpstreamEmptyOutputDetail(turn.ContentFilter, turn.Text, turn.Thinking)
+	return &OutputError{Status: status, Message: message, Code: code}
+}
+
+func UpstreamEmptyOutputDetail(contentFilter bool, text, thinking string) (int, string, string) {
+	_ = text
+	if contentFilter {
+		return http.StatusBadRequest, "Upstream content filtered the response and returned no output.", "content_filter"
+	}
+	if strings.TrimSpace(thinking) != "" {
+		return http.StatusTooManyRequests, "Upstream account hit a rate limit and returned reasoning without visible output.", "upstream_empty_output"
+	}
+	return http.StatusTooManyRequests, "Upstream account hit a rate limit and returned empty output.", "upstream_empty_output"
+}
+
+func ShouldRetryEmptyOutput(turn Turn, attempts, maxAttempts int) bool {
+	return attempts < maxAttempts &&
+		!turn.ContentFilter &&
+		len(turn.ToolCalls) == 0 &&
+		strings.TrimSpace(turn.Text) == "" &&
+		strings.TrimSpace(turn.Thinking) == ""
+}
+
+func FinishReason(turn Turn) string {
+	switch turn.StopReason {
+	case StopReasonToolCalls:
+		return "tool_calls"
+	case StopReasonContentFilter:
+		return "content_filter"
+	default:
+		return "stop"
+	}
+}

internal/assistantturn/turn_test.go

@@ -0,0 +1,100 @@
+package assistantturn
+
+import (
+	"testing"
+
+	"ds2api/internal/promptcompat"
+	"ds2api/internal/sse"
+)
+
+func TestBuildTurnFromCollectedTextCitation(t *testing.T) {
+	turn := BuildTurnFromCollected(sse.CollectResult{
+		Text:          "See [citation:1]",
+		CitationLinks: map[int]string{1: "https://example.com"},
+	}, BuildOptions{Model: "deepseek-v4-flash", Prompt: "prompt", SearchEnabled: true, StripReferenceMarkers: true})
+	if turn.Text != "See [1](https://example.com)" {
+		t.Fatalf("text mismatch: %q", turn.Text)
+	}
+	if turn.StopReason != StopReasonStop {
+		t.Fatalf("stop reason mismatch: %q", turn.StopReason)
+	}
+	if turn.Error != nil {
+		t.Fatalf("unexpected error: %#v", turn.Error)
+	}
+}
+
+func TestBuildTurnFromCollectedToolCall(t *testing.T) {
+	turn := BuildTurnFromCollected(sse.CollectResult{
+		Text: `<tool_calls><invoke name="Write"><parameter name="content">{"x":1}</parameter></invoke></tool_calls>`,
+	}, BuildOptions{
+		ToolNames: []string{"Write"},
+		ToolsRaw: []any{map[string]any{
+			"name": "Write",
+			"input_schema": map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"content": map[string]any{"type": "string"},
+				},
+			},
+		}},
+	})
+	if len(turn.ToolCalls) != 1 {
+		t.Fatalf("expected one tool call, got %d", len(turn.ToolCalls))
+	}
+	if turn.StopReason != StopReasonToolCalls {
+		t.Fatalf("stop reason mismatch: %q", turn.StopReason)
+	}
+	if _, ok := turn.ToolCalls[0].Input["content"].(string); !ok {
+		t.Fatalf("expected content coerced to string, got %#v", turn.ToolCalls[0].Input["content"])
+	}
+}
+
+func TestBuildTurnFromCollectedThinkingOnlyIsEmptyOutput(t *testing.T) {
+	turn := BuildTurnFromCollected(sse.CollectResult{Thinking: "hidden"}, BuildOptions{})
+	if turn.Error == nil || turn.Error.Code != "upstream_empty_output" {
+		t.Fatalf("expected empty output error, got %#v", turn.Error)
+	}
+}
+
+func TestBuildTurnFromCollectedToolChoiceRequired(t *testing.T) {
+	turn := BuildTurnFromCollected(sse.CollectResult{Text: "hello"}, BuildOptions{
+		ToolChoice: promptcompat.ToolChoicePolicy{Mode: promptcompat.ToolChoiceRequired},
+	})
+	if turn.Error == nil || turn.Error.Code != "tool_choice_violation" {
+		t.Fatalf("expected tool choice violation, got %#v", turn.Error)
+	}
+}
+
+func TestBuildTurnFromStreamSnapshotUsesVisibleTextAndRawToolDetection(t *testing.T) {
+	turn := BuildTurnFromStreamSnapshot(StreamSnapshot{
+		RawText:     `<tool_calls><invoke name="Write"><parameter name="content">{"x":1}</parameter></invoke></tool_calls>`,
+		VisibleText: "",
+	}, BuildOptions{
+		ToolNames: []string{"Write"},
+		ToolsRaw: []any{map[string]any{
+			"name": "Write",
+			"schema": map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"content": map[string]any{"type": "string"},
+				},
+			},
+		}},
+	})
+	if len(turn.ToolCalls) != 1 {
+		t.Fatalf("expected stream snapshot tool call, got %d", len(turn.ToolCalls))
+	}
+	if _, ok := turn.ToolCalls[0].Input["content"].(string); !ok {
+		t.Fatalf("expected stream snapshot schema coercion, got %#v", turn.ToolCalls[0].Input["content"])
+	}
+}
+
+func TestBuildTurnFromStreamSnapshotAlreadyEmittedToolAvoidsEmptyError(t *testing.T) {
+	turn := BuildTurnFromStreamSnapshot(StreamSnapshot{AlreadyEmittedCalls: true}, BuildOptions{})
+	if turn.Error != nil {
+		t.Fatalf("unexpected empty-output error after emitted tool call: %#v", turn.Error)
+	}
+	if turn.StopReason != StopReasonToolCalls {
+		t.Fatalf("stop reason mismatch: %q", turn.StopReason)
+	}
+}

internal/completionruntime/nonstream.go

@@ -0,0 +1,170 @@
+package completionruntime
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"ds2api/internal/assistantturn"
+	"ds2api/internal/auth"
+	"ds2api/internal/config"
+	"ds2api/internal/httpapi/openai/shared"
+	"ds2api/internal/promptcompat"
+	"ds2api/internal/sse"
+)
+
+type DeepSeekCaller interface {
+	CreateSession(ctx context.Context, a *auth.RequestAuth, maxAttempts int) (string, error)
+	GetPow(ctx context.Context, a *auth.RequestAuth, maxAttempts int) (string, error)
+	CallCompletion(ctx context.Context, a *auth.RequestAuth, payload map[string]any, powResp string, maxAttempts int) (*http.Response, error)
+}
+
+type Options struct {
+	StripReferenceMarkers bool
+	MaxAttempts           int
+	RetryEnabled          bool
+	RetryMaxAttempts      int
+}
+
+type NonStreamResult struct {
+	SessionID string
+	Payload   map[string]any
+	Turn      assistantturn.Turn
+	Attempts  int
+}
+
+type StartResult struct {
+	SessionID string
+	Payload   map[string]any
+	Pow       string
+	Response  *http.Response
+}
+
+func StartCompletion(ctx context.Context, ds DeepSeekCaller, a *auth.RequestAuth, stdReq promptcompat.StandardRequest, opts Options) (StartResult, *assistantturn.OutputError) {
+	maxAttempts := opts.MaxAttempts
+	if maxAttempts <= 0 {
+		maxAttempts = 3
+	}
+	sessionID, err := ds.CreateSession(ctx, a, maxAttempts)
+	if err != nil {
+		return StartResult{}, authOutputError(a)
+	}
+	pow, err := ds.GetPow(ctx, a, maxAttempts)
+	if err != nil {
+		return StartResult{SessionID: sessionID}, &assistantturn.OutputError{Status: http.StatusUnauthorized, Message: "Failed to get PoW (invalid token or unknown error).", Code: "error"}
+	}
+	payload := stdReq.CompletionPayload(sessionID)
+	resp, err := ds.CallCompletion(ctx, a, payload, pow, maxAttempts)
+	if err != nil {
+		return StartResult{SessionID: sessionID, Payload: payload, Pow: pow}, &assistantturn.OutputError{Status: http.StatusInternalServerError, Message: "Failed to get completion.", Code: "error"}
+	}
+	return StartResult{SessionID: sessionID, Payload: payload, Pow: pow, Response: resp}, nil
+}
+
+func ExecuteNonStreamWithRetry(ctx context.Context, ds DeepSeekCaller, a *auth.RequestAuth, stdReq promptcompat.StandardRequest, opts Options) (NonStreamResult, *assistantturn.OutputError) {
+	start, startErr := StartCompletion(ctx, ds, a, stdReq, opts)
+	if startErr != nil {
+		return NonStreamResult{SessionID: start.SessionID, Payload: start.Payload}, startErr
+	}
+	maxAttempts := opts.MaxAttempts
+	if maxAttempts <= 0 {
+		maxAttempts = 3
+	}
+	sessionID := start.SessionID
+	payload := start.Payload
+	pow := start.Pow
+
+	attempts := 0
+	currentResp := start.Response
+	usagePrompt := stdReq.PromptTokenText
+	accumulatedThinking := ""
+	accumulatedRawThinking := ""
+	accumulatedToolDetectionThinking := ""
+	for {
+		turn, outErr := collectAttempt(currentResp, stdReq, usagePrompt, opts)
+		if outErr != nil {
+			return NonStreamResult{SessionID: sessionID, Payload: payload, Attempts: attempts}, outErr
+		}
+		accumulatedThinking += sse.TrimContinuationOverlap(accumulatedThinking, turn.Thinking)
+		accumulatedRawThinking += sse.TrimContinuationOverlap(accumulatedRawThinking, turn.RawThinking)
+		accumulatedToolDetectionThinking += sse.TrimContinuationOverlap(accumulatedToolDetectionThinking, turn.DetectionThinking)
+		turn.Thinking = accumulatedThinking
+		turn.RawThinking = accumulatedRawThinking
+		turn.DetectionThinking = accumulatedToolDetectionThinking
+		turn = assistantturn.BuildTurnFromCollected(sse.CollectResult{
+			Text:                  turn.RawText,
+			Thinking:              turn.RawThinking,
+			ToolDetectionThinking: turn.DetectionThinking,
+			ContentFilter:         turn.ContentFilter,
+			CitationLinks:         turn.CitationLinks,
+			ResponseMessageID:     turn.ResponseMessageID,
+		}, buildOptions(stdReq, usagePrompt, opts))
+
+		retryMax := opts.RetryMaxAttempts
+		if retryMax <= 0 {
+			retryMax = shared.EmptyOutputRetryMaxAttempts()
+		}
+		if !opts.RetryEnabled || !assistantturn.ShouldRetryEmptyOutput(turn, attempts, retryMax) {
+			return NonStreamResult{SessionID: sessionID, Payload: payload, Turn: turn, Attempts: attempts}, turn.Error
+		}
+
+		attempts++
+		config.Logger.Info("[completion_runtime_empty_retry] attempting synthetic retry", "surface", stdReq.Surface, "stream", false, "retry_attempt", attempts, "parent_message_id", turn.ResponseMessageID)
+		retryPow, powErr := ds.GetPow(ctx, a, maxAttempts)
+		if powErr != nil {
+			config.Logger.Warn("[completion_runtime_empty_retry] retry PoW fetch failed, falling back to original PoW", "surface", stdReq.Surface, "retry_attempt", attempts, "error", powErr)
+			retryPow = pow
+		}
+		retryPayload := shared.ClonePayloadForEmptyOutputRetry(payload, turn.ResponseMessageID)
+		nextResp, err := ds.CallCompletion(ctx, a, retryPayload, retryPow, maxAttempts)
+		if err != nil {
+			return NonStreamResult{SessionID: sessionID, Payload: payload, Turn: turn, Attempts: attempts}, &assistantturn.OutputError{Status: http.StatusInternalServerError, Message: "Failed to get completion.", Code: "error"}
+		}
+		usagePrompt = shared.UsagePromptWithEmptyOutputRetry(usagePrompt, attempts)
+		currentResp = nextResp
+	}
+}
+
+func collectAttempt(resp *http.Response, stdReq promptcompat.StandardRequest, usagePrompt string, opts Options) (assistantturn.Turn, *assistantturn.OutputError) {
+	defer func() {
+		if err := resp.Body.Close(); err != nil {
+			config.Logger.Warn("[completion_runtime] response body close failed", "surface", stdReq.Surface, "error", err)
+		}
+	}()
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		message := strings.TrimSpace(string(body))
+		if message == "" {
+			message = http.StatusText(resp.StatusCode)
+		}
+		return assistantturn.Turn{}, &assistantturn.OutputError{Status: resp.StatusCode, Message: message, Code: "error"}
+	}
+	result := sse.CollectStream(resp, stdReq.Thinking, false)
+	return assistantturn.BuildTurnFromCollected(result, buildOptions(stdReq, usagePrompt, opts)), nil
+}
+
+func buildOptions(stdReq promptcompat.StandardRequest, prompt string, opts Options) assistantturn.BuildOptions {
+	return assistantturn.BuildOptions{
+		Model:                 stdReq.ResponseModel,
+		Prompt:                prompt,
+		RefFileTokens:         stdReq.RefFileTokens,
+		SearchEnabled:         stdReq.Search,
+		StripReferenceMarkers: opts.StripReferenceMarkers,
+		ToolNames:             stdReq.ToolNames,
+		ToolsRaw:              stdReq.ToolsRaw,
+		ToolChoice:            stdReq.ToolChoice,
+	}
+}
+
+func authOutputError(a *auth.RequestAuth) *assistantturn.OutputError {
+	if a != nil && a.UseConfigToken {
+		return &assistantturn.OutputError{Status: http.StatusUnauthorized, Message: "Account token is invalid. Please re-login the account in admin.", Code: "error"}
+	}
+	return &assistantturn.OutputError{Status: http.StatusUnauthorized, Message: "Invalid token. If this should be a DS2API key, add it to config.keys first.", Code: "error"}
+}
+
+func Errorf(status int, format string, args ...any) *assistantturn.OutputError {
+	return &assistantturn.OutputError{Status: status, Message: fmt.Sprintf(format, args...), Code: "error"}
+}

internal/completionruntime/nonstream_test.go

@@ -0,0 +1,120 @@
+package completionruntime
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"ds2api/internal/auth"
+	"ds2api/internal/promptcompat"
+)
+
+type fakeDeepSeekCaller struct {
+	responses []*http.Response
+	payloads  []map[string]any
+}
+
+func (f *fakeDeepSeekCaller) CreateSession(context.Context, *auth.RequestAuth, int) (string, error) {
+	return "session-1", nil
+}
+
+func (f *fakeDeepSeekCaller) GetPow(context.Context, *auth.RequestAuth, int) (string, error) {
+	return "pow", nil
+}
+
+func (f *fakeDeepSeekCaller) CallCompletion(_ context.Context, _ *auth.RequestAuth, payload map[string]any, _ string, _ int) (*http.Response, error) {
+	f.payloads = append(f.payloads, payload)
+	if len(f.responses) == 0 {
+		return sseHTTPResponse(http.StatusOK, `data: {"p":"response/content","v":"fallback"}`), nil
+	}
+	resp := f.responses[0]
+	f.responses = f.responses[1:]
+	return resp, nil
+}
+
+func TestExecuteNonStreamWithRetryBuildsCanonicalTurn(t *testing.T) {
+	ds := &fakeDeepSeekCaller{responses: []*http.Response{sseHTTPResponse(
+		http.StatusOK,
+		`data: {"response_message_id":42,"p":"response/content","v":"<tool_calls><invoke name=\"Write\"><parameter name=\"content\">{\"x\":1}</parameter></invoke></tool_calls>"}`,
+	)}}
+	stdReq := promptcompat.StandardRequest{
+		Surface:         "test",
+		ResponseModel:   "deepseek-v4-flash",
+		PromptTokenText: "prompt",
+		FinalPrompt:     "final prompt",
+		ToolNames:       []string{"Write"},
+		ToolsRaw: []any{map[string]any{
+			"name": "Write",
+			"input_schema": map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"content": map[string]any{"type": "string"},
+				},
+			},
+		}},
+	}
+
+	result, outErr := ExecuteNonStreamWithRetry(context.Background(), ds, &auth.RequestAuth{}, stdReq, Options{})
+	if outErr != nil {
+		t.Fatalf("unexpected output error: %#v", outErr)
+	}
+	if result.SessionID != "session-1" {
+		t.Fatalf("session mismatch: %q", result.SessionID)
+	}
+	if got := result.Turn.ResponseMessageID; got != 42 {
+		t.Fatalf("response message id mismatch: %d", got)
+	}
+	if len(result.Turn.ToolCalls) != 1 {
+		t.Fatalf("expected one tool call, got %d", len(result.Turn.ToolCalls))
+	}
+	if _, ok := result.Turn.ToolCalls[0].Input["content"].(string); !ok {
+		t.Fatalf("expected schema-normalized string argument, got %#v", result.Turn.ToolCalls[0].Input["content"])
+	}
+	if result.Turn.Usage.InputTokens == 0 || result.Turn.Usage.TotalTokens == 0 {
+		t.Fatalf("expected usage to be populated, got %#v", result.Turn.Usage)
+	}
+}
+
+func TestExecuteNonStreamWithRetryUsesParentMessageForEmptyRetry(t *testing.T) {
+	ds := &fakeDeepSeekCaller{responses: []*http.Response{
+		sseHTTPResponse(http.StatusOK, `data: {"response_message_id":77,"p":"response/status","v":"FINISHED"}`),
+		sseHTTPResponse(http.StatusOK, `data: {"response_message_id":78,"p":"response/content","v":"ok"}`),
+	}}
+	stdReq := promptcompat.StandardRequest{
+		Surface:         "test",
+		ResponseModel:   "deepseek-v4-flash",
+		PromptTokenText: "prompt",
+		FinalPrompt:     "final prompt",
+	}
+
+	result, outErr := ExecuteNonStreamWithRetry(context.Background(), ds, &auth.RequestAuth{}, stdReq, Options{RetryEnabled: true})
+	if outErr != nil {
+		t.Fatalf("unexpected output error: %#v", outErr)
+	}
+	if result.Attempts != 1 {
+		t.Fatalf("expected one retry, got %d", result.Attempts)
+	}
+	if len(ds.payloads) != 2 {
+		t.Fatalf("expected two completion calls, got %d", len(ds.payloads))
+	}
+	if got := ds.payloads[1]["parent_message_id"]; got != 77 {
+		t.Fatalf("retry parent_message_id mismatch: %#v", got)
+	}
+	if result.Turn.Text != "ok" {
+		t.Fatalf("retry text mismatch: %q", result.Turn.Text)
+	}
+}
+
+func sseHTTPResponse(status int, lines ...string) *http.Response {
+	body := strings.Join(lines, "\n")
+	if !strings.HasSuffix(body, "\n") {
+		body += "\n"
+	}
+	return &http.Response{
+		StatusCode: status,
+		Header:     make(http.Header),
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+}

internal/format/claude/render.go

@@ -1,6 +1,7 @@
 package claude
 
 import (
+	"ds2api/internal/assistantturn"
 	"ds2api/internal/toolcall"
 	"fmt"
 	"time"
@@ -9,6 +10,47 @@ import (
 	"ds2api/internal/util"
 )
 
+func BuildMessageResponseFromTurn(messageID, model string, turn assistantturn.Turn, exposeThinking bool) map[string]any {
+	content := make([]map[string]any, 0, 4)
+	if exposeThinking && turn.Thinking != "" {
+		content = append(content, map[string]any{"type": "thinking", "thinking": turn.Thinking})
+	}
+	stopReason := "end_turn"
+	if len(turn.ToolCalls) > 0 {
+		stopReason = "tool_use"
+		for i, tc := range turn.ToolCalls {
+			content = append(content, map[string]any{
+				"type":  "tool_use",
+				"id":    fmt.Sprintf("toolu_%d_%d", time.Now().Unix(), i),
+				"name":  tc.Name,
+				"input": tc.Input,
+			})
+		}
+	} else {
+		text := turn.Text
+		if text == "" && exposeThinking {
+			text = turn.Thinking
+		}
+		if text == "" {
+			text = "抱歉，没有生成有效的响应内容。"
+		}
+		content = append(content, map[string]any{"type": "text", "text": text})
+	}
+	return map[string]any{
+		"id":            messageID,
+		"type":          "message",
+		"role":          "assistant",
+		"model":         model,
+		"content":       content,
+		"stop_reason":   stopReason,
+		"stop_sequence": nil,
+		"usage": map[string]any{
+			"input_tokens":  turn.Usage.InputTokens,
+			"output_tokens": turn.Usage.OutputTokens,
+		},
+	}
+}
+
 func BuildMessageResponse(messageID, model string, normalizedMessages []any, finalThinking, finalText string, toolNames []string) map[string]any {
 	detected := toolcall.ParseToolCalls(finalText, toolNames)
 	if len(detected) == 0 && finalText == "" && finalThinking != "" {

internal/httpapi/claude/handler_messages.go

@@ -4,13 +4,19 @@ import (
 	"bytes"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
+	"time"
 
+	"ds2api/internal/auth"
+	"ds2api/internal/completionruntime"
 	"ds2api/internal/config"
+	claudefmt "ds2api/internal/format/claude"
 	"ds2api/internal/httpapi/requestbody"
+	"ds2api/internal/promptcompat"
 	streamengine "ds2api/internal/stream"
 	"ds2api/internal/translatorcliproxy"
 	"ds2api/internal/util"
@@ -22,14 +28,90 @@ func (h *Handler) Messages(w http.ResponseWriter, r *http.Request) {
 	if strings.TrimSpace(r.Header.Get("anthropic-version")) == "" {
 		r.Header.Set("anthropic-version", "2023-06-01")
 	}
-	if h.OpenAI == nil {
-		writeClaudeError(w, http.StatusInternalServerError, "OpenAI proxy backend unavailable.")
+	if isClaudeVercelProxyRequest(r) && h.proxyViaOpenAI(w, r, h.Store) {
 		return
 	}
-	if h.proxyViaOpenAI(w, r, h.Store) {
+	if h.Auth == nil || h.DS == nil {
+		if h.OpenAI != nil && h.proxyViaOpenAI(w, r, h.Store) {
+			return
+		}
+		writeClaudeError(w, http.StatusInternalServerError, "Claude runtime backend unavailable.")
 		return
 	}
-	writeClaudeError(w, http.StatusBadGateway, "Failed to proxy Claude request.")
+	if h.handleClaudeDirect(w, r) {
+		return
+	}
+	writeClaudeError(w, http.StatusBadGateway, "Failed to handle Claude request.")
+}
+
+func isClaudeVercelProxyRequest(r *http.Request) bool {
+	if r == nil || r.URL == nil {
+		return false
+	}
+	return strings.TrimSpace(r.URL.Query().Get("__stream_prepare")) == "1" ||
+		strings.TrimSpace(r.URL.Query().Get("__stream_release")) == "1"
+}
+
+func (h *Handler) handleClaudeDirect(w http.ResponseWriter, r *http.Request) bool {
+	raw, err := io.ReadAll(r.Body)
+	if err != nil {
+		if errors.Is(err, requestbody.ErrInvalidUTF8Body) {
+			writeClaudeError(w, http.StatusBadRequest, "invalid json")
+		} else {
+			writeClaudeError(w, http.StatusBadRequest, "invalid body")
+		}
+		return true
+	}
+	var req map[string]any
+	if err := json.Unmarshal(raw, &req); err != nil {
+		writeClaudeError(w, http.StatusBadRequest, "invalid json")
+		return true
+	}
+	exposeThinking := false
+	if enabled, ok := util.ResolveThinkingOverride(req); ok && enabled {
+		exposeThinking = true
+	} else if _, ok := util.ResolveThinkingOverride(req); !ok && !util.ToBool(req["stream"]) {
+		req["thinking"] = map[string]any{"type": "enabled"}
+	}
+	norm, err := normalizeClaudeRequest(h.Store, req)
+	if err != nil {
+		writeClaudeError(w, http.StatusBadRequest, err.Error())
+		return true
+	}
+	a, err := h.Auth.Determine(r)
+	if err != nil {
+		writeClaudeError(w, http.StatusUnauthorized, err.Error())
+		return true
+	}
+	defer h.Auth.Release(a)
+	if norm.Standard.Stream {
+		h.handleClaudeDirectStream(w, r, a, norm.Standard)
+		return true
+	}
+	result, outErr := completionruntime.ExecuteNonStreamWithRetry(r.Context(), h.DS, a, norm.Standard, completionruntime.Options{
+		StripReferenceMarkers: h.compatStripReferenceMarkers(),
+		RetryEnabled:          true,
+	})
+	if outErr != nil {
+		writeClaudeError(w, outErr.Status, outErr.Message)
+		return true
+	}
+	writeJSON(w, http.StatusOK, claudefmt.BuildMessageResponseFromTurn(
+		fmt.Sprintf("msg_%d", time.Now().UnixNano()),
+		norm.Standard.ResponseModel,
+		result.Turn,
+		exposeThinking,
+	))
+	return true
+}
+
+func (h *Handler) handleClaudeDirectStream(w http.ResponseWriter, r *http.Request, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) {
+	start, outErr := completionruntime.StartCompletion(r.Context(), h.DS, a, stdReq, completionruntime.Options{})
+	if outErr != nil {
+		writeClaudeError(w, outErr.Status, outErr.Message)
+		return
+	}
+	h.handleClaudeStreamRealtime(w, r, start.Response, stdReq.ResponseModel, stdReq.Messages, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw)
 }
 
 func (h *Handler) proxyViaOpenAI(w http.ResponseWriter, r *http.Request, store ConfigReader) bool {

internal/httpapi/claude/stream_runtime_finalize.go

@@ -1,6 +1,7 @@
 package claude
 
 import (
+	"ds2api/internal/assistantturn"
 	"ds2api/internal/sse"
 	"ds2api/internal/toolcall"
 	"ds2api/internal/toolstream"
@@ -9,7 +10,6 @@ import (
 	"time"
 
 	streamengine "ds2api/internal/stream"
-	"ds2api/internal/util"
 )
 
 func (s *claudeStreamRuntime) closeThinkingBlock() {
@@ -115,18 +115,28 @@ func (s *claudeStreamRuntime) finalize(stopReason string) {
 
 	s.closeTextBlock()
 
-	finalThinking := s.thinking.String()
-	finalText := cleanVisibleOutput(s.text.String(), s.stripReferenceMarkers)
+	turn := assistantturn.BuildTurnFromStreamSnapshot(assistantturn.StreamSnapshot{
+		RawText:               s.rawText.String(),
+		VisibleText:           s.text.String(),
+		RawThinking:           s.rawThinking.String(),
+		VisibleThinking:       s.thinking.String(),
+		DetectionThinking:     s.toolDetectionThinking.String(),
+		AlreadyEmittedCalls:   s.toolCallsDetected,
+		AlreadyEmittedToolRaw: s.toolCallsDetected,
+	}, assistantturn.BuildOptions{
+		Model:                 s.model,
+		Prompt:                s.promptTokenText,
+		SearchEnabled:         s.searchEnabled,
+		StripReferenceMarkers: s.stripReferenceMarkers,
+		ToolNames:             s.toolNames,
+		ToolsRaw:              s.toolsRaw,
+	})
+	finalText := turn.Text
 
 	if s.bufferToolContent && !s.toolCallsDetected {
-		detected := toolcall.ParseStandaloneToolCallsDetailed(s.rawText.String(), s.toolNames)
-		if len(detected.Calls) == 0 {
-			detected = toolcall.ParseStandaloneToolCallsDetailed(s.rawThinking.String(), s.toolNames)
-		}
-		if len(detected.Calls) > 0 {
-			normalized := toolcall.NormalizeParsedToolCallsForSchemas(detected.Calls, s.toolsRaw)
+		if len(turn.ToolCalls) > 0 {
 			stopReason = "tool_use"
-			for _, tc := range normalized {
+			for _, tc := range turn.ToolCalls {
 				idx := s.nextBlockIndex
 				s.nextBlockIndex++
 				s.sendToolUseBlock(idx, tc)
@@ -161,7 +171,6 @@ func (s *claudeStreamRuntime) finalize(stopReason string) {
 		stopReason = "tool_use"
 	}
 
-	outputTokens := util.CountOutputTokens(finalThinking, s.model) + util.CountOutputTokens(finalText, s.model)
 	s.send("message_delta", map[string]any{
 		"type": "message_delta",
 		"delta": map[string]any{
@@ -169,7 +178,7 @@ func (s *claudeStreamRuntime) finalize(stopReason string) {
 			"stop_sequence": nil,
 		},
 		"usage": map[string]any{
-			"output_tokens": outputTokens,
+			"output_tokens": turn.Usage.OutputTokens,
 		},
 	})
 	s.send("message_stop", map[string]any{"type": "message_stop"})

internal/httpapi/gemini/convert_request.go

@@ -33,6 +33,9 @@ func normalizeGeminiRequest(store ConfigReader, routeModel string, req map[strin
 
 	toolsRaw := convertGeminiTools(req["tools"])
 	finalPrompt, toolNames := promptcompat.BuildOpenAIPromptForAdapter(messagesRaw, toolsRaw, "", thinkingEnabled)
+	if len(toolNames) == 0 && len(toolsRaw) > 0 {
+		toolNames = []string{"__any_tool__"}
+	}
 	passThrough := collectGeminiPassThrough(req)
 
 	return promptcompat.StandardRequest{
@@ -42,6 +45,7 @@ func normalizeGeminiRequest(store ConfigReader, routeModel string, req map[strin
 		ResponseModel:   requestedModel,
 		Messages:        messagesRaw,
 		PromptTokenText: finalPrompt,
+		ToolsRaw:        toolsRaw,
 		FinalPrompt:     finalPrompt,
 		ToolNames:       toolNames,
 		Stream:          stream,

internal/httpapi/gemini/handler_generate.go

@@ -11,7 +11,11 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
+	"ds2api/internal/assistantturn"
+	"ds2api/internal/auth"
+	"ds2api/internal/completionruntime"
 	"ds2api/internal/httpapi/requestbody"
+	"ds2api/internal/promptcompat"
 	"ds2api/internal/sse"
 	"ds2api/internal/toolcall"
 	"ds2api/internal/translatorcliproxy"
@@ -21,14 +25,80 @@ import (
 )
 
 func (h *Handler) handleGenerateContent(w http.ResponseWriter, r *http.Request, stream bool) {
-	if h.OpenAI == nil {
-		writeGeminiError(w, http.StatusInternalServerError, "OpenAI proxy backend unavailable.")
+	if isGeminiVercelProxyRequest(r) && h.proxyViaOpenAI(w, r, stream) {
 		return
 	}
-	if h.proxyViaOpenAI(w, r, stream) {
+	if h.Auth == nil || h.DS == nil {
+		if h.OpenAI != nil && h.proxyViaOpenAI(w, r, stream) {
+			return
+		}
+		writeGeminiError(w, http.StatusInternalServerError, "Gemini runtime backend unavailable.")
 		return
 	}
-	writeGeminiError(w, http.StatusBadGateway, "Failed to proxy Gemini request.")
+	if h.handleGeminiDirect(w, r, stream) {
+		return
+	}
+	writeGeminiError(w, http.StatusBadGateway, "Failed to handle Gemini request.")
+}
+
+func isGeminiVercelProxyRequest(r *http.Request) bool {
+	if r == nil || r.URL == nil {
+		return false
+	}
+	return strings.TrimSpace(r.URL.Query().Get("__stream_prepare")) == "1" ||
+		strings.TrimSpace(r.URL.Query().Get("__stream_release")) == "1"
+}
+
+func (h *Handler) handleGeminiDirect(w http.ResponseWriter, r *http.Request, stream bool) bool {
+	raw, err := io.ReadAll(r.Body)
+	if err != nil {
+		if errors.Is(err, requestbody.ErrInvalidUTF8Body) {
+			writeGeminiError(w, http.StatusBadRequest, "invalid json")
+		} else {
+			writeGeminiError(w, http.StatusBadRequest, "invalid body")
+		}
+		return true
+	}
+	routeModel := strings.TrimSpace(chi.URLParam(r, "model"))
+	var req map[string]any
+	if err := json.Unmarshal(raw, &req); err != nil {
+		writeGeminiError(w, http.StatusBadRequest, "invalid json")
+		return true
+	}
+	stdReq, err := normalizeGeminiRequest(h.Store, routeModel, req, stream)
+	if err != nil {
+		writeGeminiError(w, http.StatusBadRequest, err.Error())
+		return true
+	}
+	a, err := h.Auth.Determine(r)
+	if err != nil {
+		writeGeminiError(w, http.StatusUnauthorized, err.Error())
+		return true
+	}
+	defer h.Auth.Release(a)
+	if stream {
+		h.handleGeminiDirectStream(w, r, a, stdReq)
+		return true
+	}
+	result, outErr := completionruntime.ExecuteNonStreamWithRetry(r.Context(), h.DS, a, stdReq, completionruntime.Options{
+		StripReferenceMarkers: h.compatStripReferenceMarkers(),
+		RetryEnabled:          true,
+	})
+	if outErr != nil {
+		writeGeminiError(w, outErr.Status, outErr.Message)
+		return true
+	}
+	writeJSON(w, http.StatusOK, buildGeminiGenerateContentResponseFromTurn(result.Turn))
+	return true
+}
+
+func (h *Handler) handleGeminiDirectStream(w http.ResponseWriter, r *http.Request, a *auth.RequestAuth, stdReq promptcompat.StandardRequest) {
+	start, outErr := completionruntime.StartCompletion(r.Context(), h.DS, a, stdReq, completionruntime.Options{})
+	if outErr != nil {
+		writeGeminiError(w, outErr.Status, outErr.Message)
+		return
+	}
+	h.handleStreamGenerateContent(w, r, start.Response, stdReq.ResponseModel, stdReq.PromptTokenText, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw)
 }
 
 func (h *Handler) proxyViaOpenAI(w http.ResponseWriter, r *http.Request, stream bool) bool {
@@ -250,6 +320,48 @@ func buildGeminiGenerateContentResponse(model, finalPrompt, finalThinking, final
 	}
 }
 
+func buildGeminiGenerateContentResponseFromTurn(turn assistantturn.Turn) map[string]any {
+	parts := buildGeminiPartsFromTurn(turn)
+	return map[string]any{
+		"candidates": []map[string]any{
+			{
+				"index": 0,
+				"content": map[string]any{
+					"role":  "model",
+					"parts": parts,
+				},
+				"finishReason": "STOP",
+			},
+		},
+		"modelVersion": turn.Model,
+		"usageMetadata": map[string]any{
+			"promptTokenCount":     turn.Usage.InputTokens,
+			"candidatesTokenCount": turn.Usage.OutputTokens,
+			"totalTokenCount":      turn.Usage.TotalTokens,
+		},
+	}
+}
+
+func buildGeminiPartsFromTurn(turn assistantturn.Turn) []map[string]any {
+	if len(turn.ToolCalls) > 0 {
+		parts := make([]map[string]any, 0, len(turn.ToolCalls))
+		for _, tc := range turn.ToolCalls {
+			parts = append(parts, map[string]any{
+				"functionCall": map[string]any{
+					"name": tc.Name,
+					"args": tc.Input,
+				},
+			})
+		}
+		return parts
+	}
+	text := turn.Text
+	if text == "" {
+		text = turn.Thinking
+	}
+	return []map[string]any{{"text": text}}
+}
+
 //nolint:unused // retained for native Gemini non-stream handling path.
 func buildGeminiUsage(model, finalPrompt, finalThinking, finalText string) map[string]any {
 	promptTokens := util.CountPromptTokens(finalPrompt, model)

internal/httpapi/gemini/handler_stream_runtime.go

@@ -7,13 +7,14 @@ import (
 	"strings"
 	"time"
 
+	"ds2api/internal/assistantturn"
 	dsprotocol "ds2api/internal/deepseek/protocol"
 	"ds2api/internal/sse"
 	streamengine "ds2api/internal/stream"
 )
 
 //nolint:unused // retained for native Gemini stream handling path.
-func (h *Handler) handleStreamGenerateContent(w http.ResponseWriter, r *http.Request, resp *http.Response, model, finalPrompt string, thinkingEnabled, searchEnabled bool, toolNames []string) {
+func (h *Handler) handleStreamGenerateContent(w http.ResponseWriter, r *http.Request, resp *http.Response, model, finalPrompt string, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any) {
 	defer func() { _ = resp.Body.Close() }()
 	if resp.StatusCode != http.StatusOK {
 		body, _ := io.ReadAll(resp.Body)
@@ -28,7 +29,7 @@ func (h *Handler) handleStreamGenerateContent(w http.ResponseWriter, r *http.Req
 
 	rc := http.NewResponseController(w)
 	_, canFlush := w.(http.Flusher)
-	runtime := newGeminiStreamRuntime(w, rc, canFlush, model, finalPrompt, thinkingEnabled, searchEnabled, h.compatStripReferenceMarkers(), toolNames)
+	runtime := newGeminiStreamRuntime(w, rc, canFlush, model, finalPrompt, thinkingEnabled, searchEnabled, h.compatStripReferenceMarkers(), toolNames, toolsRaw)
 
 	initialType := "text"
 	if thinkingEnabled {
@@ -64,9 +65,11 @@ type geminiStreamRuntime struct {
 	bufferContent         bool
 	stripReferenceMarkers bool
 	toolNames             []string
+	toolsRaw              any
 
-	thinking strings.Builder
-	text     strings.Builder
+	accumulator       *assistantturn.Accumulator
+	contentFilter     bool
+	responseMessageID int
 }
 
 //nolint:unused // retained for native Gemini stream handling path.
@@ -80,6 +83,7 @@ func newGeminiStreamRuntime(
 	searchEnabled bool,
 	stripReferenceMarkers bool,
 	toolNames []string,
+	toolsRaw any,
 ) *geminiStreamRuntime {
 	return &geminiStreamRuntime{
 		w:                     w,
@@ -92,6 +96,12 @@ func newGeminiStreamRuntime(
 		bufferContent:         len(toolNames) > 0,
 		stripReferenceMarkers: stripReferenceMarkers,
 		toolNames:             toolNames,
+		toolsRaw:              toolsRaw,
+		accumulator: assistantturn.NewAccumulator(assistantturn.AccumulatorOptions{
+			ThinkingEnabled:       thinkingEnabled,
+			SearchEnabled:         searchEnabled,
+			StripReferenceMarkers: stripReferenceMarkers,
+		}),
 	}
 }
 
@@ -111,32 +121,24 @@ func (s *geminiStreamRuntime) onParsed(parsed sse.LineResult) streamengine.Parse
 	if !parsed.Parsed {
 		return streamengine.ParsedDecision{}
 	}
+	if parsed.ResponseMessageID > 0 {
+		s.responseMessageID = parsed.ResponseMessageID
+	}
 	if parsed.ContentFilter || parsed.ErrorMessage != "" || parsed.Stop {
+		if parsed.ContentFilter {
+			s.contentFilter = true
+		}
 		return streamengine.ParsedDecision{Stop: true}
 	}
 
-	contentSeen := false
-	for _, p := range parsed.Parts {
-		cleanedText := cleanVisibleOutput(p.Text, s.stripReferenceMarkers)
-		if cleanedText == "" {
-			continue
-		}
-		if p.Type != "thinking" && s.searchEnabled && sse.IsCitation(cleanedText) {
-			continue
-		}
-		contentSeen = true
+	accumulated := s.accumulator.Apply(parsed)
+	for _, p := range accumulated.Parts {
 		if p.Type == "thinking" {
-			if s.thinkingEnabled {
-				if cleanedText != "" {
-					s.thinking.WriteString(cleanedText)
-				}
-			}
 			continue
 		}
-		if cleanedText == "" {
+		if p.RawText == "" || p.CitationOnly || p.VisibleText == "" {
 			continue
 		}
-		s.text.WriteString(cleanedText)
 		if s.bufferContent {
 			continue
 		}
@@ -146,23 +148,38 @@ func (s *geminiStreamRuntime) onParsed(parsed sse.LineResult) streamengine.Parse
 					"index": 0,
 					"content": map[string]any{
 						"role":  "model",
-						"parts": []map[string]any{{"text": cleanedText}},
+						"parts": []map[string]any{{"text": p.VisibleText}},
 					},
 				},
 			},
 			"modelVersion": s.model,
 		})
 	}
-	return streamengine.ParsedDecision{ContentSeen: contentSeen}
+	return streamengine.ParsedDecision{ContentSeen: accumulated.ContentSeen}
 }
 
 //nolint:unused // retained for native Gemini stream handling path.
 func (s *geminiStreamRuntime) finalize() {
-	finalThinking := s.thinking.String()
-	finalText := cleanVisibleOutput(s.text.String(), s.stripReferenceMarkers)
+	rawText, text, rawThinking, thinking, detectionThinking := s.accumulator.Snapshot()
+	turn := assistantturn.BuildTurnFromStreamSnapshot(assistantturn.StreamSnapshot{
+		RawText:           rawText,
+		VisibleText:       text,
+		RawThinking:       rawThinking,
+		VisibleThinking:   thinking,
+		DetectionThinking: detectionThinking,
+		ContentFilter:     s.contentFilter,
+		ResponseMessageID: s.responseMessageID,
+	}, assistantturn.BuildOptions{
+		Model:                 s.model,
+		Prompt:                s.finalPrompt,
+		SearchEnabled:         s.searchEnabled,
+		StripReferenceMarkers: s.stripReferenceMarkers,
+		ToolNames:             s.toolNames,
+		ToolsRaw:              s.toolsRaw,
+	})
 
 	if s.bufferContent {
-		parts := buildGeminiPartsFromFinal(finalText, finalThinking, s.toolNames)
+		parts := buildGeminiPartsFromTurn(turn)
 		s.sendChunk(map[string]any{
 			"candidates": []map[string]any{
 				{
@@ -190,7 +207,11 @@ func (s *geminiStreamRuntime) finalize() {
 				"finishReason": "STOP",
 			},
 		},
-		"modelVersion":  s.model,
-		"usageMetadata": buildGeminiUsage(s.model, s.finalPrompt, finalThinking, finalText),
+		"modelVersion": s.model,
+		"usageMetadata": map[string]any{
+			"promptTokenCount":     turn.Usage.InputTokens,
+			"candidatesTokenCount": turn.Usage.OutputTokens,
+			"totalTokenCount":      turn.Usage.TotalTokens,
+		},
 	})
 }

internal/httpapi/openai/chat/chat_stream_runtime.go

@@ -5,8 +5,10 @@ import (
 	"net/http"
 	"strings"
 
+	"ds2api/internal/assistantturn"
 	openaifmt "ds2api/internal/format/openai"
 	"ds2api/internal/httpapi/openai/shared"
+	"ds2api/internal/promptcompat"
 	"ds2api/internal/sse"
 	streamengine "ds2api/internal/stream"
 	"ds2api/internal/toolstream"
@@ -24,6 +26,7 @@ type chatStreamRuntime struct {
 	refFileTokens int
 	toolNames     []string
 	toolsRaw      any
+	toolChoice    promptcompat.ToolChoicePolicy
 
 	thinkingEnabled       bool
 	searchEnabled         bool
@@ -89,6 +92,7 @@ func newChatStreamRuntime(
 	stripReferenceMarkers bool,
 	toolNames []string,
 	toolsRaw any,
+	toolChoice promptcompat.ToolChoicePolicy,
 	bufferToolContent bool,
 	emitEarlyToolDeltas bool,
 ) *chatStreamRuntime {
@@ -102,6 +106,7 @@ func newChatStreamRuntime(
 		finalPrompt:           finalPrompt,
 		toolNames:             toolNames,
 		toolsRaw:              toolsRaw,
+		toolChoice:            toolChoice,
 		thinkingEnabled:       thinkingEnabled,
 		searchEnabled:         searchEnabled,
 		stripReferenceMarkers: stripReferenceMarkers,
@@ -201,14 +206,33 @@ func (s *chatStreamRuntime) finalize(finishReason string, deferEmptyOutput bool)
 	s.finalErrorCode = ""
 	finalThinking := s.accumulator.Thinking.String()
 	finalToolDetectionThinking := s.accumulator.ToolDetectionThinking.String()
-	finalText := cleanVisibleOutput(s.accumulator.Text.String(), s.stripReferenceMarkers)
-	s.finalThinking = finalThinking
-	s.finalText = finalText
-	detected := detectAssistantToolCalls(s.accumulator.RawText.String(), finalText, s.accumulator.RawThinking.String(), finalToolDetectionThinking, s.toolNames)
-	if len(detected.Calls) > 0 && !s.toolCallsDoneEmitted {
+	finalText := s.accumulator.Text.String()
+	turn := assistantturn.BuildTurnFromStreamSnapshot(assistantturn.StreamSnapshot{
+		RawText:               s.accumulator.RawText.String(),
+		VisibleText:           finalText,
+		RawThinking:           s.accumulator.RawThinking.String(),
+		VisibleThinking:       finalThinking,
+		DetectionThinking:     finalToolDetectionThinking,
+		ContentFilter:         finishReason == "content_filter",
+		ResponseMessageID:     s.responseMessageID,
+		AlreadyEmittedCalls:   s.toolCallsEmitted,
+		AlreadyEmittedToolRaw: s.toolCallsDoneEmitted,
+	}, assistantturn.BuildOptions{
+		Model:                 s.model,
+		Prompt:                s.finalPrompt,
+		RefFileTokens:         s.refFileTokens,
+		SearchEnabled:         s.searchEnabled,
+		StripReferenceMarkers: s.stripReferenceMarkers,
+		ToolNames:             s.toolNames,
+		ToolsRaw:              s.toolsRaw,
+		ToolChoice:            s.toolChoice,
+	})
+	s.finalThinking = turn.Thinking
+	s.finalText = turn.Text
+	if len(turn.ToolCalls) > 0 && !s.toolCallsDoneEmitted {
 		finishReason = "tool_calls"
 		s.sendDelta(map[string]any{
-			"tool_calls": formatFinalStreamToolCallsWithStableIDs(detected.Calls, s.streamToolCallIDs, s.toolsRaw),
+			"tool_calls": formatFinalStreamToolCallsWithStableIDs(turn.ToolCalls, s.streamToolCallIDs, s.toolsRaw),
 		})
 		s.toolCallsEmitted = true
 		s.toolCallsDoneEmitted = true
@@ -237,11 +261,14 @@ func (s *chatStreamRuntime) finalize(finishReason string, deferEmptyOutput bool)
 		batch.flush()
 	}
 
-	if len(detected.Calls) > 0 || s.toolCallsEmitted {
+	if len(turn.ToolCalls) > 0 || s.toolCallsEmitted {
 		finishReason = "tool_calls"
 	}
-	if len(detected.Calls) == 0 && !s.toolCallsEmitted && strings.TrimSpace(finalText) == "" {
-		status, message, code := upstreamEmptyOutputDetail(finishReason == "content_filter", finalText, finalThinking)
+	if len(turn.ToolCalls) == 0 && !s.toolCallsEmitted && strings.TrimSpace(turn.Text) == "" {
+		status, message, code := upstreamEmptyOutputDetail(finishReason == "content_filter", turn.Text, turn.Thinking)
+		if turn.Error != nil {
+			status, message, code = turn.Error.Status, turn.Error.Message, turn.Error.Code
+		}
 		if deferEmptyOutput {
 			s.finalErrorStatus = status
 			s.finalErrorMessage = message
@@ -251,7 +278,7 @@ func (s *chatStreamRuntime) finalize(finishReason string, deferEmptyOutput bool)
 		s.sendFailedChunk(status, message, code)
 		return true
 	}
-	usage := openaifmt.BuildChatUsageForModel(s.model, s.finalPrompt, finalThinking, finalText, s.refFileTokens)
+	usage := chatUsageFromTurn(turn)
 	s.finalFinishReason = finishReason
 	s.finalUsage = usage
 	s.sendChunk(openaifmt.BuildChatStreamChunk(
@@ -265,6 +292,17 @@ func (s *chatStreamRuntime) finalize(finishReason string, deferEmptyOutput bool)
 	return true
 }
 
+func chatUsageFromTurn(turn assistantturn.Turn) map[string]any {
+	return map[string]any{
+		"prompt_tokens":     turn.Usage.InputTokens,
+		"completion_tokens": turn.Usage.OutputTokens,
+		"total_tokens":      turn.Usage.TotalTokens,
+		"completion_tokens_details": map[string]any{
+			"reasoning_tokens": turn.Usage.ReasoningTokens,
+		},
+	}
+}
+
 func (s *chatStreamRuntime) onParsed(parsed sse.LineResult) streamengine.ParsedDecision {
 	if !parsed.Parsed {
 		return streamengine.ParsedDecision{}

internal/httpapi/openai/chat/chat_stream_runtime_test.go

@@ -6,6 +6,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"ds2api/internal/promptcompat"
 )
 
 func TestChatStreamKeepAliveEmitsEmptyChoiceDataFrame(t *testing.T) {
@@ -23,6 +25,7 @@ func TestChatStreamKeepAliveEmitsEmptyChoiceDataFrame(t *testing.T) {
 		true,
 		nil,
 		nil,
+		promptcompat.DefaultToolChoicePolicy(),
 		false,
 		false,
 	)
@@ -51,3 +54,34 @@ func TestChatStreamKeepAliveEmitsEmptyChoiceDataFrame(t *testing.T) {
 		t.Fatalf("expected empty choices heartbeat, got %#v", choices)
 	}
 }
+
+func TestChatStreamFinalizeEnforcesRequiredToolChoice(t *testing.T) {
+	rec := httptest.NewRecorder()
+	runtime := newChatStreamRuntime(
+		rec,
+		http.NewResponseController(rec),
+		true,
+		"chatcmpl-test",
+		time.Now().Unix(),
+		"deepseek-v4-flash",
+		"prompt",
+		false,
+		false,
+		true,
+		[]string{"Write"},
+		nil,
+		promptcompat.ToolChoicePolicy{Mode: promptcompat.ToolChoiceRequired},
+		true,
+		false,
+	)
+
+	if !runtime.finalize("stop", false) {
+		t.Fatalf("expected terminal error to be written")
+	}
+	if runtime.finalErrorCode != "tool_choice_violation" {
+		t.Fatalf("expected tool_choice_violation, got %q body=%s", runtime.finalErrorCode, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "tool_choice requires") {
+		t.Fatalf("expected tool choice error in stream body, got %s", rec.Body.String())
+	}
+}

internal/httpapi/openai/chat/empty_retry_runtime.go

@@ -7,10 +7,12 @@ import (
 	"strings"
 	"time"
 
+	"ds2api/internal/assistantturn"
 	"ds2api/internal/auth"
 	"ds2api/internal/config"
 	dsprotocol "ds2api/internal/deepseek/protocol"
 	openaifmt "ds2api/internal/format/openai"
+	"ds2api/internal/promptcompat"
 	"ds2api/internal/sse"
 	streamengine "ds2api/internal/stream"
 )
@@ -26,6 +28,7 @@ type chatNonStreamResult struct {
 	body                  map[string]any
 	finishReason          string
 	responseMessageID     int
+	outputError           *assistantturn.OutputError
 }
 
 func (h *Handler) handleNonStreamWithRetry(w http.ResponseWriter, ctx context.Context, a *auth.RequestAuth, resp *http.Response, payload map[string]any, pow, completionID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, historySession *chatHistorySession) {
@@ -86,35 +89,40 @@ func (h *Handler) collectChatNonStreamAttempt(w http.ResponseWriter, resp *http.
 		return chatNonStreamResult{}, false
 	}
 	result := sse.CollectStream(resp, thinkingEnabled, true)
-	stripReferenceMarkers := h.compatStripReferenceMarkers()
-	finalThinking := cleanVisibleOutput(result.Thinking, stripReferenceMarkers)
-	finalText := cleanVisibleOutput(result.Text, stripReferenceMarkers)
-	if searchEnabled {
-		finalText = replaceCitationMarkersWithLinks(finalText, result.CitationLinks)
-	}
-	detected := detectAssistantToolCalls(result.Text, finalText, result.Thinking, result.ToolDetectionThinking, toolNames)
-	respBody := openaifmt.BuildChatCompletionWithToolCalls(completionID, model, usagePrompt, finalThinking, finalText, detected.Calls, toolsRaw)
+	turn := assistantturn.BuildTurnFromCollected(result, assistantturn.BuildOptions{
+		Model:                 model,
+		Prompt:                usagePrompt,
+		SearchEnabled:         searchEnabled,
+		StripReferenceMarkers: h.compatStripReferenceMarkers(),
+		ToolNames:             toolNames,
+		ToolsRaw:              toolsRaw,
+	})
+	respBody := openaifmt.BuildChatCompletionWithToolCalls(completionID, model, usagePrompt, turn.Thinking, turn.Text, turn.ToolCalls, toolsRaw)
 	return chatNonStreamResult{
 		rawThinking:           result.Thinking,
 		rawText:               result.Text,
-		thinking:              finalThinking,
+		thinking:              turn.Thinking,
 		toolDetectionThinking: result.ToolDetectionThinking,
-		text:                  finalText,
+		text:                  turn.Text,
 		contentFilter:         result.ContentFilter,
-		detectedCalls:         len(detected.Calls),
+		detectedCalls:         len(turn.ToolCalls),
 		body:                  respBody,
 		finishReason:          chatFinishReason(respBody),
 		responseMessageID:     result.ResponseMessageID,
+		outputError:           turn.Error,
 	}, true
 }
 
 func (h *Handler) finishChatNonStreamResult(w http.ResponseWriter, result chatNonStreamResult, attempts int, usagePrompt string, refFileTokens int, historySession *chatHistorySession) {
-	if result.detectedCalls == 0 && shouldWriteUpstreamEmptyOutputError(result.text, result.thinking) {
+	if result.detectedCalls == 0 && strings.TrimSpace(result.text) == "" {
 		status, message, code := upstreamEmptyOutputDetail(result.contentFilter, result.text, result.thinking)
+		if result.outputError != nil {
+			status, message, code = result.outputError.Status, result.outputError.Message, result.outputError.Code
+		}
 		if historySession != nil {
 			historySession.error(status, message, code, result.thinking, result.text)
 		}
-		writeUpstreamEmptyOutputError(w, result.text, result.thinking, result.contentFilter)
+		writeOpenAIErrorWithCode(w, status, message, code)
 		config.Logger.Info("[openai_empty_retry] terminal empty output", "surface", "chat.completions", "stream", false, "retry_attempts", attempts, "success_source", "none", "content_filter", result.contentFilter)
 		return
 	}
@@ -147,8 +155,8 @@ func shouldRetryChatNonStream(result chatNonStreamResult, attempts int) bool {
 		strings.TrimSpace(result.thinking) == ""
 }
 
-func (h *Handler) handleStreamWithRetry(w http.ResponseWriter, r *http.Request, a *auth.RequestAuth, resp *http.Response, payload map[string]any, pow, completionID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, historySession *chatHistorySession) {
-	streamRuntime, initialType, ok := h.prepareChatStreamRuntime(w, resp, completionID, model, finalPrompt, refFileTokens, thinkingEnabled, searchEnabled, toolNames, toolsRaw, historySession)
+func (h *Handler) handleStreamWithRetry(w http.ResponseWriter, r *http.Request, a *auth.RequestAuth, resp *http.Response, payload map[string]any, pow, completionID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, toolChoice promptcompat.ToolChoicePolicy, historySession *chatHistorySession) {
+	streamRuntime, initialType, ok := h.prepareChatStreamRuntime(w, resp, completionID, model, finalPrompt, refFileTokens, thinkingEnabled, searchEnabled, toolNames, toolsRaw, toolChoice, historySession)
 	if !ok {
 		return
 	}
@@ -190,7 +198,7 @@ func (h *Handler) handleStreamWithRetry(w http.ResponseWriter, r *http.Request,
 	}
 }
 
-func (h *Handler) prepareChatStreamRuntime(w http.ResponseWriter, resp *http.Response, completionID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, historySession *chatHistorySession) (*chatStreamRuntime, string, bool) {
+func (h *Handler) prepareChatStreamRuntime(w http.ResponseWriter, resp *http.Response, completionID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, toolChoice promptcompat.ToolChoicePolicy, historySession *chatHistorySession) (*chatStreamRuntime, string, bool) {
 	if resp.StatusCode != http.StatusOK {
 		defer func() { _ = resp.Body.Close() }()
 		body, _ := io.ReadAll(resp.Body)
@@ -216,6 +224,7 @@ func (h *Handler) prepareChatStreamRuntime(w http.ResponseWriter, resp *http.Res
 	streamRuntime := newChatStreamRuntime(
 		w, rc, canFlush, completionID, time.Now().Unix(), model, finalPrompt,
 		thinkingEnabled, searchEnabled, h.compatStripReferenceMarkers(), toolNames, toolsRaw,
+		toolChoice,
 		len(toolNames) > 0, h.toolcallFeatureMatchEnabled() && h.toolcallEarlyEmitHighConfidence(),
 	)
 	streamRuntime.refFileTokens = refFileTokens

internal/httpapi/openai/chat/empty_retry_runtime_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"ds2api/internal/chathistory"
+	"ds2api/internal/promptcompat"
 	"ds2api/internal/stream"
 )
 
@@ -48,6 +49,7 @@ func TestConsumeChatStreamAttemptMarksContextCancelledState(t *testing.T) {
 		true,
 		nil,
 		nil,
+		promptcompat.DefaultToolChoicePolicy(),
 		false,
 		false,
 	)

internal/httpapi/openai/chat/handler.go

@@ -80,6 +80,10 @@ func writeOpenAIError(w http.ResponseWriter, status int, message string) {
 	shared.WriteOpenAIError(w, status, message)
 }
 
+func writeOpenAIErrorWithCode(w http.ResponseWriter, status int, message, code string) {
+	shared.WriteOpenAIErrorWithCode(w, status, message, code)
+}
+
 func openAIErrorType(status int) string {
 	return shared.OpenAIErrorType(status)
 }

internal/httpapi/openai/chat/handler_chat.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"ds2api/internal/auth"
+	"ds2api/internal/completionruntime"
 	"ds2api/internal/config"
 	dsprotocol "ds2api/internal/deepseek/protocol"
 	openaifmt "ds2api/internal/format/openai"
@@ -76,44 +77,40 @@ func (h *Handler) ChatCompletions(w http.ResponseWriter, r *http.Request) {
 	}
 	historySession := startChatHistory(h.ChatHistory, r, a, stdReq)
 
-	sessionID, err = h.DS.CreateSession(r.Context(), a, 3)
-	if err != nil {
-		if a.UseConfigToken {
+	if !stdReq.Stream {
+		result, outErr := completionruntime.ExecuteNonStreamWithRetry(r.Context(), h.DS, a, stdReq, completionruntime.Options{
+			StripReferenceMarkers: h.compatStripReferenceMarkers(),
+			RetryEnabled:          true,
+		})
+		sessionID = result.SessionID
+		if outErr != nil {
 			if historySession != nil {
-				historySession.error(http.StatusUnauthorized, "Account token is invalid. Please re-login the account in admin.", "error", "", "")
+				historySession.error(outErr.Status, outErr.Message, outErr.Code, result.Turn.Thinking, result.Turn.Text)
 			}
-			writeOpenAIError(w, http.StatusUnauthorized, "Account token is invalid. Please re-login the account in admin.")
-		} else {
-			if historySession != nil {
-				historySession.error(http.StatusUnauthorized, "Invalid token. If this should be a DS2API key, add it to config.keys first.", "error", "", "")
-			}
-			writeOpenAIError(w, http.StatusUnauthorized, "Invalid token. If this should be a DS2API key, add it to config.keys first.")
+			writeOpenAIErrorWithCode(w, outErr.Status, outErr.Message, outErr.Code)
+			return
 		}
+		respBody := openaifmt.BuildChatCompletionWithToolCalls(result.SessionID, stdReq.ResponseModel, result.Turn.Prompt, result.Turn.Thinking, result.Turn.Text, result.Turn.ToolCalls, stdReq.ToolsRaw)
+		respBody["usage"] = chatUsageFromTurn(result.Turn)
+		finishReason := chatFinishReason(respBody)
+		if historySession != nil {
+			historySession.success(http.StatusOK, result.Turn.Thinking, result.Turn.Text, finishReason, chatUsageFromTurn(result.Turn))
+		}
+		writeJSON(w, http.StatusOK, respBody)
 		return
 	}
-	pow, err := h.DS.GetPow(r.Context(), a, 3)
-	if err != nil {
+
+	start, outErr := completionruntime.StartCompletion(r.Context(), h.DS, a, stdReq, completionruntime.Options{})
+	sessionID = start.SessionID
+	if outErr != nil {
 		if historySession != nil {
-			historySession.error(http.StatusUnauthorized, "Failed to get PoW (invalid token or unknown error).", "error", "", "")
+			historySession.error(outErr.Status, outErr.Message, outErr.Code, "", "")
 		}
-		writeOpenAIError(w, http.StatusUnauthorized, "Failed to get PoW (invalid token or unknown error).")
-		return
-	}
-	payload := stdReq.CompletionPayload(sessionID)
-	resp, err := h.DS.CallCompletion(r.Context(), a, payload, pow, 3)
-	if err != nil {
-		if historySession != nil {
-			historySession.error(http.StatusInternalServerError, "Failed to get completion.", "error", "", "")
-		}
-		writeOpenAIError(w, http.StatusInternalServerError, "Failed to get completion.")
+		writeOpenAIErrorWithCode(w, outErr.Status, outErr.Message, outErr.Code)
 		return
 	}
 	refFileTokens := stdReq.RefFileTokens
-	if stdReq.Stream {
-		h.handleStreamWithRetry(w, r, a, resp, payload, pow, sessionID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, historySession)
-		return
-	}
-	h.handleNonStreamWithRetry(w, r.Context(), a, resp, payload, pow, sessionID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, historySession)
+	h.handleStreamWithRetry(w, r, a, start.Response, start.Payload, start.Pow, sessionID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, stdReq.ToolChoice, historySession)
 }
 
 func (h *Handler) autoDeleteRemoteSession(ctx context.Context, a *auth.RequestAuth, sessionID string) {
@@ -234,6 +231,7 @@ func (h *Handler) handleStream(w http.ResponseWriter, r *http.Request, resp *htt
 		stripReferenceMarkers,
 		toolNames,
 		toolsRaw,
+		promptcompat.DefaultToolChoicePolicy(),
 		bufferToolContent,
 		emitEarlyToolDeltas,
 	)

internal/httpapi/openai/responses/empty_retry_runtime.go

@@ -1,7 +1,6 @@
 package responses
 
 import (
-	"context"
 	"io"
 	"net/http"
 	"strings"
@@ -10,129 +9,10 @@ import (
 	"ds2api/internal/auth"
 	"ds2api/internal/config"
 	dsprotocol "ds2api/internal/deepseek/protocol"
-	openaifmt "ds2api/internal/format/openai"
 	"ds2api/internal/promptcompat"
-	"ds2api/internal/sse"
 	streamengine "ds2api/internal/stream"
-	"ds2api/internal/toolcall"
 )
 
-type responsesNonStreamResult struct {
-	rawThinking           string
-	rawText               string
-	thinking              string
-	toolDetectionThinking string
-	text                  string
-	contentFilter         bool
-	parsed                toolcall.ToolCallParseResult
-	body                  map[string]any
-	responseMessageID     int
-}
-
-func (h *Handler) handleResponsesNonStreamWithRetry(w http.ResponseWriter, ctx context.Context, a *auth.RequestAuth, resp *http.Response, payload map[string]any, pow, owner, responseID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, toolChoice promptcompat.ToolChoicePolicy, traceID string) {
-	attempts := 0
-	currentResp := resp
-	usagePrompt := finalPrompt
-	accumulatedThinking := ""
-	accumulatedRawThinking := ""
-	accumulatedToolDetectionThinking := ""
-	for {
-		result, ok := h.collectResponsesNonStreamAttempt(w, currentResp, responseID, model, usagePrompt, thinkingEnabled, searchEnabled, toolNames, toolsRaw)
-		if !ok {
-			return
-		}
-		accumulatedThinking += sse.TrimContinuationOverlap(accumulatedThinking, result.thinking)
-		accumulatedRawThinking += sse.TrimContinuationOverlap(accumulatedRawThinking, result.rawThinking)
-		accumulatedToolDetectionThinking += sse.TrimContinuationOverlap(accumulatedToolDetectionThinking, result.toolDetectionThinking)
-		result.thinking = accumulatedThinking
-		result.rawThinking = accumulatedRawThinking
-		result.toolDetectionThinking = accumulatedToolDetectionThinking
-		result.parsed = detectAssistantToolCalls(result.rawText, result.text, result.rawThinking, result.toolDetectionThinking, toolNames)
-		result.body = openaifmt.BuildResponseObjectWithToolCalls(responseID, model, usagePrompt, result.thinking, result.text, result.parsed.Calls, toolsRaw)
-		if refFileTokens > 0 {
-			addRefFileTokensToUsage(result.body, refFileTokens)
-		}
-
-		if !shouldRetryResponsesNonStream(result, attempts) {
-			h.finishResponsesNonStreamResult(w, result, attempts, owner, responseID, toolChoice, traceID)
-			return
-		}
-
-		attempts++
-		config.Logger.Info("[openai_empty_retry] attempting synthetic retry", "surface", "responses", "stream", false, "retry_attempt", attempts, "parent_message_id", result.responseMessageID)
-		retryPow, powErr := h.DS.GetPow(ctx, a, 3)
-		if powErr != nil {
-			config.Logger.Warn("[openai_empty_retry] retry PoW fetch failed, falling back to original PoW", "surface", "responses", "stream", false, "retry_attempt", attempts, "error", powErr)
-			retryPow = pow
-		}
-		nextResp, err := h.DS.CallCompletion(ctx, a, clonePayloadForEmptyOutputRetry(payload, result.responseMessageID), retryPow, 3)
-		if err != nil {
-			writeOpenAIError(w, http.StatusInternalServerError, "Failed to get completion.")
-			config.Logger.Warn("[openai_empty_retry] retry request failed", "surface", "responses", "stream", false, "retry_attempt", attempts, "error", err)
-			return
-		}
-		usagePrompt = usagePromptWithEmptyOutputRetry(usagePrompt, attempts)
-		currentResp = nextResp
-	}
-}
-
-func (h *Handler) collectResponsesNonStreamAttempt(w http.ResponseWriter, resp *http.Response, responseID, model, usagePrompt string, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any) (responsesNonStreamResult, bool) {
-	defer func() { _ = resp.Body.Close() }()
-	if resp.StatusCode != http.StatusOK {
-		body, _ := io.ReadAll(resp.Body)
-		writeOpenAIError(w, resp.StatusCode, strings.TrimSpace(string(body)))
-		return responsesNonStreamResult{}, false
-	}
-	result := sse.CollectStream(resp, thinkingEnabled, false)
-	stripReferenceMarkers := h.compatStripReferenceMarkers()
-	sanitizedThinking := cleanVisibleOutput(result.Thinking, stripReferenceMarkers)
-	sanitizedText := cleanVisibleOutput(result.Text, stripReferenceMarkers)
-	if searchEnabled {
-		sanitizedText = replaceCitationMarkersWithLinks(sanitizedText, result.CitationLinks)
-	}
-	textParsed := detectAssistantToolCalls(result.Text, sanitizedText, result.Thinking, result.ToolDetectionThinking, toolNames)
-	responseObj := openaifmt.BuildResponseObjectWithToolCalls(responseID, model, usagePrompt, sanitizedThinking, sanitizedText, textParsed.Calls, toolsRaw)
-	return responsesNonStreamResult{
-		rawThinking:           result.Thinking,
-		rawText:               result.Text,
-		thinking:              sanitizedThinking,
-		toolDetectionThinking: result.ToolDetectionThinking,
-		text:                  sanitizedText,
-		contentFilter:         result.ContentFilter,
-		parsed:                textParsed,
-		body:                  responseObj,
-		responseMessageID:     result.ResponseMessageID,
-	}, true
-}
-
-func (h *Handler) finishResponsesNonStreamResult(w http.ResponseWriter, result responsesNonStreamResult, attempts int, owner, responseID string, toolChoice promptcompat.ToolChoicePolicy, traceID string) {
-	if len(result.parsed.Calls) == 0 && writeUpstreamEmptyOutputError(w, result.text, result.thinking, result.contentFilter) {
-		config.Logger.Info("[openai_empty_retry] terminal empty output", "surface", "responses", "stream", false, "retry_attempts", attempts, "success_source", "none", "content_filter", result.contentFilter)
-		return
-	}
-	logResponsesToolPolicyRejection(traceID, toolChoice, result.parsed, "text")
-	if toolChoice.IsRequired() && len(result.parsed.Calls) == 0 {
-		writeOpenAIErrorWithCode(w, http.StatusUnprocessableEntity, "tool_choice requires at least one valid tool call.", "tool_choice_violation")
-		return
-	}
-	h.getResponseStore().put(owner, responseID, result.body)
-	writeJSON(w, http.StatusOK, result.body)
-	source := "first_attempt"
-	if attempts > 0 {
-		source = "synthetic_retry"
-	}
-	config.Logger.Info("[openai_empty_retry] completed", "surface", "responses", "stream", false, "retry_attempts", attempts, "success_source", source)
-}
-
-func shouldRetryResponsesNonStream(result responsesNonStreamResult, attempts int) bool {
-	return emptyOutputRetryEnabled() &&
-		attempts < emptyOutputRetryMaxAttempts() &&
-		!result.contentFilter &&
-		len(result.parsed.Calls) == 0 &&
-		strings.TrimSpace(result.text) == "" &&
-		strings.TrimSpace(result.thinking) == ""
-}
-
 func (h *Handler) handleResponsesStreamWithRetry(w http.ResponseWriter, r *http.Request, a *auth.RequestAuth, resp *http.Response, payload map[string]any, pow, owner, responseID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, toolChoice promptcompat.ToolChoicePolicy, traceID string) {
 	streamRuntime, initialType, ok := h.prepareResponsesStreamRuntime(w, resp, owner, responseID, model, finalPrompt, refFileTokens, thinkingEnabled, searchEnabled, toolNames, toolsRaw, toolChoice, traceID)
 	if !ok {

internal/httpapi/openai/responses/responses_handler.go

@@ -12,6 +12,7 @@ import (
 	"github.com/google/uuid"
 
 	"ds2api/internal/auth"
+	"ds2api/internal/completionruntime"
 	"ds2api/internal/config"
 	dsprotocol "ds2api/internal/deepseek/protocol"
 	openaifmt "ds2api/internal/format/openai"
@@ -92,34 +93,31 @@ func (h *Handler) Responses(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sessionID, err := h.DS.CreateSession(r.Context(), a, 3)
-	if err != nil {
-		if a.UseConfigToken {
-			writeOpenAIError(w, http.StatusUnauthorized, "Account token is invalid. Please re-login the account in admin.")
-		} else {
-			writeOpenAIError(w, http.StatusUnauthorized, "Invalid token. If this should be a DS2API key, add it to config.keys first.")
+	responseID := "resp_" + strings.ReplaceAll(uuid.NewString(), "-", "")
+	if !stdReq.Stream {
+		result, outErr := completionruntime.ExecuteNonStreamWithRetry(r.Context(), h.DS, a, stdReq, completionruntime.Options{
+			StripReferenceMarkers: h.compatStripReferenceMarkers(),
+			RetryEnabled:          true,
+		})
+		if outErr != nil {
+			writeOpenAIErrorWithCode(w, outErr.Status, outErr.Message, outErr.Code)
+			return
 		}
-		return
-	}
-	pow, err := h.DS.GetPow(r.Context(), a, 3)
-	if err != nil {
-		writeOpenAIError(w, http.StatusUnauthorized, "Failed to get PoW (invalid token or unknown error).")
-		return
-	}
-	payload := stdReq.CompletionPayload(sessionID)
-	resp, err := h.DS.CallCompletion(r.Context(), a, payload, pow, 3)
-	if err != nil {
-		writeOpenAIError(w, http.StatusInternalServerError, "Failed to get completion.")
+		responseObj := openaifmt.BuildResponseObjectWithToolCalls(responseID, stdReq.ResponseModel, result.Turn.Prompt, result.Turn.Thinking, result.Turn.Text, result.Turn.ToolCalls, stdReq.ToolsRaw)
+		responseObj["usage"] = responsesUsageFromTurn(result.Turn)
+		h.getResponseStore().put(owner, responseID, responseObj)
+		writeJSON(w, http.StatusOK, responseObj)
 		return
 	}
 
-	responseID := "resp_" + strings.ReplaceAll(uuid.NewString(), "-", "")
-	refFileTokens := stdReq.RefFileTokens
-	if stdReq.Stream {
-		h.handleResponsesStreamWithRetry(w, r, a, resp, payload, pow, owner, responseID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, stdReq.ToolChoice, traceID)
+	start, outErr := completionruntime.StartCompletion(r.Context(), h.DS, a, stdReq, completionruntime.Options{})
+	if outErr != nil {
+		writeOpenAIErrorWithCode(w, outErr.Status, outErr.Message, outErr.Code)
 		return
 	}
-	h.handleResponsesNonStreamWithRetry(w, r.Context(), a, resp, payload, pow, owner, responseID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, stdReq.ToolChoice, traceID)
+
+	refFileTokens := stdReq.RefFileTokens
+	h.handleResponsesStreamWithRetry(w, r, a, start.Response, start.Payload, start.Pow, owner, responseID, stdReq.ResponseModel, stdReq.PromptTokenText, refFileTokens, stdReq.Thinking, stdReq.Search, stdReq.ToolNames, stdReq.ToolsRaw, stdReq.ToolChoice, traceID)
 }
 
 func (h *Handler) handleResponsesNonStream(w http.ResponseWriter, resp *http.Response, owner, responseID, model, finalPrompt string, refFileTokens int, thinkingEnabled, searchEnabled bool, toolNames []string, toolsRaw any, toolChoice promptcompat.ToolChoicePolicy, traceID string) {

internal/httpapi/openai/responses/responses_stream_runtime_core.go

@@ -1,6 +1,7 @@
 package responses
 
 import (
+	"ds2api/internal/assistantturn"
 	"ds2api/internal/toolcall"
 	"net/http"
 	"strings"
@@ -159,9 +160,29 @@ func (s *responsesStreamRuntime) finalize(finishReason string, deferEmptyOutput
 
 	finalThinking := s.accumulator.Thinking.String()
 	finalToolDetectionThinking := s.accumulator.ToolDetectionThinking.String()
-	finalText := cleanVisibleOutput(s.accumulator.Text.String(), s.stripReferenceMarkers)
-	textParsed := detectAssistantToolCalls(s.accumulator.RawText.String(), finalText, s.accumulator.RawThinking.String(), finalToolDetectionThinking, s.toolNames)
-	detected := textParsed.Calls
+	finalText := s.accumulator.Text.String()
+	turn := assistantturn.BuildTurnFromStreamSnapshot(assistantturn.StreamSnapshot{
+		RawText:               s.accumulator.RawText.String(),
+		VisibleText:           finalText,
+		RawThinking:           s.accumulator.RawThinking.String(),
+		VisibleThinking:       finalThinking,
+		DetectionThinking:     finalToolDetectionThinking,
+		ContentFilter:         finishReason == "content_filter",
+		ResponseMessageID:     s.responseMessageID,
+		AlreadyEmittedCalls:   s.toolCallsEmitted,
+		AlreadyEmittedToolRaw: s.toolCallsDoneEmitted,
+	}, assistantturn.BuildOptions{
+		Model:                 s.model,
+		Prompt:                s.finalPrompt,
+		RefFileTokens:         s.refFileTokens,
+		SearchEnabled:         s.searchEnabled,
+		StripReferenceMarkers: s.stripReferenceMarkers,
+		ToolNames:             s.toolNames,
+		ToolsRaw:              s.toolsRaw,
+		ToolChoice:            s.toolChoice,
+	})
+	textParsed := turn.ParsedToolCalls
+	detected := turn.ToolCalls
 	s.logToolPolicyRejections(textParsed)
 
 	if len(detected) > 0 {
@@ -173,12 +194,15 @@ func (s *responsesStreamRuntime) finalize(finishReason string, deferEmptyOutput
 
 	s.closeMessageItem()
 
-	if s.toolChoice.IsRequired() && len(detected) == 0 {
-		s.failResponse(http.StatusUnprocessableEntity, "tool_choice requires at least one valid tool call.", "tool_choice_violation")
+	if turn.Error != nil && turn.Error.Code == "tool_choice_violation" {
+		s.failResponse(turn.Error.Status, turn.Error.Message, turn.Error.Code)
 		return true
 	}
-	if len(detected) == 0 && strings.TrimSpace(finalText) == "" {
-		status, message, code := upstreamEmptyOutputDetail(finishReason == "content_filter", finalText, finalThinking)
+	if len(detected) == 0 && strings.TrimSpace(turn.Text) == "" {
+		status, message, code := upstreamEmptyOutputDetail(finishReason == "content_filter", turn.Text, turn.Thinking)
+		if turn.Error != nil {
+			status, message, code = turn.Error.Status, turn.Error.Message, turn.Error.Code
+		}
 		if deferEmptyOutput {
 			s.finalErrorStatus = status
 			s.finalErrorMessage = message
@@ -190,7 +214,7 @@ func (s *responsesStreamRuntime) finalize(finishReason string, deferEmptyOutput
 	}
 	s.closeIncompleteFunctionItems()
 
-	obj := s.buildCompletedResponseObject(finalThinking, finalText, detected)
+	obj := s.buildCompletedResponseObject(turn.Thinking, turn.Text, detected)
 	if s.persistResponse != nil {
 		s.persistResponse(obj)
 	}
@@ -199,6 +223,14 @@ func (s *responsesStreamRuntime) finalize(finishReason string, deferEmptyOutput
 	return true
 }
 
+func responsesUsageFromTurn(turn assistantturn.Turn) map[string]any {
+	return map[string]any{
+		"input_tokens":  turn.Usage.InputTokens,
+		"output_tokens": turn.Usage.OutputTokens,
+		"total_tokens":  turn.Usage.TotalTokens,
+	}
+}
+
 func (s *responsesStreamRuntime) logToolPolicyRejections(textParsed toolcall.ToolCallParseResult) {
 	logRejected := func(parsed toolcall.ToolCallParseResult, channel string) {
 		rejected := filteredRejectedToolNamesForLog(parsed.RejectedToolNames)