Files
ModelRouter/internal/gateway/chat.go
JianFeeeee c9c09b2ba2 fix(opencode): 采纳客户端真实会话 id + 超窗消息不再被限流措辞封杀
两处都源于同一次排查:pi 到底有没有带会话标识、超窗为什么触发不了压缩。

## 1) 客户端会话 id:pi 一直在发,只是被配置关掉了

之前结论是「通用客户端不发会话 id」——只对了一半。pi 有会话 id,且能发:
pi-ai 的 createClient 在 compat.sendSessionAffinityHeaders 为真时,会把
平台会话 id(uuidv7,整个会话恒定)放到 x-session-affinity /
x-client-request-id / session_id 上。该开关默认 false,而 llmsproxy 的
provider 配置里没开,所以此前一直收不到。

现在网关按优先级采纳:x-session-affinity → x-session-id → session_id →
body 的 prompt_cache_key,并把值经 types.ChatRequest.ClientSession 传到
适配器 meta.client_session。适配器的会号种子优先级变为:
客户端会话 id > 首条 user 消息指纹 > 按源固定。

刻意不采纳 x-client-request-id:名字含 request,部分客户端每请求都换,
拿它当会话会让上游前缀缓存永不命中(pi 总会同时发 x-session-affinity,够用)。

实测:抓 127.0.0.1:8081 的真实 pi 请求,配置打开后收到
x-session-affinity = session_id = x-client-request-id = <子会话 uuid>。
上游缓存确为会话级隔离(同前缀、不同会号:A 冷→命中,B 首次仍为 0),
两个不同 header 值互不命中,反证网关确实采纳了客户端会话 id。

## 2) 超窗消息必须「干净」,否则被同链的限流措辞反向封杀

pi 的 isContextOverflow 先查 NON_OVERFLOW_PATTERNS(/rate limit/、
/too many requests/、Bedrock 前缀),命中就直接判为「非超窗」——**即使
消息里已经有 context_length_exceeded**,pi 也不会压缩重试。

而 AUTO 链的失败消息天生是多 tier 原因的拼接,超窗 tier(gozen 400
maximum context length)常与配额/限流 tier(429 token plan exhausted、
cooling、no free slot)同时出现。此前把 tier 明细原样拼在归一化标记后面,
等于让一条限流 tier 的措辞反过来封杀超窗识别。

现在超窗走独立的干净消息:
  context_length_exceeded: context window is full; reduce the length of
  the messages (gozen/deepseek-v4.1-flash)
只留超窗措辞 + 超窗源名,不带任何其它 tier 的文本。

测试:TestOverflowMessageSurvivesRateLimitedSiblingTier 用 pi 的完整判定
顺序(先 NON_OVERFLOW 后 OVERFLOW)断言同链限流 tier 不再封杀超窗识别;
TestClientSessionFromRequestHeaders / TestClientRequestIDIsNotUsedAsSession /
TestOpenCodePrefersClientSessionID 覆盖会话采纳与优先级。
2026-09-11 16:54:31 +08:00

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package gateway
import (
"context"
"encoding/json"
"errors"
"fmt"
"log"
"net/http"
"regexp"
"strings"
"sync/atomic"
"time"
"llmsproxy/internal/config"
"llmsproxy/internal/provider"
"llmsproxy/internal/scheduler"
"llmsproxy/internal/types"
)
// chatRequest mirrors the OpenAI chat completions request the gateway accepts.
type chatRequest struct {
Model string `json:"model"`
Messages []types.ChatMessage `json:"messages"`
Temperature *float64 `json:"temperature,omitempty"`
MaxTokens int `json:"max_tokens,omitempty"`
Stream bool `json:"stream,omitempty"`
Tools []interface{} `json:"tools,omitempty"`
ToolChoice interface{} `json:"tool_choice,omitempty"`
DisableThinking bool `json:"disable_thinking"`
ExtraBody map[string]interface{} `json:"extra_body,omitempty"`
// PromptCacheKey 是 OpenAI 原生的缓存键;部分客户端用它携带会话标识。
PromptCacheKey string `json:"prompt_cache_key,omitempty"`
}
// ChatCompletion is the non-streaming OpenAI response object.
type ChatCompletion struct {
ID string `json:"id"`
Object string `json:"object"`
Created int64 `json:"created"`
Model string `json:"model"`
Choices []ChatChoice `json:"choices"`
Usage *types.TokenUsage `json:"usage,omitempty"`
}
type ChatChoice struct {
Index int `json:"index"`
Message RespMessage `json:"message"`
FinishReason string `json:"finish_reason"`
}
type RespMessage struct {
Role string `json:"role,omitempty"`
Content string `json:"content"`
ReasoningContent string `json:"reasoning_content,omitempty"`
ToolCalls json.RawMessage `json:"tool_calls,omitempty"`
}
type ChatChunk struct {
ID string `json:"id"`
Object string `json:"object"`
Created int64 `json:"created"`
Model string `json:"model"`
Choices []ChunkChoice `json:"choices"`
// Usage is sent in the final chunk of a stream (empty choices) so
// OpenAI-compatible clients can read token usage.
Usage *types.TokenUsage `json:"usage,omitempty"`
}
type ChunkChoice struct {
Index int `json:"index"`
Delta RespMessage `json:"delta"`
FinishReason *string `json:"finish_reason"`
}
var seq int64
func newID() string {
n := atomic.AddInt64(&seq, 1)
return fmt.Sprintf("chatcmpl-%d", n)
}
func isAuto(m string) bool {
m = strings.TrimSpace(m)
return m == "" || strings.EqualFold(m, "AUTO")
}
// resolveCands picks the ordered candidate providers for a requested model.
// toolCalling requests are anchored: they resolve to exactly one provider
// (highest-priority available) so a tool-call round never switches models.
func (g *Gateway) resolveCands(ctx context.Context, req *chatRequest) ([]*provider.Provider, string) {
model := req.Model
if model == "" {
model = g.core.DefaultModel()
}
cands, effective := g.resolveByModel(model)
cands = chatOnly(cands)
allow := g.allowedModels(ctx)
if allow != nil {
cands = filterCandsByModels(cands, allow)
}
if !toolRequest(req) {
return cands, effective
}
// tool-call request: pin to one provider (no AUTO fallback across models)
if len(cands) == 0 {
return nil, effective
}
first := cands[0]
// use the prefix-stripped id (effective), never the raw "src:model" form:
// ModelFor does exact matching and would fall back to the source's best
// chat model for an unknown id
eff := first.ModelFor(effective)
if eff == "" {
eff = firstModel(first)
}
return []*provider.Provider{first}, eff
}
// filterCandsByModels keeps only providers exposing at least one model of the
// scope (used for user keys with a restricted model scope). Scope entries with
// a Source pinned to a specific upstream narrow the candidates to that source
// for the matching model.
//
// An "AUTO" scope entry only allows the AUTO routing mode; it does NOT grant
// access to specific models.
func filterCandsByModels(cands []*provider.Provider, allow []config.ModelScope) []*provider.Provider {
for _, m := range allow {
if m.Model == "" {
return cands
}
}
allowed := make(map[string]bool, len(allow))
byModelSrc := map[string]map[string]bool{}
for _, m := range allow {
allowed[m.Model] = true
if m.Source != "" {
if byModelSrc[m.Model] == nil {
byModelSrc[m.Model] = map[string]bool{}
}
byModelSrc[m.Model][m.Source] = true
}
}
out := make([]*provider.Provider, 0, len(cands))
for _, p := range cands {
for _, id := range p.Models() {
if !allowed[id] {
continue
}
if srcs := byModelSrc[id]; len(srcs) > 0 && !srcs[p.Name()] {
continue
}
out = append(out, p)
break
}
}
return out
}
// intersectModels restricts a model list to the scope (preserving order).
// An "AUTO" scope entry only allows the AUTO routing mode; it does NOT grant
// every model.
func intersectModels(models []string, allow []config.ModelScope) []string {
allowed := make(map[string]bool, len(allow))
for _, m := range allow {
if m.Model == "" {
return models
}
if !strings.EqualFold(m.Model, "AUTO") {
allowed[m.Model] = true
}
}
out := make([]string, 0, len(models))
seen := map[string]bool{}
for _, m := range models {
if allowed[m] && !seen[m] {
seen[m] = true
out = append(out, m)
}
}
return out
}
// checkModelScope validates the effective model against the key's model scope
// and token quota. Returns an error message when rejected.
//
// A scope entry with model "AUTO" only allows requests where the effective
// model is AUTO (the routing mode). It does NOT grant access to specific model
// ids — that requires an explicit scope entry for the model.
func (g *Gateway) checkModelScope(ctx context.Context, model string) string {
allow := g.allowedModels(ctx)
if allow == nil {
return ""
}
for _, sc := range allow {
if sc.Model != model {
continue
}
if sc.TokenQuota > 0 {
used := g.scopeTokens(ctx, sc)
if used >= sc.TokenQuota {
return fmt.Sprintf("token quota exceeded for %q (%d/%d)", model, used, sc.TokenQuota)
}
}
return ""
}
return fmt.Sprintf("model %q is not allowed for this key", model)
}
// scopeTokens returns the tokens a scope entry has consumed within its reset
// window (total for AUTO / per model otherwise).
func (g *Gateway) scopeTokens(ctx context.Context, sc config.ModelScope) int64 {
k := keyID(reqKey(ctx))
if sc.Model != "" && strings.EqualFold(sc.Model, "AUTO") {
return g.stats.KeyTokens(k)
}
win := AutoPeriodSeconds(sc.Period, sc.Hours)
return g.stats.WindowTokens(sc.Model, sc.Source, win)
}
// hasScopeModel reports whether a model (possibly with a "source-model" /
// "source:model" / "source/model" pinning prefix) is allowed by a key's model
// scope. The prefix is stripped strictly: only when the prefix names a real
// source that actually serves the bare model (via Registry.EffectiveModel), so
// model ids that themselves contain separators (e.g. "deepseek-v4-flash-free")
// are never corrupted (P10-2).
//
// A scope entry with model "AUTO" only matches the literal AUTO routing mode;
// it does NOT grant access to specific model ids.
func (g *Gateway) hasScopeModel(list []config.ModelScope, s string) bool {
if r := g.core.Registry(); r != nil {
s = r.EffectiveModel(s)
}
for _, x := range list {
if x.Model == s {
return true
}
}
return false
}
func (g *Gateway) resolveByModel(model string) ([]*provider.Provider, string) {
if isAuto(model) {
return g.core.Registry().Resolve("AUTO"), ""
}
return g.core.Registry().Resolve(model), g.core.Registry().EffectiveModel(model)
}
// chatOnly keeps providers that expose at least one chat-capable model, so a
// chat/AUTO request never lands on an image-only source (or borrows its image
// model id). Explicit image-kind requests stay on the imageOnly path.
func chatOnly(cands []*provider.Provider) []*provider.Provider {
out := make([]*provider.Provider, 0, len(cands))
for _, p := range cands {
for _, id := range p.Models() {
if m := p.ModelByID(id); m == nil || m.Kind != "image" {
out = append(out, p)
break
}
}
}
return out
}
// toolRequest reports whether the request participates in a tool-call round.
func toolRequest(req *chatRequest) bool {
if len(req.Tools) > 0 || req.ToolChoice != nil {
return true
}
for _, m := range req.Messages {
if m.Role == "tool" || len(m.ToolCalls) > 0 {
return true
}
}
return false
}
func (g *Gateway) handleChat(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "use POST")
return
}
var req chatRequest
if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
return
}
// 客户端自带的会话标识(若有)比推导出来的更准,见 clientSessionFromRequest。
clientSession := clientSessionFromRequest(r, req.PromptCacheKey)
if len(req.Messages) == 0 {
writeError(w, http.StatusBadRequest, "invalid_request", "messages is required")
return
}
model := req.Model
if model == "" {
model = g.core.DefaultModel()
}
if isAuto(model) {
chain := g.core.AutoChain()
if chain == nil || len(chain.Tiers) == 0 {
writeError(w, http.StatusServiceUnavailable, "no_provider", "no auto slot configured")
return
}
if msg := g.checkModelScope(r.Context(), "AUTO"); msg != "" {
writeError(w, http.StatusForbidden, "model_not_allowed", msg)
return
}
ctx := r.Context()
done := g.stats.Begin()
defer done()
inner := &types.ChatRequest{
Messages: req.Messages,
Temperature: req.Temperature,
MaxTokens: req.MaxTokens,
Stream: req.Stream,
Tools: req.Tools,
ToolChoice: req.ToolChoice,
DisableThinking: req.DisableThinking,
ExtraBody: req.ExtraBody,
ClientSession: clientSession,
}
rec := &Req{
Key: keyID(reqKey(ctx)),
Type: "chat",
OK: false,
}
// quotaExhausted reports a slot whose token window has been used up;
// exhausted slots are dropped from scheduling without penalty.
quotaExhausted := func(sl *scheduler.Slot) bool {
if sl.Quota <= 0 {
return false
}
win := AutoPeriodSeconds(sl.Period, sl.Hours)
return g.stats.WindowTokens(sl.Model, sl.Source, win) >= sl.Quota
}
if req.Stream {
rec.Type = "stream"
g.streamChatAuto(w, ctx, chain, inner, rec, quotaExhausted)
return
}
g.singleChatAuto(w, ctx, chain, inner, rec, quotaExhausted)
return
}
if !isAuto(model) {
if allow := g.allowedModels(r.Context()); allow != nil && !g.hasScopeModel(allow, model) {
writeError(w, http.StatusForbidden, "model_not_allowed", fmt.Sprintf("model %q is not allowed for this key", model))
return
}
}
cands, effective := g.resolveCands(r.Context(), &req)
if len(cands) == 0 {
writeError(w, http.StatusNotFound, "model_not_found", fmt.Sprintf("model %q is not configured", model))
return
}
if effective == "" {
effective = firstModel(cands[0])
}
if msg := g.checkModelScope(r.Context(), effective); msg != "" {
writeError(w, http.StatusForbidden, "model_not_allowed", msg)
return
}
ctx := r.Context()
done := g.stats.Begin()
defer done()
inner := &types.ChatRequest{
Model: effective,
Messages: req.Messages,
Temperature: req.Temperature,
MaxTokens: req.MaxTokens,
Stream: req.Stream,
Tools: req.Tools,
ToolChoice: req.ToolChoice,
DisableThinking: req.DisableThinking,
ExtraBody: req.ExtraBody,
ClientSession: clientSession,
}
rec := &Req{
Key: keyID(reqKey(ctx)),
Type: "chat",
Model: effective,
Source: firstSource(cands),
OK: false,
}
if req.Stream {
rec.Type = "stream"
g.streamChat(w, ctx, cands, inner, effective, rec)
return
}
g.singleChat(w, ctx, cands, inner, effective, rec)
}
func firstModel(p *provider.Provider) string {
ms := p.Models()
if len(ms) > 0 {
return ms[0]
}
return "auto"
}
// imageOnly keeps providers exposing at least one image-kind model.
func imageOnly(cands []*provider.Provider) []*provider.Provider {
var out []*provider.Provider
for _, p := range cands {
for _, id := range p.Models() {
if m := p.ModelByID(id); m != nil && m.Kind == "image" {
out = append(out, p)
break
}
}
}
return out
}
// toolCallsWire converts unified tool calls to the OpenAI wire format:
// tool_calls:[{id,type,function:{name,arguments:StringJSON}}]. Clients expect
// arguments to be a JSON string, not an object.
func toolCallsWire(tcs []types.ToolCall) json.RawMessage {
wire := make([]map[string]interface{}, 0, len(tcs))
for _, tc := range tcs {
args := "{}"
if tc.Arguments != nil {
if b, err := json.Marshal(tc.Arguments); err == nil {
args = string(b)
}
}
wire = append(wire, map[string]interface{}{
"id": tc.ID,
"type": tc.Type,
"function": map[string]interface{}{
"name": tc.Name,
"arguments": args,
},
})
}
b, _ := json.Marshal(wire)
return b
}
func firstSource(cands []*provider.Provider) string {
if len(cands) > 0 {
return cands[0].Name()
}
return ""
}
// effectiveImageModel picks the image model id that will actually be used so
// quota checks can target it (AUTO resolves to the first image candidate).
func effectiveImageModel(model string, cands []*provider.Provider) string {
if !isAuto(model) && model != "" {
return model
}
if len(cands) > 0 {
for _, id := range cands[0].Models() {
if m := cands[0].ModelByID(id); m != nil && m.Kind == "image" {
return id
}
}
}
return model
}
func estimatePromptTokens(req *types.ChatRequest) int64 {
if req == nil {
return 0
}
b, _ := json.Marshal(struct {
Messages []types.ChatMessage `json:"messages"`
Tools []interface{} `json:"tools,omitempty"`
}{Messages: req.Messages, Tools: req.Tools})
if len(b) == 0 {
return 0
}
return int64(len(b)/3 + 1)
}
func estimateTextTokens(parts ...interface{}) int64 {
var n int
for _, p := range parts {
switch v := p.(type) {
case string:
n += len(v)
case json.RawMessage:
n += len(v)
case []types.ToolCall:
b, _ := json.Marshal(v)
n += len(b)
}
}
if n == 0 {
return 0
}
return int64(n/3 + 1)
}
// toScheduler adapts concrete providers to the scheduler.Provider interface.
// It lives here (not in the scheduler package) so scheduler tests do not pull
// in the provider package and with it the Lua runtime's link requirements.
func toScheduler(cands []*provider.Provider) []scheduler.Provider {
out := make([]scheduler.Provider, len(cands))
for i, p := range cands {
out[i] = p
}
return out
}
// upstreamErrStatus maps a scheduling error to its HTTP status: a failed
// AUTO chain answers 503 with its per-tier summary, a busy source (every
// concurrency slot in use) is a transient capacity condition answered with
// 429 so clients fail fast, while other upstream failures stay 502.
func upstreamErrStatus(err error) int {
var ce *scheduler.ChainErr
if errors.As(err, &ce) {
return http.StatusServiceUnavailable
}
if errors.Is(err, provider.ErrBusy) {
return http.StatusTooManyRequests
}
return http.StatusBadGateway
}
// overflowMarkers 匹配上游「上下文超窗」类措辞。
//
// 上游写法五花八门,且**不在 pi 客户端的识别列表里**。pi 靠
// @earendil-works/pi-ai 的 OVERFLOW_PATTERNS 判断超窗并据此触发压缩重试,
// 而 justworker 返回的是「请精简对话历史…(Context window is full…)」——
// 与那 25 条正则一条都不匹配,于是 pi 既不压缩也不重试,只把它当成一条
// 普通上游错误。这里把可识别的超窗措辞归一化成 pi 一定认得的标记。
var overflowMarkers = []*regexp.Regexp{
regexp.MustCompile(`(?i)context[ _-]?window is full`),
regexp.MustCompile(`(?i)context[_ ]length[_ ]exceeded`),
regexp.MustCompile(`(?i)exceeds? the context window`),
regexp.MustCompile(`(?i)maximum context length`),
regexp.MustCompile(`(?i)reduce the length of the messages`),
regexp.MustCompile(`(?i)too many tokens`),
regexp.MustCompile(`(?i)token limit exceeded`),
regexp.MustCompile(`请精简对话历史`),
regexp.MustCompile(`上下文(长度)?超(出|限)`),
regexp.MustCompile(`对话历史过长`),
}
// overflowCanonical 命中 pi 的 /context[_ ]length[_ ]exceeded/i。
//
// 注意这个前缀只是必要条件不是充分条件——pi 还会先用
// NON_OVERFLOW_PATTERNS 排除整条消息,见 overflowClientMessage。
const overflowCanonical = "context_length_exceeded"
// looksLikeOverflow 判断错误文本是否属于上下文超窗。
func looksLikeOverflow(s string) bool {
for _, re := range overflowMarkers {
if re.MatchString(s) {
return true
}
}
return false
}
// clientUpstreamErr collapses upstream failure details into a short message
// for the client: per-tier bodies (WAF HTML pages, quota payloads, ...) stay
// in rec.Err / the stats API and the server log instead of the response.
// Per-tier one-line reasons are kept (quota/cooling skips carry no error body
// and are the actionable part); each is capped so HTML dumps can't leak.
//
// 超窗会被归一化成「干净」的 overflowCanonical 消息,见 overflowClientMessage。
func clientUpstreamErr(err error) string {
log.Printf("[gateway] upstream failure surfaced to client: %v", err)
if looksLikeOverflow(err.Error()) {
return overflowClientMessage(err)
}
return upstreamErrSummary(err)
}
// overflowHint 是给客户端的超窗说明,刻意只用 pi 认得的措辞。
const overflowHint = "context window is full; reduce the length of the messages"
// clientSessionFromRequest 取客户端自带的会话标识,拿不到时返回 ""。
//
// 通用 OpenAI 客户端默认不带会话 id但 pi 支持:只要 provider 的 compat 里打开
// sendSessionAffinityHeaderspi 就会把**平台真实的会话 id**uuidv7整个会话
// 恒定)放到 x-session-affinity / x-client-request-id 上sessionAffinityFormat
// 为 openrouter 时是 x-session-id为 openai 时是 session_id
// 有了它就不必再从首条 user 消息推导会话指纹(那只在客户端不发会话 id 时才作为
// 退路且历史压缩后会漂移。prompt_cache_key 是 OpenAI 原生的缓存键,
// 客户端若带也一并当会话用。
//
// 刻意不采纳 x-client-request-id名字含 request部分客户端每请求都换
// 拿它当会话会让上游缓存永不命中。pi 总会同时发 x-session-affinity够用。
func clientSessionFromRequest(r *http.Request, bodyKey string) string {
for _, h := range []string{"X-Session-Affinity", "X-Session-Id", "Session-Id"} {
if v := strings.TrimSpace(r.Header.Get(h)); v != "" {
return v
}
}
return strings.TrimSpace(bodyKey)
}
// overflowClientMessage 为超窗失败生成「干净」的客户端消息。
//
// 为什么不能沿用 upstreamErrSummarypi 的 isContextOverflow 先查
// NON_OVERFLOW_PATTERNS/rate limit/、/too many requests/、Bedrock 前缀),
// 一旦命中就直接判为「非超窗」——**哪怕消息里已经有 context_length_exceeded**
// pi 也不会压缩重试。而 AUTO 链的失败消息天生是多 tier 原因的拼接:
// 超窗 tiergozen 400 maximum context length常与配额/限流 tier
// 429 token plan exhausted、cooling、no free slot同时出现。
// 把明细原样带出去,等于让一条限流 tier 的措辞反过来封杀超窗识别。
// 所以这里只保留「超窗」措辞 + 是哪个源超的窗,其余一律不带。
func overflowClientMessage(err error) string {
var ce *scheduler.ChainErr
if errors.As(err, &ce) {
for _, t := range ce.Tiers {
if looksLikeOverflow(t.Err.Error()) {
return fmt.Sprintf("%s: %s (%s/%s)", overflowCanonical, overflowHint, t.Source, t.Model)
}
}
}
return fmt.Sprintf("%s: %s", overflowCanonical, overflowHint)
}
// upstreamErrSummary 把上游失败压成一行短消息。
func upstreamErrSummary(err error) string {
var ce *scheduler.ChainErr
if errors.As(err, &ce) {
parts := make([]string, 0, len(ce.Tiers)+len(ce.Skipped))
for _, t := range ce.Tiers {
// 160 而不是 80短诊断词"Context window is full")常落在尾部,
// 80 字节按字节截断正好会把它切掉,超窗就再也认不出来。
parts = append(parts, types.OneLine(fmt.Sprintf("%s/%s: %v", t.Source, t.Model, t.Err), 160))
}
for _, sk := range ce.Skipped {
parts = append(parts, types.OneLine(sk, 160))
}
msg := strings.Join(parts, "; ")
if len(msg) > 300 {
msg = msg[:300] + "..."
}
return fmt.Sprintf("all %d auto providers failed: %s", len(parts), msg)
}
return types.OneLine(err.Error(), 160)
}
// failChat maps a scheduling failure onto the audit record and answers the
// client. A failed AUTO chain additionally pins its first failed tier onto
// the record; direct-path errors never match *scheduler.ChainErr, so the
// extraction is safely shared by all four entry points. Callers own the
// writeRec call (inline for non-stream paths, deferred for stream paths).
func (g *Gateway) failChat(w http.ResponseWriter, rec *Req, err error) {
rec.OK = false
rec.Status = upstreamErrStatus(err)
rec.Err = err.Error()
var ce *scheduler.ChainErr
if errors.As(err, &ce) && len(ce.Tiers) > 0 {
rec.Source = ce.Tiers[0].Source
rec.Model = ce.Tiers[0].Model
}
writeError(w, rec.Status, "upstream_error", clientUpstreamErr(err))
}
// recordChatUsage fills token accounting for a finished non-streaming
// request: exact upstream numbers win, byte estimates fill the gaps.
func recordChatUsage(rec *Req, req *types.ChatRequest, resp *types.UnifiedResponse) {
rec.Prompt = int64(resp.TokenUsage.Prompt)
if rec.Prompt == 0 {
rec.Prompt = estimatePromptTokens(req)
}
rec.Compl = int64(resp.TokenUsage.Completion)
if rec.Compl == 0 {
rec.Compl = estimateTextTokens(resp.Content, resp.ReasoningContent, resp.ToolCalls)
}
// Cache accounting: whichever source format the adapter normalized into
// (prompt_tokens_details.cached_tokens or legacy prompt_cache_hit_tokens),
// read it back so the request record carries the hit/miss split.
if d := resp.TokenUsage.PromptTokensDetails; d != nil && d.CachedTokens > 0 {
rec.CacheHit = int64(d.CachedTokens)
}
if resp.TokenUsage.PromptTokensDetails != nil {
// Upstream reported cache details (even a 0 hit) — tag the row so
// the UI can show 0% rather than “—”.
rec.CacheReported = true
} else if resp.TokenUsage.PromptCacheHit > 0 {
rec.CacheHit = int64(resp.TokenUsage.PromptCacheHit)
rec.CacheReported = true
}
if resp.TokenUsage.PromptCacheMiss > 0 {
rec.CacheMiss = int64(resp.TokenUsage.PromptCacheMiss)
}
}
// writeChatCompletion renders a unified response as an OpenAI
// chat.completion object. modelName is the id clients see as the serving
// model: the requested id for direct routes, the exact slot model for AUTO.
func writeChatCompletion(w http.ResponseWriter, resp *types.UnifiedResponse, modelName string) {
msg := RespMessage{Role: "assistant", Content: resp.Content}
if resp.ReasoningContent != "" {
msg.ReasoningContent = resp.ReasoningContent
}
if len(resp.ToolCalls) > 0 {
msg.ToolCalls = toolCallsWire(resp.ToolCalls)
}
out := ChatCompletion{
ID: newID(),
Object: "chat.completion",
Created: time.Now().Unix(),
Model: modelName,
Choices: []ChatChoice{{Index: 0, Message: msg, FinishReason: resp.FinishReason}},
}
if resp.TokenUsage.Total > 0 || resp.TokenUsage.Prompt > 0 || resp.TokenUsage.Completion > 0 {
out.Usage = &resp.TokenUsage
}
writeJSON(w, http.StatusOK, out)
}
// singleChat runs a direct (model-pinned) non-streaming request across the
// candidate list, falling back on failure.
func (g *Gateway) singleChat(w http.ResponseWriter, ctx context.Context, cands []*provider.Provider, req *types.ChatRequest, effective string, rec *Req) {
rec.LatMs = 0
t0 := time.Now()
resp, usedSrc, usedModel, err := g.core.Scheduler().Chat(ctx, toScheduler(cands), req)
rec.LatMs = time.Since(t0).Milliseconds()
if err != nil {
g.failChat(w, rec, err)
g.writeRec(rec)
return
}
rec.OK = true
rec.Status = http.StatusOK
recordChatUsage(rec, req, resp)
rec.Source = usedSrc
rec.Model = usedModel
// Non-streaming: the whole response arrives at once, so TTFB equals
// the total latency.
rec.FirstByteMs = rec.LatMs
g.writeRec(rec)
writeChatCompletion(w, resp, effective)
}
// writeRec records a finished request (audit + aggregates).
func (g *Gateway) writeRec(rec *Req) {
if rec == nil {
return
}
if rec.Time == 0 {
rec.Time = time.Now().UnixMilli()
}
g.stats.Record(*rec)
}
// mergeUsage combines token usage across stream chunks additively. Some
// providers split usage across chunks (e.g. Anthropic reports prompt tokens
// in message_start and the final completion tokens in message_delta); a plain
// "last non-nil wins" would discard the prompt half. Non-zero fields from cur
// override prev; total is recomputed from the merged parts so a partial later
// chunk can't shrink it. For the common single-chunk case (OpenAI's terminal
// empty-choices+usage chunk) upstream totals are preserved exactly.
func mergeUsage(prev, cur *types.TokenUsage) *types.TokenUsage {
if prev == nil {
u := *cur
if u.Total == 0 && (u.Prompt > 0 || u.Completion > 0) {
u.Total = u.Prompt + u.Completion
}
return &u
}
out := *prev
if cur.Prompt > 0 {
out.Prompt = cur.Prompt
}
if cur.Completion > 0 {
out.Completion = cur.Completion
}
out.Total = out.Prompt + out.Completion
if cur.PromptTokensDetails != nil {
// Keep the details object even when CachedTokens is 0: a reported
// zero-hit is meaningful ("cache missed") and must stay
// distinguishable from "upstream never reported cache info".
// Dropping it here made streaming rows show “—” instead of 0%.
out.PromptTokensDetails = cur.PromptTokensDetails
}
if cur.PromptCacheHit > 0 {
out.PromptCacheHit = cur.PromptCacheHit
}
if cur.PromptCacheMiss > 0 {
out.PromptCacheMiss = cur.PromptCacheMiss
}
return &out
}
// pumpStream writes the full SSE sequence for a started stream: role
// preamble, one chunk per unified delta, the terminating finish_reason, the
// OpenAI-standard final usage chunk (empty choices) and [DONE]. modelName
// follows writeChatCompletion's rule (requested id for direct routes, exact
// slot model for AUTO).
func (g *Gateway) pumpStream(w http.ResponseWriter, rec *Req, chunks <-chan types.UnifiedChunk, modelName string, t0 time.Time) {
w.Header().Set("Content-Type", "text/event-stream")
w.Header().Set("Cache-Control", "no-cache")
w.Header().Set("Connection", "keep-alive")
w.WriteHeader(http.StatusOK)
flusher, _ := w.(http.Flusher)
id := newID()
created := time.Now().Unix()
send := func(obj interface{}) bool {
b, err := json.Marshal(obj)
if err != nil {
return false
}
if _, err := fmt.Fprintf(w, "data: %s\n\n", b); err != nil {
return false
}
if flusher != nil {
flusher.Flush()
}
return true
}
if !send(ChatChunk{
ID: id, Object: "chat.completion.chunk", Created: created, Model: modelName,
Choices: []ChunkChoice{{Index: 0, Delta: RespMessage{Role: "assistant"}}},
}) {
return
}
// First SSE byte sent to the client: record time-to-first-byte for the
// source's status-page latency average.
rec.FirstByteMs = time.Since(t0).Milliseconds()
var lastUsage *types.TokenUsage
lastFinish := ""
for ck := range chunks {
if ck.Usage != nil {
lastUsage = mergeUsage(lastUsage, ck.Usage)
}
chunk := ChatChunk{
ID: id, Object: "chat.completion.chunk", Created: created, Model: modelName,
}
delta := RespMessage{Role: "assistant", Content: ck.Content}
if ck.ReasoningContent != "" {
delta.ReasoningContent = ck.ReasoningContent
}
if len(ck.ToolCalls) > 0 {
delta.ToolCalls = ck.ToolCalls
}
choice := ChunkChoice{Index: 0, Delta: delta}
if ck.Done {
fin := ck.FinishReason
if fin == "" {
fin = "stop"
}
lastFinish = fin
choice.FinishReason = &fin
}
chunk.Choices = []ChunkChoice{choice}
rec.Compl += int64(len(ck.Content)+len(ck.ReasoningContent)+len(ck.ToolCalls)) / 3
if !send(chunk) {
return
}
}
finalFinish := lastFinish
if finalFinish == "" {
finalFinish = "stop"
}
send(ChatChunk{
ID: id, Object: "chat.completion.chunk", Created: created, Model: modelName,
Choices: []ChunkChoice{{Index: 0, Delta: RespMessage{}, FinishReason: &finalFinish}},
})
// Final usage chunk (OpenAI standard: empty choices + usage before [DONE]).
// Prefer the upstream's exact usage if the stream carried it; fall back to
// the gateway's estimate otherwise.
var tut *types.TokenUsage
if lastUsage != nil {
tut = lastUsage
// Write the upstream's cache accounting back onto the request record
// so the audit trail carries the hit/miss split for streaming too.
if d := tut.PromptTokensDetails; d != nil {
rec.CacheReported = true
if d.CachedTokens > 0 {
rec.CacheHit = int64(d.CachedTokens)
}
} else if tut.PromptCacheHit > 0 {
rec.CacheHit = int64(tut.PromptCacheHit)
rec.CacheReported = true
}
if tut.PromptCacheMiss > 0 {
rec.CacheMiss = int64(tut.PromptCacheMiss)
}
} else if rec.Prompt+rec.Compl > 0 {
u := types.TokenUsage{
Prompt: int(rec.Prompt),
Completion: int(rec.Compl),
Total: int(rec.Prompt + rec.Compl),
}
tut = &u
}
if tut != nil {
send(ChatChunk{
ID: id, Object: "chat.completion.chunk", Created: created, Model: modelName,
Choices: []ChunkChoice{},
Usage: tut,
})
}
fmt.Fprintf(w, "data: [DONE]\n\n")
if flusher != nil {
flusher.Flush()
}
}
// streamChat runs a direct (model-pinned) streaming request across the
// candidate list, falling back early on connect errors.
func (g *Gateway) streamChat(w http.ResponseWriter, ctx context.Context, cands []*provider.Provider, req *types.ChatRequest, effective string, rec *Req) {
rec.LatMs = 0
t0 := time.Now()
rec.OK = true
rec.Status = http.StatusOK
defer func() {
rec.LatMs = time.Since(t0).Milliseconds()
g.writeRec(rec)
}()
chunks, usedSrc, usedModel, err := g.core.Scheduler().ChatStream(ctx, toScheduler(cands), req)
if err != nil {
g.failChat(w, rec, err)
return
}
if usedModel != "" {
rec.Model = usedModel
}
// Audit accuracy: pin the source that actually served the stream (after a
// failover it differs from the first candidate). Direct streams previously
// discarded it.
rec.Source = usedSrc
rec.Prompt = estimatePromptTokens(req)
g.pumpStream(w, rec, chunks, effective, t0)
}
// singleChatAuto runs a non-streaming AUTO request down the chain (see
// scheduler.ChainChat): tiers ascending (tier 1 = highest priority first),
// per-tier round-robin ordered by preference, cooldown as the only hard skip,
// busy slots skipped without penalty and a bounded busy wait. When every
// tier fails, the response is a 503 carrying the per-tier error summary
// (which source/model failed why).
func (g *Gateway) singleChatAuto(w http.ResponseWriter, ctx context.Context, chain *scheduler.Chain, req *types.ChatRequest, rec *Req, quotaExhausted func(*scheduler.Slot) bool) {
rec.LatMs = 0
t0 := time.Now()
resp, usedSrc, usedModel, err := g.core.Scheduler().ChainChat(ctx, chain, req, quotaExhausted)
rec.LatMs = time.Since(t0).Milliseconds()
if err != nil {
g.failChat(w, rec, err)
g.writeRec(rec)
return
}
rec.OK = true
rec.Status = http.StatusOK
recordChatUsage(rec, req, resp)
rec.Source = usedSrc
rec.Model = usedModel
rec.FirstByteMs = rec.LatMs
g.writeRec(rec)
writeChatCompletion(w, resp, usedModel)
}
// streamChatAuto streams an AUTO request down the chain. A slot is abandoned
// only before its first chunk (connect error / non-200 / busy); once a stream
// starts it stays pinned. Total failure writes a JSON 503 (with the per-tier
// summary) before any SSE byte is sent.
func (g *Gateway) streamChatAuto(w http.ResponseWriter, ctx context.Context, chain *scheduler.Chain, req *types.ChatRequest, rec *Req, quotaExhausted func(*scheduler.Slot) bool) {
rec.LatMs = 0
t0 := time.Now()
rec.OK = true
rec.Status = http.StatusOK
defer func() {
rec.LatMs = time.Since(t0).Milliseconds()
g.writeRec(rec)
}()
chunks, usedSrc, usedModel, err := g.core.Scheduler().ChainChatStream(ctx, chain, req, quotaExhausted)
if err != nil {
g.failChat(w, rec, err)
return
}
if usedModel != "" {
rec.Model = usedModel
}
rec.Source = usedSrc
rec.Prompt = estimatePromptTokens(req)
g.pumpStream(w, rec, chunks, usedModel, t0)
}
func (g *Gateway) handleImage(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
writeError(w, http.StatusMethodNotAllowed, "method_not_allowed", "use POST")
return
}
var req types.ImageGenRequest
if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
writeError(w, http.StatusBadRequest, "invalid_request", "invalid json: "+err.Error())
return
}
if req.Prompt == "" {
writeError(w, http.StatusBadRequest, "invalid_request", "prompt is required")
return
}
model := req.Model
if model == "" {
model = g.core.DefaultModel()
}
if isAuto(model) {
if chain := g.core.AutoImageChain(); chain != nil && len(chain.Tiers) > 0 {
if msg := g.checkModelScope(r.Context(), "AUTO"); msg != "" {
writeError(w, http.StatusForbidden, "model_not_allowed", msg)
return
}
done := g.stats.Begin()
defer done()
rec := &Req{Key: keyID(reqKey(r.Context())), Type: "image", Model: model, OK: false}
t0 := time.Now()
resp, usedSrc, usedModel, err := g.core.Scheduler().ChainImage(r.Context(), chain, &req)
rec.LatMs = time.Since(t0).Milliseconds()
if err != nil {
rec.Status = upstreamErrStatus(err)
rec.Err = err.Error()
g.writeRec(rec)
writeError(w, rec.Status, "upstream_error", clientUpstreamErr(err))
return
}
rec.Source = usedSrc
if usedModel != "" {
rec.Model = usedModel // actual image model served, not "AUTO"
}
rec.OK = true
rec.Status = http.StatusOK
rec.Compl = int64(len(resp.ImageData))
g.writeRec(rec)
writeJSON(w, http.StatusOK, types.ImageGenResponse{
Created: time.Now().Unix(),
Data: resp.ImageData,
})
return
}
// no image chain configured: fall through to legacy discovery (all
// sources exposing an image model, tried in registry order)
}
if allow := g.allowedModels(r.Context()); allow != nil && !g.hasScopeModel(allow, model) {
writeError(w, http.StatusForbidden, "model_not_allowed", fmt.Sprintf("model %q is not allowed for this key", model))
return
}
cands, _ := g.resolveByModel(model)
cands = imageOnly(cands)
if allow := g.allowedModels(r.Context()); allow != nil {
cands = filterCandsByModels(cands, allow)
}
if len(cands) == 0 {
writeError(w, http.StatusServiceUnavailable, "no_provider", "no image source configured")
return
}
if msg := g.checkModelScope(r.Context(), effectiveImageModel(model, cands)); msg != "" {
writeError(w, http.StatusForbidden, "model_not_allowed", msg)
return
}
done := g.stats.Begin()
defer done()
rec := &Req{Key: keyID(reqKey(r.Context())), Type: "image", Model: model, Source: firstSource(cands), OK: false}
t0 := time.Now()
resp, usedSrc, err := g.core.Scheduler().Image(r.Context(), toScheduler(cands), &req)
rec.LatMs = time.Since(t0).Milliseconds()
if err != nil {
rec.Status = upstreamErrStatus(err)
rec.Err = err.Error()
g.writeRec(rec)
writeError(w, rec.Status, "upstream_error", clientUpstreamErr(err))
return
}
if usedSrc != "" {
rec.Source = usedSrc
}
if resp.Model != "" {
rec.Model = resp.Model // record the actual model served, not the raw request id
}
rec.OK = true
rec.Status = http.StatusOK
rec.Compl = int64(len(resp.ImageData))
g.writeRec(rec)
writeJSON(w, http.StatusOK, types.ImageGenResponse{
Created: time.Now().Unix(),
Data: resp.ImageData,
})
}