feat(selector): add priority support for auth selection

internal/config/config.go

@@ -242,6 +242,10 @@ type ClaudeKey struct {
 	// APIKey is the authentication key for accessing Claude API services.
 	APIKey string `yaml:"api-key" json:"api-key"`
 
+	// Priority controls selection preference when multiple credentials match.
+	// Higher values are preferred; defaults to 0.
+	Priority int `yaml:"priority,omitempty" json:"priority,omitempty"`
+
 	// Prefix optionally namespaces models for this credential (e.g., "teamA/claude-sonnet-4").
 	Prefix string `yaml:"prefix,omitempty" json:"prefix,omitempty"`
 
@@ -280,6 +284,10 @@ type CodexKey struct {
 	// APIKey is the authentication key for accessing Codex API services.
 	APIKey string `yaml:"api-key" json:"api-key"`
 
+	// Priority controls selection preference when multiple credentials match.
+	// Higher values are preferred; defaults to 0.
+	Priority int `yaml:"priority,omitempty" json:"priority,omitempty"`
+
 	// Prefix optionally namespaces models for this credential (e.g., "teamA/gpt-5-codex").
 	Prefix string `yaml:"prefix,omitempty" json:"prefix,omitempty"`
 
@@ -318,6 +326,10 @@ type GeminiKey struct {
 	// APIKey is the authentication key for accessing Gemini API services.
 	APIKey string `yaml:"api-key" json:"api-key"`
 
+	// Priority controls selection preference when multiple credentials match.
+	// Higher values are preferred; defaults to 0.
+	Priority int `yaml:"priority,omitempty" json:"priority,omitempty"`
+
 	// Prefix optionally namespaces models for this credential (e.g., "teamA/gemini-3-pro-preview").
 	Prefix string `yaml:"prefix,omitempty" json:"prefix,omitempty"`
 
@@ -355,6 +367,10 @@ type OpenAICompatibility struct {
 	// Name is the identifier for this OpenAI compatibility configuration.
 	Name string `yaml:"name" json:"name"`
 
+	// Priority controls selection preference when multiple providers or credentials match.
+	// Higher values are preferred; defaults to 0.
+	Priority int `yaml:"priority,omitempty" json:"priority,omitempty"`
+
 	// Prefix optionally namespaces model aliases for this provider (e.g., "teamA/kimi-k2").
 	Prefix string `yaml:"prefix,omitempty" json:"prefix,omitempty"`
 

internal/config/vertex_compat.go

@@ -13,6 +13,10 @@ type VertexCompatKey struct {
 	// Maps to the x-goog-api-key header.
 	APIKey string `yaml:"api-key" json:"api-key"`
 
+	// Priority controls selection preference when multiple credentials match.
+	// Higher values are preferred; defaults to 0.
+	Priority int `yaml:"priority,omitempty" json:"priority,omitempty"`
+
 	// Prefix optionally namespaces model aliases for this credential (e.g., "teamA/vertex-pro").
 	Prefix string `yaml:"prefix,omitempty" json:"prefix,omitempty"`
 

internal/watcher/synthesizer/config.go

@@ -2,6 +2,7 @@ package synthesizer
 
 import (
 	"fmt"
+	"strconv"
 	"strings"
 
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/watcher/diff"
@@ -59,6 +60,9 @@ func (s *ConfigSynthesizer) synthesizeGeminiKeys(ctx *SynthesisContext) []*corea
 			"source":  fmt.Sprintf("config:gemini[%s]", token),
 			"api_key": key,
 		}
+		if entry.Priority != 0 {
+			attrs["priority"] = strconv.Itoa(entry.Priority)
+		}
 		if base != "" {
 			attrs["base_url"] = base
 		}
@@ -103,6 +107,9 @@ func (s *ConfigSynthesizer) synthesizeClaudeKeys(ctx *SynthesisContext) []*corea
 			"source":  fmt.Sprintf("config:claude[%s]", token),
 			"api_key": key,
 		}
+		if ck.Priority != 0 {
+			attrs["priority"] = strconv.Itoa(ck.Priority)
+		}
 		if base != "" {
 			attrs["base_url"] = base
 		}
@@ -147,6 +154,9 @@ func (s *ConfigSynthesizer) synthesizeCodexKeys(ctx *SynthesisContext) []*coreau
 			"source":  fmt.Sprintf("config:codex[%s]", token),
 			"api_key": key,
 		}
+		if ck.Priority != 0 {
+			attrs["priority"] = strconv.Itoa(ck.Priority)
+		}
 		if ck.BaseURL != "" {
 			attrs["base_url"] = ck.BaseURL
 		}
@@ -202,6 +212,9 @@ func (s *ConfigSynthesizer) synthesizeOpenAICompat(ctx *SynthesisContext) []*cor
 				"compat_name":  compat.Name,
 				"provider_key": providerName,
 			}
+			if compat.Priority != 0 {
+				attrs["priority"] = strconv.Itoa(compat.Priority)
+			}
 			if key != "" {
 				attrs["api_key"] = key
 			}
@@ -233,6 +246,9 @@ func (s *ConfigSynthesizer) synthesizeOpenAICompat(ctx *SynthesisContext) []*cor
 				"compat_name":  compat.Name,
 				"provider_key": providerName,
 			}
+			if compat.Priority != 0 {
+				attrs["priority"] = strconv.Itoa(compat.Priority)
+			}
 			if hash := diff.ComputeOpenAICompatModelsHash(compat.Models); hash != "" {
 				attrs["models_hash"] = hash
 			}
@@ -275,6 +291,9 @@ func (s *ConfigSynthesizer) synthesizeVertexCompat(ctx *SynthesisContext) []*cor
 			"base_url":     base,
 			"provider_key": providerName,
 		}
+		if compat.Priority != 0 {
+			attrs["priority"] = strconv.Itoa(compat.Priority)
+		}
 		if key != "" {
 			attrs["api_key"] = key
 		}

sdk/cliproxy/auth/conductor.go

@@ -271,7 +271,6 @@ func (m *Manager) Execute(ctx context.Context, providers []string, req cliproxye
 	if len(normalized) == 0 {
 		return cliproxyexecutor.Response{}, &Error{Code: "provider_not_found", Message: "no provider supplied"}
 	}
-	rotated := m.rotateProviders(req.Model, normalized)
 
 	retryTimes, maxWait := m.retrySettings()
 	attempts := retryTimes + 1
@@ -281,14 +280,12 @@ func (m *Manager) Execute(ctx context.Context, providers []string, req cliproxye
 
 	var lastErr error
 	for attempt := 0; attempt < attempts; attempt++ {
-		resp, errExec := m.executeProvidersOnce(ctx, rotated, func(execCtx context.Context, provider string) (cliproxyexecutor.Response, error) {
+		resp, errExec := m.executeMixedOnce(ctx, normalized, req, opts)
-			return m.executeWithProvider(execCtx, provider, req, opts)
-		})
 		if errExec == nil {
 			return resp, nil
 		}
 		lastErr = errExec
-		wait, shouldRetry := m.shouldRetryAfterError(errExec, attempt, attempts, rotated, req.Model, maxWait)
+		wait, shouldRetry := m.shouldRetryAfterError(errExec, attempt, attempts, normalized, req.Model, maxWait)
 		if !shouldRetry {
 			break
 		}
@@ -309,7 +306,6 @@ func (m *Manager) ExecuteCount(ctx context.Context, providers []string, req clip
 	if len(normalized) == 0 {
 		return cliproxyexecutor.Response{}, &Error{Code: "provider_not_found", Message: "no provider supplied"}
 	}
-	rotated := m.rotateProviders(req.Model, normalized)
 
 	retryTimes, maxWait := m.retrySettings()
 	attempts := retryTimes + 1
@@ -319,14 +315,12 @@ func (m *Manager) ExecuteCount(ctx context.Context, providers []string, req clip
 
 	var lastErr error
 	for attempt := 0; attempt < attempts; attempt++ {
-		resp, errExec := m.executeProvidersOnce(ctx, rotated, func(execCtx context.Context, provider string) (cliproxyexecutor.Response, error) {
+		resp, errExec := m.executeCountMixedOnce(ctx, normalized, req, opts)
-			return m.executeCountWithProvider(execCtx, provider, req, opts)
-		})
 		if errExec == nil {
 			return resp, nil
 		}
 		lastErr = errExec
-		wait, shouldRetry := m.shouldRetryAfterError(errExec, attempt, attempts, rotated, req.Model, maxWait)
+		wait, shouldRetry := m.shouldRetryAfterError(errExec, attempt, attempts, normalized, req.Model, maxWait)
 		if !shouldRetry {
 			break
 		}
@@ -347,7 +341,6 @@ func (m *Manager) ExecuteStream(ctx context.Context, providers []string, req cli
 	if len(normalized) == 0 {
 		return nil, &Error{Code: "provider_not_found", Message: "no provider supplied"}
 	}
-	rotated := m.rotateProviders(req.Model, normalized)
 
 	retryTimes, maxWait := m.retrySettings()
 	attempts := retryTimes + 1
@@ -357,14 +350,12 @@ func (m *Manager) ExecuteStream(ctx context.Context, providers []string, req cli
 
 	var lastErr error
 	for attempt := 0; attempt < attempts; attempt++ {
-		chunks, errStream := m.executeStreamProvidersOnce(ctx, rotated, func(execCtx context.Context, provider string) (<-chan cliproxyexecutor.StreamChunk, error) {
+		chunks, errStream := m.executeStreamMixedOnce(ctx, normalized, req, opts)
-			return m.executeStreamWithProvider(execCtx, provider, req, opts)
-		})
 		if errStream == nil {
 			return chunks, nil
 		}
 		lastErr = errStream
-		wait, shouldRetry := m.shouldRetryAfterError(errStream, attempt, attempts, rotated, req.Model, maxWait)
+		wait, shouldRetry := m.shouldRetryAfterError(errStream, attempt, attempts, normalized, req.Model, maxWait)
 		if !shouldRetry {
 			break
 		}
@@ -378,6 +369,167 @@ func (m *Manager) ExecuteStream(ctx context.Context, providers []string, req cli
 	return nil, &Error{Code: "auth_not_found", Message: "no auth available"}
 }
 
+func (m *Manager) executeMixedOnce(ctx context.Context, providers []string, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
+	if len(providers) == 0 {
+		return cliproxyexecutor.Response{}, &Error{Code: "provider_not_found", Message: "no provider supplied"}
+	}
+	routeModel := req.Model
+	tried := make(map[string]struct{})
+	var lastErr error
+	for {
+		auth, executor, provider, errPick := m.pickNextMixed(ctx, providers, routeModel, opts, tried)
+		if errPick != nil {
+			if lastErr != nil {
+				return cliproxyexecutor.Response{}, lastErr
+			}
+			return cliproxyexecutor.Response{}, errPick
+		}
+
+		entry := logEntryWithRequestID(ctx)
+		debugLogAuthSelection(entry, auth, provider, req.Model)
+
+		tried[auth.ID] = struct{}{}
+		execCtx := ctx
+		if rt := m.roundTripperFor(auth); rt != nil {
+			execCtx = context.WithValue(execCtx, roundTripperContextKey{}, rt)
+			execCtx = context.WithValue(execCtx, "cliproxy.roundtripper", rt)
+		}
+		execReq := req
+		execReq.Model, execReq.Metadata = rewriteModelForAuth(routeModel, req.Metadata, auth)
+		execReq.Model, execReq.Metadata = m.applyOAuthModelMapping(auth, execReq.Model, execReq.Metadata)
+		resp, errExec := executor.Execute(execCtx, auth, execReq, opts)
+		result := Result{AuthID: auth.ID, Provider: provider, Model: routeModel, Success: errExec == nil}
+		if errExec != nil {
+			result.Error = &Error{Message: errExec.Error()}
+			var se cliproxyexecutor.StatusError
+			if errors.As(errExec, &se) && se != nil {
+				result.Error.HTTPStatus = se.StatusCode()
+			}
+			if ra := retryAfterFromError(errExec); ra != nil {
+				result.RetryAfter = ra
+			}
+			m.MarkResult(execCtx, result)
+			lastErr = errExec
+			continue
+		}
+		m.MarkResult(execCtx, result)
+		return resp, nil
+	}
+}
+
+func (m *Manager) executeCountMixedOnce(ctx context.Context, providers []string, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
+	if len(providers) == 0 {
+		return cliproxyexecutor.Response{}, &Error{Code: "provider_not_found", Message: "no provider supplied"}
+	}
+	routeModel := req.Model
+	tried := make(map[string]struct{})
+	var lastErr error
+	for {
+		auth, executor, provider, errPick := m.pickNextMixed(ctx, providers, routeModel, opts, tried)
+		if errPick != nil {
+			if lastErr != nil {
+				return cliproxyexecutor.Response{}, lastErr
+			}
+			return cliproxyexecutor.Response{}, errPick
+		}
+
+		entry := logEntryWithRequestID(ctx)
+		debugLogAuthSelection(entry, auth, provider, req.Model)
+
+		tried[auth.ID] = struct{}{}
+		execCtx := ctx
+		if rt := m.roundTripperFor(auth); rt != nil {
+			execCtx = context.WithValue(execCtx, roundTripperContextKey{}, rt)
+			execCtx = context.WithValue(execCtx, "cliproxy.roundtripper", rt)
+		}
+		execReq := req
+		execReq.Model, execReq.Metadata = rewriteModelForAuth(routeModel, req.Metadata, auth)
+		execReq.Model, execReq.Metadata = m.applyOAuthModelMapping(auth, execReq.Model, execReq.Metadata)
+		resp, errExec := executor.CountTokens(execCtx, auth, execReq, opts)
+		result := Result{AuthID: auth.ID, Provider: provider, Model: routeModel, Success: errExec == nil}
+		if errExec != nil {
+			result.Error = &Error{Message: errExec.Error()}
+			var se cliproxyexecutor.StatusError
+			if errors.As(errExec, &se) && se != nil {
+				result.Error.HTTPStatus = se.StatusCode()
+			}
+			if ra := retryAfterFromError(errExec); ra != nil {
+				result.RetryAfter = ra
+			}
+			m.MarkResult(execCtx, result)
+			lastErr = errExec
+			continue
+		}
+		m.MarkResult(execCtx, result)
+		return resp, nil
+	}
+}
+
+func (m *Manager) executeStreamMixedOnce(ctx context.Context, providers []string, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (<-chan cliproxyexecutor.StreamChunk, error) {
+	if len(providers) == 0 {
+		return nil, &Error{Code: "provider_not_found", Message: "no provider supplied"}
+	}
+	routeModel := req.Model
+	tried := make(map[string]struct{})
+	var lastErr error
+	for {
+		auth, executor, provider, errPick := m.pickNextMixed(ctx, providers, routeModel, opts, tried)
+		if errPick != nil {
+			if lastErr != nil {
+				return nil, lastErr
+			}
+			return nil, errPick
+		}
+
+		entry := logEntryWithRequestID(ctx)
+		debugLogAuthSelection(entry, auth, provider, req.Model)
+
+		tried[auth.ID] = struct{}{}
+		execCtx := ctx
+		if rt := m.roundTripperFor(auth); rt != nil {
+			execCtx = context.WithValue(execCtx, roundTripperContextKey{}, rt)
+			execCtx = context.WithValue(execCtx, "cliproxy.roundtripper", rt)
+		}
+		execReq := req
+		execReq.Model, execReq.Metadata = rewriteModelForAuth(routeModel, req.Metadata, auth)
+		execReq.Model, execReq.Metadata = m.applyOAuthModelMapping(auth, execReq.Model, execReq.Metadata)
+		chunks, errStream := executor.ExecuteStream(execCtx, auth, execReq, opts)
+		if errStream != nil {
+			rerr := &Error{Message: errStream.Error()}
+			var se cliproxyexecutor.StatusError
+			if errors.As(errStream, &se) && se != nil {
+				rerr.HTTPStatus = se.StatusCode()
+			}
+			result := Result{AuthID: auth.ID, Provider: provider, Model: routeModel, Success: false, Error: rerr}
+			result.RetryAfter = retryAfterFromError(errStream)
+			m.MarkResult(execCtx, result)
+			lastErr = errStream
+			continue
+		}
+		out := make(chan cliproxyexecutor.StreamChunk)
+		go func(streamCtx context.Context, streamAuth *Auth, streamProvider string, streamChunks <-chan cliproxyexecutor.StreamChunk) {
+			defer close(out)
+			var failed bool
+			for chunk := range streamChunks {
+				if chunk.Err != nil && !failed {
+					failed = true
+					rerr := &Error{Message: chunk.Err.Error()}
+					var se cliproxyexecutor.StatusError
+					if errors.As(chunk.Err, &se) && se != nil {
+						rerr.HTTPStatus = se.StatusCode()
+					}
+					m.MarkResult(streamCtx, Result{AuthID: streamAuth.ID, Provider: streamProvider, Model: routeModel, Success: false, Error: rerr})
+				}
+				out <- chunk
+			}
+			if !failed {
+				m.MarkResult(streamCtx, Result{AuthID: streamAuth.ID, Provider: streamProvider, Model: routeModel, Success: true})
+			}
+		}(execCtx, auth.Clone(), provider, chunks)
+		return out, nil
+	}
+}
+
 func (m *Manager) executeWithProvider(ctx context.Context, provider string, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
 	if provider == "" {
 		return cliproxyexecutor.Response{}, &Error{Code: "provider_not_found", Message: "provider identifier is empty"}
@@ -1191,6 +1343,77 @@ func (m *Manager) pickNext(ctx context.Context, provider, model string, opts cli
 	return authCopy, executor, nil
 }
 
+func (m *Manager) pickNextMixed(ctx context.Context, providers []string, model string, opts cliproxyexecutor.Options, tried map[string]struct{}) (*Auth, ProviderExecutor, string, error) {
+	providerSet := make(map[string]struct{}, len(providers))
+	for _, provider := range providers {
+		p := strings.TrimSpace(strings.ToLower(provider))
+		if p == "" {
+			continue
+		}
+		providerSet[p] = struct{}{}
+	}
+	if len(providerSet) == 0 {
+		return nil, nil, "", &Error{Code: "provider_not_found", Message: "no provider supplied"}
+	}
+
+	m.mu.RLock()
+	candidates := make([]*Auth, 0, len(m.auths))
+	modelKey := strings.TrimSpace(model)
+	registryRef := registry.GetGlobalRegistry()
+	for _, candidate := range m.auths {
+		if candidate == nil || candidate.Disabled {
+			continue
+		}
+		providerKey := strings.TrimSpace(strings.ToLower(candidate.Provider))
+		if providerKey == "" {
+			continue
+		}
+		if _, ok := providerSet[providerKey]; !ok {
+			continue
+		}
+		if _, used := tried[candidate.ID]; used {
+			continue
+		}
+		if _, ok := m.executors[providerKey]; !ok {
+			continue
+		}
+		if modelKey != "" && registryRef != nil && !registryRef.ClientSupportsModel(candidate.ID, modelKey) {
+			continue
+		}
+		candidates = append(candidates, candidate)
+	}
+	if len(candidates) == 0 {
+		m.mu.RUnlock()
+		return nil, nil, "", &Error{Code: "auth_not_found", Message: "no auth available"}
+	}
+	selected, errPick := m.selector.Pick(ctx, "mixed", model, opts, candidates)
+	if errPick != nil {
+		m.mu.RUnlock()
+		return nil, nil, "", errPick
+	}
+	if selected == nil {
+		m.mu.RUnlock()
+		return nil, nil, "", &Error{Code: "auth_not_found", Message: "selector returned no auth"}
+	}
+	providerKey := strings.TrimSpace(strings.ToLower(selected.Provider))
+	executor, okExecutor := m.executors[providerKey]
+	if !okExecutor {
+		m.mu.RUnlock()
+		return nil, nil, "", &Error{Code: "executor_not_found", Message: "executor not registered"}
+	}
+	authCopy := selected.Clone()
+	m.mu.RUnlock()
+	if !selected.indexAssigned {
+		m.mu.Lock()
+		if current := m.auths[authCopy.ID]; current != nil && !current.indexAssigned {
+			current.EnsureIndex()
+			authCopy = current.Clone()
+		}
+		m.mu.Unlock()
+	}
+	return authCopy, executor, providerKey, nil
+}
+
 func (m *Manager) persist(ctx context.Context, auth *Auth) error {
 	if m.store == nil || auth == nil {
 		return nil

sdk/cliproxy/auth/selector.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"sort"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -103,13 +104,29 @@ func (e *modelCooldownError) Headers() http.Header {
 	return headers
 }
 
-func collectAvailable(auths []*Auth, model string, now time.Time) (available []*Auth, cooldownCount int, earliest time.Time) {
+func authPriority(auth *Auth) int {
-	available = make([]*Auth, 0, len(auths))
+	if auth == nil || auth.Attributes == nil {
+		return 0
+	}
+	raw := strings.TrimSpace(auth.Attributes["priority"])
+	if raw == "" {
+		return 0
+	}
+	parsed, err := strconv.Atoi(raw)
+	if err != nil {
+		return 0
+	}
+	return parsed
+}
+
+func collectAvailableByPriority(auths []*Auth, model string, now time.Time) (available map[int][]*Auth, cooldownCount int, earliest time.Time) {
+	available = make(map[int][]*Auth)
 	for i := 0; i < len(auths); i++ {
 		candidate := auths[i]
 		blocked, reason, next := isAuthBlockedForModel(candidate, model, now)
 		if !blocked {
-			available = append(available, candidate)
+			priority := authPriority(candidate)
+			available[priority] = append(available[priority], candidate)
 			continue
 		}
 		if reason == blockReasonCooldown {
@@ -119,9 +136,6 @@ func collectAvailable(auths []*Auth, model string, now time.Time) (available []*
 			}
 		}
 	}
-	if len(available) > 1 {
-		sort.Slice(available, func(i, j int) bool { return available[i].ID < available[j].ID })
-	}
 	return available, cooldownCount, earliest
 }
 
@@ -130,18 +144,35 @@ func getAvailableAuths(auths []*Auth, provider, model string, now time.Time) ([]
 		return nil, &Error{Code: "auth_not_found", Message: "no auth candidates"}
 	}
 
-	available, cooldownCount, earliest := collectAvailable(auths, model, now)
+	availableByPriority, cooldownCount, earliest := collectAvailableByPriority(auths, model, now)
-	if len(available) == 0 {
+	if len(availableByPriority) == 0 {
 		if cooldownCount == len(auths) && !earliest.IsZero() {
+			providerForError := provider
+			if providerForError == "mixed" {
+				providerForError = ""
+			}
 			resetIn := earliest.Sub(now)
 			if resetIn < 0 {
 				resetIn = 0
 			}
-			return nil, newModelCooldownError(model, provider, resetIn)
+			return nil, newModelCooldownError(model, providerForError, resetIn)
 		}
 		return nil, &Error{Code: "auth_unavailable", Message: "no auth available"}
 	}
 
+	bestPriority := 0
+	found := false
+	for priority := range availableByPriority {
+		if !found || priority > bestPriority {
+			bestPriority = priority
+			found = true
+		}
+	}
+
+	available := availableByPriority[bestPriority]
+	if len(available) > 1 {
+		sort.Slice(available, func(i, j int) bool { return available[i].ID < available[j].ID })
+	}
 	return available, nil
 }
 

sdk/cliproxy/auth/selector_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"sync"
 	"testing"
+	"time"
 
 	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
 )
@@ -56,6 +57,69 @@ func TestRoundRobinSelectorPick_CyclesDeterministic(t *testing.T) {
 	}
 }
 
+func TestRoundRobinSelectorPick_PriorityBuckets(t *testing.T) {
+	t.Parallel()
+
+	selector := &RoundRobinSelector{}
+	auths := []*Auth{
+		{ID: "c", Attributes: map[string]string{"priority": "0"}},
+		{ID: "a", Attributes: map[string]string{"priority": "10"}},
+		{ID: "b", Attributes: map[string]string{"priority": "10"}},
+	}
+
+	want := []string{"a", "b", "a", "b"}
+	for i, id := range want {
+		got, err := selector.Pick(context.Background(), "mixed", "", cliproxyexecutor.Options{}, auths)
+		if err != nil {
+			t.Fatalf("Pick() #%d error = %v", i, err)
+		}
+		if got == nil {
+			t.Fatalf("Pick() #%d auth = nil", i)
+		}
+		if got.ID != id {
+			t.Fatalf("Pick() #%d auth.ID = %q, want %q", i, got.ID, id)
+		}
+		if got.ID == "c" {
+			t.Fatalf("Pick() #%d unexpectedly selected lower priority auth", i)
+		}
+	}
+}
+
+func TestFillFirstSelectorPick_PriorityFallbackCooldown(t *testing.T) {
+	t.Parallel()
+
+	selector := &FillFirstSelector{}
+	now := time.Now()
+	model := "test-model"
+
+	high := &Auth{
+		ID:         "high",
+		Attributes: map[string]string{"priority": "10"},
+		ModelStates: map[string]*ModelState{
+			model: {
+				Status:         StatusActive,
+				Unavailable:    true,
+				NextRetryAfter: now.Add(30 * time.Minute),
+				Quota: QuotaState{
+					Exceeded: true,
+				},
+			},
+		},
+	}
+	low := &Auth{ID: "low", Attributes: map[string]string{"priority": "0"}}
+
+	got, err := selector.Pick(context.Background(), "mixed", model, cliproxyexecutor.Options{}, []*Auth{high, low})
+	if err != nil {
+		t.Fatalf("Pick() error = %v", err)
+	}
+	if got == nil {
+		t.Fatalf("Pick() auth = nil")
+	}
+	if got.ID != "low" {
+		t.Fatalf("Pick() auth.ID = %q, want %q", got.ID, "low")
+	}
+}
+
 func TestRoundRobinSelectorPick_Concurrent(t *testing.T) {
 	selector := &RoundRobinSelector{}
 	auths := []*Auth{