fix(claude): enhance ensureModelMaxTokens to use registered max_completion_tokens and fallback to default

internal/runtime/executor/claude_executor.go

@@ -45,33 +45,14 @@ type ClaudeExecutor struct {
 // Previously "proxy_" was used but this is a detectable fingerprint difference.
 const claudeToolPrefix = ""
 
-// Anthropic-compatible upstreams may reject or even crash when dynamically
+// Anthropic-compatible upstreams may reject or even crash when Claude models
-// registered Claude models omit max_tokens. Use a conservative default.
+// omit max_tokens. Prefer registered model metadata before using a fallback.
 const defaultModelMaxTokens = 1024
 
 func NewClaudeExecutor(cfg *config.Config) *ClaudeExecutor { return &ClaudeExecutor{cfg: cfg} }
 
 func (e *ClaudeExecutor) Identifier() string { return "claude" }
 
-func ensureModelMaxTokens(body []byte, modelID string) []byte {
-	if len(body) == 0 || !gjson.ValidBytes(body) {
-		return body
-	}
-
-	if maxTokens := gjson.GetBytes(body, "max_tokens"); maxTokens.Exists() {
-		return body
-	}
-
-	for _, provider := range registry.GetGlobalRegistry().GetModelProviders(strings.TrimSpace(modelID)) {
-		if strings.EqualFold(provider, "claude") {
-			body, _ = sjson.SetBytes(body, "max_tokens", defaultModelMaxTokens)
-			return body
-		}
-	}
-
-	return body
-}
-
 // PrepareRequest injects Claude credentials into the outgoing HTTP request.
 func (e *ClaudeExecutor) PrepareRequest(req *http.Request, auth *cliproxyauth.Auth) error {
 	if req == nil {
@@ -1906,3 +1887,26 @@ func injectSystemCacheControl(payload []byte) []byte {
 
 	return payload
 }
+
+func ensureModelMaxTokens(body []byte, modelID string) []byte {
+	if len(body) == 0 || !gjson.ValidBytes(body) {
+		return body
+	}
+
+	if maxTokens := gjson.GetBytes(body, "max_tokens"); maxTokens.Exists() {
+		return body
+	}
+
+	for _, provider := range registry.GetGlobalRegistry().GetModelProviders(strings.TrimSpace(modelID)) {
+		if strings.EqualFold(provider, "claude") {
+			maxTokens := defaultModelMaxTokens
+			if info := registry.GetGlobalRegistry().GetModelInfo(strings.TrimSpace(modelID), "claude"); info != nil && info.MaxCompletionTokens > 0 {
+				maxTokens = info.MaxCompletionTokens
+			}
+			body, _ = sjson.SetBytes(body, "max_tokens", maxTokens)
+			return body
+		}
+	}
+
+	return body
+}

internal/runtime/executor/claude_executor_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/klauspost/compress/zstd"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
 	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
 	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
 	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
@@ -1183,6 +1184,83 @@ func testClaudeExecutorInvalidCompressedErrorBody(
 	}
 }
 
+func TestEnsureModelMaxTokens_UsesRegisteredMaxCompletionTokens(t *testing.T) {
+	reg := registry.GetGlobalRegistry()
+	clientID := "test-claude-max-completion-tokens-client"
+	modelID := "test-claude-max-completion-tokens-model"
+	reg.RegisterClient(clientID, "claude", []*registry.ModelInfo{{
+		ID:                  modelID,
+		Type:                "claude",
+		OwnedBy:             "anthropic",
+		Object:              "model",
+		Created:             time.Now().Unix(),
+		MaxCompletionTokens: 4096,
+		UserDefined:         true,
+	}})
+	defer reg.UnregisterClient(clientID)
+
+	input := []byte(`{"model":"test-claude-max-completion-tokens-model","messages":[{"role":"user","content":"hi"}]}`)
+	out := ensureModelMaxTokens(input, modelID)
+
+	if got := gjson.GetBytes(out, "max_tokens").Int(); got != 4096 {
+		t.Fatalf("max_tokens = %d, want %d", got, 4096)
+	}
+}
+
+func TestEnsureModelMaxTokens_DefaultsMissingValue(t *testing.T) {
+	reg := registry.GetGlobalRegistry()
+	clientID := "test-claude-default-max-tokens-client"
+	modelID := "test-claude-default-max-tokens-model"
+	reg.RegisterClient(clientID, "claude", []*registry.ModelInfo{{
+		ID:          modelID,
+		Type:        "claude",
+		OwnedBy:     "anthropic",
+		Object:      "model",
+		Created:     time.Now().Unix(),
+		UserDefined: true,
+	}})
+	defer reg.UnregisterClient(clientID)
+
+	input := []byte(`{"model":"test-claude-default-max-tokens-model","messages":[{"role":"user","content":"hi"}]}`)
+	out := ensureModelMaxTokens(input, modelID)
+
+	if got := gjson.GetBytes(out, "max_tokens").Int(); got != defaultModelMaxTokens {
+		t.Fatalf("max_tokens = %d, want %d", got, defaultModelMaxTokens)
+	}
+}
+
+func TestEnsureModelMaxTokens_PreservesExplicitValue(t *testing.T) {
+	reg := registry.GetGlobalRegistry()
+	clientID := "test-claude-preserve-max-tokens-client"
+	modelID := "test-claude-preserve-max-tokens-model"
+	reg.RegisterClient(clientID, "claude", []*registry.ModelInfo{{
+		ID:                  modelID,
+		Type:                "claude",
+		OwnedBy:             "anthropic",
+		Object:              "model",
+		Created:             time.Now().Unix(),
+		MaxCompletionTokens: 4096,
+		UserDefined:         true,
+	}})
+	defer reg.UnregisterClient(clientID)
+
+	input := []byte(`{"model":"test-claude-preserve-max-tokens-model","max_tokens":2048,"messages":[{"role":"user","content":"hi"}]}`)
+	out := ensureModelMaxTokens(input, modelID)
+
+	if got := gjson.GetBytes(out, "max_tokens").Int(); got != 2048 {
+		t.Fatalf("max_tokens = %d, want %d", got, 2048)
+	}
+}
+
+func TestEnsureModelMaxTokens_SkipsUnregisteredModel(t *testing.T) {
+	input := []byte(`{"model":"test-claude-unregistered-model","messages":[{"role":"user","content":"hi"}]}`)
+	out := ensureModelMaxTokens(input, "test-claude-unregistered-model")
+
+	if gjson.GetBytes(out, "max_tokens").Exists() {
+		t.Fatalf("max_tokens should remain unset, got %s", gjson.GetBytes(out, "max_tokens").Raw)
+	}
+}
+
 // TestClaudeExecutor_ExecuteStream_SetsIdentityAcceptEncoding verifies that streaming
 // requests use Accept-Encoding: identity so the upstream cannot respond with a
 // compressed SSE body that would silently break the line scanner.