fix(claude): add default max_tokens for models

internal/runtime/executor/claude_executor.go

@@ -22,6 +22,7 @@ import (
 	claudeauth "github.com/router-for-me/CLIProxyAPI/v6/internal/auth/claude"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/misc"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/thinking"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
 	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
@@ -44,10 +45,33 @@ 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
+// registered Claude models omit max_tokens. Use a conservative default.
+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 {
@@ -127,6 +151,7 @@ func (e *ClaudeExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, r
 
 	requestedModel := payloadRequestedModel(opts, req.Model)
 	body = applyPayloadConfigWithRoot(e.cfg, baseModel, to.String(), "", body, originalTranslated, requestedModel)
+	body = ensureModelMaxTokens(body, baseModel)
 
 	// Disable thinking if tool_choice forces tool use (Anthropic API constraint)
 	body = disableThinkingIfToolChoiceForced(body)
@@ -293,6 +318,7 @@ func (e *ClaudeExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.A
 
 	requestedModel := payloadRequestedModel(opts, req.Model)
 	body = applyPayloadConfigWithRoot(e.cfg, baseModel, to.String(), "", body, originalTranslated, requestedModel)
+	body = ensureModelMaxTokens(body, baseModel)
 
 	// Disable thinking if tool_choice forces tool use (Anthropic API constraint)
 	body = disableThinkingIfToolChoiceForced(body)