修复Chat生成预算字段兼容

新增Chat生成预算字段能力并兼容新旧网关
VectorEngine编辑器客户端改用max_completion_tokens
补充BGM请求体回归与协议文档约束

server-rs/crates/api-server/src/editor_background_music_prompt_assist.rs

@@ -887,6 +887,11 @@ mod tests {
             requests[0].body["model"],
             BACKGROUND_MUSIC_PROMPT_ASSIST_MODEL
         );
+        assert_eq!(
+            requests[0].body["max_completion_tokens"],
+            BACKGROUND_MUSIC_PROMPT_ASSIST_MAX_OUTPUT_TOKENS
+        );
+        assert!(requests[0].body.get("max_tokens").is_none());
         assert_eq!(requests[0].body["reasoning_effort"], "medium");
         assert!(requests[0].body.get("tools").is_none());
         assert!(requests[0].body.get("tool_choice").is_none());

server-rs/crates/api-server/src/state.rs

@@ -21,7 +21,7 @@ use platform_auth::{
     RefreshCookieConfig, RefreshCookieError, RefreshCookieSameSite, SmsAuthConfig, SmsAuthProvider,
     SmsAuthProviderKind, SmsProviderError, WechatProvider, sign_access_token, verify_access_token,
 };
-use platform_llm::{LlmClient, LlmConfig, LlmError, LlmProvider};
+use platform_llm::{LlmClient, LlmConfig, LlmError, LlmProvider, OpenAiChatTokenBudgetField};
 use platform_matting::{MattingClient, MattingConfig};
 use platform_oss::{OssClient, OssConfig, OssError};
 use platform_wechat::{WechatClient, WechatConfig, pay::WechatPayClient};
@@ -2187,7 +2187,8 @@ fn build_editor_agent_llm_client(
         config
             .llm_retry_backoff_ms
             .min(EDITOR_AGENT_LLM_MAX_RETRY_BACKOFF_MS),
-    )?;
+    )?
+    .with_openai_chat_token_budget_field(OpenAiChatTokenBudgetField::MaxCompletionTokens);
 
     Ok(Some(LlmClient::new(llm_config)?))
 }
@@ -2508,6 +2509,10 @@ mod tests {
             "https://api.vectorengine.test/v1/chat/completions"
         );
         assert!(!client.config().official_fallback());
+        assert_eq!(
+            client.config().openai_chat_token_budget_field(),
+            OpenAiChatTokenBudgetField::MaxCompletionTokens
+        );
         assert_eq!(client.config().max_retries(), 1);
         assert_eq!(client.config().retry_backoff_ms(), 60_000);
     }