feat(compress): improve quality guardrails and format conversion

src/api/compress.rs

@@ -77,6 +77,22 @@ fn default_units_charged() -> i32 {
     1
 }
 
+fn ensure_target_size_supported(
+    target_size_bytes: Option<u64>,
+    format_out: ImageFmt,
+) -> Result<(), AppError> {
+    if target_size_bytes.is_some() && !compress::supports_target_size_format(format_out) {
+        return Err(AppError::new(
+            ErrorCode::InvalidRequest,
+            format!(
+                "target_size_bytes 仅支持输出 jpeg/webp/avif，当前为 {}",
+                format_out.as_str()
+            ),
+        ));
+    }
+    Ok(())
+}
+
 async fn compress_json(
     State(state): State<AppState>,
     jar: axum_extra::extract::cookie::CookieJar,
@@ -90,15 +106,8 @@ async fn compress_json(
     let req = parse_single_file_request(&mut multipart).await?;
 
     let format_in = compress::detect_format(&req.file_bytes)?;
-    if let Some(format_out) = req.output_format {
-        if format_out != format_in {
-            return Err(AppError::new(
-                ErrorCode::InvalidRequest,
-                "当前仅支持保持原图片格式",
-            ));
-        }
-    }
-    let format_out = format_in;
+    let format_out = req.output_format.unwrap_or(format_in);
+    ensure_target_size_supported(req.target_size_bytes, format_out)?;
     let effective_level = req
         .compression_rate
         .map(compress::rate_to_level)
@@ -407,15 +416,8 @@ async fn compress_direct(
     }
 
     let format_in = compress::detect_format(&req.file_bytes)?;
-    if let Some(format_out) = req.output_format {
-        if format_out != format_in {
-            return Err(AppError::new(
-                ErrorCode::InvalidRequest,
-                "当前仅支持保持原图片格式",
-            ));
-        }
-    }
-    let format_out = format_in;
+    let format_out = req.output_format.unwrap_or(format_in);
+    ensure_target_size_supported(req.target_size_bytes, format_out)?;
     let effective_level = req
         .compression_rate
         .map(compress::rate_to_level)

src/api/tasks.rs

@@ -540,12 +540,10 @@ async fn parse_batch_request(
         opts.level = compress::rate_to_level(rate);
     }
 
-    if opts.output_format.is_some() {
-        cleanup_file_paths(&files).await;
-        return Err(AppError::new(
-            ErrorCode::InvalidRequest,
-            "当前仅支持保持原图片格式",
-        ));
+    if let Some(format_out) = opts.output_format {
+        for file in &mut files {
+            file.output_format = format_out;
+        }
     }
 
     let mw = opts.max_width.map(|v| v.to_string()).unwrap_or_default();