fix: block ALL LS follow-up requests across connections

Move the in-flight blocking check to the top of the LLM request flow,
BEFORE request modification. This catches follow-ups on ALL connections
(the LS opens multiple parallel TLS connections). Only the very first
modified request reaches Google — all others get fake STOP responses.

Previously, each new connection independently allowed one request
through before blocking, letting 4-5 requests leak per turn.

src/api/util.rs

@@ -27,7 +27,9 @@ pub(crate) fn err_response(
 
 /// Convert a MITM-captured upstream error from Google into an HTTP response.
 /// Maps Google's HTTP status codes and preserves the error message.
-pub(crate) fn upstream_err_response(err: &crate::mitm::store::UpstreamError) -> axum::response::Response {
+pub(crate) fn upstream_err_response(
+    err: &crate::mitm::store::UpstreamError,
+) -> axum::response::Response {
     // Map Google's status code to HTTP status
     let status = StatusCode::from_u16(err.status).unwrap_or(StatusCode::BAD_GATEWAY);
 
@@ -41,7 +43,9 @@ pub(crate) fn upstream_err_response(err: &crate::mitm::store::UpstreamError) ->
         _ => "upstream_error",
     };
 
-    let message = err.message.clone()
+    let message = err
+        .message
+        .clone()
         .unwrap_or_else(|| format!("Google API returned HTTP {}", err.status));
 
     err_response(status, message, error_type)
@@ -99,7 +103,8 @@ pub(crate) fn extract_image_from_content(item: &serde_json::Value) -> Option<Ima
         }
         // OpenAI Responses API format
         "input_image" => {
-            let url = item["image_url"].as_str()
+            let url = item["image_url"]
+                .as_str()
                 .or_else(|| item["url"].as_str())?;
             parse_data_uri(url)
         }
@@ -109,5 +114,8 @@ pub(crate) fn extract_image_from_content(item: &serde_json::Value) -> Option<Ima
 
 /// Extract the first image from a content array (Value::Array of content parts).
 pub(crate) fn extract_first_image(content: &serde_json::Value) -> Option<ImageData> {
-    content.as_array()?.iter().find_map(extract_image_from_content)
+    content
+        .as_array()?
+        .iter()
+        .find_map(extract_image_from_content)
 }