Guess mime type on multi-part when not set

src-tauri/Cargo.lock

@@ -2929,9 +2929,9 @@ checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
 [[package]]
 name = "mime_guess"
-version = "2.0.4"
+version = "2.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4192263c238a5f0d0c6bfd21f336a313a4ce1c450542449ca191bb657b4642ef"
+checksum = "f7c44f8e672c00fe5308fa235f821cb4198414e1c77935c1ab6948d3fd78550e"
 dependencies = [
  "mime",
  "unicase",
@@ -7347,6 +7347,7 @@ dependencies = [
  "hex_color",
  "http 1.1.0",
  "log",
+ "mime_guess",
  "objc",
  "openssl-sys",
  "plugin_runtime",

src-tauri/Cargo.toml

@@ -55,3 +55,4 @@ tokio = { version = "1.36.0", features = ["sync"] }
 tokio-stream = "0.1.15"
 uuid = "1.7.0"
 thiserror = "1.0.61"
+mime_guess = "2.0.5"

src-tauri/src/http_request.rs

@@ -10,6 +10,7 @@ use base64::Engine;
 use http::header::{ACCEPT, USER_AGENT};
 use http::{HeaderMap, HeaderName, HeaderValue};
 use log::{error, info, warn};
+use mime_guess::Mime;
 use reqwest::redirect::Policy;
 use reqwest::Method;
 use reqwest::{multipart, Url};
@@ -318,13 +319,21 @@ pub async fn send_http_request(
                         .as_str()
                         .unwrap_or_default();
 
+                    // Set or guess mimetype
                     if !ct_raw.is_empty() {
                         let content_type = render::render(ct_raw, &vars);
                         part = part
                             .mime_str(content_type.as_str())
                             .map_err(|e| e.to_string())?;
+                    } else if !file_path.is_empty() {
+                        let default_mime = Mime::from_str("application/octet-stream").unwrap();
+                        let mime = mime_guess::from_path(file_path).first_or(default_mime);
+                        part = part
+                            .mime_str(mime.essence_str())
+                            .map_err(|e| e.to_string())?;
                     }
 
+                    // Set fil path if not empty
                     if !file_path.is_empty() {
                         let filename = PathBuf::from(file_path)
                             .file_name()