diff --git a/src/mime.rs b/src/mime.rs
index fd9c448..3761ab3 100644
--- a/src/mime.rs
+++ b/src/mime.rs
@@ -146,4 +146,128 @@ mod tests {
     let data = b"\x80\x81\x82\x83\x84\x85\x86\x87";
     assert_eq!(detect_mime(data), None);
   }
+
+  #[test]
+  fn test_uri_list_trailing_newline() {
+    let data = b"file:///foo\n";
+    assert_eq!(detect_mime(data), Some("text/uri-list".to_string()));
+  }
+
+  #[test]
+  fn test_uri_list_ftp() {
+    let data = b"ftp://host/path";
+    assert_eq!(detect_mime(data), Some("text/uri-list".to_string()));
+  }
+
+  #[test]
+  fn test_uri_list_mixed_schemes() {
+    let data = b"file:///home/user/doc.pdf\nhttps://example.com/file.zip";
+    assert_eq!(detect_mime(data), Some("text/uri-list".to_string()));
+  }
+
+  #[test]
+  fn test_plain_url_in_text() {
+    let data = b"visit http://example.com for info";
+    assert_eq!(detect_mime(data), Some("text/plain".to_string()));
+  }
+
+  #[test]
+  fn test_png_magic_bytes() {
+    // Real PNG header: 8-byte signature + minimal IHDR chunk
+    let data: &[u8] = &[
+      0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG signature
+      0x00, 0x00, 0x00, 0x0D, // IHDR chunk length
+      0x49, 0x48, 0x44, 0x52, // "IHDR"
+      0x00, 0x00, 0x00, 0x01, // width: 1
+      0x00, 0x00, 0x00, 0x01, // height: 1
+      0x08, 0x02, // bit depth: 8, color type: 2 (RGB)
+      0x00, 0x00, 0x00, // compression, filter, interlace
+      0x90, 0x77, 0x53, 0xDE, // CRC
+    ];
+    assert_eq!(detect_mime(data), Some("image/png".to_string()));
+  }
+
+  #[test]
+  fn test_jpeg_magic_bytes() {
+    // JPEG SOI marker + APP0 (JFIF) marker
+    let data: &[u8] = &[
+      0xFF, 0xD8, 0xFF, 0xE0, // SOI + APP0
+      0x00, 0x10, // Length
+      0x4A, 0x46, 0x49, 0x46, 0x00, // "JFIF\0"
+      0x01, 0x01, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00,
+    ];
+    assert_eq!(detect_mime(data), Some("image/jpeg".to_string()));
+  }
+
+  #[test]
+  fn test_gif_magic_bytes() {
+    // GIF89a header
+    let data: &[u8] = &[
+      0x47, 0x49, 0x46, 0x38, 0x39, 0x61, // "GIF89a"
+      0x01, 0x00, 0x01, 0x00, // 1x1
+      0x80, 0x00, 0x00, // GCT flag, bg, aspect
+    ];
+    assert_eq!(detect_mime(data), Some("image/gif".to_string()));
+  }
+
+  #[test]
+  fn test_webp_magic_bytes() {
+    // RIFF....WEBP header
+    let data: &[u8] = &[
+      0x52, 0x49, 0x46, 0x46, // "RIFF"
+      0x24, 0x00, 0x00, 0x00, // file size
+      0x57, 0x45, 0x42, 0x50, // "WEBP"
+      0x56, 0x50, 0x38, 0x20, // "VP8 "
+      0x18, 0x00, 0x00, 0x00, // chunk size
+      0x30, 0x01, 0x00, 0x9D, 0x01, 0x2A, // VP8 bitstream
+      0x01, 0x00, 0x01, 0x00, // width/height
+    ];
+    assert_eq!(detect_mime(data), Some("image/webp".to_string()));
+  }
+
+  #[test]
+  fn test_whitespace_only() {
+    let data = b"   \n\t  ";
+    // Valid UTF-8 text, even if only whitespace. [`detect_mime`] doesn't reject
+    // it (store_entry rejects it separately). As text it's text/plain.
+    assert_eq!(detect_mime(data), Some("text/plain".to_string()));
+  }
+
+  #[test]
+  fn test_image_type_to_mime_coverage() {
+    assert_eq!(image_type_to_mime(ImageType::Png), "image/png");
+    assert_eq!(image_type_to_mime(ImageType::Jpeg), "image/jpeg");
+    assert_eq!(image_type_to_mime(ImageType::Gif), "image/gif");
+    assert_eq!(image_type_to_mime(ImageType::Bmp), "image/bmp");
+    assert_eq!(image_type_to_mime(ImageType::Tiff), "image/tiff");
+    assert_eq!(image_type_to_mime(ImageType::Webp), "image/webp");
+    assert_eq!(image_type_to_mime(ImageType::Aseprite), "image/x-aseprite");
+    assert_eq!(image_type_to_mime(ImageType::Dds), "image/vnd.ms-dds");
+    assert_eq!(image_type_to_mime(ImageType::Exr), "image/aces");
+    assert_eq!(image_type_to_mime(ImageType::Farbfeld), "image/farbfeld");
+    assert_eq!(image_type_to_mime(ImageType::Hdr), "image/vnd.radiance");
+    assert_eq!(image_type_to_mime(ImageType::Ico), "image/x-icon");
+    assert_eq!(image_type_to_mime(ImageType::Ilbm), "image/ilbm");
+    assert_eq!(image_type_to_mime(ImageType::Jxl), "image/jxl");
+    assert_eq!(image_type_to_mime(ImageType::Ktx2), "image/ktx2");
+    assert_eq!(
+      image_type_to_mime(ImageType::Pnm),
+      "image/x-portable-anymap"
+    );
+    assert_eq!(
+      image_type_to_mime(ImageType::Psd),
+      "image/vnd.adobe.photoshop"
+    );
+    assert_eq!(image_type_to_mime(ImageType::Qoi), "image/qoi");
+    assert_eq!(image_type_to_mime(ImageType::Tga), "image/x-tga");
+    assert_eq!(image_type_to_mime(ImageType::Vtf), "image/x-vtf");
+    assert_eq!(
+      image_type_to_mime(ImageType::Heif(imagesize::Compression::Hevc)),
+      "image/heic"
+    );
+    assert_eq!(
+      image_type_to_mime(ImageType::Heif(imagesize::Compression::Av1)),
+      "image/heif"
+    );
+  }
 }