refactor: use named constants for image format magic bytes

- Remove __future__ annotations import from input_model.py
- Replace inline byte literals with named constants in image_format_detector.py
- Calculate lengths dynamically using len() instead of hardcoded values
- Eliminates need for noqa comments on magic value comparisons

Author: corpo-iwillspeak

src/resolver_athena_client/client/image_format_detector.py

@@ -2,6 +2,16 @@
 
 from resolver_athena_client.generated.athena.models_pb2 import ImageFormat
 
+PNG_MAGIC_BYTES = b"\x89PNG"
+JPEG_MAGIC_BYTES = b"\xFF\xD8\xFF"
+GIF87A_MAGIC_BYTES = b"GIF87a"
+GIF89A_MAGIC_BYTES = b"GIF89a"
+BMP_MAGIC_BYTES = b"BM"
+WEBP_RIFF_MAGIC_BYTES = b"RIFF"
+WEBP_WEBP_MAGIC_BYTES = b"WEBP"
+TIFF_LE_MAGIC_BYTES = b"II*\x00"
+TIFF_BE_MAGIC_BYTES = b"MM\x00*"
+
 
 def detect_image_format(data: bytes) -> ImageFormat.ValueType:  # noqa: PLR0911
     """Detect image format from raw bytes using magic number signatures.
@@ -19,29 +29,45 @@ def detect_image_format(data: bytes) -> ImageFormat.ValueType:  # noqa: PLR0911
         return ImageFormat.IMAGE_FORMAT_UNSPECIFIED
 
     # Check magic numbers for common image formats
-    # PNG: starts with \x89PNG (need at least 4 bytes)
-    if len(data) >= 4 and data[:4] == b"\x89PNG":  # noqa: PLR2004
+    # PNG: starts with PNG_MAGIC_BYTES
+    png_len = len(PNG_MAGIC_BYTES)
+    if len(data) >= png_len and data[:png_len] == PNG_MAGIC_BYTES:
         return ImageFormat.IMAGE_FORMAT_PNG
 
-    # JPEG: starts with \xFF\xD8\xFF (need at least 3 bytes)
-    if len(data) >= 3 and data[:3] == b"\xff\xd8\xff":  # noqa: PLR2004
+    # JPEG: starts with JPEG_MAGIC_BYTES
+    jpeg_len = len(JPEG_MAGIC_BYTES)
+    if len(data) >= jpeg_len and data[:jpeg_len] == JPEG_MAGIC_BYTES:
         return ImageFormat.IMAGE_FORMAT_JPEG
 
-    # GIF: starts with GIF87a or GIF89a (need at least 6 bytes)
-    if len(data) >= 6 and data[:6] in (b"GIF87a", b"GIF89a"):  # noqa: PLR2004
+    # GIF: starts with GIF87A_MAGIC_BYTES or GIF89A_MAGIC_BYTES
+    gif_len = len(GIF87A_MAGIC_BYTES)
+    if len(data) >= gif_len and data[:gif_len] in (
+        GIF87A_MAGIC_BYTES,
+        GIF89A_MAGIC_BYTES,
+    ):
         return ImageFormat.IMAGE_FORMAT_GIF
 
-    # BMP: starts with BM (need at least 2 bytes)
-    if len(data) >= 2 and data[:2] == b"BM":  # noqa: PLR2004
+    # BMP: starts with BMP_MAGIC_BYTES
+    bmp_len = len(BMP_MAGIC_BYTES)
+    if len(data) >= bmp_len and data[:bmp_len] == BMP_MAGIC_BYTES:
         return ImageFormat.IMAGE_FORMAT_BMP
 
-    # WebP: starts with RIFF....WEBP (need at least 12 bytes)
-    if len(data) >= 12 and data[:4] == b"RIFF" and data[8:12] == b"WEBP":  # noqa: PLR2004
+    # WebP: RIFF....WEBP (12 bytes minimum for full signature)
+    webp_min_len = len(WEBP_RIFF_MAGIC_BYTES) + len(WEBP_WEBP_MAGIC_BYTES) + 4
+    if (
+        len(data) >= webp_min_len
+        and data[:4] == WEBP_RIFF_MAGIC_BYTES
+        and data[8:12] == WEBP_WEBP_MAGIC_BYTES
+    ):
         return ImageFormat.IMAGE_FORMAT_WEBP
 
-    # TIFF: starts with II* or MM* (need at least 4 bytes)
-    if len(data) >= 4 and data[:4] in (b"II*\x00", b"MM\x00*"):  # noqa: PLR2004
+    # TIFF: little-endian or big-endian magic bytes
+    tiff_len = len(TIFF_LE_MAGIC_BYTES)
+    if len(data) >= tiff_len and (
+        data[:tiff_len] == TIFF_LE_MAGIC_BYTES
+        or data[:tiff_len] == TIFF_BE_MAGIC_BYTES
+    ):
         return ImageFormat.IMAGE_FORMAT_TIFF
 
-    # If we can't detect the format, return UNSPECIFIED
+    # Fallback when format cannot be determined
     return ImageFormat.IMAGE_FORMAT_UNSPECIFIED

src/resolver_athena_client/client/models/input_model.py

@@ -5,8 +5,6 @@
 consistent input handling across the application.
 """
 
-from __future__ import annotations
-
 import hashlib
 from typing import TYPE_CHECKING