feat(cv): qualify templates and reliable local import processing

JobTrackerApi/Controllers/AuthController.cs

@@ -16,6 +16,7 @@ namespace JobTrackerApi.Controllers;
 [Route("api/auth")]
 public sealed class AuthController : ControllerBase
 {
+    private static readonly SemaphoreSlim AvatarProcessingSlots = new(2, 2);
     private readonly IConfiguration _cfg;
     private readonly UserManager<ApplicationUser> _users;
     private readonly ITokenService _tokens;
@@ -933,9 +934,16 @@ public sealed class AuthController : ControllerBase
         }
 
         await using var stream = file.OpenReadStream();
-        using var memory = new MemoryStream();
-        await stream.CopyToAsync(memory);
-        var bytes = memory.ToArray();
+        var bytes = new byte[MaxAvatarBytes + 1];
+        var length = 0;
+        while (length < bytes.Length)
+        {
+            var read = await stream.ReadAsync(bytes.AsMemory(length), HttpContext.RequestAborted);
+            if (read == 0) break;
+            length += read;
+        }
+        if (length > MaxAvatarBytes) return BadRequest("Avatar image is too large.");
+        Array.Resize(ref bytes, length);
 
         var detectedContentType = DetectAvatarContentType(bytes);
         if (detectedContentType is null)
@@ -943,15 +951,40 @@ public sealed class AuthController : ControllerBase
             return BadRequest("Only PNG, JPEG, or WebP images are supported.");
         }
 
-        user.AvatarImageDataUrl = await AvatarStorage.StoreAsync(_avatarDataRoot, user.Id, bytes, detectedContentType, HttpContext.RequestAborted);
-
-        var result = await _users.UpdateAsync(user);
-        if (!result.Succeeded)
+        if (!await AvatarProcessingSlots.WaitAsync(0, HttpContext.RequestAborted))
+            return StatusCode(503, new { code = "avatar_busy", message = "Image processing is busy. Try again shortly." });
+        try
         {
-            return BadRequest(string.Join("; ", result.Errors.Select(e => e.Description)));
+            byte[]? normalized;
+            try { normalized = AvatarImageProcessor.Normalize(bytes); }
+            catch (Exception exception) when (exception is DllNotFoundException or TypeInitializationException or EntryPointNotFoundException or BadImageFormatException)
+            {
+                return StatusCode(503, new { code = "avatar_decoder_unavailable", message = "Image processing is unavailable. Your previous photo has been preserved." });
+            }
+            if (normalized is null) return BadRequest("Select a valid, still PNG, JPEG or WebP image up to 2048 pixels per side and 4 megapixels. Crop or resize larger images.");
+            var previous = user.AvatarImageDataUrl;
+            var staged = await AvatarStorage.StageAsync(_avatarDataRoot, user.Id, normalized, HttpContext.RequestAborted);
+            try
+            {
+                user.AvatarImageDataUrl = staged;
+                var result = await _users.UpdateAsync(user);
+                if (!result.Succeeded)
+                {
+                    user.AvatarImageDataUrl = previous;
+                    AvatarStorage.TryDelete(staged);
+                    return BadRequest("The photo could not be saved. Your previous photo has been preserved.");
+                }
+            }
+            catch
+            {
+                user.AvatarImageDataUrl = previous;
+                // An acknowledgement failure may follow a committed identity write; retention checks references.
+                throw;
+            }
+            AvatarStorage.TryDelete(previous);
+            return Ok(new { avatarImageDataUrl = $"data:image/png;base64,{Convert.ToBase64String(normalized)}" });
         }
-
-        return Ok(new { avatarImageDataUrl = AvatarStorage.Resolve(user.AvatarImageDataUrl) });
+        finally { AvatarProcessingSlots.Release(); }
     }
 
     [HttpDelete("avatar")]
@@ -972,7 +1005,7 @@ public sealed class AuthController : ControllerBase
             return BadRequest(string.Join("; ", result.Errors.Select(e => e.Description)));
         }
 
-        AvatarStorage.Delete(storedAvatar);
+        AvatarStorage.TryDelete(storedAvatar);
         return NoContent();
     }