fix(send): set Width/Height on image messages so clients keep the aspect ratio

[mediam4kers]

Problem

ImageMessage is sent without Width/Height. WhatsApp clients use these fields to size the chat bubble before the media is downloaded. When they are missing, the iOS app shows every image in a square bubble and center-crops it.

We sent 1:1, 4:5, 3:4, 2:3 and 9:16 test images through /send/media (v0.7.2) to a group. On iPhone all five rendered in the same square, and the 4:5 image lost about 10% at the top and 10% at the bottom. The same image sent from the official app renders at its real ratio.

Fix

• Reading the size. imageDimensions(fileData) reads the pixel size with image.DecodeConfig, so only the header is parsed, not the whole image.
• Where it is set. Width/Height are set on every ImageMessage built from uploaded bytes:
  • /send/media by file and by URL, regular and newsletter;
  • carousel image headers;
  • reply-button image headers;
  • image status.
• EXIF orientation. Phone cameras often store a JPEG sideways and mark it with EXIF orientation 5-8. Clients display it rotated, so for those orientations the dimensions are swapped to the displayed size.
  • The JPEG preview from makeJPEGThumbnail is rotated or mirrored the same way (orientations 2-8), so it no longer previews sideways.
  • The orientation is read from the APP1 EXIF segment with a small parser, with no new dependency.
• Fallback. When the size cannot be read, both fields stay nil and the message is sent exactly as before.

Testing

• Unit tests for:
  • PNG landscape and JPEG portrait;
  • invalid data;
  • EXIF orientation reading (with and without EXIF, and a PNG);
  • dimensions swapped for orientation 6 and 8 and not for 1 and 3;
  • a portrait preview for a sideways JPEG;
  • the 90° rotation of orientRGBA.
• gofmt -l is clean and go test ./pkg/sendMessage/service/ passes. Both were run in a Docker build from tag 0.7.2 with this branch applied.
• In production. The first commit (dimensions) runs on our production instance. /send/media responses now include imageMessage.width/height, for example 1080x1350 and 1080x1920.

🤖 Generated with Claude Code

[sourcery-ai]

Reviewer's Guide

The PR fixes client-side image aspect-ratio rendering by reading image dimensions from file headers and attaching them to every uploaded ImageMessage path, while retaining backward-compatible behavior when dimensions cannot be determined.

Sequence diagram for attaching image dimensions to media messages

sequenceDiagram
    participant Client
    participant SendService
    participant ImageHeader
    participant MediaUpload
    participant WhatsApp

    Client->>SendService: sendMediaFileWithRetry() or sendMediaUrlWithRetry()
    SendService->>ImageHeader: imageDimensions(fileData)
    ImageHeader-->>SendService: width, height or nil, nil
    SendService->>MediaUpload: upload image data
    SendService->>WhatsApp: Send ImageMessage with Width and Height
    WhatsApp-->>Client: Image bubble sized to image ratio

Loading

File-Level Changes

Change	Details	Files
Adds header-only image dimension detection with graceful fallback for unreadable data.	Uses image.DecodeConfig to extract pixel width and height without fully decoding images. Returns nil dimensions on invalid or unsupported image data, preserving prior send behavior. Adds unit coverage for PNG landscape, JPEG portrait, and invalid input.	pkg/sendMessage/service/send_service.go pkg/sendMessage/service/dimensions_test.go
Propagates detected dimensions into all supported uploaded image message variants.	Sets Width and Height for regular and newsletter media sent by file or URL. Sets dimensions on carousel image headers. Sets dimensions on image status messages.	pkg/sendMessage/service/send_service.go

Possibly linked issues

• #GOWS/send: The PR directly fixes the issue by populating Width/Height for uploaded and URL-sourced image messages.

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[sourcery-ai]

Hey - I've found 2 issues

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="pkg/sendMessage/service/send_service.go" line_range="1046" />
<code_context>
 			// particular). On failure jpegThumb is nil and the message is sent
 			// without a preview rather than failing the request.
 			jpegThumb := makeJPEGThumbnail(fileData, 72)
+			imgWidth, imgHeight := imageDimensions(fileData)
 			if isNewsletter {
 				// Newsletter: SEM MediaKey e FileEncSHA256
</code_context>
<issue_to_address>
**Button images use square sizing**

When a button message sends a non-square image URL, `SendButton` builds the uploaded button `ImageMessage` without calling `imageDimensions` or setting `Width` and `Height`, so clients fall back to square sizing and crop the image to the wrong aspect ratio.

Call `imageDimensions` on the downloaded image and set the returned `Width` and `Height` on the button image message.

Also at `pkg/sendMessage/service/send_service.go:1057-1058`, `pkg/sendMessage/service/send_service.go:1351`, `pkg/sendMessage/service/send_service.go:2147-2148`.
</issue_to_address>

### Comment 2
<location path="pkg/sendMessage/service/send_service.go" line_range="2148" />
<code_context>
+// center-crops portrait and landscape images. It returns nil pointers when the
+// size cannot be read, so the message is still sent (just without dimensions).
+func imageDimensions(fileData []byte) (width, height *uint32) {
+	cfg, _, err := image.DecodeConfig(bytes.NewReader(fileData))
+	if err != nil || cfg.Width < 1 || cfg.Height < 1 {
+		return nil, nil
</code_context>
<issue_to_address>
**Rotated JPEGs get wrong dimensions**

When an uploaded JPEG has EXIF orientation 5, 6, 7, or 8, `image.DecodeConfig` returns the encoded dimensions, and `imageDimensions` copies them unchanged, so the outgoing `Width` and `Height` have the wrong aspect ratio and clients size the bubble incorrectly.

Read the JPEG orientation and swap the dimensions for orientations 5 through 8 before returning them.
</issue_to_address>

Sourcery assessment

Needs a human reviewer. 2 findings to address first, and the change adds image dimensions to outbound message metadata, so an incorrect or unsupported dimension could be retained in already-sent messages and cause clients to render the image with the wrong aspect ratio. Reverting stops future messages from using the values, but does not change messages that were already sent; the impact is bounded to presentation and can generally be corrected by resending the image.

Blocking findings: pkg/sendMessage/service/send_service.go:1046, pkg/sendMessage/service/send_service.go:2148

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