neo/docs/superpowers/specs/2026-07-15-pure-go-exiv-design.md

Pure-Go WebP EXIF RIFF Injector

1. Goal

Completely remove file-based IO and the webpmux dependency by weaving the EXIF chunk into the WebP RIFF byte struct physically in memory.

2. Architecture

Instead of using webpmux passing paths around, helper/exif.go will implement InjectExif(webpBytes []byte, packName, publisher string) ([]byte, error).

3. RIFF Parsing Logic

1. Validate RIFF and WEBP signatures.
2. Read all chunks to extract Canvas Width/Height (from VP8X, VP8L, or VP8 ).
3. Identify if VP8X is missing, and if so, construct it. We must ensure the EXIF bit flag is set.
4. Construct the custom EXIF chunk (which holds the exact binary array and JSON metadata we validated via F-BOT_GO earlier).
5. Append EXIF to the end of the WebP chunks, update the main RIFF file size pointer, and return the aggregated []byte slice.

4. Main Command Refactor

cmds/media/sticker.go will stop requesting files via ResolveExif(). It will simply pass the raw Webp bytes received from ConvertImageToWebp or ConvertVideoToWebp into InjectExif and instantly upload the resulting byte array.