HyperOS Gallery reads EXIF 0x889e (a JSON blob) to build its watermark
frame; without it a photo fails with "cannot recognize the parameters".
CameraX/HAL never supplies that vendor tag, so a capture from this app
lacked it while a stock-camera photo carried it.
Read back the same props the stock camera derives the blob from
(ro.product.device / ro.product.marketname / Build.MANUFACTURER) via the
native module, synthesize the blob in exifWrite, and write it only when
the source has none and the device is Xiaomi/Redmi/POCO - a source blob
is never overwritten.
Match the layout the sample camera file uses: a fourth Interoperability IFD
(0xa005 = R98/0100) and the baseline tags the emulator HAL omits (ExifVersion
0230, FlashPixVersion 0100, ComponentsConfiguration, ColorSpace), plus the
OffsetTime/OffsetTimeOriginal/OffsetTimeDigitized tags for shots this app
timestamps. Source-owned tags are still kept as-is.
Also fix swapToLittleEndian: Buffer.slice() aliases, so the big-endian swap was
mutating the caller's bytes (a Xiaomi source read back as ISO 36865 instead of
400). Use new Uint8Array(data).
- FRAME/CROP: choosing a ratio shows the amber band (border + 0.55 dim);
APPLY collapses the preview to the crop rect with an opaque mask and
removes the amber stroke; RESET returns to 'none'.
- Viewfinder: libCropView (k = min(vw/dw, vh/dh)) + cropScreenPx drive the
mask/band, libViewMatrix folds the crop transform into the image groups,
libCropTouchStyle keeps touch mapping aligned.
- Persist cropApplied in the session snapshot and restore it only when it
still matches cropRatio.
- Add PLAN-2026-09-09.md with the measurements.
tsc --noEmit unchanged at 14 pre-existing errors.
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