The Tika preview extractor does a network call; it was using context.Background().
Pass the request context from the gRPC handler through Convert so the unpack call
respects cancellation and deadlines. Non-I/O decoders ignore the context.
Tika sniffs TIFF-based raws (NEF/DNG/ARW/PEF) as generic image/tiff by
content; only the filename extension routes them to the raw parser. Thread
the source name through to the unpack request via Content-Disposition.
Replace the in-process TIFF/BigTIFF walker (rawtiff.go) with a Tika-based
extractor: raw images are sent to a Tika server's /unpack endpoint, which
returns the embedded JPEG previews (Tika's RawTiffParser emits them as embedded
documents). The largest renderable JPEG is decoded through the image pipeline.
This aligns preview extraction with the search service (same Tika, same format
coverage) and drops a large hand-rolled parser. Raw thumbnails now require
THUMBNAILS_TIKA_TIKA_URL; without it, raw types fall back to the default decoder
(no thumbnail).
Audio artwork extraction stays in process for now and moves in a follow-up.
Add big-endian, largest-candidate, orientation-direction, isRenderableJPEG
classification and maxPreviewLength tests plus a ForType raw-dispatch check;
log a raw file without an embedded preview at debug instead of error; name the
TIFF magic constant and de-enumerate the decoder doc comment.
Dominik Schmidt