Retry Canon AFInfo2 scan; add Nikon D850 tag

Improve MakerNote decoding and contextual naming. Canon AFInfo2 decoding now retries by scanning a bounded region inside the MakerNote when the primary offset points at a non-AFInfo2 block, via new helpers (canon_afinfo2_payload_looks_valid, canon_find_afinfo2_payload). Add contextual Canon main tag handling for MakerNote tag 0x0000 (EntryNameContextKind::CanonMain0000) to select appropriate names for certain models. Add Nikon ShotInfo D850 tag 0x0024 (PhotoShootingMenuBank) to the registry. Also includes small refactors/formatting cleanups, updated tests, and VERSION/CHANGES updates.

Author: ssh4net

CHANGES.md

@@ -1,5 +1,22 @@
 # OpenMeta Changes
 
+## 0.4.26 - 2026-05-22
+
+Changes compared with `0.4.25`.
+
+### Added
+
+- Added contextual Canon MakerNote main tag `0x0000` names for the observed
+  camcorder and Cinema EOS cohorts.
+- Added Nikon ShotInfo D850 tag `0x0024` as `PhotoShootingMenuBank`.
+
+### Changed
+
+- Canon AFInfo2 decoding now retries with a bounded in-MakerNote payload scan
+  when the primary Canon offset points at a non-AFInfo2 block.
+- Nikon ShotInfo `0x0024` compatibility naming now covers the Z f ShotInfo
+  layout used by the interpretation path.
+
 ## 0.4.25 - 2026-05-21
 
 Changes compared with `0.4.24`.

VERSION

@@ -1 +1 @@
-0.4.25
+0.4.26

registry/exif/makernotes/nikon.jsonl

@@ -1289,6 +1289,7 @@
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod810","tag":"0x013c","name":"SecondarySlotFunction"}
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod850","tag":"0x0000","name":"ShotInfoVersion"}
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod850","tag":"0x0004","name":"FirmwareVersion"}
+{"kind":"exif.tag","ifd":"makernote:nikon:shotinfod850","tag":"0x0024","name":"PhotoShootingMenuBank"}
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod90","tag":"0x0000","name":"ShotInfoVersion"}
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod90","tag":"0x0004","name":"FirmwareVersion"}
 {"kind":"exif.tag","ifd":"makernote:nikon:shotinfod90","tag":"0x02b5","name":"ISO2"}

src/include/openmeta/meta_store.h

@@ -70,6 +70,7 @@ enum class EntryNameContextKind : uint8_t {
     CanonCustomFunctions2010C,
     CanonCustomFunctions20510,
     CanonCustomFunctions20701,
+    CanonMain0000,
 };
 
 /// Wire-format element type + family (e.g. TIFF type code).