API Stability

This page defines the adoption status for public OpenMeta APIs. Python bindings mirror these labels unless a Python wrapper documents a different status.

Stability levels

Level	Meaning
Stable	Intended for downstream use. Breaking changes require a new contract version, a compatibility path, or a documented migration.
Experimental	Public and tested, but the exact shape or semantics may still evolve while the surrounding workflow is being hardened.
Internal	Publicly visible only because it is part of a lower-level implementation surface. Do not build new downstream integrations on it unless another doc names it as supported.

Host-facing API map

API surface	Header	Stability	Notes
Runtime capability query: metadata_capability(...)	openmeta/metadata_capabilities.h	Stable	v1 query contract for read, structured decode, transfer preparation, target edit, and raw-preservation status by format/family.
Compatibility dumps: dump_metadata_compatibility(...), dump_transfer_compatibility(...)	openmeta/compatibility_dump.h	Stable	Stable v1 line-oriented compatibility dump contract, including generic BMFF component membership, role, relation-summary, policy, and derived-image construction fields as normal bmff_field entries. See Compatibility Dump Contract.
XMP sync and writeback policy enums: XmpConflictPolicy, existing-carrier precedence enums, XmpWritebackMode, destination carrier modes	openmeta/xmp_dump.h, openmeta/metadata_transfer.h	Stable	Stable bounded writer policy for generated portable XMP. See XMP Sync And Writeback Policy.
Generic metadata traversal: visit_metadata(...), MetadataSink, ExportOptions, ExportItem	openmeta/interop_export.h	Stable	v1 traversal contract. Borrowed names are valid only during MetadataSink::on_item(...).
ExportNameStyle::Canonical and ExportNameStyle::XmpPortable	openmeta/interop_export.h	Stable	Stable naming modes for key-space-aware and portable exports.
ExportNameStyle::FlatHost	openmeta/interop_export.h	Stable	Stable v1 flat host naming contract. See FlatHost Mapping Contract.
EXIF/TIFF orientation helpers: interpret_exif_orientation(...), exif_orientation_name(...), exif_orientation_rotation_degrees_cw(...), exif_orientation_rotation_only(...)	openmeta/orientation.h	Stable	Small utility contract for user-facing orientation labels, clockwise rotation degrees, mirrored-state detection, dimension-swap detection, and rotation-only fallbacks. Python exposes the same helpers through thin scalar/dictionary wrappers.
EXIF/TIFF/DNG numeric value names and version formatting: exif_tag_numeric_value_name(...), exif_tag_numeric_value_format(...), exif_tag_byte_value_format(...), and focused helpers	openmeta/exif_value_names.h	Stable	Small helper contract for common enum-like TIFF/EXIF/DNG numeric values such as compression, photometric interpretation, planar configuration, exposure program/mode, metering mode, light source, flash, color space, white balance, scene capture type, gain control, CFA layout, and DNG calibration illuminants, and EXIF 3.1 lens-correction / noise-reduction status values, plus selected bounded Canon/Nikon/ Sony/Fujifilm/Pentax/Olympus/Panasonic/Phase One/Kodak/Minolta/Sigma/ Samsung/Ricoh/Apple/FLIR/JVC/GE/Reconyx/Microsoft/Motorola/Nintendo/Sanyo MakerNote contexts including NikonSettings On/Off labels, Reconyx scalar labels, Microsoft stitch labels, Motorola CustomRendered labels, Nintendo category labels, Sanyo public-context scalar labels, current Canon RF lens-type labels, current Nikon Z LensData0800 LensID labels, and an ambiguous Pentax Sigma/Samsung/Tokina lens-family label where stable. Version/firmware helpers format selected standard EXIF byte-version fields, Nikon version-like payloads, Olympus packed firmware values, and native RAF firmware payloads without treating formatted versions as enum labels. Unknown or ambiguous values return an empty string or false and remain lossless metadata.
Photoshop IRB decode: decode_photoshop_irb(...) and measure_photoshop_irb(...)	openmeta/photoshop_irb_decode.h	Experimental	Bounded resource traversal with stable raw resource preservation behavior, but the interpreted subset can still grow. Current interpretation includes fixed-layout resource fields, display/grid/thumbnail/color-sampler headers, working-path and numbered clipping-path byte counts / record summaries, descriptor-header summaries plus safe descriptor class-name/class-ID/ item-count fields, bounded descriptor item bodies for bool, long, doub, UntF, TEXT, enum, and tdta raw-data byte counts with descriptor item type-name/type-code fields, parsed maximum depth, and parsed per-type counters, nested object/list traversal with item path/depth/list-index and parsed-value count fields, XMLData, ImageReady ASCII text resources, Lightroom workflow text, Macintosh PrintInfo, Macintosh NSPrintInfo, Windows DEVMODE, alternate duotone-color, alternate spot-color, and obsolete Photoshop tag byte counts, legacy halftone/transfer/duotone/EPS byte summaries, embedded IPTC/ICC/EXIF/EXIF2/XMP byte-count fields, and optional embedded IPTC-IIM, XMP, and ICC payload decode.
Semantic metadata query: query_metadata(...), query_crop_metadata(...), focused query helpers, and metadata_query_fuzzy_search_available()	openmeta/metadata_query.h	Experimental	Query contract for inspection matches plus normalized candidates. Current coverage includes crop/active-area/border margins, exposure/gain, white balance, color/profile/source-color-transform, lens correction, orientation, descriptive EXIF/IPTC/XMP fields, container-graph evidence for BMFF content-bound metadata and multi-image scene policy, and RAW/source-processing metadata across standard tags, selected DNG tags, RAW value curves, RAW linearity limits, RAW calibration curves, RAW curve control points, EXIF color-space evidence, ICC header/tag entries, XMP ICC/profile/color-space fields, XMP camera RAW profile/look/tone-curve fields, PNG profile text carriers, Fujifilm RAF raw crop/zoom rectangles, Canon aspect/crop metadata, Canon AF micro-adjustment, Canon ambience-selection, Canon ColorData source color-transform, NikonSettings source-processing aliases, Nikon Capture crop bounds, Sony panorama crop margins, selected decoded vendor/MakerNote exposure names, fuzzy XMP paths, and vendor RAW-processing classification. Matches report exact_match, fuzzy_match, and fuzzy_score so tools can label exact results separately from RapidFuzz near-miss hits. OPENMETA_ENABLE_RAPIDFUZZ=ON adds optional near-miss XMP/property-path scoring. Grouped candidates include matrix_set, vector_set, and table shapes for related non-crop metadata, including RAW black/white levels, linearization, raw value curves, raw linearity limits, raw calibration curves, raw curve control points, CFA/sensor layout, source geometry, raw-storage identifiers, and source-processing buckets, and per-family vendor MakerNote/RAW white-balance, source-color-transform, raw-storage, sensor, computational, thermal, stitch/panorama, and source-processing groups. Matrix/vector/table groups are promoted only when the available numeric payloads meet conservative minimum shapes, so malformed color matrices, white-balance vectors, and lens-correction records remain per-entry inspection data instead of becoming normalized groups. Long-tail source color/style/lens/source-processing aliases such as camera-to-XYZ/RGB matrices, creative/picture style, film simulation, dynamic-range, optical-correction, AF micro-adjustment, ambience selection, Canon ColorData, NikonSettings, and raw-development terms are classified for query and transfer-policy inspection; camera RAW profiles, looks, tone curves, and vendor source color tables use the explicit source_color_transform semantic, RAW curve/linearity metadata uses dedicated RAW-processing semantics, and computational, thermal, and stitch/panorama fields use explicit source-processing subroles. Python Document and TransferSourceSnapshot mirror this as thin dictionary-returning wrappers.
Structured metadata interpretation records: interpret_metadata(...) and interpret_metadata_query(...)	openmeta/metadata_interpretation.h	Experimental	Thin structured projection over semantic query candidates. Records carry query class, semantic kind, normalized shape, confidence, source entry ids, and normalized origin/size/rect/margins/value arrays where available. Current scope covers orientation, geometry/crop/border including Fujifilm RAF, Canon, Nikon Capture, and Sony panorama geometry patterns, exposure/gain, color/white-balance/profile/source-color-transform records, lens-correction, and RAW/source-processing records including raw value curves, linearity limits, calibration curves, curve control points, computational, thermal, and stitch/panorama subroles, and grouped vendor-family table/vector records where classification supports them. Python Document and TransferSourceSnapshot expose matching dictionary wrappers.
Cross-family concept resolution: resolve_metadata_concepts(...) and resolve_metadata_concept(...)	openmeta/metadata_concepts.h	Experimental	First bounded resolver for duplicated host-facing concepts. Current scope reports candidates, candidate source entries, source families, preferred entries, normalized numeric/text keys, full normalized value vectors, transfer hints, RAW applicability states, normalized date/time fields, date/time precision, timezone kind, normalized geometry fields, normalized exposure values, and same-role conflicts for orientation, date/time, exposure/gain, color/profile/source-color-transform, GPS, geometry, lens-correction, RAW-processing, and container-graph evidence across EXIF, XMP, IPTC, ICC, PNG text, BMFF fields, and query-backed interpretation records where applicable. Exposure candidates cover exposure time, aperture, ISO sensitivity, exposure bias, exposure program/mode, gain, and raw exposure-adjustment roles across standard EXIF/DNG/XMP evidence and selected decoded vendor/MakerNote exposure names. Standard EXIF exposure program/mode and gain-control values plus selected Canon/Nikon/Sony/Fujifilm/ Pentax/Olympus/Panasonic/Phase One/Kodak/Minolta/Sigma/Samsung/Ricoh MakerNote values include human-readable labels where stable. Capture exposure facts are safe, while raw/DNG exposure adjustments stay rendered-unsafe. Geometry candidates cover crop, active area, border, and sensor geometry with canonical origin, size, rect, and margin fields when available, including normalized DNG, Phase One/Leaf, Fujifilm RAF, Canon, Nikon Capture, and Sony panorama geometry patterns. Candidate transfer hints distinguish safe, source_bound, rendered_unsafe, and requires_target_image_spec evidence, with compatible-file and rendered-image safety booleans. Color/white-balance, source-color-transform, lens-correction, RAW-processing, and container-graph concepts preserve source evidence for host inspection; source-bound color transforms and RAW curve/linearity/calibration roles are marked rendered-unsafe, computational, thermal, and stitch/panorama RAW-processing roles are marked source-bound, and BMFF whole-scene, primary-component, and per-component content-bound metadata / multi-image policy plus derived-image construction fields are marked source-bound. RAW curve/LUT-like concept roles are conservatively marked conditional_on_raw_encoding until a raw data descriptor can confirm whether they affect the stored samples. Descriptor-aware overloads accept MetadataRawDataDescriptor and can collapse supported stored-RAW descriptors to applies_to_stored_raw or rendered descriptors to not_applicable_to_stored_raw, or compressed-only descriptors to not-applicable when the supplied storage encoding is uncompressed or packed, and primary-plane-only descriptors to not-applicable when the supplied plane index is non-primary. EXIF and XMP GPS date/time are combined from GPSDateStamp plus GPSTimeStamp when both entries exist, IPTC digital-creation date/time and XMP DateTimeDigitized map to the Digitized date/time role, and GPS altitude candidates expose altitude-reference code plus below-sea-level state when reference metadata is present; metadata_concept_gps_altitude_reference_name(...) provides a stable display token for the reference code. It is intended for inspection UI and host policy decisions; it does not rewrite metadata or hide ambiguity. Python Document and TransferSourceSnapshot expose matching dictionary wrappers, including the thin MetadataRawDataDescriptor object with storage, compression, and plane-binding fields.
Transfer concept diagnostics: transfer_concept_diagnostics_from_store(...), transfer_concept_diagnostic_message(...), transfer_concept_diagnostic_token(...), transfer_concept_diagnostic_message_token(...), transfer_concept_diagnostic_message_arguments(...)	openmeta/metadata_transfer.h	Experimental	Preflight view over concept candidates for TransferSafetyMode. Each diagnostic reports concept kind/role, transfer hint, keep/drop/requires-target-image-spec action, reason token, severity token, stable host-facing summary token, stable localization message token, localizable argument tokens, default message text, conflict flag, source entries, compatible/rendered safety booleans, RAW applicability state, and GPS altitude-reference presentation fields. Descriptor-aware overloads accept MetadataRawDataDescriptor and make RAW-processing keep/drop decisions reflect the supplied stored-RAW, compressed-only, primary-plane-only, or rendered storage context. PrepareTransferRequest::source_raw_data_descriptor can apply the same coarse rendered-source RAW filtering during prepare_metadata_for_target(...); it is still intentionally conservative and does not prove vendor curve/LUT activity for a specific compression mode or decoder stage. Rendered-transfer drop messages distinguish source color transforms, white balance, lens-correction records, source RAW curves/linearity metadata that still require storage-context confirmation, and BMFF content-bound/multi-image scene/derived-image construction policy, plus computational/thermal/stitch source-processing drops from generic source-processing metadata. Python Document and TransferSourceSnapshot expose transfer_concept_diagnostics(...) dictionaries with severity_name, token, message_token, message_arguments, message, and RAW applicability fields, with overloads that accept the thin MetadataRawDataDescriptor object. Python transfer helpers also accept source_raw_data_descriptor for prepare-time filtering.
Vendor RAW-processing summaries: vendor_raw_processing_from_store(...), classify_vendor_raw_processing_field(...)	openmeta/vendor_raw_processing.h	Experimental	Conservative grouped source-RAW/source-processing field summaries for decoded Sony, Canon, Nikon, Fujifilm, Pentax, Panasonic, Olympus, Kodak, Minolta, Sigma, Samsung, Ricoh, Apple, DJI, Google, FLIR, Casio, Sanyo, KyoceraRaw, Reconyx, HP, JVC, GE, Motorola, Nintendo, and Microsoft MakerNotes, including vendor-private, computational, thermal, preview, face-geometry, stitch/panorama, Apple computational capture/HDR/motion, DJI pose/thermal, Google HDR+/shot-log, pixel-shift/multi-shot/ composite/auto-lighting/source-style processing, and FLIR radiometric/raw-value buckets. Long-tail aliases cover source color/style, camera-to-XYZ/RGB matrix, white-balance gain, optical/lens correction, dynamic-range, and raw-development terms. Direct field classification also recognizes decoded Phase One/Leaf RAW-processing tags; use the dedicated Phase One/Leaf helpers for normalized geometry and processing summaries. Intended for audit/UI and rendered-transfer safety decisions, not for writing vendor RAW/source-processing values into rendered targets.
Transfer safety audit: transfer_safety_audit_from_store(...)	openmeta/metadata_transfer.h	Experimental	Preflight summary of source entries and entries filtered or invalidated by TransferSafetyMode, including Sony/Canon/Nikon/Fujifilm/Pentax/Panasonic/Olympus/Kodak/Minolta/ Sigma/Samsung/Ricoh/Apple/DJI/Google/FLIR/Casio/Sanyo/KyoceraRaw/ Reconyx/HP/JVC/GE/Motorola/Nintendo/Microsoft RAW/source-processing buckets. Intended for diagnostics and host UI before preparing rendered-image transfers.
Raw-carrier passthrough audit: raw_carrier_passthrough_audit_from_snapshot(...)	openmeta/metadata_transfer.h	Experimental	Diagnostic preflight for opt-in raw carriers. Reports candidate carriers and primary block reasons such as missing payload, target incompatibility, safety filtering, content-bound C2PA, explicit profile policy, missing decoded-entry links, or unsupported carrier kind. Does Hosts can call it directly before enabling snapshot passthrough.
Source snapshot type and read helpers: TransferSourceSnapshot, read_transfer_source_snapshot_file(...), read_transfer_source_snapshot_bytes(...), build_transfer_source_snapshot(...)	openmeta/metadata_transfer.h	Experimental	Current snapshots are decoded-store-backed by default. Opt-in raw carriers preserve bounded source payload/provenance records and snapshot-local decoded entry ids for host diagnostics and bounded passthrough decisions. Const reuse is safe when callers do not mutate the snapshot and do not share returned result objects across writers.
Fileless preparation: prepare_metadata_for_target_snapshot(...)	openmeta/metadata_transfer.h	Experimental	Intended for hosts that already decoded metadata and want to prepare transfer artifacts without reopening the source file. TransferRawCarrierPassthroughMode::WhenSafe is an opt-in snapshot mode; the current writer path only reuses eligible non-C2PA JUMBF and draft unsigned C2PA invalidation carriers for JPEG, JXL, and BMFF targets, plus draft unsigned C2PA invalidation carriers for WebP.
Snapshot execution: execute_prepared_transfer_snapshot(...)	openmeta/metadata_transfer.h	Experimental	Intended for deferred save/writeback from a reusable decoded source snapshot.
Bundle execution: execute_prepared_transfer_bundle(...)	openmeta/metadata_transfer.h	Experimental	Intended for hosts that already own a prepared bundle and destination bytes. Treat bundles as immutable except through documented patch helpers.
Adapter-view execution: build_prepared_transfer_adapter_view(...), emit_prepared_transfer_adapter_view(...)	openmeta/metadata_transfer.h	Experimental	Target-neutral operation view for host-owned encoders and writers. Route and dispatch details may still evolve.
Generated transfer payload internals, route strings, low-level package chunks, and diagnostic counters not documented by a stable API page	openmeta/metadata_transfer.h	Internal	These fields may be useful for tests and diagnostics, but they are not a compatibility contract for downstream integrations.

Practical guidance

Use stable APIs for normal application integrations. Use experimental APIs when they match a real workflow and the integration can track OpenMeta releases. Avoid internal surfaces unless you are contributing to OpenMeta itself or writing a test that is intentionally tied to implementation details.