lightcraft/docs/lightroom-catalog-import.md

Lightroom Classic catalog import

File → Import Lightroom Catalog… opens .lrcat directly. Lightroom, Python, DNG conversion and a C SQLite runtime are not required. The source database is read-only, including committed -wal pages; a catalog that changes during the read is rejected. LightCraft owns subsequent edits.

File → Open Library… given a Lightroom catalog folder (or an .lrdata / .lrcat-data folder, or the .lrcat) doesn't make a LightCraft library there: it offers this import instead, with the catalog found (crates/engine/src/lightroom_folder.rs, issue #891). lightcraft-cli --library refuses those places too.

Equivalent commands:

lightcraft-cli run --library "LightCraft Library" library.inspectLightroom path="Lightroom Catalog.lrcat"
lightcraft-cli run --library "LightCraft Library" library.importLightroom path="Lightroom Catalog.lrcat"

Original files are referenced in place. Ratings, picks/rejects, color labels, XMP metadata, hierarchical keywords, regular collections/collection sets, virtual copies and mapped develop settings are imported. Missing originals remain catalogued for relinking. Existing LightCraft edits are preserved by default; updateExisting=true explicitly replaces them. Persistent import identity prevents reimport from duplicating virtual copies and collections. One undo step reverses catalog changes; any saved recovery archives remain available.

Before changing records, the importer attempts to save source image records, decoded XMP, verbatim develop settings, history, snapshots and collection content to compressed Interop/lightroom-import-N.lca recovery archives in the LightCraft library. Archiving is best-effort: a size limit or write failure produces a warning and does not prevent photo import. Unchanged source data reuses its existing archive. Opaque SQL BLOBs are skipped. Each archive is capped at 32 MiB (uncompressed and on disk), with at most eight archives and 128 MiB total retained. Oldest managed archives are retired; legacy .json archives remain untouched. Interop/lightroom-index.json records imported identities. Source catalogs and originals are never overwritten.

Native import is bounded to a 1 GiB database/WAL, 16 MiB XMP packets and one million rows per table. The in-tree, read-only Rust SQLite B-tree reader follows SQLite’s public file-format specification; it introduces no dependency or C runtime. Table payloads are capped at 256 MiB. Optional history, keyword and collection tables that exceed limits are skipped with warnings; required photo tables still report errors. Unrelated unsupported schemas are ignored. A needed WITHOUT ROWID or virtual table produces an explicit error, handled as a warning when optional.

Develop settings reuse the existing XMP/preset mapper. Supported sliders, curves and supported mask structures remain editable, but this is approximate rendering: camera profiles, Adobe AI models, some masking/retouch fields and process-version algorithms are not reproduced. Unmapped fields are reported. Lightroom's ProcessVersion is not mapped: newly imported photos are on LightCraft's latest rendering process, and photos already in the library keep theirs (process-versions.md). When a recovery archive is saved, it retains source settings/history/snapshots and original smart-collection rules. Smart collections become regular albums with current membership. Archived history and snapshots are source data, not native LightCraft history yet. A Custom white balance on a raw LightCraft develops relative to its as-shot look (ARW, NEF, RW2, RAF, CR3, CR2, PEF, SRW; Lightroom names them all RAW) can't be taken as Kelvin: the catalog keeps no as-shot white for Custom photos, so the photo stays As Shot and Temperature, Tint are reported (issue #510; a DNG keeps the Kelvin value, and an XMP packet with crs:AsShotTemperature is shifted by the same mired difference, see xmp-interop.md). A raw whose camera has measured colour matrices (lightcraft_raw::spectral: ILCE-7M3, D850, EOS 5D Mark III…), or whose white-balance presets give a Kelvin scale (lightcraft_raw::kelvin_presets: ILCA-99M2, ILCA-77M2…), edits in Kelvin and keeps the Kelvin value too (issue #730) — when its file was found and probed, since the camera is read from the file, not from the Lightroom catalog; a missing file is treated as a relative-scale raw until Reload reads it. Lightroom's -999999 deferred-adjustment sentinel is omitted from both catalog and XMP mappings; it is reported, included in any saved archive, and never clamped into a real slider value. Deferred Adobe Auto Tone is not evaluated by the importer; LightCraft's Auto control remains available after migration.

Native desktop inspection/import runs on a cancellable background worker with progress. Only prepared catalog operations commit on the owner thread; archive index writing stays on a worker. Late results from a closed or switched library are rejected, including reopening the same path. Ordinary edits during preparation remain intact. CLI commands complete synchronously using the same preparation/commit pipeline; browser builds reject native catalog import.

Archive version 1 begins with the 12 bytes LC-LRARCH\0\x01Z, followed by zlib-compressed JSON. Recovery readers must cap decompression at 32 MiB. JSON retains source identities, photo paths, settings, decoded XMP, keywords, history, snapshots, collection definitions and membership.

The importer uses shared Rust code on macOS, Windows and Linux. When a root folder's recorded path isn't a folder on this computer (a catalog copied from another machine), the importer uses the path relative to the catalog that Lightroom records for root folders on the catalog's volume (relativePathFromCatalog), when that is a folder, and reports the remapping as a warning. Copying a project folder with its catalog inside it therefore keeps its originals linked. Other moved originals stay missing; use LightCraft's missing-photo relinking tools to update their paths.