A desktop version-control client built specifically for Krita's .kra art files, backed by a version-control engine written from scratch rather than wrapping Git. Git treats a .kra as an opaque binary blob and can't diff or dedup it.
Context — Krita artists have no good way to version their work. Git exists, but a .kra file is a zip of tiled raster layers, and Git's blob model can only store full copies, never diff or delta-compress it.
Constraints — Must run local-only (no cloud or remote: artists shouldn't need an account or network), stay usable on modest hardware (explicitly benched against 2-core/4 GB-class machines), and integrate with Krita itself via a companion CLI a PyKrita plugin can shell out to.
Build a version-control engine that understands Krita's tiled zip format well enough to store only the tiles that actually changed, and produce a visual before/after diff fast enough to feel instant on documents with thousands of tiles.
Wrote my own content-addressed object store with tile-level bsdiff deltas against Krita's own tile grid, rather than wrapping Git.
tradeoff → I own a lot more code (chains, packs, GC), but Git's opaque-blob model would never let me dedup or diff a .kra's internal tiles.
Delta history is split into one file per tracked file (.kvc/chains/, lazy-loaded) instead of one monolithic file rewritten on every commit.
tradeoff → More small files on disk, in exchange for commit cost that no longer scales with total repo history.
A commit adding ≥32 new objects gets bundled into one .pack file instead of one file per object.
tradeoff → On Windows, per-file creation (Defender's real-time screening) was ~28s of a 33s initial commit. Parallelism can't hide that cost, since it's the file creation itself that's slow — batching was the only fix.
commit_diff returns the capped composite image + layer metadata immediately; the expensive per-layer rasters stream in afterwards over a Tauri Channel as rayon finishes each one in parallel.
tradeoff → More IPC plumbing (streamed messages merged by layer id on the frontend) for a diff panel that paints instantly instead of blocking on the slowest layer.
Mark-and-sweep GC threads one content-hash memo through the marking pass instead of replaying each file's whole patch chain independently per commit.
tradeoff → Turned marking a long-lived repo's history from a quadratic (seconds-scale) operation into a linear one (milliseconds).
