mirror of epic games' lore open source version control
  • Rust 84%
  • Python 12.2%
  • C 3.3%
  • HCL 0.2%
  • Shell 0.2%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Mattias Jansson 2b0d60fdf9 lore-revision: Prepare for unifying file system walks by adding the staging intent to the walk
## Summary

Adds `FilesystemDiffIntent::Stage(StageIntent)` to the filesystem walk, teaching it what a staging walk records beyond the dirty flags that `MarkDirty` already sets.

- `StageIntent` carries per-node flags, an optional file identity (`Context`) to assign new file nodes, and a `CasePolicy` for resolving case differences between the tree and the filesystem.
- `FilesystemDiffIntent::marks_dirty` and `stage()` let the walk's existing branching handle both intents without duplication.
- A new `SettledAction` enum centralises dirty/staged flag pairs; `mark_settled` applies both for a staging walk and only the dirty flag for a marking one.
- New files created during a staging walk have their `mode`, `size`, and a minted (or caller-supplied) `file_id` written onto the node at creation time.
- Deleted subtrees under a staging walk descend past filter-excluded children, so a commit built from the result removes what the view leaves out too; `MarkDirty` continues to answer for the view alone.
- `FileDiffContext` now carries the `FileInfo` measured at the path so a node can be populated without re-reading the file.

No caller selects the new intent yet; behavior is unchanged for existing code paths. The follow up change will use the stage intent to unify the walks.

## Test Plan
Ran the new integration tests in `lore-revision/tests/stage_intent.rs`:
- `a_staging_walk_records_an_add_with_its_identity` — verifies a staged add carries `StagedAdd`, `DirtyAdd`, the file's measured size, and a non-zero file identity.
- `a_marking_walk_records_no_staged_action` — verifies `MarkDirty` sets `DirtyAdd` only.
- `a_staged_delete_settles_an_excluded_child` — verifies a staging walk marks excluded children `StagedDelete`.
- `a_marking_delete_leaves_an_excluded_child_alone` — verifies `MarkDirty` leaves filter-excluded nodes untouched.

Ran the existing unit test `an_action_records_matching_dirty_and_staged_flags` to confirm `SettledAction` maps each action to the correct flag pair.

Ran the full test suite and verified no regressions.

Lore-RevId: 960
Lore-Signature: 769025c1403b33ee39fa5e70a0b898fc49345f041ce4266a527a9e5bac6c08b8
2026-09-07 17:04:34 +00:00
.cargo Emit macOS .dSYM for release-lto (split-debuginfo = packed) 2026-06-09 21:22:45 +00:00
.github chore(deps): bump actions/setup-python from 6.2.0 to 7.0.0 2026-09-01 12:00:18 +00:00
contrib lore-aws-migrate: Cover the migration end to end against a local stack 2026-08-26 10:30:48 +00:00
docs lore-revision: Keep one instance registration per root directory 2026-09-07 17:03:54 +00:00
lore lore-revision: Keep one instance registration per root directory 2026-09-07 17:03:54 +00:00
lore-aws lore-storage: Let a stopped GC pass give up inside the group work 2026-08-29 17:11:23 +00:00
lore-base lore-base: Fail calls made after shutdown instead of hanging 2026-09-03 15:37:04 +00:00
lore-capi lore-revision: Keep one instance registration per root directory 2026-09-07 17:03:54 +00:00
lore-chaos-client lore-revision: Classify what a merge or cherry-pick inherits from the source revision 2026-08-31 18:45:56 +00:00
lore-client lore-revision: Keep one instance registration per root directory 2026-09-07 17:03:54 +00:00
lore-credential lore-credential: Make the client's name claim optional 2026-09-04 09:20:06 +00:00
lore-error-set lore-error-set: Re-bless internal guard snapshots for the hidden root re-export 2026-08-28 11:24:06 +00:00
lore-error-set-macro lore-core: Group FFI error codes into blocks and keep them exit-code safe 2026-08-28 04:16:59 +00:00
lore-hashicorp Initial code copy from private repo 2026-05-29 18:50:20 +00:00
lore-integration-tests lore-revision: Keep one instance registration per root directory 2026-09-07 17:03:54 +00:00
lore-io lore-revision, lore-io: Avoid extra allocations for error messages when operations succeed 2026-08-25 08:06:53 +00:00
lore-macro build: Build test targets with line tables, and not at all where they hold no tests 2026-08-26 16:53:21 +00:00
lore-notification lore-core: Migrate errors to use internal or forward for error propagation, and enforce correct usage 2026-08-28 04:01:54 +00:00
lore-proto lore-server-epic: enable request forwarding for Repository Service's RepositoryGet RPC 2026-09-02 19:48:24 +00:00
lore-revision lore-revision: Prepare for unifying file system walks by adding the staging intent to the walk 2026-09-07 17:04:34 +00:00
lore-server lore-server: Support resolving jwks_uri through OIDC discovery 2026-09-07 15:09:05 +00:00
lore-storage lore-storage: record the level a group's bucket files were written at 2026-09-03 21:11:10 +00:00
lore-telemetry lore-transport: Add a ClientIdentify opcode so QUIC clients report a user agent in traces 2026-09-07 11:35:28 +00:00
lore-transport lore-transport: Add a ClientIdentify opcode so QUIC clients report a user agent in traces 2026-09-07 11:35:28 +00:00
notices notices: resolve license text for base64-simd, vsimd, and rs-consul 2026-06-05 17:53:57 +00:00
scripts lore-revision: Prepare for unifying file system walks by adding the staging intent to the walk 2026-09-07 17:04:34 +00:00
vendor lore-revision: split filter into exclusion and descent queries 2026-09-02 13:10:37 +00:00
.dockerignore Initial code copy from private repo 2026-05-29 18:50:20 +00:00
.gitignore gitignore: Ignore entire .claude/ directory 2026-07-16 11:17:18 +00:00
.loreignore ci: allow .github directory to be tracked for GHA integration 2026-06-16 16:59:34 +00:00
.markdownlint-cli2.jsonc docs: add content_tabs hook for comment-delimited tabs 2026-06-12 20:50:31 +00:00
.pre-commit-clippy.py Add missing executable bit on precommit script and add missing entries to ignore file 2026-06-01 09:00:30 +00:00
.pre-commit-config.yaml lore-core: Migrate errors to use internal or forward for error propagation, and enforce correct usage 2026-08-28 04:01:54 +00:00
.rustfmt.toml Initial code copy from private repo 2026-05-29 18:50:20 +00:00
.vale.ini docs: add project level README, migrate Lore design doc, updated branding assets, and glossary 2026-06-05 22:47:33 +00:00
about.toml notices: resolve license text for base64-simd, vsimd, and rs-consul 2026-06-05 17:53:57 +00:00
build-helper.rs lore-base: allow injectable library version name 2026-06-04 10:25:53 +00:00
Cargo.lock lore-revision: split filter into exclusion and descent queries 2026-09-02 13:10:37 +00:00
Cargo.toml lore-revision: split filter into exclusion and descent queries 2026-09-02 13:10:37 +00:00
clippy.toml lore-base: Shrink the tokio blocking pool to a fixed two-thread vestige and unify the thread count calculations 2026-08-08 15:07:09 +00:00
CODE_OF_CONDUCT.md Initial code copy from private repo 2026-05-29 18:50:20 +00:00
CONTRIBUTING.md Add structured GitHub issue forms and PR template for triage intake 2026-08-18 13:24:10 +00:00
DCO Initial code copy from private repo 2026-05-29 18:50:20 +00:00
deny.toml Initial code copy from private repo 2026-05-29 18:50:20 +00:00
GOVERNANCE.md Add structured GitHub issue forms and PR template for triage intake 2026-08-18 13:24:10 +00:00
LICENSE Initial code copy from private repo 2026-05-29 18:50:20 +00:00
MAINTAINERS.md update MAINTAINERS to propose adding specialist maintainers 2026-06-23 21:51:30 +00:00
mkdocs.yml docs: add content_tabs hook for comment-delimited tabs 2026-06-12 20:50:31 +00:00
pyproject.toml chore(deps): bump pytest from 8.4.2 to 9.1.1 2026-09-01 11:11:56 +00:00
pyrightconfig.json Initial code copy from private repo 2026-05-29 18:50:20 +00:00
README.md docs: add public roadmap and crosslink to it across the docs 2026-06-17 11:11:32 +00:00
SECURITY.md update SECURITY to include link to Vulnerability Disclosure Program 2026-06-15 15:39:15 +00:00
uv.lock chore(deps): bump the dependencies group across 1 directory with 4 updates 2026-09-01 12:00:01 +00:00

Lore — open source version control by Epic Games

Lore

Next-generation open source version control

Download Lore  ·  Quickstart  ·  Read the docs  ·  Join the conversation

License: MIT Built with Rust

Table of contents

About Lore

Lore is an open source version control system designed for unprecedented scalability of both data and teams. It is optimized for projects that combine code with large binary assets, including games and entertainment, and caters for the needs of developers and artists alike.

Note

Lore is pre-1.0 and under active development. Interfaces, on-disk formats, and APIs may change between releases.

(back to top)

Get started with Lore

  • Quickstart — install Lore and make your first commit by following the quickstart guide.
  • Read the docs — delve into Lore's ethos and architecture in the Lore documentation.
  • Have questions? — the FAQ covers licensing, supported platforms, production readiness, and how Lore compares to other version control systems.
  • See where Lore is headed — the roadmap lays out the big-rock features by time horizon, from scalable locking to an open source desktop client.
  • Join the conversation — chat with us and our community on Discord.

Or try it right now — install Lore and start a local server in demo mode:

macOS / Linux

curl -fsSL https://raw.githubusercontent.com/EpicGames/lore/main/scripts/install.sh | bash -s -- --demo

Windows (PowerShell)

$env:LORE_DEMO=1; irm https://raw.githubusercontent.com/EpicGames/lore/main/scripts/install.ps1 | iex

(back to top)

Overview

  • Easy setup, on-demand scalability — Get started in local mode in minutes. Then, scale up as far and as fast as you need.
  • Fast and efficient processes — Scale without slowdowns, thanks to shared, reusable data and as-needed downloads.
  • Free branching — Quickly and easily create, manage, and sync branches to freely experiment, iterate, and release.
  • History you can trust — Confidently track and manage revisions with Lore's verifiable tamper-evident source of truth.
  • Intuitive interface — Enjoy complete one-to-one access to the full Lore functionality via the CLI.
  • Full-surface API — Extend, customize, and integrate Lore via C/C++, C#, Rust, Go, Python, or JavaScript.

Note

Lore is the built-in version control system for UEFN (Unreal Editor for Fortnite), but today's open source tooling can't yet talk to it: the UEFN build uses a proprietary compression format that can't ship with the open source project. We're actively moving UEFN onto an open compression format — the same one this open source project uses — to eliminate the gap between the two.

(back to top)

Lore's architecture

Lore is a centralized, content-addressed version control system that represents repository state as Merkle trees and an immutable revision chain, optimized for binary-first storage, deduplication, and sparse/on-demand data hydration at scale. For the full model—on-disk formats, chunking internals, and the mechanics of the Merkle tree—read the system design doc.

Highlights

  • Content-addressed storage — Repository data is stored and referenced by content hash in a Merkle tree, enabling fast comparisons, integrity checks, and reuse across history and branches.
  • Immutable revision chain — A revision's hash signature is derived from its revision state, including parent revision hashes and contained data hashes, forming an immutable chain with cryptographic integrity.
  • Chunked storage for large files — Files are stored as reusable chunks with indexed lookup, reducing duplication and enabling efficient updates and transfer for large binary assets.
  • On-demand hydration and sparse workspaces — Workspaces can stay lightweight by fetching file data only when needed, so you don't have to download everything up front.
  • Centralized service with caching — A service-backed architecture uses caching in front of durable storage to scale throughput for large teams and repositories.
  • Lightweight branches and fast switching — Branches are lightweight mutable references, so creating and switching branches is low-overhead without duplication of underlying data.

(back to top)

Lore's repositories

Lore spans a family of repositories: the core library, server, and CLI in this repository, plus a software development kit (SDK) for each supported language.

Repository Description Link
Lore Library, Server & CLI The core Lore library, the Lore Server, and the Lore CLI. You are here. View on GitHub
JavaScript SDK The JavaScript binding for the Lore API. View on GitHub
Python SDK The Python binding for the Lore API. View on GitHub
C# SDK The C# binding for the Lore API. View on GitHub
Go SDK The Go binding for the Lore API. View on GitHub

(back to top)

Fully open source

We believe a truly open ecosystem is built collectively using open standards. Lore is fully open source under an MIT license, and we invite you to build the version control system of the future in the open. See CONTRIBUTING.md to get involved.

(back to top)

Contributing

Contributions of every kind are welcome — code, documentation, bug reports, and reviews. Start with CONTRIBUTING.md for the development workflow, then read the Code of Conduct and the project governance model. New to the codebase? The good-first-issue label is a good place to start.

(back to top)

License

Lore is released under the MIT License. See LICENSE for the full text. Copyright (c) 2026 Epic Games, Inc.

(back to top)

Contact and community

  • Discord — chat with the team and community on Discord.
  • GitHub Issues — report bugs and request features through GitHub Issues.

(back to top)