Levi Neuwirth
4aa610dc8b
Review of 2026-07-30-A declined the silent state it disclosed. When a `.seg`
occupies the logical generation the active tail carries, the frames must be
renamed, and the two cases part on what that costs:
- orphan alone: nothing names the displaced identity, the seal falls back to
a free generation, and recovery succeeds — an orphan segment is a state in
which the active journal is still the authority, and refusing would turn a
recoverable root into an outage;
- orphan plus a run the manifest names: recovery would publish a manifest
naming a run whose every location resolves to nothing. It refuses with
Corruption instead, naming the run.
Refusing is an outage on a root whose data is all present. It is chosen because
the alternative opens and lies, and because the replay delta above the run hides
that from every lookup until the first consumer that reads runs directly — which
is the checkpointer this precedes.
`IndexRun::references_segment_generation` is the frozen seam, read-only, with
recovery as its one caller (contract review 2026-07-30-B). Exact rather than a
range test over section headers: entries pack a 16-bit delta from the section
base, so the header says only what a section could name, and a `true` it does
not owe refuses a recovery with nothing to lose.
`coverable_through` keeps the coverage 2026-07-30-A widened — the unsound state
is now refused where it arises rather than designed around at every seal — and
its comment, which still described the pre-split world, says so.
Evidence: the refusing test asserts the damage rather than an expectation, so
disabling the guard reports that the reopened root pins None at the generation
the run names. A first draft of it passed for the wrong reason, re-pushing the
genesis object id as a blob so the reopen failed on a duplicate-object Conflict
either way; the mutation exposed that.
Still open and recorded in scope §6.5: recovery discarding a run whose covered
identity was not preserved, which turns this refusal into reclamation.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XKzM69CHmBuDcA3qN1jFdh
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| .github/workflows | ||
| bench | ||
| crates | ||
| deploy | ||
| doc | ||
| scripts | ||
| .gitignore | ||
| Cargo.lock | ||
| Cargo.toml | ||
| LICENSE | ||
| README.md | ||
README.md
LeVCS
A distributed version control system with first-class federation, signed authority chains, and a cascading merge engine. Content-addressed by BLAKE3, signed with Ed25519, and built to fix what git can't.
Status: v0.1.0 — protocol substrate complete, workflow surface deferred. The object model, federation API, merge cascade, and instance server all work end-to-end. There is no PR review surface, issue tracker, or web UI yet — those are the next layer up. See
doc/technical-report.mdfor a full framing of where this project is and why.
What's different from git
- Identity is in the protocol. A repo's membership is a versioned, signed authority object with explicit roles (Reader/Contributor/Maintainer/Owner). Force-push enforcement and push authorization are protocol-level, not server policy.
- Federation is first-class. Every repo has a global
repo_id(BLAKE3 of its genesis authority); instances mirror each other in three storage modes (full / release-only / metadata-only). - Merge is a cascade, not a line-level diff. Per-file dispatch to a handler ranked by aggressiveness: textual fallback, format-aware (JSON / YAML / TOML / XML / Markdown / prose), tree-sitter for source code (Rust, Python, JS/TS, Go, C/C++, Java, Ruby, Bash), and wasm-sandboxed plugins for the long tail.
- BLAKE3, not SHA-1. Tree-hashed, ~5 GiB/s on a laptop, 32-byte IDs everywhere.
- Releases are signed objects, not mutable name pointers.
For a deeper comparison and context, see the technical report.
Building
LeVCS is a Rust workspace. You'll need a recent stable toolchain (workspace MSRV is 1.75) and a C compiler for the tree-sitter grammars.
cargo build --release
Two binaries land in target/release/:
levcs— the user-facing CLI.levcs-instance— the federation HTTP server.
Install them somewhere on PATH:
sudo install -m 0755 \
target/release/levcs target/release/levcs-instance \
/usr/local/bin/
Quick start (single user, local only)
# Generate an identity key (stored in $XDG_CONFIG_HOME/levcs/keys.toml).
levcs key generate --label me
# Create a repository wherever you have files to track.
mkdir /tmp/demo && cd /tmp/demo
echo "hello" > a.txt
levcs init --key me
levcs track --all
levcs commit -m "first commit"
levcs log
That's a fully working LeVCS repo. Branch and merge:
levcs branch feature/x
echo "more" >> a.txt
levcs commit -m "wip"
levcs branch main
levcs merge feature/x
If a merge produces conflicts, drop into the resolution TUI:
levcs merge --resolve
Cut a release:
levcs release v0.1.0 --notes "first release"
Hosting an instance
To dogfood the federation surface, run levcs-instance on a VPS behind
nginx or Caddy. The full walkthrough is in
deploy/README.md: build, systemd unit, reverse
proxy templates, firewall, and the laptop-side bootstrap.
The compressed version:
sudo cp deploy/levcs-instance.service /etc/systemd/system/
sudo cp deploy/instance.toml.example /etc/levcs/instance.toml
sudo $EDITOR /etc/levcs/instance.toml
sudo systemctl enable --now levcs-instance
# ... then drop deploy/Caddyfile.example into /etc/caddy/Caddyfile
From your laptop, point the local repo at the instance and push:
levcs instance --set https://levcs.example.com/levcs/v1
levcs push refs/branches/main
The first push to a fresh instance auto-inits the repo with your genesis authority. Subsequent pushes are role-checked against the authority chain.
Repository layout
crates/
levcs-core/ Object model (Blob/Tree/Commit/Release/Authority),
hash, store, refs, repository abstractions.
levcs-identity/ Authority objects, Ed25519 keys, signing/verify.
levcs-merge/ Cascade engine, format and tree-sitter handlers,
plugin runtime, merge records.
levcs-protocol/ Pack codec, wire types, request signing, P2P.
levcs-client/ Thin HTTP client over the federation API.
levcs-instance/ Axum HTTP server (the federation peer).
levcs-cli/ The `levcs` user-facing CLI.
levcs-tui/ Conflict-resolution terminal UI.
deploy/ Production deployment artifacts (systemd, Caddy, nginx).
scripts/ Reproducible benchmark and ops scripts.
doc/ Technical report and architecture docs.
.github/workflows/ CI configuration.
Testing
cargo test --workspace
Runs the full suite — unit tests, integration tests, federation end-to-end tests including the three-instance "dogfood" scenario, the merge conformance corpus, and property-based fuzz tests. ~194 tests at v0.1.0; full run is well under a minute on a modern laptop.
Useful subsets:
# A single crate's tests
cargo test -p levcs-merge
# A specific integration test
cargo test -p levcs-instance --test dogfood
# Property tests only
cargo test -p levcs-merge --test proptest_textual
Benchmarks
Microbenchmarks live in each crate's benches/ directory and use
criterion. A reproducible runner with metadata capture and optional
flamegraph generation is at scripts/bench.sh:
scripts/bench.sh --quick # smoke test (~ a minute total)
scripts/bench.sh # full criterion run (~ a few minutes)
scripts/bench.sh --flamegraph # generate per-bench SVG flamegraphs
scripts/bench.sh --bench pack_codec # one bench only
Output goes to bench-results/<host>-<UTC-timestamp>/ with a parsed
summary.txt, criterion's HTML reports, and a metadata.txt capturing
rustc version, kernel, CPU, and git rev for run-to-run comparison.
Headline numbers on a Ryzen 7 laptop:
- Pack decode at 10 × 1 MiB entries: ~2.3 ms (4.3 GiB/s).
- Blob serialize + BLAKE3 at 1 MiB: ~190 µs (5.1 GiB/s).
- Textual three-way merge of a 100 KiB document: ~4.6 ms.
Pack encoding is the throughput floor at ~380 MiB/s — bottlenecked by zstd level 3 on incompressible data.
Documentation
doc/technical-report.md— Distribution document. What LeVCS is, how to use it, and how it differs from / improves upon git. Targets technical evaluators and the workflow-spec reader.deploy/README.md— Comprehensive VPS deployment walkthrough.spec/— The protocol specification and trust-root revision. Currently kept private; ask the maintainer for a copy.
Contributing
This is a young project. The most useful contributions right now are:
- Trying it. Run
levcs initon a real project, push to a local instance, and report friction. - Workflow design. The next major piece of work is the workflow spec — PR/review surface, issues, CI conventions. Discussion welcome.
- Plugin handlers. The wasm plugin protocol exists; concrete handlers (e.g. protobuf, SQL migrations) are needed to validate it.
- Tightening CI. The
fmtandclippyGitHub jobs are informational; flipping them to gating would close a small but real quality gap.
Please open an issue or reach out before starting non-trivial work so we can coordinate.
License
Released under the Apache License 2.0 — see LICENSE for the
full text.
Citation
If LeVCS supports academic work, please cite the v0.1.0 release. A formal citation entry will land with the workflow spec; in the meantime a repository-URL reference is fine.