Cairn — content-addressed chunked sync & storage engine for professional video teams

Git-style versioning, FastCDC chunking, BLAKE3 integrity, placeholder hydration for NLE media. Headless core: sync engine, storage server, local daemon, CLI. The ctl API is a deliverable.

Name (ADR-0002): a cairn is a deliberate stack of stones marking a route — every stone is unique and immutable (content-addressed chunks), the stack marks the trail (journal + cursors), each summit is a checkpoint (snapshots/refs), and it survives weather (crash safety, I2).

Repository layout

crates/
  cairn-proto      wire protocol v4 (tonic/prost), package cairn.v4, fields 100-199 reserved
  cairn-tl         OTIO/FCPXML three-way timeline merge (ADR-0015): exact rationals,
                   identity ladder, C0-C10 classifier, canonical serializer, FCPXML bridge
  cairn-tray       Windows system tray (ADR-0016): thin onboarding layer over cairn-cli
  cairn-core       chunk/hash/manifest/compress/bloom/error-taxonomy (pure, heavily tested)
  cairn-store      local CAS + client SQLite (WAL) + outbox + header cache
  cairn-sync       sync engine: state machine, AIMD uploader, conflict copies, fold
  cairn-server     metadata plane + control-plane jobs + data-plane presigning
  cairn-cli        CLI + local daemon (ctl gRPC :17777, local dashboard :17778)
  cairn-sim        deterministic simulation suite (I2 enforcement)
  cairn-fs-linux   FUSE (fuser)
  cairn-fs-mac     File Provider shim (cfg(target_os = "macos"))
  cairn-fs-win     CfAPI via windows-rs (cfg(windows))
  cairn-x          e2e + fault-injection harness (kill -9 at every step), golden corpus
proto/cairn/v4     .proto source of truth
docs/              SPEC.md, adr/, ctl-api.md, runbooks/, STATUS.md

Install (Windows, one command)

irm https://raw.githubusercontent.com/ssmurfgg04-gif/cairn/main/install.ps1 | iex

Installs the engine + the system tray (tray icon in the notification area: connect a project folder, check status, open the project — no terminal needed; ADR-0016). SHA-verified downloads, per-user autostart, no admin rights. The CLI path below remains for servers and power users.

What you're evaluating: the merge is cairn tl-merge --base b.otio --ours a.otio --theirs b2.otio (exit 0 clean / 1 notes / 2 conflicts / 3 refused) — add --semantic to auto-merge frame-disjoint re-cuts (ADR-0023, opt-in). Also new: cairn tl-branch (git-for-video), cairn search (find clips by what's IN them), cairn review export-changelist | apply-changelist (client notes → mechanical edits, with a YES/NO gate), and live presence between editors (daemon flag live_presence, off by default). The honest competitive ledger — where we win, where LucidLink and friends win — is docs/COMPETITIVE.md.

Quick start

just build        # cargo build --workspace
just test         # cargo nextest run --workspace
just clippy       # pedantic on core crates, -D warnings in CI
just sim          # deterministic simulation suite
just run-server   # metadata+data plane on :7443 (dev TLS off)
just run-daemon   # local ctl gRPC :17777 + dashboard :17778
just doctor       # end-to-end health check

The two questions every design argument resolves against

• I1: "I opened a 50GB BRAW in Resolve — how long until I can scrub?" (<50ms cached header serve)
• I2: "A crash happened at any point — did we lose an acknowledged save or corrupt a project file?" (Answer must always be: no.)

Read SPEC.md first. Every deviation from it is a bug unless an ADR in docs/adr/ says otherwise. Ported/studied code provenance lives in THIRD_PARTY.md. The frozen control contract lives in docs/ctl-api.md.

License

Apache-2.0 for Cairn itself; see THIRD_PARTY.md for referenced implementations.