EdgeSync

Replace Fossil's HTTP sync with NATS messaging or direct peer-to-peer sync. Leaf agents can act as both sync clients and servers — a stock fossil clone/fossil sync can talk to them directly.

Architecture

graph LR
    Leaf[Leaf Agent]

    subgraph Bridged
        Bridge[Bridge] --> Fossil[Fossil Server]
    end

    subgraph Peer-to-Peer
        Peer[Other Leaf]
    end

    Leaf -- NATS --> Bridge
    Leaf -- NATS --> Peer
    Leaf -- HTTP --> Peer
    Leaf -- "NATS over iroh (QUIC)" --> Peer

Four sync modes:

1. Leaf → Bridge → Fossil Server — Original mode. Bridge translates NATS to HTTP /xfer.
2. Leaf → Leaf (NATS) — Peer-to-peer via ServeNATS. No bridge or server needed.
3. Leaf → Leaf (HTTP) — Peer-to-peer via ServeHTTP. Stock fossil clone/fossil sync works.
4. Leaf → Leaf (iroh) — Peer-to-peer over QUIC with NAT traversal. Each agent runs an embedded NATS server; leaf node connections tunnel over iroh. Enables presence and messaging without central infrastructure.

Quick Start

# One command: install hooks + build + test
make setup

# Run the leaf agent
bin/leaf --repo my.fossil --nats nats://localhost:4222 --serve-http :8080

# Run the edgesync CLI
bin/edgesync repo info

Dual VCS Note

This repo is tracked by both Git and Fossil. Go's VCS stamping gets confused by this, so all go build commands need -buildvcs=false. The Makefile handles this automatically. If you run go build directly:

# Either pass the flag every time:
go build -buildvcs=false ./cmd/edgesync/

# Or set it once per shell session:
export GOFLAGS="-buildvcs=false"
go build ./cmd/edgesync/   # works without the flag now

If you use direnv, the included .envrc sets this for you automatically.

Telemetry (Optional)

Traces, metrics, and structured logs via OpenTelemetry. Zero overhead when disabled — the leaf agent logs whether telemetry is active at startup.

# With Doppler (manages OTel secrets):
doppler run -- bin/leaf --repo my.fossil --nats nats://localhost:4222

# Or set the endpoint directly:
OTEL_EXPORTER_OTLP_ENDPOINT=localhost:4318 bin/leaf --repo my.fossil --nats nats://localhost:4222

Project Layout

cmd/edgesync/          Unified CLI binary (50 subcommands)

libfossil/             Core library — Go port of Fossil internals
  annotate/            Line-level blame/annotate
  bisect/              Binary search for regressions
  blob/                Blob compression (Fossil's 4-byte prefix + zlib)
  content/             Artifact storage and expansion (delta chains)
  db/                  SQLite adapter (3 drivers via build tags)
  deck/                Manifest/control-artifact parsing
  delta/               Fossil delta codec (ported from delta.c)
  hash/                SHA1/SHA3-256 content addressing
  manifest/            Checkin, file listing, timeline
  merge/               3-way merge with swappable strategies
  path/                Checkout path resolution
  repo/                Fossil repo DB operations (create, open, verify)
  simio/               Simulation I/O abstractions (Clock, Rand, Env)
  stash/               Working-tree stash save/restore
  sync/                Sync engine: client (Sync, Clone), server (HandleSync,
                         ServeHTTP), transport (HTTP, NATS, mock)
  tag/                 Tag read/write on artifacts
  testutil/            Shared test helpers
  undo/                Undo/redo state tracking
  xfer/                Xfer card protocol encoder/decoder

leaf/                  Leaf agent module
  agent/               Agent logic, NATS transport, ServeNATS, ServeP2P stub
  cmd/leaf/            Standalone leaf daemon binary

bridge/                Bridge module
  bridge/              Bridge logic (NATS <-> HTTP /xfer translation)
  cmd/bridge/          Standalone bridge daemon binary

dst/                   Deterministic simulation testing
                         SimNetwork (bridge mode), PeerNetwork (leaf-to-leaf)
sim/                   Integration simulation testing
                         Real NATS + Fossil + fault proxy + serve tests
  cmd/soak/            Continuous soak test runner

docs/                  Documentation
  dev/specs/           Design specifications
  dev/plans/           Implementation plans

Go Modules

Module	Path	Purpose
github.com/danmestas/EdgeSync	.	Root: CLI, sim/, soak runner
github.com/danmestas/libfossil	libfossil/	Core library (public, v0.3.x)
github.com/danmestas/EdgeSync/leaf	leaf/	Leaf agent
github.com/danmestas/EdgeSync/bridge	bridge/	Bridge
github.com/danmestas/EdgeSync/dst	dst/	Deterministic sim tests

SQLite Drivers

go build ./...                            # modernc (default, pure Go)
go build -tags ncruces ./...              # ncruces (WASM-based)
CGO_ENABLED=1 go build -tags mattn ./...  # mattn (CGo, best performance)

Testing

make test              # CI tests + sim serve (~15s)
make dst               # DST: 8 seeds, normal (~2s)
make dst-full          # DST: 16 seeds x 3 levels (~40s)
make sim               # Integration sim: 1 seed (requires fossil)
make sim-full          # Integration sim: 16 seeds x 3 severities
make drivers           # Test all 3 SQLite drivers

Dependencies

• modernc.org/sqlite — Pure Go SQLite (default driver)
• github.com/nats-io/nats.go — NATS + JetStream client
• github.com/alecthomas/kong — CLI framework
• github.com/hexops/gotextdiff — Unified diff output

Reference

• Fossil sync protocol
• Fossil delta format
• Fossil password authentication