Third POC iteration (alknet-fs-sync-poc, 9/9 tests) proves multi-node
path-tree sync:
- Path tree modeled as automerge CRDT document, synced via automerge's
sync protocol over iroh QUIC connections
- Each node has a local replica; writes are local + immediate (no
network latency); sync is async, gossip-style, eventually consistent
- Concurrent writes to different paths converge cleanly; concurrent
writes to same path resolve via LWW (NFS-equivalent semantics)
- Content (blobs) and metadata (path tree) sync separately — automerge
for path edges, iroh-blobs for file bytes
- Branch inheritance works through automerge sync
Key finding: automerge concurrent put_object on same key creates a
conflict, not a merge. Root structures must be created by one node and
synced before other nodes write. This is a design constraint for the
spec.
24 total tests pass across both POC crates. All remaining unknowns are
implementation-scope, not feasibility blockers.
Validates the three-layer architecture for a content-addressed, branch-aware,
mountable filesystem:
- SQLite path tree over iroh-blobs MemStore (15/15 tests pass)
- Fossil-style branching with free content dedup via BLAKE3 content addressing
- honker-core for notify-on-commit inside the same transaction as path-tree
mutations (transactional outbox pattern)
- Write path: "branch on write, merge on close" reconciles BLAKE3-must-hash-
complete-file with chunked filesystem writes; concurrent readers see old
version until close commits atomically; crash/abort leaves old version intact
- Multi-tenancy via bucket_id column (free isolation, auth is an adapter problem)
Remaining unknowns (FsStore/redb coexistence, distributed incomplete-blob reads,
SFTP wiring, GC/tag management, branch chain depth) are implementation-scope,
not feasibility blockers.
