# RESUME POINT — cubefs FUSE <-> cube-server daemon durability wiring Saved: 2026-08-13 (user paused session; pick up from here). ## GOAL (from task list) Make cubefs a real FUSE view of the running `cube-server` daemon's durable store, and prove a FUSE write lands in the daemon WAL and survives a daemon restart. (Cube-server is a pure command server — it does NOT mount FUSE itself; the FUSE view is a separate `cubefs-mount --socket` process, per the PDF/spec architecture.) ## WHAT IS DONE (compiles + tests green) 1. Raw-coordinate command family added to `cubesys/src/commands.rs` dispatch: `rawget `, `rawput `, `rawdel `, `rawkeys`, `rawscan [z] [y]`. Helpers added: `parse_u8`, `hex_encode`, `hex_decode`. (rawput/rawdel go through the durable `ConcurrentStore` so they hit the WAL.) 2. `cubefs/src/backend.rs` — new `DaemonBackend` implementing `CubeBackend` over the daemon Unix socket (lazy length-prefixed framing, duplicated from `cubesys::net` to keep cubefs free of a cubesys dep). Registered in `cubefs/src/lib.rs` (`pub mod backend; pub use backend::DaemonBackend;`). `DaemonBackend` is Clone (clones share socket path, reconnect lazily). 3. `cubefs/src/bin/cubefs_mount.rs` — `--socket PATH` mounts against a live daemon; without `--socket` it falls back to an in-memory `HashBackend`. 4. `cargo build --workspace` GREEN. `cargo test --workspace` GREEN. (Note: `DaemonBackend` is NOT yet exercised by any unit/integration test — only manual host verification below.) ## WHAT IS PROVEN (host-level, same kernel/code path as the VM) A. Daemon durability + WAL replay: launched daemon with `--store`, `rawput`, killed it with `kill -9` (crash), relaunched same `--store` → `rawget` returned the written value; recovery log showed `wal_recovery: applied 1`. So the DAEMON half of the durability story works. B. Direct `rawput` from a Python client checkpoints to `store.json` (4-byte record appeared after the checkpoint interval). Confirmed daemon is alive, reachable, and durable on the host. ## WHAT IS BROKEN (the open bug) — RESOLVED 2026-08-13 (commit 0300def) Two separate bugs hid behind the "FUSE write didn't reach the daemon" symptom: 1. `--features mount` did not compile (E0308: `CubeFs` vs `CubeFs` are distinct types in the `match &socket`). The build failed silently, so the running binary was the IN-MEMORY build and `--socket` was ignored. FIXED in 8f9e7e0 by type-erasing the backend (`Box` + a forwarding impl). 2. Even after (1), `DaemonBackend` round-tripped the WRONG layer: `put` stripped the record envelope to a bare body before `rawput`, but `get` returned that bare body as if it were a full record — so the FUSE read-back path (`get_record`) could not decode it, and the socket backend diverged from the in-memory backend. FIXED in 0300def: `DaemonBackend::put`/`get` now round-trip the FULL envelope (header+body) verbatim through rawput/rawget, matching the in-memory `HashBackend` exactly. This is now an enforced `./check daemon` integration test (spins up a live cube-server, runs the two `#[ignore]`d daemon-backed tests via `--ignored`). ## GATE STATUS (2026-08-13, end of session) - `./check` (fmt+test+clippy -D warnings) GREEN. - `./check daemon` GREEN — proves the socket-backed record round-trip against a real daemon (3 ignored tests via --ignored all pass). - `./check mount` (live FUSE, root) GREEN — 27/27 pass. This is the regression guard exercising the real kernel VFS path; it now runs cleanly with the fixed durable-mount code. Run before any future filesystem work. ## NEXT STEPS (current) 1. ~~Repeat the single-daemon + single-mount e2e INSIDE the VM...~~ DONE (see below). 2. Add a `--features mount` build to the VM image's build step / `./check` so the durable mount can't silently regress to in-memory again. (DONE on host ./check; VM image build step not yet updated.) 3. Optionally surface `DaemonBackend::put` failures as FUSE EIO instead of eprintln-only (best-effort today, acceptable). 4. ~~Confirm the desktop "CUBE Shell" launcher execs `cubec`...~~ DONE 2026-08-13: `/usr/share/applications/cube.desktop` -> Exec `/opt/cube/bin/cube-term`, which exports `CUBE_SOCKET=/run/cube/cube.sock` and `exec /opt/cube/bin/cubec`. The skill's #1 gotcha (must use `cubec`, not `cube repl`) is satisfied at the file level (not visually launched, per user instruction to not block on viewability). ## COMPLETED THIS SESSION - Fixed `DaemonBackend` envelope round-trip (commit 0300def) — was returning the bare body instead of the full record envelope; the `--socket` mount could not read back FUSE writes. Fixed by round-tripping the full envelope verbatim. - Fixed `--features mount` compile break (commit 8f9e7e0) — `Czyx` field access. - Enforced BOTH bugs via `./check daemon` (the two #[ignore]d integration tests now run via --ignored and would fail if either regressed). - Host: `./check` + `./check daemon` + `./check mount` all GREEN. - VM (/var/lib/cubevm/cubelinux-vm.qcow2, was pre-fix): rebuilt cubefs-mount from the fixed source, rewired cubefs.service to `--socket /run/cube/cube.sock` with `Requires=cube-server.service`, and proved a FUSE write survives a daemon restart (WAL persistence). Injected SSH key for cube+root to drive the VM. ./check also passes inside the VM (rustfmt+clippy components added). ## KEY FILES - /home/CUBELinux/CUBELinux-2/cubesys/src/commands.rs (raw* commands + helpers) - /home/CUBELinux/CUBELinux-2/cubefs/src/backend.rs (DaemonBackend — FIX HERE) - /home/CUBELinux/CUBELinux-2/cubefs/src/lib.rs (module export) - /home/CUBELinux/CUBELinux-2/cubefs/src/bin/cubefs_mount.rs (--socket wiring) - /home/CUBELinux/CUBELinux-2/cubestore/src/lib.rs (CubeStore::put_raw L358) - /home/CUBELinux/CUBELinux-2/cubefs/src/vfs.rs (CubeFs::write L392) ## TEST HARNESS NOTES - Launch daemon/mount as `terminal(background=true)` so Hermes tracks them. - A `python3` one-shot client for rawget/rawput: socket connect, sendall(struct.pack('