docs: record DaemonBackend envelope round-trip fix + gate status in RESUME doc

RESUME-cubefs-daemon.md

@@ -35,17 +35,31 @@ 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
-FUSE write did NOT reach the daemon. Root cause was NOT a connection-caching bug
-(the earlier `RefCell` cache was already removed in favour of fresh-per-call
-sockets). The real blocker: `cubefs-mount` requires `--features mount` to build,
-and at that point it did NOT compile (E0308: `CubeFs<DaemonBackend>` vs
-`CubeFs<HashBackend>` are different types in the `match &socket`). The build was
-silently failing, so the running binary was the IN-MEMORY build and `--socket`
-was ignored. Fixed by type-erasing the backend (`Box<dyn CubeBackend + Send +
-Sync>` + a forwarding impl in cubestore). Now compiles and the FUSE mount reaches
-the daemon; durability across a daemon `kill -9` is proven (see
-VERIFICATION-cubefs-daemon.md, REVISED).
+## 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<DaemonBackend>` vs
+   `CubeFs<HashBackend>` 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<dyn CubeBackend + Send + Sync>` + 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)
+- `./check` (fmt+test+clippy -D warnings) GREEN.
+- `./check daemon` GREEN — proves the socket-backed record round-trip against a
+  real daemon.
+- `./check mount` (live FUSE, root) — should be run before any future
+  filesystem work; it is the only stage exercising the real kernel VFS path.
 
 ## NEXT STEPS (current)
 1. Repeat the single-daemon + single-mount e2e INSIDE the VM to confirm the