v0.13.0

0.13.0 is a ground-up rewrite of the project since 0.12.1: a single hluk CLI plus a library, a typed guest-to-host boundary, one reproducible embedded Unikraft kernel, and a formal runtime support-tier policy. It is not CLI- or API-compatible with 0.12.x; see Removed and the behavioral notes under Changed.

Added

• Single hluk CLI with subcommands run, snapshot save / snapshot run, and bench (cold / cold-snap / warm-restore / warm-stateful / parallel). Flags: --mount HOST:GUEST[:ro], --net / --net-allow / --net-block / --port, --exec, --guest-exec (urunc-style, runs a binary baked into the initrd), --entry, --env KEY=VALUE, and --scratch-mb.
• Library API: a SandboxBuilder — from_initrd(rootfs) / from_kernel / from_snapshot, then .boot() to get a running sandbox — plus the run dispatch call, Mount, Exec, GuestConfig, and re-exported Snapshot / OciTag. hluk is built on the same API.
• 11 guest runtimes on a 3-tier support policy (docs/guest-support-tiers.md), a shared C driver toolkit, and a CPython conformance suite. .NET runs both ahead-of-time (AOT) and in-guest JIT (Roslyn source compilation).
• Typed fs_* / net_* host functions with new filesystem operations (rename, symlink, readlink, hard link, chmod), multi-mount support, net_resolve (host DNS), real guest stdin (ReadStdin + EOF), and host environment-variable passthrough (--env, re-applied across snapshot restore).
• --kernel <path> (advanced) to boot an external kernel instead of the embedded one, and a reproducible native-kernel test fixture (just build-native-kernel / just verify-native-kernel).
• Snapshot save/restore as OCI-layout directories; macOS (hvf) support; parallel multi-VM benchmarking; on-demand Windows surrogates.

Changed

• Guest-to-host boundary: a single JSON-RPC __dispatch function plus a host-side ToolRegistry became many small, typed FlatBuffer host functions returning real -errno (Linux numbers, with a Win32/Winsock-to-Linux translation table).
• Boot metadata: pushed as magic-tagged TLVs prepended to the initrd became pulled via host functions at boot (GetCmdLine, GetInitrdBase/Size, GetWallClockNs, GetEnvVars, …), re-answerable after a snapshot restore.
• Filesystem sandbox: a hand-rolled path resolver became cap-std with kernel-enforced openat2(RESOLVE_BENEATH) on Linux (component-by-component resolution on Windows). Networking: blocking socket2 became non-blocking rustix with a net_poll readiness model.
• Guest memory: a no-paging design with a bespoke lib/cpiovfs and lib/ukmmap became the standard Unikraft paging/vmem/mmap stack with a ramfs initrd.
• Kernel provisioning: per-example kraft builds became one reproducible, Docker-built Unikraft kernel embedded in the binary via include_bytes! and verified in CI (kraftkit dropped).
• VMM: hyperlight-host 0.16 to 0.17. On Linux the default build is KVM-only (for the fast MADV_DONTNEED snapshot-restore path); MSHV support is behind --features mshv.
• Behavioral (breaking): in 0.12.x --port implied --net; now --port requires an explicit --net (or --net-allow / --net-block) and errors on its own. Under --net, the default AllowAll policy permits the host loopback interface (needed for intra-guest server+client patterns); --net-allow / --net-block still block loopback.
• PowerShell runtime moved from a 7.6.x tarball to the 7.4 (LTS) Alpine image.
• The Unikraft kernel is now embedded by default (0.12.x took a positional kernel path); use --kernel to override it.

Removed

• Wasm custom host tools (--tool, --tool-wasi-*), the public ToolRegistry / SandboxBuilder::tool() extension API, and the WASIp1 host-function sandbox.
• The pyhl Python tool (image pull from GHCR, warm-then-snapshot, --deterministic) and the multifn-test / pydriver-run dev binaries; the snapshot workflow folded into hluk snapshot.
• The --memory / --stack knobs (replaced by --scratch-mb), the reserved-mountpoint rejection list (/, /bin, /dev, /proc, /sys, /usr), and the implicit default /host mount path (mounts now require an explicit guest path).
• Kernel-internal: the bespoke lib/cpiovfs, the /dev/hcall userspace device, the per-syscall TSC profiler, and the trace ports. File-backed mmap and demand paging move from the custom lib/ukmmap/cow.c to the standard ukvmem fault handler. (mmap's mremap is currently ENOSYS; glibc tolerates it.)
• The app-elfloader and kraftkit forks; the platform builds against upstream app-elfloader and a single unikraft kernel fork.
• Docs: the old host_functions.md (dispatch wire format / attack surface) and python-packages.md.

Fixed

• Host-mount path-escape resolution is now OS-enforced (openat2 RESOLVE_BENEATH / RESOLVE_NO_MAGICLINKS on Linux; component-by-component on Windows), with defense-in-depth :ro enforcement on both the VFS and host sides.
• Guest output is captured via a HostPrint host function (one VM exit per buffer instead of per byte) and exposed programmatically through GuestConfig::drain_output.

Pull requests

• @jsturtevant made their first contribution in #110
• @cmainas made their first contribution in #113

Full Changelog: v0.12.1...v0.13.0