v0.7.0

v0.7.0 2026-05-12

New backends:

• Add an Overlayfs store backend (@mtelvers #180)
• Add a QEMU sandbox backend, enabling Windows, OpenBSD and RISC-V builds
  (@mtelvers #195, reviewed by @MisterDA, @samoht, and @shonfeder)
• Add an HCS (Host Compute Service) backend for native Windows containers
  via containerd (@mtelvers #204)

Build, store and runtime fixes:

• Failed builds now correctly return a failure exit status (@mtelvers)
• Fix stale base image cache causing worker crash after pruning (@mtelvers)
• Re-raise exceptions to preserve backtraces and prefer failwith over
  Lwt.fail_with (@MisterDA)
• Remove unused Os.copy, delete_recursively and win32_unlink
  (@MisterDA, @shonfeder)

Copy step fixes:

• Fix copy step failure with tar 1.34 and the CVE-2025-45582 patch
  (@mtelvers #205)
• Also strip ./ segments from destination tar paths (@mtelvers #206)
• Remove synchronous Windows workaround in copy_file (@mtelvers)

Windows fixes:

• Display Windows NTSTATUS exit codes in hex
  (@MisterDA #197, reviewed by @mtelvers)
• Fix opam pin on Windows (@mtelvers #196, reviewed by @shonfeder)

Base images, CI and toolchain:

• Update base images and workers to opam 2.5, opam 2.4.1, opam 2.3,
  OCaml 5.4 and OCaml 5.3; add OpenBSD 7.7 support
  (@mtelvers #198 #201 #202)
• Update GHA scripts: use the latest OCaml 5, switch to setup-ocaml@v3,
  update runc to 1.1.14 (@MisterDA)
• Update opam image hashes and dependency lower bounds for bug fixes;
  add an upper bound on tar-unix 3 (@MisterDA, @shonfeder)