name: asset-pipeline description: Asset building, manifest format, hash verification, and boot-time resolution for Capsem VM images. Use when debugging boot failures, manifest issues, hash mismatches, or understanding how assets flow from build to boot.

Asset Pipeline

How VM assets (kernel, initrd, rootfs) are built, checksummed, resolved, and verified at boot.

Versioning

Binary and asset versions are independent:

• Binary: 1.0.{unix_timestamp} -- changes every build
• Assets: YYYY.MMDD.patch -- changes only on kernel/rootfs/initrd rebuilds

The manifest tracks both with compatibility ranges (min_binary, min_assets).

Key Commands

File Locations

Manifest Format (v2)

{
  "format": 2,
  "assets": {
    "current": "2026.0415.1",
    "releases": {
      "2026.0415.1": {
        "date": "2026-04-15",
        "deprecated": false,
        "min_binary": "1.0.0",
        "arches": {
          "arm64": {
            "vmlinuz": { "hash": "<64-char blake3>", "size": 7797248 },
            "initrd.img": { "hash": "...", "size": 2270154 },
            "rootfs.squashfs": { "hash": "...", "size": 454230016 }
          }
        }
      }
    }
  },
  "binaries": {
    "current": "1.0.1776269479",
    "releases": {
      "1.0.1776269479": {
        "date": "2026-04-15",
        "deprecated": false,
        "min_assets": "2026.0415.1"
      }
    }
  }
}

Two producers: docker.py:generate_checksums() (full build) and scripts/gen_manifest.py (initrd repack). Both produce v2 format.

Disk Layouts

Dev (repo assets/ dir -- logical names, per-arch subdirs):

assets/arm64/vmlinuz
assets/arm64/initrd.img
assets/arm64/rootfs.squashfs
assets/manifest.json

Installed (~/.capsem/assets/ -- flat, hash-based filenames):

manifest.json
vmlinuz-2c0bd752db929642
initrd-e5e910e9ab38b873.img
rootfs-89eb92b83534d9d0.squashfs

Hash-based naming: {stem}-{hash[..16]}{ext}. Same hash = same file across versions = natural dedup.

Boot-Time Resolution

1. Dev mode: Service detects arch subdirs, passes --kernel assets/{arch}/vmlinuz etc. to capsem-process
2. Installed mode: Service reads v2 manifest, resolves ManifestV2::resolve(binary_version, arch, base_dir) to get hash-based file paths, passes --kernel, --initrd, --rootfs individually to capsem-process
3. Hash check at boot: VmConfig::builder().build() verifies BLAKE3 against compile-time hashes if available

Cleanup

cleanup_unused_assets(base_dir, manifest) removes hash-named files not referenced by any non-deprecated asset release. Also removes legacy v*/ directories.

Common Issues

Hash mismatch at boot: Assets on disk don't match the hashes baked into the binary. Fix: just shell (repacks initrd, regenerates manifest, touches build.rs to force recompile).

Hashes silently skipped: If build.rs can't extract hashes (manifest missing, wrong format), option_env!() returns None and verification is skipped.