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banger/AGENTS.md
Thales Maciel c8d9a122f9
Speed up VM create with work seeds 
Beat VM create wall time without changing VM semantics.

Generate a work-seed ext4 sidecar during image builds and rootfs rebuilds, then clone and resize that seed for each new VM instead of rebuilding /root from scratch. Plumb the new seed artifact through config, runtime metadata, store state, runtime-bundle defaults, doctor checks, and default-image reconciliation so older images still fall back cleanly.

Add a daemon TAP pool to keep idle bridge-attached devices warm, expose stage timing in lifecycle logs, add a create/SSH benchmark script plus Make target, and teach verify.sh that tap-pool-* devices are reusable capacity rather than cleanup leaks.

Validated with go test ./..., make build, ./verify.sh, and make bench-create ARGS="--runs 2".
2026-03-18 21:22:12 -03:00

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Repository Guidelines

Project Structure & Module Organization

  • cmd/banger and cmd/bangerd are the primary user-facing entrypoints.
  • internal/ contains the daemon, CLI, RPC, storage, Firecracker, and system integration code.
  • The VM lifecycle is now organized around daemon capabilities plus a structured guest-config builder. New host-integrated VM features should plug into that Go path instead of adding more one-off branches through internal/daemon/vm.go.
  • customize.sh, make-rootfs.sh, and interactive.sh remain as manual rootfs/customization helpers; normal VM lifecycle, NAT, .vm DNS, and daemon-driven image builds are handled by the Go control plane.
  • Source checkouts use a generated ./runtime/ bundle for Firecracker, kernels, modules, rootfs images, and helper copies. Bundle defaults come from ./runtime/bundle.json when present. Those runtime artifacts are not meant to be tracked directly in Git.
  • The daemon keeps state under XDG directories rather than the old repo-local state/ layout.

Build, Test, and Development Commands

  • make build builds ./banger, ./bangerd, and the bundled ./runtime/banger-vsock-pingd guest helper.
  • make bench-create benchmarks vm create and first-SSH readiness on the current host.
  • make runtime-bundle bootstraps ./runtime/ from the archive referenced by RUNTIME_MANIFEST; the checked-in runtime-bundle.toml is only a template.
  • banger validates required host tools per command and reports actionable missing-tool errors; do not assume one workstation's package set.
  • ./banger vm create --name testbox creates and starts a VM.
  • ./banger vm ssh testbox connects to a running guest and reminds the user if the VM is still running when the session exits.
  • ./banger vm stop testbox stops a VM while preserving its disks.
  • ./banger vm stop vm-a vm-b vm-c and ./banger vm set --nat web-1 web-2 are supported; multi-VM lifecycle and set actions fan out concurrently through the CLI.
  • ./banger doctor reports runtime bundle, host tool, feature, and image-build readiness from the same Go checks used by the daemon.
  • ./banger tui launches the terminal UI.
  • make test runs go test ./....
  • ./verify.sh runs the smoke test for the Go VM workflow.

Coding Style & Naming Conventions

  • Go code should stay small, direct, and standard-library-first unless there is a clear reason otherwise.
  • Shell helpers use Bash with set -euo pipefail; keep remaining shell scripts strict and explicit.
  • Prefer lowercase filenames with short descriptive names.
  • Use gofmt for Go formatting; no extra formatter is configured for shell files.

Testing Guidelines

  • Primary automated coverage is go test ./....
  • Manual verification for VM lifecycle changes: ./banger vm create, confirm SSH access, then stop/delete the VM.
  • For host-integration changes, run ./banger doctor as a quick readiness check before the live VM smoke.
  • Rebuilt images now include mise, opencode, tmux-resurrect/tmux-continuum defaults for root, and the banger-vsock-pingd service used by the SSH reminder path; if you change guest provisioning, document whether users need to rebuild ./runtime/rootfs-docker.ext4 or another base image to pick it up.
  • Rebuilt images also emit a work-seed.ext4 sidecar used to speed up future VM creates. If you touch /root provisioning, verify both the rootfs and the work-seed output.
  • The daemon may keep idle TAP devices in a pool for faster creates. Smoke tests should treat tap-pool-* devices as reusable capacity, not cleanup leaks.
  • If you add a new operational workflow, document how to exercise it in README.md.
  • For NAT changes, verify both guest outbound access and host rule cleanup, for example with ./verify.sh --nat.

Commit & Pull Request Guidelines

  • Git history uses short, imperative subjects.
  • Prefer a real commit body when the change affects lifecycle behavior, storage semantics, or host integration.
  • PRs should call out runtime requirements, migration impact, and any host-side verification performed.

Security & Configuration Tips

  • The VM workflow requires sudo and /dev/kvm access; do not commit secrets.
  • id_ed25519 lives inside the runtime bundle; rotate or replace it before publishing a shared bundle.