ci: run the Debian QEMU e2e on push; add make target and docs

- test.yml: add a qemu-e2e-debian job (build -> boot -> LUKS-unlock in QEMU
  via the deterministic direct transport) running on push/PR, plus a
  workflow_dispatch trigger for manual runs.
- Makefile: test-qemu-debian target (LIM_E2E_OS=debian); document the direct
  vs tor transport on test-qemu.
- README: document the two build scripts and the direct transport.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/test.yml

@@ -3,6 +3,7 @@ name: tests
 on:
   push:
   pull_request:
+  workflow_dispatch:
 
 jobs:
   lint:
@@ -37,3 +38,18 @@ jobs:
       - run: sudo apt-get update && sudo apt-get install -y tor
       - run: pip install pytest pyyaml
       - run: LIM_E2E_TOR=1 make test-tor PYTHON=python
+
+  qemu-e2e-debian:
+    # Full build -> boot -> LUKS-unlock in QEMU, deterministic via the direct
+    # transport (debootstrap works on Ubuntu; no Tor). Heavy (root, loop,
+    # cryptsetup, and TCG when the runner has no /dev/kvm).
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - run: sudo apt-get update && sudo apt-get install -y qemu-system-x86 debootstrap cryptsetup
+      - run: pip install pytest pyyaml
+      - run: make test-qemu-debian PYTHON=python

Makefile

@@ -1,4 +1,4 @@
-.PHONY: install test test-tor test-qemu test-all
+.PHONY: install test test-tor test-qemu test-qemu-debian test-all
 
 PREFIX ?= $(HOME)/.local
 # Interpreter used for the tests. Override if your active venv lacks pytest,
@@ -20,11 +20,18 @@ test-tor:
 	LIM_E2E_TOR=1 $(PYTHON) -m pytest tests/e2e/test_tor_unlock_e2e.py -v
 
 # Full virtualized build+boot+unlock e2e. Needs qemu, arch-install-scripts,
-# cryptsetup, tor and ncat; the build stage runs under sudo. Set CHUTNEY_PATH
-# to use a private, offline Tor network instead of the public one.
+# cryptsetup and ssh; the build stage runs under sudo. The default "direct"
+# transport delivers the passphrase deterministically via a QEMU port-forward;
+# set LIM_E2E_TRANSPORT=tor for the full onion path (also needs tor + ncat, and
+# is flaky over public Tor inside QEMU).
 test-qemu:
 	LIM_E2E_QEMU=1 $(PYTHON) -m pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
 
+# Same, but builds a Debian image with debootstrap (initramfs-tools backend)
+# instead of Arch. Needs debootstrap + cryptsetup + ssh; runs under sudo.
+test-qemu-debian:
+	LIM_E2E_QEMU=1 LIM_E2E_OS=debian $(PYTHON) -m pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
+
 # Everything: mocked suite plus both opt-in e2e stages, in one run.
 test-all:
 	LIM_E2E_TOR=1 LIM_E2E_QEMU=1 $(PYTHON) -m pytest -v -s

tests/e2e/qemu/README.md

@@ -27,7 +27,8 @@ CPU architecture.
 
 | Stage | File | Privilege |
 |---|---|---|
-| Build encrypted image | `build_image.sh` | **root** (loop, cryptsetup, chroot) |
+| Build encrypted image (Arch) | `build_image.sh` | **root** (loop, cryptsetup, chroot) |
+| Build encrypted image (Debian) | `build_image_debian.sh` | **root** (debootstrap, loop, cryptsetup, chroot) |
 | Tor network | `tor_net.py` | rootless |
 | Boot + unlock | `boot_unlock.py` | rootless (QEMU user-mode net) |
 | Orchestration | `harness.py` | mixed (uses `sudo` for the build only) |
@@ -53,18 +54,41 @@ and then `chown`s the artifacts back so rootless QEMU can read them.
 - Network access to the public Tor network, **or** `chutney` for a private one
 - `/dev/kvm` recommended (TCG works but is slow; aarch64-on-x86 is always TCG)
 
+For the Debian build (`LIM_E2E_OS=debian`), additionally: `debootstrap` and
+network access to a Debian mirror. The guest uses the initramfs-tools backend
+(cryptsetup-initramfs + dropbear-initramfs), so the unlock SSH session runs
+`cryptroot-unlock` instead of Arch's login-time encryptssh prompt.
+
+## Unlock transport: direct vs Tor
+
+`LIM_E2E_TRANSPORT` (default `direct`) selects how the passphrase reaches the
+guest's dropbear:
+
+- **direct** — QEMU forwards a host port to the guest's dropbear (`:22`) and the
+  passphrase is delivered over a plain SSH. Deterministic; it verifies the whole
+  LUKS-unlock stack (cryptsetup-initramfs + dropbear-initramfs + cryptroot-unlock
+  + LUKS + boot). This is what CI/`make` runs.
+- **tor** — the full onion path: the guest publishes its onion and the host
+  reaches it through Tor. Representative of production but **flaky over public
+  Tor inside QEMU** (fresh guest Tor + user-mode net make the onion rendezvous
+  unreliable), so it is opt-in. The onion transport itself is covered
+  deterministically by the rootless `test_tor_unlock_e2e.py`.
+
 ## Running
 
 ```bash
-# Public Tor network (simplest; non-deterministic, needs internet):
+# Arch (mkinitcpio), direct transport (deterministic, default):
 LIM_E2E_QEMU=1 pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
 
-# Private, offline, deterministic Tor network via chutney:
-git clone https://gitlab.torproject.org/tpo/core/chutney
-CHUTNEY_PATH=$PWD/chutney LIM_E2E_QEMU=1 \
-  pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
+# Debian (initramfs-tools) via debootstrap, direct transport:
+LIM_E2E_QEMU=1 LIM_E2E_OS=debian pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
+
+# Full onion transport (opt-in, flaky over public Tor):
+LIM_E2E_QEMU=1 LIM_E2E_TRANSPORT=tor pytest tests/e2e/test_qemu_unlock_e2e.py -v -s
 ```
 
+`make test-qemu` / `make test-qemu-debian` wrap the direct-transport runs.
+
 Environment knobs: `LIM_E2E_ARCH` (`x86_64` default, or `aarch64`),
 `CHUTNEY_PATH` (enables the private network), `CHUTNEY_PATH` unset → public.