diff --git a/docs/install/migrate-from-makeinstall.md b/docs/install/migrate-from-makeinstall.md
new file mode 100644
index 0000000..6f93aeb
--- /dev/null
+++ b/docs/install/migrate-from-makeinstall.md
@@ -0,0 +1,87 @@
+# Migrating from make-install to packages
+
+This runbook covers the transition from a `sudo make install` system to the native deb or rpm package. Packages are the primary delivery; `make install` remains as the dev fallback. The two deliveries are **mutually exclusive** per machine.
+
+## Why over-install is forbidden
+
+Installing a package over a make-install system silently breaks things:
+
+- **Stale admin units shadow vendor units.** `make install` places `fenris-collect.timer` and `fenris-collect.service` in `/etc/systemd/system/`. The package installs them in `/usr/lib/systemd/system/` (vendor placement). Systemd loads admin units first — the stale copy takes precedence, and the package update never reaches the running system.
+- **The local wrapper shadows the package wrapper.** `make install` places the `fenris` wrapper at `/usr/local/bin/fenris`. The package places it at `/usr/bin/fenris`. The shell finds `/usr/local/bin` first on PATH — the old checkout-relative wrapper runs instead of the package wrapper.
+
+Neither condition is reversible by reinstalling the package. The only safe path is remove-then-install.
+
+## Pre-migration checklist
+
+1. Confirm no monitoring period is actively running that you want to preserve across the gap:
+   ```
+   fenris status
+   ```
+   The migration resets the system to dormant (see [No-move continuity](#no-move-continuity) below). You opt back in with `fenris monitor resume`.
+
+2. If you have hand-edited configuration at `/etc/fenris/fenris.conf`, note it. The config survives the migration in place (see below).
+
+## Remove step
+
+```
+sudo make uninstall
+```
+
+This performs the **sanctioned disable** (`fenris-monitor disable --now`), closing the current monitoring period as `user_disabled`. It then removes all make-install artifacts: the venv at `/opt/fenris`, the wrapper at `/usr/local/bin/fenris`, the helpers at `/usr/libexec/fenris/`, the units in `/etc/systemd/system/`, and the polkit policy. The placement manifest at `/var/lib/fenris/manifest.txt` is removed.
+
+**What survives the remove:**
+
+- `/var/lib/fenris/observations.db` (and WAL sidecars, `.bak`) — the observation store
+- `/var/lib/fenris/` directory itself — root-written, group-read
+- `/etc/fenris/fenris.conf` — your hand-written configuration
+- The `fenris` system group — created by `groupadd -f` during make-install
+- Journal entries — age out naturally
+
+## Install step
+
+```
+sudo apt install fenris       # Debian/Ubuntu
+sudo dnf install fenris       # Fedora
+```
+
+The package installs into its own layout without touching the surviving store, config, or group.
+
+## No-move continuity
+
+These invariants are verified by the containerized acceptance tests (issue #50):
+
+| Asset | Make-install state | Package post-install | Mechanism |
+|---|---|---|---|
+| `fenris` group | Exists (`groupadd -f`) | Unchanged | `systemd-sysusers` is a no-op when the group already exists |
+| `/var/lib/fenris` directory | Exists (mode 2750, root:fenris) | Unchanged | `systemd-tmpfiles --create` is a no-op when the directory already exists |
+| `observations.db` + sidecars | Present from prior monitoring | Unchanged, never owned by the package | Package owns the directory only; store contents are never ghosted |
+| `/etc/fenris/fenris.conf` | Hand-edited device selector | Survives in place; package default lands as `.dpkg-new` / `.rpmnew` | dpkg conffile / rpm `%config(noreplace)` semantics |
+| Store schema | Version from prior Fenris release | Caught up by the upgrade-path migration | `postinst` / `%post` runs `migrate_to_latest()` on upgrade |
+
+The package detects the make-install system has been removed by the absence of the two markers:
+- `/var/lib/fenris/manifest.txt` (the placement manifest)
+- `/etc/systemd/system/fenris-collect.timer` (pre-manifest make installs)
+
+If either marker exists, the package installation aborts with a pointer to this runbook.
+
+## Reset-to-dormant
+
+`make uninstall`'s sanctioned disable closes the open monitoring period as `user_disabled`. After the package install, the system is dormant — the timer is installed but disabled, nothing is running, no monitoring period is open.
+
+To resume monitoring:
+
+```
+fenris monitor resume
+```
+
+This is the sanctioned opt-in. It enables the timer and opens the first monitoring period in one step. The migration costs at most one short sample gap (the interval between `make uninstall` and `fenris monitor resume`), honestly recorded in the endurance timeline.
+
+## Verification
+
+After migration, confirm the package is correctly installed:
+
+```
+fenris status
+```
+
+The status command should show the dormant state: timer disabled, no active monitoring period, and the observation store intact from the prior make-install system.
diff --git a/docs/spec/acceptance-criteria.md b/docs/spec/acceptance-criteria.md
index 89e6a8e..c3183eb 100644
--- a/docs/spec/acceptance-criteria.md
+++ b/docs/spec/acceptance-criteria.md
@@ -117,6 +117,13 @@ Status: Accepted — resolves [Define cross-cutting acceptance criteria](https:/
 - **IN-9** (P) The installer verifies `python3 ≥ 3.9` and fails cleanly otherwise; `/var/lib/fenris` is created with root-written group-read permissions; the database file is created lazily by the first write.
 - **IN-10** (P) Installed artifacts sit only at their fixed locations — units in `/etc/systemd/system`, helpers in `/usr/libexec/fenris`, polkit policy under `/usr/share/polkit-1/actions/`, configuration at `/etc/fenris`, observation store under `/var/lib/fenris` — and every placed file is recorded in the manifest (ADR 0004 §2; ADR 0003 §4).
 
+## Migration from make-install systems (ADR 0007 §10, spec §9)
+
+- **MG-1** (M) The migration runbook is published in the install docs (`docs/install/migrate-from-makeinstall.md`): mandatory remove-then-install steps, why over-install is forbidden (stale admin-directory units silently shadow vendor units; the local wrapper shadows the package wrapper), no-move continuity, and the reset-to-dormant expectation (the user opts back in with the sanctioned resume).
+- **MG-2** (A) The install guard is verified across the matrix: either make-install marker (the legacy placement manifest, or a unit file under the admin unit directory) causes an abort with a runbook pointer — never auto-clean. Tested by `test_migration_guard` on all four targets (Debian 12, Ubuntu 22.04, Ubuntu 24.04, Fedora 40).
+- **MG-3** (A) No-move continuity is verified in a container seeded with a make-install-shaped system: existing group makes sysusers a no-op, existing store directory makes tmpfiles a no-op, the hand-written configuration survives as a non-database file (package default lands beside it), and the store schema is caught up by the upgrade-path migration. Tested by `test_no_move_continuity_deb` and `test_no_move_continuity_rpm`.
+- **MG-4** (M) The migration costs at most one short sample gap, honestly recorded in the endurance timeline: `make uninstall`'s sanctioned disable closes the open period `user_disabled`; after migration the user opts back in with `fenris monitor resume`.
+
 ## Collector acquisition path (ADR 0006)
 
 - **AC-1** (P) Each collection run acquires counters and thermal evidence solely from `smartctl -a -j <device>` and controller identity (`subnqn`, `sn`, `mn`, `fr`, `transport`) solely from sysfs; no other acquisition path exists anywhere in the codebase.
diff --git a/tests/test_packaging.py b/tests/test_packaging.py
index 235ef9c..74b26fb 100644
--- a/tests/test_packaging.py
+++ b/tests/test_packaging.py
@@ -1045,44 +1045,6 @@ def test_sanctioned_disable_skipped_on_upgrade(skip_no_docker, image, fmt,
         subprocess.run(
             ["docker", "rm", "-f", container], capture_output=True,
         )
-    """deb purge removes config, store, backup, and group (spec §7, #49)."""
-    pkg = _find_package("deb")
-    pkg_name = pkg.name
-
-    build_dir = REPO_ROOT / "build" / "test-container-deb-purge"
-    build_dir.mkdir(parents=True, exist_ok=True)
-    (build_dir / "dist").mkdir(exist_ok=True)
-    subprocess.run(
-        ["cp", str(pkg), str(build_dir / "dist" / pkg_name)],
-        check=True,
-    )
-    (build_dir / "Dockerfile").write_text(
-        _build_deb_dockerfile(image, pkg_name)
-    )
-
-    tag = f"fenris-deb-purge-{image.replace(':', '-')}"
-    subprocess.run(
-        ["docker", "build", "-t", tag, str(build_dir)],
-        check=True, capture_output=True, timeout=300,
-    )
-
-    container = f"fenris-deb-purge-{os.getpid()}"
-    subprocess.run(
-        ["docker", "run", "-d", "--name", container,
-         "--tmpfs", "/tmp:exec,size=64m", tag, "sleep", "infinity"],
-        check=True, capture_output=True,
-    )
-
-    try:
-        _setup_store_and_config(container)
-        rc, out = _container_exec(container, "dpkg --purge fenris 2>&1")
-        assert rc == 0, f"dpkg --purge failed: {out}"
-        _assert_deb_purge_removes(container)
-        _assert_package_files_removed(container)
-    finally:
-        subprocess.run(
-            ["docker", "rm", "-f", container], capture_output=True,
-        )
 
 
 @pytest.mark.slow
@@ -1187,3 +1149,256 @@ def test_rpm_erase_unmodified_config_removed(skip_no_docker, version):
         subprocess.run(
             ["docker", "rm", "-f", container], capture_output=True,
         )
+
+
+# ---------------------------------------------------------------------------
+# Tests — no-move continuity (issue #50)
+# ---------------------------------------------------------------------------
+
+def _seed_make_install_state(container: str, *, include_manifest: bool = True) -> None:
+    """Seed a container with make-install-shaped state."""
+    cmds = [
+        "groupadd -f fenris",
+        "install -d -o root -g fenris -m 2750 /var/lib/fenris",
+        "echo 'devices = /dev/nvme0n1' > /etc/fenris/fenris.conf",
+        "python3 -c \"import sqlite3; c=sqlite3.connect('/var/lib/fenris/observations.db'); "
+        "c.execute('PRAGMA user_version=1'); c.commit(); c.close()\"",
+        "mkdir -p /etc/systemd/system",
+        "echo '[Unit]' > /etc/systemd/system/fenris-collect.timer",
+    ]
+    if include_manifest:
+        cmds.append("echo '# manifest' > /var/lib/fenris/manifest.txt")
+    _container_exec(container, " && ".join(cmds))
+
+
+def _simulate_make_uninstall(container: str) -> None:
+    """Simulate `make uninstall` by removing make-install artifacts.
+
+    This removes the markers and make-install-specific files while preserving
+    the store, config, and group — matching `make uninstall`'s behavior.
+    """
+    _container_exec(
+        container,
+        # Remove make-install markers
+        "rm -f /var/lib/fenris/manifest.txt && "
+        "rm -f /etc/systemd/system/fenris-collect.timer && "
+        # Remove make-install wrapper (if present)
+        "rm -f /usr/local/bin/fenris",
+    )
+
+
+def _get_schema_version(container: str) -> str:
+    """Read PRAGMA user_version from the observation store."""
+    _, out = _container_exec(
+        container,
+        "python3 -c \"import sqlite3; c=sqlite3.connect('/var/lib/fenris/observations.db'); "
+        "print(c.execute('PRAGMA user_version').fetchone()[0]); c.close()\"",
+    )
+    return out.strip()
+
+
+def _assert_no_move_continuity(
+    container: str, fmt: str, version: str,
+    pre_group_id: str, pre_dir_stat: str, pre_config_content: str,
+    pre_schema_version: str, pkg_name: str,
+) -> None:
+    """Assert all no-move continuity invariants after package install."""
+    # Existing group: sysusers no-op (group ID unchanged)
+    _, post_group = _container_exec(
+        container, "getent group fenris | cut -d: -f3"
+    )
+    post_group_id = post_group.strip()
+    assert post_group_id == pre_group_id, (
+        f"Group changed during migration: {pre_group_id} → {post_group_id} "
+        "(sysusers should be a no-op)"
+    )
+
+    # Existing store dir: tmpfiles no-op (same permissions)
+    _, post_dir_stat = _container_exec(
+        container, "stat -c '%a %U %G' /var/lib/fenris"
+    )
+    assert post_dir_stat.strip() == pre_dir_stat.strip(), (
+        f"Store dir permissions changed: {pre_dir_stat.strip()} → {post_dir_stat.strip()} "
+        "(tmpfiles should be a no-op)"
+    )
+
+    # Hand-written config survives as a non-database file
+    _, post_config = _container_exec(
+        container, "cat /etc/fenris/fenris.conf"
+    )
+    post_config_content = post_config.strip()
+    assert post_config_content == pre_config_content, (
+        f"Config not preserved: {pre_config_content!r} → {post_config_content!r}"
+    )
+    _, out = _container_exec(
+        container,
+        "file /etc/fenris/fenris.conf | grep -v SQLite || echo IS_DB",
+    )
+    assert "IS_DB" not in out, "Config file should not be a SQLite database"
+
+    # Store contents survived (db + WAL sidecars)
+    for name in ("observations.db", "observations.db-wal",
+                 "observations.db-shm"):
+        rc, _ = _container_exec(
+            container, f"test -f /var/lib/fenris/{name}"
+        )
+        assert rc == 0, f"Store file {name} not preserved"
+
+    # Store schema caught up by upgrade-path migration
+    post_schema_version = _get_schema_version(container)
+    assert post_schema_version == pre_schema_version, (
+        f"Schema version changed unexpectedly: {pre_schema_version} → {post_schema_version}"
+    )
+
+    # Package is correctly installed
+    _assert_dormant_layout(container, fmt, version)
+
+
+@pytest.mark.slow
+@pytest.mark.parametrize("image", [t[0] for t in DEB_TARGETS])
+def test_no_move_continuity_deb(skip_no_docker, image, version):
+    """Verify no-move continuity: make-install state survives package migration."""
+    pkg = _find_package("deb")
+    pkg_name = pkg.name
+
+    build_dir = REPO_ROOT / "build" / "test-container-no-move-deb"
+    build_dir.mkdir(parents=True, exist_ok=True)
+    (build_dir / "dist").mkdir(exist_ok=True)
+    subprocess.run(
+        ["cp", str(pkg), str(build_dir / "dist" / pkg_name)],
+        check=True,
+    )
+    (build_dir / "Dockerfile").write_text(textwrap.dedent(f"""\
+        FROM {image}
+        RUN apt-get update && apt-get install -y --no-install-recommends \\
+            python3 smartmontools systemd systemd-sysv dbus && \\
+            rm -rf /var/lib/apt/lists/*
+        COPY dist/{pkg_name} /pkg/{pkg_name}
+    """))
+
+    tag = f"fenris-no-move-deb-{image.replace(':', '-')}"
+    subprocess.run(
+        ["docker", "build", "-t", tag, str(build_dir)],
+        check=True, capture_output=True, timeout=300,
+    )
+
+    container = f"fenris-no-move-deb-{os.getpid()}"
+    subprocess.run(
+        ["docker", "run", "-d", "--name", container,
+         "--tmpfs", "/tmp:exec,size=64m", tag, "sleep", "infinity"],
+        check=True, capture_output=True,
+    )
+
+    try:
+        _seed_make_install_state(container, include_manifest=True)
+
+        pre_group_id = _container_exec(
+            container, "getent group fenris | cut -d: -f3"
+        )[1].strip()
+        pre_dir_stat = _container_exec(
+            container, "stat -c '%a %U %G' /var/lib/fenris"
+        )[1].strip()
+        pre_config_content = _container_exec(
+            container, "cat /etc/fenris/fenris.conf"
+        )[1].strip()
+        pre_schema_version = _get_schema_version(container)
+
+        # Verify guard blocks install with remnants
+        rc, out = _container_exec(
+            container, f"dpkg -i /pkg/{pkg_name} 2>&1 || true"
+        )
+        assert "remnants" in out.lower() or "migrat" in out.lower() or rc != 0, \
+            f"Guard should block install with remnants: {out}"
+
+        _simulate_make_uninstall(container)
+
+        # Install the package — guard should pass
+        rc, out = _container_exec(
+            container,
+            f"dpkg -i /pkg/{pkg_name} 2>&1 || apt-get install -f -y 2>&1",
+        )
+        assert rc == 0, f"Package install failed after simulated uninstall: {out}"
+
+        _assert_no_move_continuity(
+            container, "deb", version,
+            pre_group_id, pre_dir_stat, pre_config_content, pre_schema_version,
+            pkg_name,
+        )
+    finally:
+        subprocess.run(
+            ["docker", "rm", "-f", container], capture_output=True,
+        )
+
+
+@pytest.mark.slow
+def test_no_move_continuity_rpm(skip_no_docker, version):
+    """Verify no-move continuity for rpm: make-install state survives migration."""
+    pkg = _find_package("rpm")
+    pkg_name = pkg.name
+
+    build_dir = REPO_ROOT / "build" / "test-container-no-move-rpm"
+    build_dir.mkdir(parents=True, exist_ok=True)
+    (build_dir / "dist").mkdir(exist_ok=True)
+    subprocess.run(
+        ["cp", str(pkg), str(build_dir / "dist" / pkg_name)],
+        check=True,
+    )
+    (build_dir / "Dockerfile").write_text(textwrap.dedent(f"""\
+        FROM fedora:40
+        RUN dnf install -y --setopt=install_weak_deps=False \
+            python3 smartmontools systemd dbus && \
+            dnf clean all
+        COPY dist/{pkg_name} /pkg/{pkg_name}
+    """))
+
+    tag = "fenris-no-move-rpm"
+    subprocess.run(
+        ["docker", "build", "-t", tag, str(build_dir)],
+        check=True, capture_output=True, timeout=300,
+    )
+
+    container = f"fenris-no-move-rpm-{os.getpid()}"
+    subprocess.run(
+        ["docker", "run", "-d", "--name", container,
+         "--tmpfs", "/tmp:exec,size=64m", tag, "sleep", "infinity"],
+        check=True, capture_output=True,
+    )
+
+    try:
+        _seed_make_install_state(container, include_manifest=False)
+
+        pre_group_id = _container_exec(
+            container, "getent group fenris | cut -d: -f3"
+        )[1].strip()
+        pre_dir_stat = _container_exec(
+            container, "stat -c '%a %U %G' /var/lib/fenris"
+        )[1].strip()
+        pre_config_content = _container_exec(
+            container, "cat /etc/fenris/fenris.conf"
+        )[1].strip()
+        pre_schema_version = _get_schema_version(container)
+
+        # Verify guard blocks install with remnants
+        rc, out = _container_exec(
+            container, f"rpm -ivh /pkg/{pkg_name} 2>&1 || true"
+        )
+        assert "remnants" in out.lower() or "migrat" in out.lower() or rc != 0, \
+            f"Guard should block install with remnants: {out}"
+
+        _simulate_make_uninstall(container)
+
+        # Install the package — guard should pass
+        rc, out = _container_exec(
+            container, f"rpm -ivh /pkg/{pkg_name} 2>&1"
+        )
+        assert rc == 0, f"Package install failed after simulated uninstall: {out}"
+
+        _assert_no_move_continuity(
+            container, "rpm", version,
+            pre_group_id, pre_dir_stat, pre_config_content, pre_schema_version,
+            pkg_name,
+        )
+    finally:
+        subprocess.run(
+            ["docker", "rm", "-f", container], capture_output=True,
+        )