Per-OS hosts, and an init asked for only start and restart

0060 -- the host is built per operating system. systemd and pacman are the Arch
host's implementation, not abstractions the mesh has to grow. They are not
independent choices: a machine has pacman because it is Arch, and the package
manager, service manager and packaging format arrive together as one decision
somebody made at install time.

Rejected abstracting them, and the reason is correctness rather than effort.
The service applier reads LoadState to tell "not installed" apart from
"stopped", which is what stops it reporting absence as success. An interface
spanning systemd and OpenRC degrades to what both express, and the lowest
common denominator is exactly where that fault lives.

Almost all of it is shared -- the vocabulary, store, apply loop, read-back
discipline, refusal model, bundle and link are portable. Two appliers differ.
And delivery was already per-OS, since a .pkg.tar.zst is an Arch artifact, so
this is the seam that already existed.

Android is the interesting case rather than Debian: no service manager, no
package installation, usually no root. Such a host implements file, directory
and action and refuses the rest -- the same refusal a host already gives an
unknown type, with a different reason. Those three are the portable floor.

The container runtime is deliberately left open: it is not an OS split, since
Arch runs docker or podman.

0061 -- the init is asked for start-at-boot and restart-on-exit, and nothing
else. Both are expressible in OpenRC, runit, s6 and an Android init.rc.
Counting failed starts and rolling back moves into a launcher, because that is
the one piece which must work when the host does not, and a script with a
counter can be tested where OnFailure= can only be hoped for. Supersedes 0059,
keeping its reasoning in full.

The checker found all six places citing 0059 and refused the commit until they
named the replacement.

03-DESIGN/01-to-be/05-the-node-host.md

@@ -13,7 +13,7 @@ decisions:
   - 02-DECISIONS/0041-the-host-depends-on-nothing.md
   - 02-DECISIONS/0043-a-declaration-is-an-ordered-list-of-owned-resources.md
   - 02-DECISIONS/0057-the-host-is-a-root-service-installed-as-a-package.md
-  - 02-DECISIONS/0059-a-host-that-cannot-start-rolls-itself-back.md
+  - 02-DECISIONS/0061-the-host-asks-an-init-for-start-and-restart.md
 ---
 
 # The node host
@@ -162,23 +162,28 @@ After=network-online.target
 Wants=network-online.target
 
 [Service]
-Type=notify
-ExecStart=/usr/bin/nox-mesh-host run
+ExecStart=/usr/lib/nox-mesh-host/launch
 Restart=always
 RestartSec=5s
-StartLimitBurst=3
-StartLimitIntervalSec=120
 StateDirectory=mesh-host
 
 [Install]
 WantedBy=multi-user.target
 ```
 
+**Two lines of policy, and that is deliberate**
+([ADR 0061](../../02-DECISIONS/0061-the-host-asks-an-init-for-start-and-restart.md)). The init is
+asked to *start this at boot* and *start it again if it exits*, and nothing else. Both are
+expressible in OpenRC, runit, s6 and an Android `init.rc`, so porting this file is transcription
+rather than design.
+
 **`Restart=always` and not `on-failure`**: the host restarts onto a new binary by exiting
-*cleanly*, and `on-failure` would not restart it — an upgraded node would be left stopped,
-having successfully upgraded. The start limit is what
-[ADR 0059](../../02-DECISIONS/0059-a-host-that-cannot-start-rolls-itself-back.md) uses to decide
-a binary is broken rather than unlucky.
+*cleanly*, so a supervisor that only restarts on failure would leave every upgraded node stopped,
+having successfully upgraded.
+
+**What the init does not do is decide when to give up.** Counting failed starts and rolling back
+lives in the launcher, where it can be tested — `OnFailure=` in a unit file can only be read and
+hoped for, and it is the one thing that has to work on a machine where nothing else does.
 
 **The package owns this file. The host never does.** It manages `service` resources, and its own
 unit is a service — the temptation is obvious and it ends with a host stopping itself half way