0062: a host may be episodic; 0060's Android gap closed

0060 named the gap and did not close it: everywhere else an init runs the
launcher at boot, and Android grants neither an init to register with nor
anything worth supervising, because a supervisor would be killed alongside what
it supervises.

Closed by narrowing what is required rather than building something. A host is
resident or episodic, and both are hosts. Being killed by the platform is
disconnection, which 0036 already made ordinary -- and every mechanism an
episodic host needs already exists because it was built for laptops that close.

A partial host can join a mesh and cannot be the first node, since every
bootstrap step is a shape it refuses. Its bundle says so.

Two consequences that are easy to miss: last-heard-from means much less on an
episodic host, so a healthy phone reads as a dead server unless the reader
knows which kind it is; and a declaration may take a long time to land, which
makes 0058's outstanding-versus-failed distinction load-bearing.

Still open, and in that order: what an Android node is FOR, and only then how
it is started.

03-DESIGN/01-to-be/09-the-node-lifecycle.md

@@ -14,6 +14,7 @@ decisions:
   - 02-DECISIONS/0058-delivery-ends-in-a-declaration.md
   - 02-DECISIONS/0060-the-host-is-built-per-operating-system.md
   - 02-DECISIONS/0061-the-host-asks-an-init-for-start-and-restart.md
+  - 02-DECISIONS/0062-a-host-may-be-episodic.md
 ---
 
 # The node lifecycle
@@ -189,6 +190,43 @@ used months later on node two.
 
 ---
 
+## Two kinds of host
+
+Everything above assumes a machine with an init that runs the host at boot. Not every machine
+has one ([ADR 0062](../../02-DECISIONS/0062-a-host-may-be-episodic.md)).
+
+| | **resident** | **episodic** |
+|---|---|---|
+| examples | Alpine, Arch | Android |
+| started by | an init, at boot | whatever the platform allows |
+| supervised by | the launcher | nothing — the platform decides when it runs |
+| the link | held open | opened while it runs |
+| being stopped | shutdown, or a failure | **ordinary** |
+| shapes | all six | `file`, `directory`, `action` |
+| can be the first node | yes | **no** |
+
+**An episodic host being killed is disconnection, not failure.** That is
+[ADR 0036](../../02-DECISIONS/0036-a-node-is-a-managed-machine.md) doing the work it was written
+for: reachability is state, not class. Everything the design already does for a laptop that
+closes — an authoritative local store, reconcile on start, *last heard from* reported without an
+alarm — is what an episodic host needs, at a shorter period.
+
+**It cannot be the first node**, and that is not a limitation to work around. Every step of
+raising a substrate is a `package`, a `container` or an `action` against one, and a partial host
+refuses the first two. So `mesh-host-android bundle` returns a file that says so rather than an
+empty placeholder waiting to be filled in.
+
+**Two things this changes for anything reading the mesh.** *Last heard from* is a much weaker
+signal on an episodic host — a healthy phone looks like a dead server — so a reader has to know
+which kind it is looking at. And a declaration may take a long time to land, which makes
+[ADR 0058](../../02-DECISIONS/0058-delivery-ends-in-a-declaration.md)'s separation of
+*outstanding* from *failed* load-bearing rather than tidy.
+
+**Still open:** how an episodic host is started in practice — an APK with a foreground service,
+or Termux with its boot addon — and, first, **what an Android node is for.** A device that can
+write files and run commands is not a workload host; it is a presence, or somewhere an agent
+runs. Building the start mechanism before deciding that would be building it for nobody.
+
 ## Adoption: what happens to what is already there
 
 Adoption is not a state. It is what the **first apply** does when it is told to own something a