Give every view a TSIG key that selects it

Each view's match-clients starts with "key jarl-view-NAME" (after
"!key" for the views listed after it), so a query signed with a view's
key lands in that view from any address. The secrets are derived from a
random seed in Jarl's database. The delegation check signs its queries
to this server's own addresses with the key of the zone's view: before,
they got whichever view matched the server's address, usually internal.
jarl view key / GET /views/{id}/key show a key for dig -k (tsig:write,
audited). jarl-view- key names are reserved; the importer drops view
keys from a configuration Jarl wrote.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/views.md

@@ -116,7 +116,44 @@ dig @<public-ip> example.com                            # from outside: status R
 jarl check
 ```
 
-On the server, `dig -b <source address>` picks which view you test.
+On the server, `dig -b <source address>` picks which view you test, or,
+from anywhere, sign the query with the view's key (below):
+
+```sh
+jarl view key external --named-conf > external.key
+dig -k external.key @ns1.adbraun.lol nas.adbraun.lol +short   # 203.0.113.20, even from the LAN
+```
+
+## View keys
+
+named picks a view by where a query comes from, so a query this server
+sends to its own public address usually lands in the internal view: its
+source is one of your own networks. That makes checks of the external view
+from the server itself (such as Jarl's delegation check) see the wrong
+view.
+
+So Jarl gives every view a TSIG key, `jarl-view-NAME`, and puts it at the
+front of the view's `match-clients`:
+
+```
+view "internal" {
+	match-clients { !key jarl-view-external; key jarl-view-internal; homelab; };
+	...
+view "external" {
+	match-clients { key jarl-view-external; any; };
+```
+
+A query signed with a view's key lands in that view, whatever its source;
+the `!key` stops an earlier view from taking a later view's queries.
+Clients don't send these keys, so for them nothing changes. Jarl signs its
+own queries to this server's addresses with the key of the zone's view.
+The keys live in `keys.conf` with your other keys, never in diffs or in
+`jarl tsig list`; their secrets are derived from a random value in Jarl's
+database (and in its backups), so they stay the same from one apply to
+the next. `jarl view key VIEW`
+shows one (it needs `tsig:write` and is audited). Key names starting with
+`jarl-view-` are reserved, and the view keys can be used in your own
+options (`allow-transfer { key jarl-view-external; }`).
 
 ## Living with views
 
@@ -130,7 +167,9 @@ On the server, `dig -b <source address>` picks which view you test.
   `jarl view list` shows it.
 * Deleting a view is refused while it still has zones, unless you pass
   `--cascade`.
-* Give each view a colour (Views → Edit → Colour, or
+* Each view has its own page (Views → the view's name): its settings,
+  options and zones.
+* Give each view a colour (the view's page → Settings → Colour, or
   `jarl view color internal green`) to tell the zones of each view apart
   in the zone list. The colour only affects the web UI, so it applies at
   once, with no changeset or deploy. `jarl view color internal default`