Compare views: start with a view the zone is linked to

The tab picked the first other view in view order, so a zone linked with
one view opened compared with an unrelated one.

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

CHANGELOG.md

@@ -12,6 +12,11 @@ All notable changes to Jarl are documented here. The format follows
   jarld` works too. The alias is linked when the unit is enabled; the
   package relinks a unit enabled by an older version on upgrade.
 
+### Changed
+
+- A linked zone's Compare views tab starts with a view it is linked to,
+  not the first other view.
+
 ## [0.6.0] - 2026-10-13
 
 ### Added

docs/views.md

@@ -235,7 +235,10 @@ before it).
 ## Comparing views
 
 A zone's **Compare views** tab, or `jarl zone diff`, compares it with the
-same zone in another view (or all of them), from the view you're on:
+same zone in another view (or all of them), from the view you're on.
+The tab starts with a view the zone is linked to, if any, else the
+first other view; `jarl zone diff` compares with every other view unless
+`--with` names some:
 
 ```
 $ jarl zone diff adbraun.lol --view internal

internal/web/static/assets/pages/zone.js

@@ -88,7 +88,10 @@ export async function render(el, params, query) {
 // the same. ?name= (and &type=) narrows it to one name.
 async function compareTab(el, zone, query) {
   const others = zone.other_views || [];
-  const withSel = select([...(others.length > 1 ? [["", "all other views"]] : []), ...others.map((v) => [v, v])], query.get("with") || others[0] || "");
+  // A linked zone starts with a view it is linked to: that is the
+  // comparison that matters (its differences are its own records).
+  const linked = (zone.linked_with || []).filter((v) => others.includes(v));
+  const withSel = select([...(others.length > 1 ? [["", "all other views"]] : []), ...others.map((v) => [v, v])], query.get("with") || linked[0] || others[0] || "");
   const nameIn = input({ value: query.get("name") || "", placeholder: "all names, or one: www, @", class: "mono", style: { width: "200px" } });
   const typeIn = input({ value: query.get("type") || "", placeholder: "any type", class: "mono", style: { width: "90px" } });
   let showSame = false;