fix(white-label): back-to-clients link points at the byra cockpit's home domain (#1973)

* fix(white-label): back-to-clients link points at the byra cockpit's home domain

A byra member working a company homed on another host (e.g. a pre-byra
company on canonical) got a relative /clients on the wrong host instead
of their white-label cockpit. resolveCockpitHref mirrors WL-14's home
rule: relative when the current host is the cockpit's home (brand domain,
or canonical for a brandless byra), else an absolute URL there. Cross-
host links render a plain <a> with a 'Hanteras via' hint; the hop lands
on the brand host's login (per-host sessions, WL-01) and WL-14 then
lands on /clients.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(white-label): show the cross-host cockpit hint as visible text

CodeRabbit: title-only hints never surface on touch devices, so the
expanded-sidebar and mobile external back-links now render the
'Hanteras via {domain}' line as small muted text under the label
(same pattern as the switcher's foreign entries). Also corrects the
comments claiming the no-company branch never renders the back-link:
it can, on its cockpit/settings surfaces, where the relative fallback
matches pre-change behavior.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/company/__tests__/home-domain.test.ts

@@ -4,6 +4,7 @@ import {
   isCompanyHomedOnHost,
   isCockpitLandingRole,
   resolveLandingPath,
+  resolveCockpitHref,
   type TeamBrandRef,
 } from '../home-domain'
 
@@ -200,3 +201,77 @@ describe('resolveLandingPath', () => {
     expect(resolveLandingPath({ hostBrandTeamId: 'byra-1', byraTeams: [] })).toBe('/')
   })
 })
+
+describe('resolveCockpitHref', () => {
+  const brandByTeam = new Map([['byra-1', siffraBrand]])
+  const canonicalDomain = CANONICAL.canonicalDomain
+
+  it('brandless byrå on the canonical host stays relative', () => {
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam: new Map(),
+        hostBrandTeamId: null,
+        canonicalDomain,
+      }),
+    ).toBe('/clients')
+  })
+
+  it('branded byrå on its own brand host stays relative', () => {
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam,
+        hostBrandTeamId: 'byra-1',
+        canonicalDomain,
+      }),
+    ).toBe('/clients')
+  })
+
+  it('branded byrå on the canonical host points at the brand domain (problem 4)', () => {
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam,
+        hostBrandTeamId: null,
+        canonicalDomain,
+      }),
+    ).toBe('https://app.siffra.se/clients')
+  })
+
+  it("branded byrå on someone ELSE's brand host points at its own brand domain", () => {
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam,
+        hostBrandTeamId: 'byra-2',
+        canonicalDomain,
+      }),
+    ).toBe('https://app.siffra.se/clients')
+  })
+
+  it('brandless byrå on a foreign brand host points home to canonical (WL-14 symmetry)', () => {
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam: new Map(),
+        hostBrandTeamId: 'byra-2',
+        canonicalDomain,
+      }),
+    ).toBe('https://app.gnubok.se/clients')
+  })
+
+  it('byrå with zero client companies still resolves via its own brand entry', () => {
+    // The layout adds the byrå team id to the resolveBrandsForTeams id list
+    // precisely so this map entry exists even when no membership company
+    // belongs to the byrå (pre-byrå companies have team_id null).
+    expect(
+      resolveCockpitHref({
+        byraTeamId: 'byra-1',
+        brandByTeam: new Map([['byra-1', siffraBrand]]),
+        hostBrandTeamId: null,
+        canonicalDomain,
+      }),
+    ).toBe('https://app.siffra.se/clients')
+  })
+})

lib/company/home-domain.ts

@@ -129,3 +129,35 @@ export function resolveLandingPath(opts: {
   // Canonical host: only a brandless byrå homes its cockpit here.
   return opts.byraTeams.some((t) => !t.hasBrand) ? '/clients' : '/'
 }
+
+/**
+ * Href for the pinned "Tillbaka till klienter" link: the byrå cockpit lives
+ * on the byrå's home domain (its brand domain when the team has a brand, else
+ * the canonical domain, same rule as WL-14's resolveLandingPath). Relative
+ * '/clients' when the current host IS that home; an absolute URL otherwise,
+ * so a byrå member working a company homed on a different host (e.g. a
+ * pre-byrå company on canonical) is sent to their white-label cockpit.
+ *
+ * Navigation rule only, like everything in this file: the hop lands on the
+ * brand host's login when there is no session there (per-host sessions,
+ * WL-01), and WL-14 then lands the user on /clients.
+ */
+export function resolveCockpitHref(opts: {
+  /** teams.id of the user's byrå team. */
+  byraTeamId: string
+  brandByTeam: Map<string, TeamBrandRef>
+  /** teams.id of the brand serving the current host, null on canonical. */
+  hostBrandTeamId: string | null
+  canonicalDomain: string
+}): string {
+  const brand = opts.brandByTeam.get(opts.byraTeamId)
+  if (brand) {
+    return opts.hostBrandTeamId === opts.byraTeamId
+      ? '/clients'
+      : `https://${brand.domain}/clients`
+  }
+  // Brandless byrå: the cockpit is homed on the canonical domain.
+  return opts.hostBrandTeamId === null
+    ? '/clients'
+    : `https://${opts.canonicalDomain}/clients`
+}