Open locked accounts handed to you, beside your own mail

When the server hands a locked account to the reader (urn:inbuxa:jmap
delegation), the account popover offers it. Only mail follows the switch;
the reader's own settings, push and notifications stay theirs. A red bar,
a red wordmark with a padlock and the tab title say which account is in
view. Read delegates can't change anything, organize delegates can't
delete, and writing needs send-as. A delegation taken away drops back to
the reader's own mail.

14 new strings in all nine catalogs, unreviewed (inbuxa AL-7, AL-8).

web/src/lib/delegation.ts

@@ -0,0 +1,67 @@
+/**
+ * Locked accounts handed to the reader (inbuxa audit-hold-lock spec, AL-7).
+ *
+ * The server marks one in the account's `urn:inbuxa:jmap` capability, as
+ * `delegation: {locked, access, sendAs, until}`. Only that mark makes an
+ * account switchable: a server advertises every capability on any shared
+ * account, so "it has mail" proves nothing about what was handed over.
+ */
+
+import type { Id, JmapSession } from "@/jmap/types";
+
+export type DelegationAccess = "read" | "organize" | "full";
+
+export interface Delegation {
+  locked: boolean;
+  access: DelegationAccess;
+  sendAs: boolean;
+  /** UTC date the delegation ends, if it does. */
+  until: string | null;
+}
+
+export interface DelegatedAccount {
+  id: Id;
+  name: string;
+  delegation: Delegation;
+}
+
+const INBUXA = "urn:inbuxa:jmap";
+
+type SessionLike = Pick<JmapSession, "accounts">;
+
+export function delegationOf(session: SessionLike | null, accountId: Id | null): Delegation | null {
+  if (!session || !accountId) return null;
+  const account = session.accounts[accountId];
+  if (!account || account.isPersonal) return null;
+  const raw = (account.accountCapabilities?.[INBUXA] as { delegation?: Partial<Delegation> } | undefined)?.delegation;
+  if (!raw || raw.locked !== true) return null;
+  const access: DelegationAccess = raw.access === "organize" || raw.access === "full" ? raw.access : "read";
+  return {
+    locked: true,
+    access,
+    sendAs: raw.sendAs === true && access !== "read",
+    until: typeof raw.until === "string" ? raw.until : null,
+  };
+}
+
+/** Every locked account handed to the reader, by name. */
+export function delegatedAccounts(session: SessionLike | null): DelegatedAccount[] {
+  if (!session) return [];
+  return Object.entries(session.accounts)
+    .map(([id, account]) => {
+      const delegation = delegationOf(session, id);
+      return delegation ? { id, name: account.name, delegation } : null;
+    })
+    .filter((a): a is DelegatedAccount => a !== null)
+    .sort((a, b) => a.name.localeCompare(b.name));
+}
+
+/** Whether the reader may change anything in the account (AL-6). */
+export function mayWrite(delegation: Delegation | null): boolean {
+  return !delegation || delegation.access !== "read";
+}
+
+/** Whether the reader may delete in the account (AL-6). */
+export function mayDestroy(delegation: Delegation | null): boolean {
+  return !delegation || delegation.access === "full";
+}