feat(learn): a private studyset goes to an assistant only once agreed

ADR 0021, D9 and D17. Before a question sends a private studyset's
content to a remote model, through the parts chosen or a wider reach
with private studysets switched on, a warning names the studysets, the
provider's host and its terms (where checked: Anthropic, OpenAI,
Google, OpenRouter), and is asked once per studyset and assistant: the
agreement is kept in the person's sealed settings (schema 13,
privateAgreements, folded only where both rows hold it), shown in the
studyset's privacy dialog with Take back, and marked on the folded
button while it holds. Follow-ups and Try again ask again once taken
back, as the scope keeps where the parts came from (partsFrom). No
warning for an own assistant on this machine (loopback or localhost,
halkyon_llm's LlmEndpoint.onThisMachine); the local network may be
shared.

Texts that step 3 made untrue: the consent sheet now says what an
assistant looks up goes too and that conversations are kept encrypted
for the person's devices; the privacy dialogs no longer mention
showing a studyset to Claude; the privacy page says what is looked up
and when a private studyset goes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_flutter/lib/l10n/app_localizations.dart

@@ -10953,6 +10953,65 @@ abstract class AppLocalizations {
   /// **'Looked for a note, found none'**
   String get assistantLookedUpNoNote;
 
+  /// The warning before a private studyset's content goes to a remote model (ADR 0021, D9).
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{Send a private studyset to {name}?} other{Send private studysets to {name}?}}'**
+  String assistantPrivateTitle(int count, String name);
+
+  /// The warning for an assistant the operator granted, asked through the instance.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{It is end-to-end encrypted, so that not even {instance} can read it. What {name} looks up in it, or what you chose of it, passes through {instance}, which keeps none of it, to {host}, which reads it under the provider\'s terms.} other{They are end-to-end encrypted, so that not even {instance} can read them. What {name} looks up in them, or what you chose of them, passes through {instance}, which keeps none of it, to {host}, which reads it under the provider\'s terms.}}'**
+  String assistantPrivateGranted(
+    int count,
+    String name,
+    String instance,
+    String host,
+  );
+
+  /// The warning for the person's own assistant, asked directly.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{It is end-to-end encrypted, so that not even the instance can read it. What {name} looks up in it, or what you chose of it, goes straight to {host}, which reads it under the provider\'s terms.} other{They are end-to-end encrypted, so that not even the instance can read them. What {name} looks up in them, or what you chose of them, goes straight to {host}, which reads it under the provider\'s terms.}}'**
+  String assistantPrivateOwn(int count, String name, String host);
+
+  /// D17: asked once, taken back in the privacy dialog.
+  ///
+  /// In en, this message translates to:
+  /// **'You\'re asked once for each studyset and assistant. Take it back from the lock beside the studyset.'**
+  String get assistantPrivateOnce;
+
+  /// No description provided for @assistantPrivateTerms.
+  ///
+  /// In en, this message translates to:
+  /// **'The provider\'s terms'**
+  String get assistantPrivateTerms;
+
+  /// Agrees and sends.
+  ///
+  /// In en, this message translates to:
+  /// **'Send'**
+  String get assistantPrivateSend;
+
+  /// The mark on the assistant's button while an agreement holds (D17).
+  ///
+  /// In en, this message translates to:
+  /// **'{name} may be sent this private studyset'**
+  String assistantPrivateMark(String name);
+
+  /// The privacy dialog's list of the assistants agreed to (D17).
+  ///
+  /// In en, this message translates to:
+  /// **'Assistants it may go to'**
+  String get studysetPrivacyAssistants;
+
+  /// Takes an agreement back.
+  ///
+  /// In en, this message translates to:
+  /// **'Take back'**
+  String get studysetPrivacyTakeBack;
+
   /// No description provided for @settingsSearchEngine.
   ///
   /// In en, this message translates to:
@@ -12144,7 +12203,7 @@ abstract class AppLocalizations {
   /// No description provided for @studysetPrivateBody.
   ///
   /// In en, this message translates to:
-  /// **'Everything in it is end-to-end encrypted on your devices: the instance can\'t read it, publish it or show it to Claude. Copies in the instance\'s backups stay readable until those expire.'**
+  /// **'Everything in it is end-to-end encrypted on your devices: the instance can\'t read it or publish it, and an assistant gets only what you agree to send it. Copies in the instance\'s backups stay readable until those expire.'**
   String get studysetPrivateBody;
 
   /// No description provided for @studysetReadableTitle.
@@ -12366,7 +12425,7 @@ abstract class AppLocalizations {
   /// No description provided for @studysetPrivacyPrivateBody.
   ///
   /// In en, this message translates to:
-  /// **'Everything in it is end-to-end encrypted: only your devices can read it. The instance can\'t publish it, nor show it to Claude. Making it non-private decrypts it and syncs it again, so the instance can read it.'**
+  /// **'Everything in it is end-to-end encrypted: only your devices can read it. The instance can\'t publish it, and an assistant gets only what you agree to send it. Making it non-private decrypts it and syncs it again, so the instance can read it.'**
   String get studysetPrivacyPrivateBody;
 
   /// No description provided for @studysetPrivacyReadableTitle.