Merge branch 'learn-fb' into integration

docs/adr/0021-private-instance-and-assistant.md

@@ -462,6 +462,31 @@ assistants' effort work:
     asking for the microphone only once it is tapped; on Linux there is none, and the
     field shows no microphone. On Android the recogniser may send the sound to Google or
     the phone's maker, which the instance's privacy page says; the instance never gets it.
+- **D68 Voice mode is a conversation spoken, as Claude's "Let's talk"** (the developer's
+  review of 3 Nov 2026, full conversation chosen over dictation alone): beside the
+  microphone, while nothing could be sent, a button opens it over the whole screen (no
+  bar beneath), with a glow rising from the foot of it, brighter while it listens or
+  reads, a big microphone and one row: + attaching to the next question, who answers (any
+  other assistant picked starts a conversation with it, once agreed to as any question,
+  D40, D9), the speaker and End. It listens (D67's recogniser), asks what was heard in
+  one conversation kept as any other (D48), reads the answer aloud and listens again;
+  the microphone tapped while it reads or waits listens at once, and nothing heard waits
+  for it. The field's scope, the parts chosen and the files attached go with the first
+  question. Only the question's text goes to the assistant, as typed ones do.
+  - **Reading aloud is the device's own speech** (recommended): `flutter_tts` (4.2,
+    maintained, Android's TextToSpeech, Apple's AVSpeechSynthesizer, Windows' SAPI), in
+    the app's language where the device has it, the answer read without its Markdown
+    (`speakableText`: no marks, a table's rows as their cells, a link as its words). Over
+    a MethodChannel of our own to Android's TextToSpeech, which would spare the Kotlin
+    Gradle plugin `flutter_tts` applies (as `flutter_web_auth_2` and
+    `keyboard_height_plugin` do) but leave iOS, macOS and Windows to be written too; and
+    over the provider's speech (OpenAI's, as the instance would forward it), which would
+    send the answers out again and cost the operator's budget. Android 11 on needs the
+    `TTS_SERVICE` query in the manifest to find the engine.
+  - **Where the device can't**: on Linux nothing recognises speech, so there is no voice
+    mode (as no microphone, D67); where nothing reads aloud (`flutter_tts` has no Linux,
+    and a phone may lack the language), answers are shown in it as text, and it listens
+    again at once, as with the speaker off. The speaker starts on.
 
 As built on 26 Oct, for v0.22.0 (build 25, which the server needs: `minimumAppBuild` 25,
 as older apps read limits per grant), D57–D63 read so where they left something open: