Add dictation and streamed read-aloud to the chat

- A mic in the composer records, transcribes with the bot's
  transcription model (api/admin/bots/transcribe) and writes the text
  into the input at the cursor to edit before sending. Escape cancels;
  recordings aren't stored.
- Every bot message has a read-aloud button that plays
  GET api/admin/bots/speak-message, streamed from the provider as the
  audio is made, so it starts in a couple of seconds. One message plays
  at a time; only the user's own sessions can be read.
- Both buttons stay visible but disabled while the bot has no model for
  them (bot_voice page prop).
- Transcription and speech no longer pick free models automatically:
  they're not available until a model is picked, and Settings says so.
  Transcription lists speech-to-text models only, so the chat-model
  transcript path and its missing-audio check are gone.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/settings/models/(partials)/harness-current-model.tsx

@@ -21,7 +21,9 @@ export default function HarnessCurrentModel({ harness }: Props) {
             }`
           : harness.required
             ? "Nothing to run on yet: no provider has a usable key."
-            : "No free model can do this right now. Pick one to turn it on.";
+            : !harness.automatic
+              ? "Not available until a model is picked."
+              : "No free model can do this right now. Pick one to turn it on.";
 
     return (
         <Span className="text-[13px] leading-[18px] text-ink-secondary">

src/pages/admin/settings/models/(partials)/harness-model-select.tsx

@@ -12,17 +12,20 @@ type Props = {
     models: HarnessModelOption[];
     model_id: number | null;
     provider_name?: string;
+    automatic: boolean;
     onChange: (model_id: number | null) => void;
 };
 
 /**
- * Searchable model picker: automatic, or any model that can do the job.
+ * Searchable model picker: automatic (or not available, for a harness
+ * without automatic picks), or any model that can do the job.
  */
 export default function HarnessModelSelect({
     id,
     models,
     model_id,
     provider_name,
+    automatic,
     onChange,
 }: Props) {
     return (
@@ -32,7 +35,7 @@ export default function HarnessModelSelect({
             label="Model"
             showLabel
             placeholder="Search models"
-            options={harnessModelSelectOptions({ models, model_id, provider_name })}
+            options={harnessModelSelectOptions({ models, model_id, provider_name, automatic })}
             defaultValues={[model_id ? String(model_id) : AutoModelValue]}
             changeHandler={(value) => {
                 const picked = Array.isArray(value) ? value[0] : value;

src/pages/admin/settings/models/(partials)/harness-setting-group.tsx

@@ -14,7 +14,8 @@ type Props = {
 
 /**
  * One harness: its provider, then its model (narrowed to that provider),
- * whether it falls back to the automatic picks, whether it's on, and its
+ * whether it falls back to the automatic picks (for a harness that has
+ * them), whether it's on, and its
  * voice for speech. On a bot's page the provider select can also use the
  * default, which hides the rest.
  */
@@ -31,7 +32,7 @@ export default function HarnessSettingGroup({ harness, value, onChange }: Props)
         ? "turned off"
         : harness.default?.current
           ? `${harness.default.current.name} on ${harness.default.current.provider_name}`
-          : "nothing available";
+          : "not available";
 
     return (
         <SettingsGroup title={harness.title} description={harness.description}>
@@ -60,6 +61,7 @@ export default function HarnessSettingGroup({ harness, value, onChange }: Props)
                     models={models}
                     model_id={value.model_id}
                     provider_name={provider?.name}
+                    automatic={harness.automatic}
                     onChange={(model_id) => onChange({ ...value, model_id, voice: undefined })}
                 />
             )}
@@ -68,7 +70,7 @@ export default function HarnessSettingGroup({ harness, value, onChange }: Props)
             ) : (
                 <HarnessCurrentModel harness={harness} />
             )}
-            {!value.inherit && value.model_id ? (
+            {!value.inherit && value.model_id && harness.automatic ? (
                 <Checkbox
                     title="Fall back to the automatic picks if this model fails"
                     label={`Fall back to the automatic picks${provider ? ` on ${provider.name}` : ""} if this model fails`}

src/pages/admin/settings/models/(utils)/harness-model-select-options.ts

@@ -13,24 +13,33 @@ type Params = {
      * The picked provider's name; undefined for any provider.
      */
     provider_name?: string;
+    /**
+     * False: there's no automatic pick, so the empty choice reads "Not
+     * available".
+     */
+    automatic: boolean;
 };
 
 /**
  * The model picker's options: automatic (the best free model, on the
  * picked provider if there is one), then every model that can do the job
- * (free ones first, as the server sorts them).
+ * (free ones first, as the server sorts them). A harness without
+ * automatic picks starts with "Not available" instead.
  */
 export default function harnessModelSelectOptions({
     models,
     model_id,
     provider_name,
+    automatic,
 }: Params): TWUISelectOptionObject[] {
     const has_free = models.some((model) => model.free);
 
     return [
         {
             value: AutoModelValue,
-            title: provider_name
+            title: !automatic
+                ? "Not available (pick a model to turn it on)"
+                : provider_name
                 ? has_free
                     ? `Automatic (best free model on ${provider_name})`
                     : `Automatic (no free models on ${provider_name}: pick one)`