First Version

src/frontend/api/transcribe_audio.rs

@@ -0,0 +1,75 @@
+use axum::{
+    Json,
+    extract::{Multipart, State},
+    http::StatusCode,
+};
+use serde::Serialize;
+
+use std::sync::Arc;
+use crate::core::skald::Skald;
+use super::ApiError;
+
+#[derive(Serialize)]
+pub struct TranscribeResponse {
+    pub text: String,
+}
+
+/// POST /api/transcribe/audio
+///
+/// Accepts a multipart/form-data body with a single field `audio` containing
+/// the raw audio bytes. The `Content-Type` of the part determines the format
+/// passed to the transcriber (e.g. `audio/webm` → `"webm"`).
+pub async fn transcribe_audio(
+    State(skald): State<Arc<Skald>>,
+    mut multipart: Multipart,
+) -> Result<Json<TranscribeResponse>, ApiError> {
+    let transcriber = skald.transcribe_manager().get().await
+        .ok_or_else(|| ApiError::bad_request("no transcription model configured"))?;
+
+    let mut audio_bytes: Option<Vec<u8>> = None;
+    let mut format = "webm".to_string();
+
+    while let Some(field) = multipart.next_field().await
+        .map_err(|e| ApiError::bad_request(format!("multipart error: {e}")))?
+    {
+        if field.name() == Some("audio") {
+            // Derive format from content-type header of the part, e.g. "audio/webm" → "webm"
+            if let Some(ct) = field.content_type() {
+                if let Some(ext) = ct.split('/').nth(1) {
+                    // Strip codec suffix: "webm;codecs=opus" → "webm"
+                    format = ext.split(';').next().unwrap_or("webm").to_string();
+                }
+            }
+            audio_bytes = Some(
+                field.bytes().await
+                    .map_err(|e| ApiError::bad_request(format!("failed to read audio: {e}")))?
+                    .to_vec(),
+            );
+        }
+    }
+
+    let audio = audio_bytes
+        .ok_or_else(|| ApiError::bad_request("missing 'audio' field in multipart body"))?;
+
+    if audio.is_empty() {
+        return Err(ApiError::bad_request("audio field is empty"));
+    }
+
+    let text = transcriber.transcribe(audio, &format).await
+        .map_err(|e| {
+            tracing::warn!(error = %e, "transcription failed");
+            ApiError::from(e)
+        })?;
+
+    Ok(Json(TranscribeResponse { text }))
+}
+
+pub async fn has_transcribe(
+    State(skald): State<Arc<Skald>>,
+) -> StatusCode {
+    if skald.transcribe_manager().get().await.is_some() {
+        StatusCode::NO_CONTENT
+    } else {
+        StatusCode::NOT_FOUND
+    }
+}