diff --git a/mu-plugins/fea-subir-audio-api.php b/mu-plugins/fea-subir-audio-api.php
new file mode 100644
index 0000000..fa7d24b
--- /dev/null
+++ b/mu-plugins/fea-subir-audio-api.php
@@ -0,0 +1,197 @@
+<?php
+/**
+ * Plugin Name: Fe Adulta — API subir audio TTS
+ * Description: Endpoint REST acotado para publicar el MP3 TTS de un artículo.
+ * Version: 1.0
+ *
+ * POST /wp-json/fea/v1/subir-audio
+ * multipart/form-data: post_id=<id>, audio=<MP3>, voice_id=<opcional>
+ *
+ * Ver issue gitea.feadulta.com/rafa/feadulta#222.
+ */
+
+if (!defined('ABSPATH')) exit;
+
+const FEA_AUDIO_MAX_BYTES = 268435456; // 256 MiB: admite cartas largas.
+
+add_action('rest_api_init', function () {
+    register_rest_route('fea/v1', '/subir-audio', [
+        'methods'             => WP_REST_Server::CREATABLE,
+        'callback'            => 'fea_subir_audio_handle',
+        'permission_callback' => 'fea_subir_audio_can_call',
+        // La validación de post_id ocurre en el handler, después de autorizar:
+        // una llamada anónima siempre recibe 401 aunque omita parámetros.
+        'args'                => [
+            'post_id' => [
+                'sanitize_callback' => 'absint',
+            ],
+            'voice_id' => [
+                'sanitize_callback' => 'sanitize_text_field',
+            ],
+        ],
+    ]);
+});
+
+/** Editor o superior: mismo nivel que los endpoints de escritura existentes. */
+function fea_subir_audio_can_call(WP_REST_Request $request) {
+    if (!is_user_logged_in()) {
+        return new WP_Error(
+            'fea_subir_audio_not_authenticated',
+            'Debes autenticarte para subir un audio.',
+            ['status' => 401]
+        );
+    }
+    if (!current_user_can('edit_others_posts')) {
+        return new WP_Error(
+            'fea_subir_audio_forbidden',
+            'No tienes permiso para subir audios.',
+            ['status' => 403]
+        );
+    }
+    return true;
+}
+
+function fea_subir_audio_handle(WP_REST_Request $request) {
+    $post_id = absint($request->get_param('post_id'));
+    if (!$post_id) {
+        return new WP_Error(
+            'fea_subir_audio_invalid_post',
+            'post_id es obligatorio.',
+            ['status' => 400]
+        );
+    }
+    if (!get_post($post_id)) {
+        return new WP_Error(
+            'fea_subir_audio_post_not_found',
+            'No existe el artículo indicado.',
+            ['status' => 404]
+        );
+    }
+
+    $files = $request->get_file_params();
+    $file = $files['audio'] ?? null;
+    $validation = fea_subir_audio_validate_file($file);
+    if (is_wp_error($validation)) return $validation;
+
+    $previous = [
+        'url'    => get_post_meta($post_id, 'fea_audio_url', true) ?: null,
+        'voice'  => get_post_meta($post_id, 'fea_audio_voice', true) ?: null,
+        'done'   => get_post_meta($post_id, 'fea_audio_done', true) ?: null,
+        'sha256' => get_post_meta($post_id, 'fea_audio_sha256', true) ?: null,
+        'error'  => get_post_meta($post_id, 'fea_audio_error', true) ?: null,
+    ];
+
+    require_once ABSPATH . 'wp-admin/includes/file.php';
+    $upload_dir_filter = 'fea_subir_audio_upload_dir';
+    add_filter('upload_dir', $upload_dir_filter);
+    try {
+        $uploaded = wp_handle_upload($file, [
+            'test_form'                => false,
+            'mimes'                    => ['mp3' => 'audio/mpeg'],
+            'unique_filename_callback' => function ($dir, $name, $ext) use ($post_id) {
+                return $post_id . '.mp3';
+            },
+        ]);
+    } finally {
+        remove_filter('upload_dir', $upload_dir_filter);
+    }
+    if (!empty($uploaded['error']) || empty($uploaded['file'])) {
+        return new WP_Error(
+            'fea_subir_audio_upload_failed',
+            'No se pudo guardar el audio: ' . ($uploaded['error'] ?? 'error desconocido'),
+            ['status' => 400]
+        );
+    }
+
+    $sha256 = hash_file('sha256', $uploaded['file']);
+    if ($sha256 === false) {
+        wp_delete_file($uploaded['file']);
+        return new WP_Error(
+            'fea_subir_audio_hash_failed',
+            'No se pudo calcular la huella del audio subido.',
+            ['status' => 500]
+        );
+    }
+
+    // El path es estable para que los players y el proceso de backfill no dependan
+    // de las carpetas por mes que normalmente crea WordPress.
+    $audio_url = home_url('/wp-content/uploads/tts/' . $post_id . '.mp3');
+    update_post_meta($post_id, 'fea_audio_url', $audio_url);
+    update_post_meta($post_id, 'fea_audio_voice', (string) $request->get_param('voice_id'));
+    update_post_meta($post_id, 'fea_audio_done', '1');
+    update_post_meta($post_id, 'fea_audio_sha256', $sha256);
+    delete_post_meta($post_id, 'fea_audio_error');
+
+    return new WP_REST_Response([
+        'post_id'        => $post_id,
+        'audio_url'      => $audio_url,
+        'voice_id'       => (string) $request->get_param('voice_id'),
+        'sha256'         => $sha256,
+        'previous_audio' => $previous,
+    ], 201);
+}
+
+/** Guarda el binario en uploads/tts sin cambiar globalmente la configuración. */
+function fea_subir_audio_upload_dir($uploads) {
+    $uploads['subdir'] = '/tts';
+    $uploads['path'] = $uploads['basedir'] . $uploads['subdir'];
+    $uploads['url'] = $uploads['baseurl'] . $uploads['subdir'];
+    if (!wp_mkdir_p($uploads['path'])) {
+        $uploads['error'] = 'No se pudo crear el directorio de audios.';
+    }
+    return $uploads;
+}
+
+function fea_subir_audio_validate_file($file) {
+    if (!is_array($file) || empty($file['tmp_name']) || !isset($file['error'])) {
+        return new WP_Error(
+            'fea_subir_audio_missing_file',
+            'audio es obligatorio.',
+            ['status' => 400]
+        );
+    }
+    if ((int) $file['error'] !== UPLOAD_ERR_OK) {
+        return new WP_Error(
+            'fea_subir_audio_file_error',
+            'La subida de audio falló.',
+            ['status' => 400]
+        );
+    }
+    if ((int) $file['size'] <= 0 || (int) $file['size'] > FEA_AUDIO_MAX_BYTES) {
+        return new WP_Error(
+            'fea_subir_audio_file_too_large',
+            'El audio debe ocupar entre 1 byte y 256 MiB.',
+            ['status' => 400]
+        );
+    }
+
+    $type = wp_check_filetype((string) ($file['name'] ?? ''), ['mp3' => 'audio/mpeg']);
+    if (($type['ext'] ?? '') !== 'mp3' || ($type['type'] ?? '') !== 'audio/mpeg') {
+        return new WP_Error(
+            'fea_subir_audio_unsupported_type',
+            'Solo se admiten archivos MP3 (audio/mpeg).',
+            ['status' => 400]
+        );
+    }
+    if (strtolower((string) ($file['type'] ?? '')) !== 'audio/mpeg') {
+        return new WP_Error(
+            'fea_subir_audio_unsupported_type',
+            'audio debe declararse como audio/mpeg.',
+            ['status' => 400]
+        );
+    }
+
+    if (function_exists('finfo_open')) {
+        $finfo = finfo_open(FILEINFO_MIME_TYPE);
+        $mime = $finfo ? finfo_file($finfo, $file['tmp_name']) : false;
+        if ($finfo) finfo_close($finfo);
+        if ($mime !== false && $mime !== 'audio/mpeg') {
+            return new WP_Error(
+                'fea_subir_audio_invalid_audio',
+                'audio debe contener datos MPEG válidos.',
+                ['status' => 400]
+            );
+        }
+    }
+    return true;
+}
diff --git a/tests/integration/test_subir_audio_api.sh b/tests/integration/test_subir_audio_api.sh
new file mode 100755
index 0000000..2973a36
--- /dev/null
+++ b/tests/integration/test_subir_audio_api.sh
@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+# Integración local para POST /wp-json/fea/v1/subir-audio (#222).
+# Requiere FEA_TEST_URL, FEA_TEST_AUTH y FEA_TEST_POST_ID (post temporal).
+set -euo pipefail
+
+: "${FEA_TEST_URL:?Falta FEA_TEST_URL}"
+: "${FEA_TEST_AUTH:?Falta FEA_TEST_AUTH}"
+: "${FEA_TEST_POST_ID:?Falta FEA_TEST_POST_ID}"
+
+endpoint="${FEA_TEST_URL%/}/wp-json/fea/v1/subir-audio"
+tmpdir="$(mktemp -d)"
+trap 'rm -rf "$tmpdir"' EXIT
+
+# MP3 pequeño y válido (silencio MPEG-1 Layer III), sin depender de ffmpeg.
+printf '\377\373\220\144' > "$tmpdir/audio.mp3"
+dd if=/dev/zero bs=1 count=413 >> "$tmpdir/audio.mp3" 2>/dev/null
+printf 'no es un mp3' > "$tmpdir/not-audio.txt"
+
+assert_status() {
+  local expected="$1" actual="$2" label="$3" response_file="$4"
+  if [[ "$actual" != "$expected" ]]; then
+    echo "FAIL: $label — esperado HTTP $expected, recibido $actual" >&2
+    cat "$response_file" >&2 || true
+    exit 1
+  fi
+}
+
+status="$(curl -sS -o "$tmpdir/unauth.json" -w '%{http_code}' -X POST "$endpoint")"
+assert_status 401 "$status" 'llamada sin autenticar' "$tmpdir/unauth.json"
+
+status="$(curl -sS -o "$tmpdir/no-post.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -X POST "$endpoint")"
+assert_status 400 "$status" 'falta post_id' "$tmpdir/no-post.json"
+
+status="$(curl -sS -o "$tmpdir/no-audio.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -F "post_id=$FEA_TEST_POST_ID" "$endpoint")"
+assert_status 400 "$status" 'falta audio' "$tmpdir/no-audio.json"
+
+status="$(curl -sS -o "$tmpdir/wrong-type.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -F "post_id=$FEA_TEST_POST_ID" -F "audio=@$tmpdir/not-audio.txt;type=text/plain" "$endpoint")"
+assert_status 400 "$status" 'extensión o mime no MP3' "$tmpdir/wrong-type.json"
+
+status="$(curl -sS -o "$tmpdir/no-such-post.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -F 'post_id=999999999' -F "audio=@$tmpdir/audio.mp3;type=audio/mpeg" "$endpoint")"
+assert_status 404 "$status" 'post inexistente' "$tmpdir/no-such-post.json"
+
+status="$(curl -sS -o "$tmpdir/success.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -F "post_id=$FEA_TEST_POST_ID" -F 'voice_id=NicoFeadulta2026' -F "audio=@$tmpdir/audio.mp3;type=audio/mpeg" "$endpoint")"
+assert_status 201 "$status" 'subida válida' "$tmpdir/success.json"
+
+python3 - "$tmpdir/success.json" "$FEA_TEST_POST_ID" "$tmpdir/audio.mp3" <<'PY'
+import hashlib, json, sys
+payload = json.load(open(sys.argv[1]))
+assert int(payload['post_id']) == int(sys.argv[2]), payload
+assert payload['audio_url'].endswith(f'/wp-content/uploads/tts/{sys.argv[2]}.mp3'), payload
+assert payload['voice_id'] == 'NicoFeadulta2026', payload
+assert payload['sha256'] == hashlib.sha256(open(sys.argv[3], 'rb').read()).hexdigest(), payload
+assert 'previous_audio' in payload, payload
+print('PASS: audio subido', payload['audio_url'])
+PY
+
+# La siguiente subida del mismo post debe exponer el estado anterior, para que
+# el cliente pueda restaurarlo si su flujo posterior falla.
+status="$(curl -sS -o "$tmpdir/replaced.json" -w '%{http_code}' -u "$FEA_TEST_AUTH" -F "post_id=$FEA_TEST_POST_ID" -F 'voice_id=NicoFeadulta2026' -F "audio=@$tmpdir/audio.mp3;type=audio/mpeg" "$endpoint")"
+assert_status 201 "$status" 'reemplazo de audio' "$tmpdir/replaced.json"
+
+python3 - "$tmpdir/replaced.json" "$FEA_TEST_POST_ID" <<'PY'
+import json, sys
+payload = json.load(open(sys.argv[1]))
+assert payload['previous_audio']['url'].endswith(f'/wp-content/uploads/tts/{sys.argv[2]}.mp3'), payload
+assert payload['previous_audio']['done'] == '1', payload
+print('PASS: estado anterior devuelto')
+PY