From 07bba426d144229ae4b39522bf5d0413c25e4c0d Mon Sep 17 00:00:00 2001
From: Pratik Bodkhe <pratikbodkhe@gmail.com>
Date: Mon, 20 Jul 2026 08:50:14 +0900
Subject: [PATCH] Map companion m4a mime variants to the m4a transcription
 format

supabase-swift derives the storage content type from the .m4a extension
instead of the explicit FileOptions value, so companion recordings are
stored as audio/x-m4a. audioFormatFromMime mapped only audio/mp4 and
fell through to webm, so the STT provider rejected every companion
upload with 415 unsupported_format; no companion recording could ever
transcribe. audio/mp4, audio/x-m4a, and audio/m4a now map to m4a.
audio/aac keeps its raw-ADTS aac mapping since nothing in the pipeline
labels m4a files that way.
---
 scripts/verify-transcription-client.test.mjs | 22 ++++++++++++++++++++
 src/lib/transcription/openrouter-stt.ts      |  9 +++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/scripts/verify-transcription-client.test.mjs b/scripts/verify-transcription-client.test.mjs
index 017d0a6..45ae2bb 100644
--- a/scripts/verify-transcription-client.test.mjs
+++ b/scripts/verify-transcription-client.test.mjs
@@ -173,6 +173,28 @@ test("transcribeWithOpenRouter posts base64 JSON with attribution headers", asyn
   assert.equal(result.durationSeconds, 3); // from usage.seconds
 });
 
+test("transcribeWithOpenRouter maps the macOS companion's m4a mime variants to the m4a format", async () => {
+  // supabase-swift stores the companion's AAC-in-MP4 upload under audio/x-m4a
+  // (see supabase/migrations/20260704120000_meeting_audio_m4a_mime.sql); every
+  // mime the storage layer admits for that same file must resolve to "m4a" here,
+  // or the provider 415s real companion recordings as unsupported.
+  const cases = [
+    ["audio/mp4", "m4a"],
+    ["audio/x-m4a", "m4a"],
+    ["audio/m4a", "m4a"],
+    ["audio/aac", "aac"],
+    ["audio/x-m4a; codecs=mp4a.40.2", "m4a"],
+    ["audio/webm", "webm"],
+    ["audio/unknown", "webm"],
+  ];
+  for (const [mimeType, expectedFormat] of cases) {
+    const calls = fakeFetch(() => okResponse({ text: "x" }));
+    await transcribeWithOpenRouter(audioBlob(64), { apiKey: "or-key", mimeType });
+    const body = JSON.parse(calls[0].options.body);
+    assert.equal(body.input_audio.format, expectedFormat, `${mimeType} -> ${expectedFormat}`);
+  }
+});
+
 // ---------------------------------------------------------------------------
 // AssemblyAI client (diarizing primary)
 // ---------------------------------------------------------------------------
diff --git a/src/lib/transcription/openrouter-stt.ts b/src/lib/transcription/openrouter-stt.ts
index 40817cb..e7a6f13 100644
--- a/src/lib/transcription/openrouter-stt.ts
+++ b/src/lib/transcription/openrouter-stt.ts
@@ -12,10 +12,17 @@ import { sendTranscription, type TranscriptionResult } from "./shared";
 export const OPENROUTER_STT_URL = "https://openrouter.ai/api/v1/audio/transcriptions";
 export const OPENROUTER_STT_DEFAULT_MODEL = "openai/whisper-1";
 
+// supabase-swift stores the macOS companion's AAC-in-MP4 upload under a mime
+// derived from the ".m4a" extension, not the explicit FileOptions content
+// type, so the same recording can arrive as audio/mp4, audio/x-m4a, or
+// audio/m4a (see supabase/migrations/20260704120000_meeting_audio_m4a_mime.sql).
+// All must map to "m4a" or the provider 415s a real companion upload.
+const M4A_MIME_TYPES = new Set(["audio/mp4", "audio/x-m4a", "audio/m4a"]);
+
 /** OpenRouter's `input_audio.format` from a MIME type (codecs suffix ignored). */
 function audioFormatFromMime(mime: string): string {
   const base = mime.split(";")[0].trim();
-  if (base === "audio/mp4") return "m4a";
+  if (M4A_MIME_TYPES.has(base)) return "m4a";
   if (base === "audio/ogg") return "ogg";
   if (base === "audio/mpeg") return "mp3";
   if (base === "audio/wav") return "wav";