Problem

Distributed product teams needed live transcripts and summaries for bilingual (ES/EN) roadmap reviews. Off-the-shelf tools struggled with code-switching and required manual exporting.

Approach

• Built a Next.js edge function that proxies AssemblyAI live transcription with auth token rotation.
• Created a WebRTC capture widget that streams microphone audio via MediaRecorder chunks over WebSockets.
• Implemented bilingual speaker diarization with language hints and automatic glossary injection.
• Added highlights + action item extraction using a hybrid of AssemblyAI summarization and custom prompt engineering in Vercel AI SDK.
• Stored sessions in Supabase with row-level security for invite-only access and auto-cleanup after 14 days.

Results

• End-to-end streaming latency around 450 ms, validated with synthetic tests.
• Meeting summaries and action items ready <2 minutes after call end.
• Boosted async participation; PMs reuse transcripts in Linear + Notion automation.

Links

• Source repository
• Live demo