Developer Details Architecture Behind Reliable AI Transcription App on Cloudflare

A developer has published a technical breakdown of HiTranscript, a web app that converts public video URLs and local media uploads into searchable transcripts and subtitle files. The post focuses not on the transcription model itself but on the engineering patterns required to keep the pipeline reliable under real-world conditions such as large uploads, duplicate callbacks, and partial batch failures. The system uses TanStack Start, TypeScript, PostgreSQL, and Cloudflare Workers, Queues, and R2 for orchestration and storage. Key architectural decisions include explicit multi-state job tracking, storing media in private object storage rather than passing it through HTTP requests, and idempotent callback handlers that prevent duplicate processing. These patterns ensure stale workers cannot overwrite completed tasks and that billing and result persistence occur exactly once even when retries occur.