https://abdulahadqureshi.dev/notes/ Engineering notes on the decisions behind Balti and Fractional Coordinator. en https://abdulahadqureshi.dev/notes/undo-without-bucket-versioning/ https://abdulahadqureshi.dev/notes/undo-without-bucket-versioning/ Thu, 29 Oct 2026 09:00:00 +0500 How Balti makes deletes, overwrites and moves reversible on any S3-compatible bucket without object versioning, using a trash prefix and typed rollback recipes. https://abdulahadqureshi.dev/notes/entitlements-that-fail-closed/ https://abdulahadqureshi.dev/notes/entitlements-that-fail-closed/ Thu, 29 Oct 2026 09:00:00 +0500 Entitlements in a multi-tenant NestJS portal: grants on the membership, presence-as-granted rows, shared Zod keys and a guard that denies undeclared routes. https://abdulahadqureshi.dev/notes/uploads-past-the-serverless-body-limit/ https://abdulahadqureshi.dev/notes/uploads-past-the-serverless-body-limit/ Thu, 29 Oct 2026 09:00:00 +0500 How Balti uploads large files to S3-compatible buckets from a Vercel app: presigned PUTs with automatic CORS, and a chunked fallback joined by S3 multipart.