Purpose
Tessa is a private, non-commercial application built for one Tesla owner. It records and analyses vehicle telemetry to provide drive history, charging analysis, parked-drain insights, battery trends, and evidence-based alerts.
Permissions
Tessa requests sign-in, offline access, profile information, vehicle data, precise vehicle location, and charging management. It does not request vehicle commands, camera access, or media data.
Charging management is requested for what it reads — charge history and the amounts actually billed — so charging cost can be reported as measured rather than estimated from a tariff table. That permission also carries the ability to start, stop, and schedule charging. Tessa never sends those commands, and never wakes the vehicle, but the permission exists in the token and is named here rather than left for the owner to discover.
Storage
Raw and derived telemetry is stored in the owner’s private Railway project. OAuth refresh tokens are encrypted. The Vercel interface does not persist Tesla credentials. Authenticated API responses are never stored by the service worker.
Map tiles
Route maps request background tiles from OpenFreeMap unless a different style is configured. Those requests reveal the approximate areas of a drive to that provider; they never include the VIN, the recorded route, or any Tessa account data. Pointing Tessa at a paid or self-hosted style removes the third party entirely.
Retention and deletion
The owner selected permanent retention. Railway backups and encrypted owner-controlled exports protect the history. Revoking Tessa in Tesla’s account settings stops future access. Database deletion remains an explicit owner operation.
Estimates and affiliation
Battery capacity, charging loss, drain causes, and personalized range are estimates—not official Tesla diagnostics, safety advice, or warranty assessments. Tessa is not affiliated with, endorsed by, or sponsored by Tesla, Inc.