Gnothiahost

Developers may trust an auditable local reflection companion but still want cross-device continuity without operating a server. Gnothiahost synchronizes client-encrypted vault objects, device and key metadata, conflict versions and user-controlled exports while keeping the sync service unable to decrypt conversation content under the declared threat model. The supplied research confirms a live permissively licensed desktop-only upstream whose author intentionally provides no backend, one verified capability and no managed wrapper. Closed cloud competitors do not target the same privacy-first BYOK segment. “Zero knowledge” applies only to the sync provider and must be backed by protocol and independent testing. When a user invokes an external model with their own key, selected content leaves the device for that provider under its separate terms; “my data never leaves” is false. BYOK does not eliminate provider logs, billing, retention or safety boundaries. The product is a wellbeing and reflection tool, not therapy, diagnosis, crisis care or medical treatment. Local entry, encryption, sync upload, device download, decrypt, model invocation, provider acknowledgement, generated response, user interpretation and wellbeing outcome remain separate. Success is usable encrypted continuity and honest data-path control—not clinical benefit, total secrecy or safe AI advice.

A privacy-conscious technical user of a local open-source reflection companion who wants managed cross-device sync without surrendering plaintext to the sync operator.