Security Parameters

Tessera is built on an **isolation-first security model**. We reject open-ended cloud agents that can freely access systems. Instead, Tessera enforces strict hardware-level and process-level boundaries directly on your computer.

1. The Sandboxed Process Boundary

Tessera divides operations into a lightweight UI shell (built on Tauri v2) and a high-performance local daemon (the sidecar).

• Strict Capability Scoping: System capabilities are explicitly defined inside a local configuration file. The sidecar can only spawn specific processes authorized by you.
• Local Sockets only: The communication between the UI and sidecar is restricted to local Unix sockets or Windows named pipes. TCP fallback uses randomized ports and binds strictly to `127.0.0.1` (never `0.0.0.0`) to block external network access.

2. Bearer Authentication & DNS Rebinding Protection

Every time the Tessera sidecar starts up, it generates an ephemeral, randomized 256-bit bearer token.

• Protected Upgrades: Every web request and websocket upgrade between the UI and the sidecar requires this token, preventing unauthorized scripts running in your browser from calling sidecar APIs.
• Origin Verification: The sidecar enforces a strict `Host` header and `Origin` check, accepting requests only from the local Tauri webview origin.

3. OS-Secure Keychain Storage

Tessera integrates with native OS credential stores (Apple Keychain on macOS, Windows Credential Manager on Windows) through encrypted platform APIs. Plaintext passwords or API tokens are never saved to disk, ensuring that your keys stay safe even if your computer's files are accessed.

4. The Version Ledger (Git Service)

Whenever an automated task edits files, Tessera uses an internal local Git Service to commit changes. The user has access to side-by-side visual diff summaries and single-click rollbacks. This ensures all agent actions are auditable and reversible.

5. On-Demand Connector Sandbox

Third-party software connectors (such as Salesforce or Google Workspace adapters) are not bundled by default. They are downloaded and checked against checksum hashes only when you explicitly add them, keeping the core app footprint small and secure.