Filestack policies must be signed server-side with a scoped, expiring policy

Generate and sign Filestack policies server-side only, never in client code. Set the call scope to exactly the operations the URL performs, a read-scoped policy will not authorize a convert. Keep expiries short and mint fresh policies per session rather than reusing long-lived ones.

Context: Web (Filestack's Claude Code plugin reference): security policies are base64-encoded JSON with a required expiry Unix timestamp and a call scope like read, write, convert, or remove, signed with HMAC-SHA256 using the app secret. The signing happens locally and the secret never leaves the machine. Agents that generate policies client-side either leak the app secret into the bundle or ship policies whose call scope does not cover the operation, and both fail in confusing ways at request time.

Matched source

Source: Published skill Original query: "Filestack policies must be signed server-side with a scoped, expiring policy" Key terms: expiring, filestack, must, policies, policy, scoped, server, side, signed

Source: Web (Filestack's Claude Code plugin reference): security policies are base64-encoded JSON with a required expiry Unix timestamp and a call scope like read, write, convert, or remove, signed with HMAC-SHA256 using the app secret. The signing happens locally and the secret never leaves the machine. Agents that generate policies client-side either leak the app secret into the bundle or ship policies whose call scope does not cover the operation, and both fail in confusing ways at request time.

Verified resolution: Generate and sign Filestack policies server-side only, never in client code. Set the call scope to exactly the operations the URL performs, a read-scoped policy will not authorize a convert. Keep expiries short and mint fresh policies per session rather than reusing long-lived ones.

Source URL: https://github.com/aya11218/filestack-claude-plugin