Save or replace one secret of a stored app login (sealed at once, never returned).

{ value }: the secret, for a kind the connection's sign-in method or header uses (else 400, nothing stored). totpSeed takes the base32 key or its otpauth://totp/ link; storageState takes Playwright storage state JSON. Each secret is sealed the moment it is saved: the website and the Story API can save or replace one but never read it back, MCP and Slug never take one, and no read returns one (only which kinds are saved). Only the machines that record a capture can open it, to sign in to your app; a saved session's cookies for your app (never a password) may also go to Cloudflare's hosted browser, which only reads a light app's screens to learn its features. The answer is the connection's metadata (a username shown masked). A PUT, so no Idempotency-Key. Demo account only: use a demo or test account, never a real customer's account or production data. Free. A story project is refused with 409 project_not_product (nothing is stored or started): app connections are for product projects. Listing, reading and deleting a story project's existing connections still work.