reverse-engineering-anything/docs/specs/agent-environments/scenario-saved-values/spec.md

Saved values in browser scenarios

Outcome

A browser scenario could not carry a value from one step to a later one. An agent recording an application from a prompt therefore guessed the id of the object it had just created, created probe objects to learn the next id, or read the object back by list only. An API that takes Basic auth, or a header a frontend builds from a login token, could not be sent at all, so the agent stopped and asked for an API key.

Steps now save strings and numbers from JSON responses, and later steps send them. A click or key press saves from a newly observed matching response, so a scenario can create an object the way the application's UI does and then open, read, edit or delete it by the id the application assigned. A request header can send Basic credentials built from literal, secret, saved or page values.

Requirements

• A request step saves [{name, json_pointer, secret}] from its own JSON response. A click or press step's save_response: {method, path, save} saves from the first response that matches its method and a path on the start origin ({*} matches one segment; the query is ignored), which must be 2xx JSON. The wait starts before the step acts, and the step fails, saving nothing, unless such a response arrives and is read before its timeout or cancellation.
• A pointer that names no string or number, a number that is not finite (such as 1e400), a response that is not JSON or is larger than 4,000,000 characters (a UI step reads none received as more than 12,000,000 bytes, three per character), and a non-2xx save_response fail the step.
• {saved:name} sends a saved value, percent-encoded, in a request path and its query and in a goto URL, and in a request's JSON body: a string that is only the placeholder becomes the saved value with its JSON type, and a placeholder inside a longer string is filled as text. Header values and Basic credential parts send {source: "saved", name}. Other braces are sent as written. A saved value that makes a path segment . or .., alone or with the text beside it, fails the step.
• basic_credentials sends the base64 of username:password from parts: [username, password], each a literal, declared secret, saved value, cookie or local storage entry. The encoded value and parts read from the page are redacted as page values are. A username with a colon fails the step.
• Validation refuses a saved value no earlier step saves.
• A scenario keeps at most 4,000,000 characters of saved values at once, counting the redaction spellings of values saved as secret; a save past that fails its step before the value is kept.
• A value saved with secret: true is redacted from the selected source response before retention and from subsequent records. The environment build warns about saved values named like credentials that are not marked secret (credential-named-saved-values).
• New Evidence records the current parsed request step, including an empty save list, in its parameters and scenario_sha256. Retained Evidence keeps its original representation and identity.
• The compact MCP catalog stays under its measured one-megabyte frame.
• The skill records writes the way the application's UI does and falls back to request steps when the UI cannot reach an operation or coverage withholds the UI-shaped write.
• A UI-made create must be served as faithfully as one made through the API:
  • a string composed from a generated id and another field, such as Grafana's folder address, is learned as composed, not as a template around the id;
  • a slug learns how the application spells & from the call that shows it, and held entities that spell it both ways leave no slug rule;
  • an id that equals the title's slug is told apart by the entities the type holds, or by a later create;
  • a template a later create answers otherwise is withheld, as a composed string is.

Non-goals

• No general value transforms, string templates or script steps: the value kinds are fixed.
• No saved values in fill or select_option values.
• No retroactive redaction of earlier unrelated records.
• No multi-factor sign-in.