source fidelity Shipped
What this lens looks for
When formalizing from code, describe observed behavior, not intended behavior. Read the source thoroughly before writing. Every behavioral requirement traces to a specific code path. Capture the non-obvious behaviors a casual reader would miss (default values, edge handling, side effects). Flag any behavior you could not confirm in the source rather than guessing.
What its verifier checks
Every requirement is supported by the source; no requirement describes behavior the code does not implement; non-obvious behaviors are captured, not glossed; unconfirmed behaviors are flagged, not invented.