@sourceacademy/common-e-stepper

Shared, language-agnostic protocol for the Source Academy environment stepper ("e-stepper"): a cross between the substitution stepper and the CSE machine. Each step pairs the program, rewritten one reduction at a time as in the stepper, with the environment frames and heap objects it refers to. Design note: docs/e-stepper.md.

This package contains:

• the ids the runner and web plugins use to find each other (E_STEPPER_CHANNEL_ID, RUNNER_ID, WEB_ID, E_STEPPER_DIRECTORY_ID),
• the step type EStepperStep: a SerializedStepperStep (from @sourceacademy/common-stepper) plus frames, heap, activeFrameId and lookups,
• the two program node types that refer into the store, rendered by the host itself: EnvBlock { envId, body } (a function body under evaluation in frame envId) and Ref { objectId } (a reference to a heap object), with type guards,
• the channel messages (EStepperMessage), which have the same shape as the stepper's.

To produce steps from a language, extend BaseEStepperRunnerPlugin from @sourceacademy/runner-e-stepper.