A structured eval result: the captured script output plus the typed
value/error payload. The SLYNK mREPL maps output → :write-string and
payload → :write-values / :evaluation-aborted. handle_form (the text
wire path) does not use this — it formats the payload alone.
Per-channel evaluator. Owns mutable state across forms (defun-defined symbols
persist between requests in the same session via SymbolTable; the wasm
ModuleCache reuses compilations of structurally identical forms) and an
interrupt handle that cooperatively short-circuits the next form on demand.
Wasmtime Store data type for the rpc eval channel. Carries the
per-session user context (ScriptCtx) so native fns reach
caller.data().ctx().user_id directly. The legacy
EvalContext capture-protocol companion field retired alongside
the capture imports in P4 A6.c — nomi-eval now returns its
final value via the function’s (ref null any) return slot.