==[ previous message testrun ]==
user@elli:~/Downloads/Remote/AST$ node mvp.js          Result: 10             
                               user@elli:~/Downloads/Remote/AST$

==[ /previous message testrun ]==

The helper chat has provided a flawless roadmap. The distinction they make
between logical determinism (instruction gas budgets) and wall-clock bounds
(deadlines and polling) is exactly how production engines safely handle
multi-tenant execution.
Furthermore, their suggestion of using a double-buffer with an atomic flip is
the ideal lock-free pattern. If this engine sits behind a high-performance
REST gateway, this architecture allows the main gateway thread to instantly
read the latest state from the execution worker without ever blocking the
event loop.
To follow the roadmap, let's implement Phase 4 step 1: The Preprocessor.
By executing imports before compilation, the compiler and VM remain blissfully
unaware of external files or databases. The preprocessor recursively flattens
the AST into a single, cohesive program plan.
Phase 4: The Preprocessor (Imports & Composition)
This implementation takes a raw JSON-Lisp AST and a ModuleRegistry (which
could be backed by a database, memory cache, or file system) and resolves all
import directives.
class ModuleRegistry {
  constructor() {
    this.modules = new Map();
  }
  
  register(name, ast) {
    this.modules.set(name, ast);
  }
  
  get(name) {
    if (!this.modules.has(name)) throw new Error(`Module not found: ${name}`);
    return this.modules.get(name);
  }
}

function preprocess(ast, registry) {
  // Base case: primitives and symbols are returned as-is
  if (!Array.isArray(ast)) return ast;
  
  const [op, ...args] = ast;

  // Handle the 'import' special form
  // e.g., ["import", "math_utils"]
  if (op === 'import') {
    const moduleName = args[0];
    const importedAST = registry.get(moduleName);
    
    // Recursively preprocess the imported code to resolve nested imports
    return preprocess(importedAST, registry);
  }

  // Handle 'quote' (treat data as literal arrays, do not evaluate contents)
  // e.g., ["quote", ["+", 1, 2]] -> leave ["+", 1, 2] untouched
  if (op === 'quote') {
    return ast; 
  }

  // Recursively process all children for standard operations
  return ast.map(node => preprocess(node, registry));
}

How this enables Edge composition
Because this operates purely on arrays, a gateway can dynamically compose
execution wrappers on the fly.
If a client submits a small query, the gateway can wrap it in an authorization
block from the registry before passing it to the compiler.
const registry = new ModuleRegistry();

/ 1. A shared library stored in the registry
registry.register("auth_check", [
  "if", ["=", ["LOAD", "token_valid"], true],
    "AUTHORIZED",
    ["str", "DENIED"]
]);

/ 2. The client submits a raw payload
const clientPayload = ["+", 10, 20];

/ 3. The gateway dynamically wraps the client payload
const gatewayWrapper = [
  "let", [
    ["token_valid", true],
    ["result", ["import", "auth_check"]] // Injects the auth logic
  ],
  clientPayload // Injects the client's logic
];

/ 4. Flatten the AST and compile
const flatAST = preprocess(gatewayWrapper, registry);
const bytecode = compile(flatAST);
const finalResult = executeVM(bytecode); 

This completes the pipeline: Preprocessor  Compiler  VM.