Function generatePrompt

packages/lang-core/src/parser/prompt.ts:587–684

(spec: PromptSpec)

// ─── Prompt assembly ────────────────────────────────────────────────────────

export function generatePrompt(spec: PromptSpec): string {
  const rootName = spec.root ?? "Root";
  const hasTools = !!spec.tools?.length;

  // Resolve prompt flags — defaults preserve backward compat
  const toolCalls = spec.toolCalls ?? hasTools;
  const bindings = spec.bindings ?? toolCalls;
  const supportsExpressions = toolCalls || bindings;

  // Detect component-level feature usage
  const usesActionExpression = Object.values(spec.components).some((c) =>
    c.signature?.includes("ActionExpression"),
  );

  const parts: string[] = [];

  parts.push(spec.preamble ?? PREAMBLE);
  parts.push("");
  parts.push(syntaxRules(rootName, { supportsExpressions, bindings }));
  parts.push("");
  parts.push(generateComponentSignatures(spec, { toolCalls, bindings, usesActionExpression }));

  // Built-in functions — only when expressions are enabled (Query/reactive state)
  if (supportsExpressions) {
    parts.push("");
    parts.push(builtinFunctionsSection());
  }

  // Query + Mutation sections
  if (toolCalls) {
    parts.push("");
    parts.push(querySection());
    parts.push("");
    parts.push(mutationSection());
  }

  // Action section — only when components use ActionExpression (v0.5 action syntax)
  if (usesActionExpression) {
    parts.push("");
    parts.push(actionSection({ toolCalls, bindings }));
  }

  // Interactive filters (needs both toolCalls and bindings)
  if (toolCalls && bindings) {
    parts.push("");
    parts.push(interactiveFiltersSection());
  }

  // Tool workflow
  if (toolCalls) {
    parts.push("");
    parts.push(toolWorkflowSection());
  }

  // Tools list (only if actual tools provided)
  if (spec.tools?.length) {
    parts.push("");
    parts.push(renderToolsSection(spec.tools));