Skeleton Coding (arXiv:2610.38214): Program Structure sebagai Spesifikasi AI Coding Agents — Mengapa Behavioral Testing Gagal, Reduksi 48.4% Test Error, dan Efisiensi Biaya 26x Lipat

// Production Implementation: Skeleton Coding & Contract Verification Engine
// Berdasarkan Prinsip Rekayasa arXiv:2610.38214 (AWS Agentic AI)
// Memisahkan Verifikasi Struktur (Hypothesis Shrinking) dari Sintesis Fungsi (Local Contracts)

export interface LocalContract {
  requires: string[]; // Prakondisi input (caller obligations)
  ensures: string[];  // Pasca-kondisi output (callable guarantees)
  pure?: boolean;     // Menjamin ketiadaan mutasi pada state eksternal
}

export interface FunctionStub {
  name: string;
  signature: string;
  parameters: Record<string, string>;
  returnType: string;
  docstring: string;
  contract?: LocalContract;
  cyclomaticLimit?: number;
}

export interface SkeletonModule {
  modulePath: string;
  dataTypes: Record<string, string>; // Typed interfaces / structs
  dependencies: string[];            // Imported module boundaries
  functions: FunctionStub[];
  globalInvariants: string[];        // Invarian lintas fungsi pada INVARIANTS.md
}

export interface VerificationResult {
  passed: boolean;
  stage: 'STRUCTURAL_AST' | 'LOCAL_CONTRACT' | 'GLOBAL_INVARIANT';
  component: string;
  error?: string;
  cyclomaticComplexity: number;
}

export class SkeletonCodingHarness {
  private readonly modules: Map<string, SkeletonModule> = new Map();

  public registerSkeleton(module: SkeletonModule): void {
    this.modules.set(module.modulePath, module);
  }

  /**
   * Menilai apakah implementasi agen mematuhi Skeleton Structure H_S
   * Mencegah agen melakukan over-engineering atau mengubah layout tipe data internal
   */
  public verifyStructuralAdherence(
    modulePath: string,
    generatedAst: {
      exportedTypes: string[];
      exportedFunctions: string[];
      externalImports: string[];
    }
  ): { valid: boolean; violations: string[] } {
    const skeleton = this.modules.get(modulePath);
    if (!skeleton) throw new Error(`Module ${modulePath} not registered in skeleton!`);

    const violations: string[] = [];

    // 1. Verifikasi Batas Dependensi (Mencegah arsitektur bocor)
    for (const imp of generatedAst.externalImports) {
      if (!skeleton.dependencies.includes(imp)) {
        violations.push(`Illegal dependency import: '${imp}' violates module boundary of ${modulePath}`);
      }
    }

    // 2. Verifikasi Deklarasi Fungsi (Mencegah fungsi publik siluman)
    const expectedFuncs = new Set(skeleton.functions.map(f => f.name));
    for (const fn of generatedAst.exportedFunctions) {
      if (!expectedFuncs.has(fn)) {
        violations.push(`Undeclared public function '${fn}' alters architecture hypothesis class H_S`);
      }
    }

    return {
      valid: violations.length === 0,
      violations,
    };
  }

  /**
   * Mengevaluasi Local Contracts (Pre & Post Conditions)
   * Mengisolasi kegagalan pada level subrutin (Theorem 2.4: O(sum N_i) vs O(2^n))
   */
  public async evaluateLocalContract(
    modulePath: string,
    funcName: string,
    inputState: any,
    executionFn: () => Promise<any>
  ): Promise<VerificationResult> {
    const skeleton = this.modules.get(modulePath);
    const stub = skeleton?.functions.find(f => f.name === funcName);

    if (!stub || !stub.contract) {
      return { passed: true, stage: 'LOCAL_CONTRACT', component: funcName, cyclomaticComplexity: 1 };
    }

    // 1. Verifikasi Prakondisi (Requires)
    for (const req of stub.contract.requires) {
      const isReqValid = this.assertCondition(req, inputState);
      if (!isReqValid) {
        return {
          passed: false,
          stage: 'LOCAL_CONTRACT',
          component: funcName,
          error: `Precondition violation: ${req}`,
          cyclomaticComplexity: 1,
        };
      }
    }

    // Snapshot state jika fungsi bertanda pure
    const stateSnapshot = stub.contract.pure ? JSON.stringify(inputState) : null;

    // 2. Eksekusi Fungsi yang Dihasilkan Agen
    let result: any;
    try {
      result = await executionFn();
    } catch (err) {
      return {
        passed: false,
        stage: 'LOCAL_CONTRACT',
        component: funcName,
        error: `Execution threw runtime error: ${(err as Error).message}`,
        cyclomaticComplexity: 1,
      };
    }

    // 3. Verifikasi Purity
    if (stateSnapshot && JSON.stringify(inputState) !== stateSnapshot) {
      return {
        passed: false,
        stage: 'LOCAL_CONTRACT',
        component: funcName,
        error: 'Purity violation: Function mutated input argument state in-place',
        cyclomaticComplexity: 1,
      };
    }

    // 4. Verifikasi Pasca-kondisi (Ensures)
    for (const ens of stub.contract.ensures) {
      const isEnsValid = this.assertCondition(ens, { input: inputState, result });
      if (!isEnsValid) {
        return {
          passed: false,
          stage: 'LOCAL_CONTRACT',
          component: funcName,
          error: `Postcondition violation: ${ens}`,
          cyclomaticComplexity: 1,
        };
      }
    }

    return {
      passed: true,
      stage: 'LOCAL_CONTRACT',
      component: funcName,
      cyclomaticComplexity: 1,
    };
  }

  private assertCondition(conditionExpr: string, context: any): boolean {
    // Evaluasi deklaratif predikat lokal kontrak
    try {
      const fn = new Function('ctx', `with(ctx) { return Boolean(${conditionExpr}); }`);
      return Boolean(fn(context));
    } catch {
      return true; // Fallback jika ekspresi berbasis bahasa alami EARS
    }
  }
}