backend-worker

name	backend-worker
description	Worker for implementing TypeScript library features with TDD

Backend Worker

Worker for implementing TypeScript library features. Follows strict TDD (test-driven development).

When to Use This Skill

Use for implementing features in the universal-llm-client library:

• Core types and interfaces
• Provider implementations
• API surface methods
• Schema validation logic
• Streaming functionality

Work Procedure

1. Understand the Feature

• Read the feature description in features.json
• Read mission.md for context
• Read AGENTS.md for coding conventions
• Identify which assertions in validation-contract.md this feature fulfills

2. Write Tests First (RED)

• Create a new test file or add to existing test file in src/tests/
• Use bun:test framework
• Use describe and test/it blocks
• Mock globalThis.fetch for HTTP requests
• Write tests that FAIL initially (no implementation yet)
• Run tests to confirm they fail: bun test --grep 'pattern'

3. Implement (GREEN)

• Implement the minimum code to make tests pass
• Follow existing patterns in the codebase
• Use TypeScript strict typing
• Keep functions small and focused

4. Verify and Refactor

• Run tests to confirm they pass
• Run type check: bun run typecheck
• Run all tests: bun test
• Refactor if needed while keeping tests green

5. Document Public APIs

• Add JSDoc comments to public functions/types
• Ensure exports are correct in index.ts

Example Handoff

{
  "salientSummary": "Implemented OpenAI-compatible structured output with response_format. Tests pass, typecheck clean.",
  "whatWasImplemented": "Added response_format support to OpenAI-compatible provider. Implemented schema conversion to JSON Schema. Added validation logic for API responses. Created unit tests for schema conversion and response parsing.",
  "whatWasLeftUndone": "",
  "verification": {
    "commandsRun": [
      {
        "command": "bun test src/tests/providers/openai.test.ts --grep 'structured'",
        "exitCode": 0,
        "observation": "All 5 structured output tests pass"
      },
      {
        "command": "bun run typecheck",
        "exitCode": 0,
        "observation": "No type errors"
      }
    ],
    "interactiveChecks": []
  },
  "tests": {
    "added": [
      {
        "file": "src/tests/providers/openai.test.ts",
        "cases": [
          { "name": "converts Zod schema to JSON Schema", "verifies": "VAL-SCHEMA-002" },
          { "name": "sends response_format in request", "verifies": "VAL-PROVIDER-OPENAI-001" },
          { "name": "validates response against schema", "verifies": "VAL-SCHEMA-005" }
        ]
      }
    ]
  },
  "discoveredIssues": []
}

When to Return to Orchestrator

• Dependency missing: A required dependency is not installed and you cannot add it
• Type errors: TypeScript errors you cannot resolve
• Tests won't pass: After reasonable effort, tests still fail
• API uncertainty: Unclear how to integrate with existing code
• Provider unavailable: Smoke test requires API that is not accessible