/**
 * TDD enforcement instructions for sub-agent prompts.
 * Matches supipowers' test-driven-development skill depth.
 */
export function buildTddInstructions(): string {
  return [
    "## Test-Driven Development",
    "",
    "### Iron Law",
    "",
    "NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST.",
    "",
    "Write code before the test? Delete it. Start over.",
    "",
    "### Red-Green-Refactor Cycle",
    "",
    "**RED — Write failing test:**",
    "- One behavior per test, clear name, real code (no mocks unless unavoidable)",
    "- Watch it fail. MANDATORY. Never skip.",
    "- Confirm: test fails (not errors), failure message is expected, fails because feature is missing",
    "- Test passes? You're testing existing behavior. Fix the test.",
    "",
    "**GREEN — Write the simplest code to pass:**",
    "- Minimal, simplest code that makes the test pass",
    "- Don't add features, refactor other code, or improve beyond the test",
    "- Watch it pass. MANDATORY.",
    "- Confirm: test passes, other tests still pass, output pristine",
    "- Test fails? Fix code, not test. Other tests fail? Fix now.",
    "",
    "**REFACTOR — Clean up (after green only):**",
    "- Remove duplication, improve names, extract helpers",
    "- Keep tests green. Don't add behavior.",
    "",
    "### Verification Checklist",
    "",
    "Before marking work complete:",
    "- Every new function/method has a test",
    "- Watched each test fail before implementing",
    "- Each test failed for expected reason (feature missing, not typo)",
    "- Wrote minimal code to pass each test",
    "- All tests pass with pristine output",
    "- Tests use real code (mocks only if unavoidable)",
    "- Edge cases and errors covered",
    "",
    "### Red Flags — STOP and Start Over",
    "",
    "- Code before test",
    "- Test after implementation",
    "- Test passes immediately",
    "- Can't explain why test failed",
    "- Tests added later",
    '- Rationalizing "just this once"',
    "",
    "### Testing Anti-Patterns",
    "",
    "- Don't test mock behavior instead of real behavior",
    "- Don't add test-only methods to production classes",
    "- Don't mock without understanding dependencies",
    "- Don't use incomplete mocks (partial data structures)",
    "- Mocks are tools to isolate, not things to test",
    "",
    "### When Stuck",
    "",
    "| Problem | Solution |",
    "|---------|----------|",
    "| Don't know how to test | Write wished-for API. Write assertion first. Ask. |",
    "| Test too complicated | Design too complicated. Simplify interface. |",
    "| Must mock everything | Code too coupled. Use dependency injection. |",
    "| Test setup huge | Extract helpers. Still complex? Simplify design. |",
    "",
    "### Bug Fix Flow",
    "",
    "Bug found? Write a failing test reproducing it first.",
    "Follow the TDD cycle. The test proves the fix and prevents regression.",
    "Never fix bugs without a failing test.",
  ].join("\n");
}