fortify

name	fortify
effort	high
description	Fortify existing code by splitting large functions, adding edge-case coverage, and backfilling unit tests. Use when user asks to "fortify", "harden", "bulletproof", "make robust", "make solid", "strengthen", "add missing tests", "split functions", or wants to improve reliability of existing code. Don't use for new features (use tdd), refactoring plans, or code review (use code-review).

Fortify

Target: $ARGUMENTS (file, directory, or module — if blank, use unstaged changes)

Workflow

1. Scope

Identify target files. If $ARGUMENTS is blank, use unstaged changed files.

• Read each target file
• Read its existing test file (co-located *.test.ts or __tests__/)
• If no test file exists, note it

2. Audit

For each file, list findings in three buckets:

Bucket	What to look for
Split	Functions > 20 lines, multiple responsibilities, deeply nested logic (> 2 levels), God functions doing I/O + logic
Edge cases	Missing null/empty/boundary checks at system boundaries, unhandled error paths, implicit assumptions
Test gaps	Untested public functions, branches with no coverage, missing sad-path tests

Present the audit as a checklist. Ask "Which items should I address?" — list each finding as an option, with "All items" as first option marked (Recommended). Use AskUserQuestion (multiSelect) when available; otherwise present as a numbered checklist.

3. Harden (TDD loop per item)

For each approved item, apply red-green-refactor:

RED:    Write a failing test that exposes the gap
GREEN:  Minimal code change to pass
REFACTOR: Extract/simplify if the fix introduced complexity

One item at a time. Run tests after each cycle. Never batch.

Splitting rules:

• Extract pure logic into named helpers — keep I/O at the edges
• New functions must be testable through public interface when possible
• Preserve the original function's signature (no breaking changes)

Test rules:

• Test behavior, not implementation
• Each test gets a descriptive name: it('returns empty array when input is null')
• Prefer real values over mocks; mock only external I/O

4. Verify

• Run full test suite
• Confirm no regressions
• Report summary: items addressed, tests added, functions extracted

Output format

## Fortify Report

### Audit
- [ ] Split: `processOrder` (45 lines, validation + persistence + notification)
- [ ] Edge: `parseConfig` — no handling for missing file
- [ ] Test: `formatOutput` — zero test coverage

### Changes
- Extracted `validateOrder()` from `processOrder()` (+1 fn, +3 tests)
- Added null-guard to `parseConfig` (+2 tests)
- Backfilled `formatOutput` tests (+4 tests)

### Result
Tests: 42 passed (was 35) | 0 failed

Rules

• Never change external behavior — hardening is internal improvement
• Skip files with zero test infrastructure unless user explicitly asks to set it up

Error Handling

• If no test runner found → ask user which runner to use before proceeding
• If test suite fails before hardening → report failures and stop; don't harden broken code
• If a split introduces a regression → revert that split immediately, note it as blocked
• If target file has no exports (script/entrypoint) → audit only, skip test backfill unless user confirms