code-dedup

name	code-dedup
description	Searches for duplicate code, duplicate tests, and dead code, then safely merges or removes them. Use when the user says "deduplicate", "find duplicates", "remove dead code", "DRY up", or "code dedup". Requires test coverage — refuses to touch untested code.

Code Dedup

Carefully search for duplicate code, duplicate tests, and dead code across the repo. Merge duplicates and delete dead code — but only when test coverage proves the change is safe.

Prerequisites — hard gate

Before touching ANY code, verify these conditions. If any fail, stop and report why.

1. Run make test — all tests must pass. If tests fail, stop.
2. make test already enforces the coverage threshold from coverage-thresholds.json. If it failed on coverage, stop.
3. This is a Dart repo with static typing via austerity — proceed.

Steps

Step 1 — Inventory test coverage

1. Run make test and note coverage per package from the output
2. Only packages WITH coverage are candidates for dedup

Step 2 — Scan for dead code

1. Look for unused exports, functions, classes, variables across all packages
2. Use dart analyze output for unused element warnings
3. Grep the entire codebase for references before marking as dead
4. List all dead code found. Do NOT delete yet.

Step 3 — Scan for duplicate code

1. Look for functions with identical or near-identical logic across packages
2. Check across package boundaries
3. List all duplicates found. Do NOT merge yet.

Step 4 — Scan for duplicate tests

1. Look for tests that verify the same behavior
2. Look for test helpers duplicated across test files
3. List all duplicate tests found. Do NOT delete yet.

Step 5 — Apply changes (one at a time)

For each change: change -> test -> verify coverage -> continue or revert.

• After each change: run ./tools/test.sh
• If tests fail or coverage drops: revert immediately

Step 6 — Final verification

1. Run make test — all tests must still pass
2. Run make lint and make fmt CHECK=1 — code must be clean
3. Report: what was removed, what was merged, final coverage vs baseline

Rules

• No test coverage = do not touch.
• Coverage must not drop.
• One change at a time.
• When in doubt, leave it. False dedup is worse than duplication.
• Three similar lines is fine. Only dedup substantial (>10 lines) or 3+ copies.