Code Dedup

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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. Do not dedup a broken codebase.
2. Run make test — tests are fail-fast AND enforce the coverage threshold from coverage-thresholds.json. If anything fails, stop and fix it before deduping.
3. Verify the project uses static typing. Check for:
   • Rust, C#, F#: typed by default — proceed
   • TypeScript: tsconfig.json must have "strict": true — proceed

Steps

Copy this checklist and track progress:

Dedup Progress:
- [ ] Step 1: Prerequisites passed (tests green, coverage met, typed)
- [ ] Step 2: Dead code scan complete
- [ ] Step 3: Duplicate code scan complete
- [ ] Step 4: Duplicate test scan complete
- [ ] Step 5a: Dead code removed
- [ ] Step 5b: Duplicate code merged
- [ ] Step 5c: Duplicate tests removed
- [ ] Step 6: Verification passed (tests green, coverage stable)

Step 1 — Inventory test coverage

Before deciding what to touch, understand what is tested.

1. Run make test to confirm green baseline. make test is fail-fast AND enforces the coverage threshold from coverage-thresholds.json. It exits non-zero on any test failure OR coverage shortfall.
2. Note the current coverage percentage per project — this is the floor. It must not drop.
3. Identify which files/modules have coverage and which do not. Only files WITH coverage are candidates for dedup.

Step 2 — Scan for dead code

Search for code that is never called, never imported, never referenced.

1. Look for unused exports, unused functions, unused classes, unused variables
2. Use language-appropriate tools:
   • Rust: the compiler already warns on dead code — check make lint output for clippy warnings
   • TypeScript: check for noUnusedLocals/noUnusedParameters in tsconfig, look for unexported functions with zero references
   • C#: Roslyn analyzer warnings IDE0051 (unused private member), IDE0052 (unread private member), CS0169 (unused field)
   • F#: compiler warnings FS0040 (unused value), FS0060 (unused binding)
3. For each candidate: grep the entire codebase for references (including tests, scripts, configs). Only mark as dead if truly zero references.
4. List all dead code found with file paths and line numbers. Do NOT delete yet.

Step 3 — Scan for duplicate code

Search for code blocks that do the same thing in multiple places.

1. Look for functions/methods with identical or near-identical logic
2. Look for copy-pasted blocks (same structure, maybe different variable names)
3. Look for multiple implementations of the same algorithm or pattern
4. Check across module boundaries — duplicates often hide in different Rust crates, .NET sidecar projects, or TypeScript modules
5. For each duplicate pair: note both locations, what they do, and how they differ (if at all)
6. List all duplicates found. Do NOT merge yet.

Step 4 — Scan for duplicate tests

Search for tests that verify the same behavior.

1. Look for test functions with identical assertions against the same code paths
2. Look for test fixtures/helpers that are duplicated across test files
3. Look for integration tests that fully cover what a unit test also covers (keep the integration test, mark the unit test as redundant per CLAUDE.md rules)
4. List all duplicate tests found. Do NOT delete yet.

Step 5 — Apply changes (one at a time)

For each change, follow this cycle: change -> test -> verify coverage -> continue or revert.