safe-refactor

name	safe-refactor
description	Refactor code safely by analyzing blast radius and dependencies before making changes. Covers renaming, moving, extracting, and restructuring code with verification at each step. Use when refactoring, renaming symbols, extracting functions, moving files, or restructuring code.
compatibility	Requires tokenlean CLI tools (npm i -g tokenlean) and git

Safe Refactor

Change code structure without breaking dependents.

Workflow

Analyze → Plan → Change → Verify

1. Analyze what you're changing

tl parallel \
  "impact=tl impact <file>" \
  "exports=tl exports <file>" \
  "symbols=tl symbols <file>"

These three commands tell you:

• Blast radius — how many files will be affected
• Contract — which exports are consumed externally
• Shape — what you're working with

If tl impact shows 10+ dependents, consider whether this refactor is worth the risk. Discuss with the user.

2. Understand consumers

For each file that imports from the target:

tl snippet <imported-symbol> <consumer-file>

This shows how the symbol is actually used without reading the entire consumer file.

3. Make the changes

Apply the refactor. Then immediately check:

tl guard              # Circular deps, unused exports, other issues

4. Verify

tl parallel "test=tl run '<test-command>'" "impact=tl impact <file>"

If tests fail, tl run output shows only the failures. Fix and re-run.

Decision tree: refactor type

What are you changing?
  ├─ Renaming a symbol
  │   → tl impact to find all importers
  │   → Update all import sites
  │   → tl guard to verify no broken imports
  │
  ├─ Moving a file
  │   → tl impact for full dependent list
  │   → Move file, update all import paths
  │   → tl guard for circular deps
  │
  ├─ Extracting a function/module
  │   → tl symbols + tl deps on source file
  │   → Extract, add exports
  │   → tl impact on original to update importers
  │   → tl guard + tl run tests
  │
  └─ Changing a function signature
      → tl impact + tl flow to find all callers
      → tl snippet on each caller to see usage
      → Update signature + all call sites
      → tl run tests

Tips

• Always check tl impact BEFORE starting — discovering 50 dependents mid-refactor is painful
• Run tl exports before and after: the diff shows if you accidentally changed the public API
• For large refactors (10+ files), make incremental commits so you can bisect failures
• tl unused after refactoring catches exports you forgot to clean up