Git-Aware Refactor

I need to refactor {{what_to_refactor}} but want to keep a clean git history.

Current implementation: {{current_approach}}
Target implementation: {{target_approach}}
Files affected: {{affected_files}}

Break this into atomic, reviewable commits:

**Commit 1 — Preparation** (no behavior change):
- Add any new types/interfaces needed
- Create new files with empty stubs
- Add feature flags if needed for gradual rollout

**Commit 2 — Implementation** (behind feature flag if applicable):
- Implement the new approach
- Old code remains functional throughout

**Commit 3 — Migration**:
- Switch call sites from old to new
- Update tests to use new approach
- Each test should pass at every commit

**Commit 4 — Cleanup**:
- Remove old implementation
- Remove feature flag
- Update documentation/comments

For each commit, provide:
- Commit message following conventional commits (feat:, refactor:, chore:)
- List of files changed
- The actual code changes

The key constraint: the app should work correctly at every commit. No "break things now, fix later" commits.