## 1. OpenSpec And Issue Setup

- [x] 1.1 Create slug-based issue and devflow tracking files.
- [x] 1.2 Create OpenSpec proposal, design, delta spec, and tasks.

## 2. Baseline Diff Implementation

- [x] 2.1 Add diff result data structures for summary and per-item changes.
- [x] 2.2 Implement deterministic report comparison rules.
- [x] 2.3 Implement JSON and Markdown diff report writing.

## 3. Documentation

- [x] 3.1 Document baseline diff inputs, outputs, and interpretation in eval docs.
- [x] 3.2 Add sample diff output for a representative regression.

## 4. Tests And Validation

- [x] 4.1 Add focused tests for aggregate and case-level diff behavior.
- [x] 4.2 Add focused tests for JSON and Markdown diff output.
- [x] 4.3 Run evaluator/diff tests.
- [x] 4.4 Run compile verification.
- [x] 4.5 Run OpenSpec validation.