# Diff

> This skill should be used when the user asks "analyze my changes", "what did I change", "review my diff", "impact of changes", "show changes", "git analysis", or wants semantic analysis of code changes. Use when this capability is needed.

- Skill: `tomevault-io/diff` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/diff`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/diff/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/diff

---


# Semantic Diff Analysis

Analyze git changes semantically with classification, impact analysis, and risk assessment.

**Arguments:** $ARGUMENTS

## Instructions

1. Parse optional arguments:
   - `--from REF` → Starting git ref (default: HEAD~1 or staged changes)
   - `--to REF` → Ending git ref (default: HEAD)
   - `--no-impact` → Skip impact analysis (faster)

2. Use the `mcp__mira__diff` tool:
   ```
   diff(from_ref="...", to_ref="...", include_impact=true)
   ```

3. Present results in sections:

### Change Classification
- **NewFunction**: Entirely new functions/methods
- **ModifiedFunction**: Changed existing functions
- **DeletedFunction**: Removed functions
- **NewFile**: New files added
- **Refactored**: Structural changes without behavior change

### Impact Analysis
- What callers are affected by these changes
- Which modules depend on modified code
- Potential ripple effects

### Risk Assessment
- **Breaking changes**: API signature changes, removed exports
- **Security relevance**: Auth, input validation, crypto changes
- **Test coverage**: Are changes covered by tests?

## Examples

```
/mira:diff
→ Analyzes staged/working changes vs HEAD

/mira:diff --from main
→ Analyzes current branch vs main

/mira:diff --from v1.0 --to v1.1
→ Analyzes changes between tags

/mira:diff --no-impact
→ Quick classification without call graph analysis
```

## Example Output

```
## Semantic Diff Analysis

### Changes (5 files, +142 -38 lines)

**New Functions:**
- `validate_token()` in src/auth.rs:45

**Modified Functions:**
- `handle_login()` in src/auth.rs:23 (added rate limiting)
- `create_session()` in src/session.rs:67 (changed return type)

### Impact Analysis
- `handle_login()` is called by 3 endpoints
- `create_session()` change affects 12 callers

### Risk Assessment
[WARNING] **Breaking**: `create_session()` return type changed
[SECURITY] **Security**: Rate limiting added (positive)
```

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->