review-history

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Translated

Analyze how code changed over time. Use when investigating regressions, understanding why code was written a certain way, or finding when a behavior changed.

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Sourcenielsmadan/agentic-coding
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npx skill4agent add nielsmadan/agentic-coding review-history

Tags

Translated version includes tags in frontmatter
git-history-analysisregression-investigationcode-change-trackinggit-commandsissue-log-search

SKILL.md Content

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Review History

Investigate how code evolved over time to understand current behavior or find regressions.

Usage

/review-history src/auth/login.ts
/review-history the authentication flow
/review-history UserProfile component

Workflow

Step 1: Identify Target Files

From the provided topic, identify the relevant files:
  • If a file path is given, use it directly
  • If a feature/function name, locate relevant files using this strategy:
    1. Grep for the exact function/class name to find where it is defined and used
    2. Glob for files with the feature name in the path (e.g., 
      **/*payment*
      )
    3. Prioritize source files over test files; include tests only if investigating test behavior
    4. Limit to the 5 most relevant files to keep the analysis focused

Step 2: Git History Analysis

Run these in parallel:
Recent commits touching the area:
bash
git log --oneline -20 -- <file_or_directory>
Detailed blame for key sections:
bash
# For files > 200 lines: target the specific function or section under investigation.
# Use Grep to find the line range first, then:
git blame -L <start>,<end> <file>

# For files ≤ 200 lines: blame the entire file:
git blame <file>
Find when specific code was introduced:
bash
git log -S "<search_term>" --oneline -- <file>
Check for recent refactors:
bash
git log --oneline --since="3 months ago" -- <file_or_directory>
Adjust the time window based on context:
  • Investigating a recent regression: use 
    --since="2 weeks ago"
  • Understanding a feature's evolution: use 
    --since="6 months ago"
    or omit 
    --since
    entirely
  • If the initial window returns fewer than 3 commits, double the window and retry once

Step 3: Search Past Issue Logs

Check if this problem occurred before:
  1. List past issue logs:
    • Glob pattern: 
      docs/log/*.md
  2. Search logs for relevant keywords:
    • Grep pattern: 
      {keywords}
      path: 
      docs/log/
Look for:
  • Similar error messages
  • Same file/function names
  • Related symptoms

Step 4: Synthesize Findings

Populate the report using these methods:
  • Recent Changes: List commits from 
    git log
    , most recent first. Include only commits that touch the target code.
  • Key Code Introduction: Use 
    git log -S
    results to identify when the function/feature first appeared and its last substantive change (skip formatting-only commits).
  • Related Past Issues: Direct matches from Step 3. If none found, state "None found in docs/log/".
  • Regression Risk: Compare current behavior against commit history. If code worked before a specific commit and broke after, name that commit. If no clear regression point, state "No clear regression identified — behavior may be by design."
Report:
markdown
## History Analysis: {target}

### Recent Changes
| Date | Commit | Author | Summary |
|------|--------|--------|---------|
| {date} | {hash} | {author} | {message} |

### Key Code Introduction
- `{function/feature}` introduced in {commit} on {date}
- Last modified: {commit} by {author}

### Related Past Issues
{any matching docs/log entries, or "None found"}

### Regression Risk
{assessment: was this working before? when did it break?}

Examples

Trace when a payment bug was introduced:
/review-history processPayment
Uses 
git log -S
and 
git blame
to trace the payment processing function, identifies the commit that changed the rounding logic three weeks ago, and cross-references with past issue logs to confirm this is when the billing discrepancy started.
Understand why validation works a certain way:
/review-history src/validators/address.ts
Analyzes the git history of the address validator, surfaces the original commit that added the unusual postal code regex along with its commit message explaining a partner API requirement, and checks past issue logs for related context.

Troubleshooting

Relevant commit was squashed or rebased away

Solution: Use 
git reflog
to find the original commit before the squash or rebase. If the reflog has expired, search for the change using 
git log -S "<code_snippet>" --all
to locate it in any branch or dangling commit.

History is too large to analyze effectively

Solution: Narrow the scope by passing a specific file path or function name instead of a broad directory. Use 
--since
with 
git log
to limit the time window, or focus on a single author's contributions with 
--author
.

Notes

  • Focus on commits from the last 3-6 months unless investigating older issues
  • Pay attention to refactors, dependency updates, and merge commits
  • If a past issue log matches, read it fully - it may contain the solution