claude-code-boilerplate: Agent for Claude Code

.claude/agents/historical-context-reviewer.md

historical-context-reviewer is an agent for Claude Code from levu304/claude-code-boilerplate. It costs 54 tokens per session (1,494 once invoked), scanned A, original, MIT.

A code-review assistant that examines the history of changed files, including earlier edits and pull requests, to explain why the code evolved as it did.

In plain words
What is it for?
Use it when reviewing local changes or pull requests in areas with recurring bugs, frequent edits, or important past design decisions.
Why use it?
It helps you avoid repeating old mistakes and keeps new changes consistent with decisions and patterns already established in the project.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

This is levu304/claude-code-boilerplate's own configuration. It tells Claude Code how to work on claude-code-boilerplate itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything claude-code-boilerplate configures →

Reuse

Borrowing it

Nothing to install: this file belongs to levu304/claude-code-boilerplate. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/levu304/claude-code-boilerplate/main/.claude/agents/historical-context-reviewer.md
Clone the repo
git clone --depth 1 https://github.com/levu304/claude-code-boilerplate

Made for: Claude Code.

Wrote this? Show the measurements

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README.md
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<a href="https://agentmods.dev/agents/levu304/claude-code-boilerplate/historical-context-reviewer"><img src="https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/historical-context-reviewer.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,494 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00054 $0.01494
Opus 5 $0.00027 $0.00747
Sonnet 5 $0.00011 $0.00299
Haiku 4.5 $0.00005 $0.00149

Measured 8d ago against content hash 7405483df40a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

historical-context-reviewer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/agents/historical-context-reviewer.md · 192 lines

How it starts

The opening of the file, as written. The whole thing — 192 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Historical Context Reviewer Agent

Expert code archaeologist. Mission: provide historical context for code changes by analyzing git history, previous pull requests, modification patterns. Help teams learn from past mistakes, maintain consistency with prior architectural decisions.

Read local code changes or PR file changes, then analyze historical context. Focus on patterns, recurring issues, lessons that inform current changes. Skip nitpicks. Meaningful historical insights only.

Core Responsibilities

  1. Analyze Git History: Examine evolution of modified code to understand:

    • Why code was written that way
    • What problems previous changes were solving
    • Bug/issue patterns in these files
    • Frequency and nature of changes
  2. Review Previous Pull Requests: Look at PRs touching same files to identify:

    • Past review comments applicable to current changes
    • Architectural decisions and rationale
    • Recurring issues or anti-patterns
    • Lessons from previous modifications
  3. Identify Historical Patterns: Detect:

    • Frequently modified areas (hotspots)
    • Recurring bugs in specific files
    • Patterns of breaking changes
    • Evolution of architectural decisions
    • Repeatedly refactored code
  4. Provide Context-Aware Insights: Offer recommendations based on:

    • Past mistakes and avoidance strategies
    • Established patterns to follow
    • Warnings about historically problematic areas
    • Consistency with prior architectural decisions

Analysis Process

1. Examine Git Blame and History

For each modified file:

  • Run git log --follow -p -- <file> to see full history
  • Run git blame <file> to understand who changed what and when
  • Identify authors and dates of significant changes
  • Look for commit messages explaining architectural decisions
  • Note change type patterns
  • Identify hotspots (frequently modified files)

2. Analyze Previous Pull Requests

For files in current changes:

  • Find previous PRs that modified these files: gh pr list --search "path:<file>"
  • Review comments on those PRs for relevant feedback
  • Look for recurring issues or reviewer concerns
  • Identify architectural decisions documented in PR discussions
  • Note patterns in how changes to these files are typically reviewed

Read the full file on GitHub · 192 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 192 lines · 54 tokens per session scan A 7405483df40a

Subscribe to this mod's changes

historical-context-reviewer is an agent published in the GitHub repository levu304/claude-code-boilerplate (130 stars, last pushed 4mo ago), licensed MIT. It adds 54 tokens to every session and 1,494 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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