Claude Code Simplifier Pre-commit Hook: Complete 2026 Guide

By the third or fourth iteration of a Claude Code session, something predictable happens - and it’s exactly why a claude code simplifier pre-commit hook earns its place in your workflow. Claude stops thinking about the architecture and starts serving your latest request. Each change layers on top of the last. Nobody planned what shipped.

The result is code full of redundant logic, inconsistent naming, and patterns that made sense five changes ago. The obvious fix - run a cleanup pass - is the one you never actually do. You’re in flow, you’re in a hurry, or you just forget.

The Claude Code Simplifier plugin solves this. And by wiring it to a pre-commit hook, the cleanup becomes automatic. It runs on every commit without any discipline required.

This guide covers the full setup for the claude code simplifier pre-commit hook: plugin install, hook configuration, platform-specific notes for Windows, Mac, and Linux, and how to test everything works.

What the Claude Code Simplifier Pre-Commit Hook Actually Does

Before setup, it’s worth being clear about what this tool does and doesn’t do.

What it removes:

• Redundant code - duplicate logic, unused variables, dead code paths
• Inconsistent naming - mixed conventions within the same file or function
• Unnecessary complexity - nested conditions that can be flattened, overly verbose patterns
• Misleading comments - comments that no longer match what the code actually does
• Inefficient patterns - patterns with cheaper equivalents that do the same thing

What it never touches:

• Your logic
• Your outputs or return values
• Your feature behavior

Functionality is preserved. The simplifier only targets structural noise. If it ever changes behavior, that’s a bug in the simplifier, not the intended outcome.

Why a pre-commit hook specifically? Manual cleanup is the step everyone says they’ll do “later.” Wiring the simplifier to the commit moment makes it the natural friction point - you’re already pausing to write a commit message, so a 20-second review of structural improvements fits the same rhythm. The alternative is running the simplifier on a schedule (daily, weekly), which catches issues but only after they’ve already shipped to main and been built on.

The hook is also lighter-weight than a CI step. Running the simplifier in CI means waiting for a runner to spin up, pull dependencies, and execute - typically 2-5 minutes. The local hook runs against staged files only and finishes in well under a minute for normal-sized commits. It’s the right place for fast, opinionated checks that benefit from immediate feedback.

Step 1: Install the Plugin

The Claude Code Simplifier is an official Anthropic plugin for Claude Code. Install it by running this in your terminal from any directory:

claude plugin install code-simplifier

Verify it installed correctly:

claude plugin list

You should see code-simplifier in the output. The plugin uses Claude Opus to analyze your staged files before each commit.

Step 2: Add the Pre-Commit Hook

Option A: Let Claude Set It Up For You (Quickest)

Open Claude Code in your project and paste this:

Set up the Claude Code Simplifier as a pre-commit hook for this project.

Here's the hook script to use:

#!/usr/bin/env bash
#
# Pre-commit hook: Claude Code Simplifier
# Runs the code simplifier on staged files before each commit.

set -euo pipefail

EXTENSIONS="js|ts|tsx|jsx|py|go|rb|rs|java|cs|cpp|c|h|swift|kt|php"

STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM \
  | grep -E "\.($EXTENSIONS)$" \
  || true)

if [ -z "$STAGED_FILES" ]; then
  exit 0
fi

FILE_COUNT=$(echo "$STAGED_FILES" | wc -l | tr -d ' ')
echo ""
echo "Code simplifier: scanning $FILE_COUNT staged file(s)..."

SIMPLIFIER_OUTPUT=$(claude simplify --staged 2>&1) || SIMPLIFIER_EXIT=$?

if [ "${SIMPLIFIER_EXIT:-0}" -ne 0 ]; then
  echo ""
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  echo "  Code simplifier found issues to review:"
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  echo "$SIMPLIFIER_OUTPUT"
  echo ""
  echo "  Review the diff above. To proceed:"
  echo "  1. Apply the suggested changes"
  echo "  2. git add <changed files>"
  echo "  3. git commit again"
  echo ""
  echo "  To skip (not recommended): git commit --no-verify"
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  exit 1
fi

echo "Code simplifier: clean. Proceeding with commit."
exit 0

Place this in .git/hooks/pre-commit and make it executable if on Mac/Linux.

Claude will create the file, place it in the right directory, and handle the chmod step on Mac/Linux. Job done.

Option B: Manual Setup

Create the file .git/hooks/pre-commit in your repository root with the following content:

#!/usr/bin/env bash
#
# Pre-commit hook: Claude Code Simplifier
#
# Runs the code simplifier on staged files before each commit.
# Blocks the commit if significant issues are found, so you can
# review the diff before it ships.
#
# To skip in emergencies: git commit --no-verify

set -euo pipefail

# File extensions to scan. Add or remove as needed for your stack.
EXTENSIONS="js|ts|tsx|jsx|py|go|rb|rs|java|cs|cpp|c|h|swift|kt|php"

# Get staged files matching the extensions (excluding deletions)
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM \
  | grep -E "\.($EXTENSIONS)$" \
  || true)

# Nothing to check
if [ -z "$STAGED_FILES" ]; then
  exit 0
fi

# Count for logging
FILE_COUNT=$(echo "$STAGED_FILES" | wc -l | tr -d ' ')
echo ""
echo "Code simplifier: scanning $FILE_COUNT staged file(s)..."

# Run the simplifier via Claude Code plugin
SIMPLIFIER_OUTPUT=$(claude simplify --staged 2>&1) || SIMPLIFIER_EXIT=$?

if [ "${SIMPLIFIER_EXIT:-0}" -ne 0 ]; then
  echo ""
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  echo "  Code simplifier found issues to review:"
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  echo "$SIMPLIFIER_OUTPUT"
  echo ""
  echo "  Review the diff above. To proceed:"
  echo "  1. Apply the suggested changes"
  echo "  2. git add <changed files>"
  echo "  3. git commit again"
  echo ""
  echo "  To skip (not recommended): git commit --no-verify"
  echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
  exit 1
fi

echo "Code simplifier: clean. Proceeding with commit."
exit 0

Step 3: Make It Executable

Mac / Linux

chmod +x .git/hooks/pre-commit

That’s all. The hook will now run on every commit.

Windows (Git Bash)

No chmod needed. Git Bash treats files in .git/hooks/ as executable automatically.

Important Windows notes:

The hook uses #!/usr/bin/env bash. This works correctly when you commit via:

• Git Bash terminal
• VS Code (it uses Git Bash for hooks internally)
• GitHub Desktop and most GUI clients

It will not run if you commit via PowerShell or cmd.exe directly. Use Git Bash or a GUI client for all commits.

The claude command also needs to be in your PATH. If the hook fails with “command not found”, check the Claude Code installation docs or add the full path to the claude binary at the top of the hook script:

# Add this near the top of the hook if claude isn't in PATH on Windows:
export PATH="$PATH:/c/Users/YourName/AppData/Local/Programs/claude-code"

Step 4: Test It

Make a small change to any code file, stage it, and run a test commit:

git add some-file.js
git commit -m "test: verify pre-commit hook"

You’ll see one of two outcomes:

Clean code:

Code simplifier: scanning 1 staged file(s)...
Code simplifier: clean. Proceeding with commit.

The commit goes through normally.

Issues found:

Code simplifier: scanning 1 staged file(s)...

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  Code simplifier found issues to review:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
[diff showing suggested changes]

  Review the diff above. To proceed:
  1. Apply the suggested changes
  2. git add <changed files>
  3. git commit again

  To skip (not recommended): git commit --no-verify
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

The commit is blocked. Review the diff, apply what looks right, re-stage, and commit again.

Troubleshooting Common Issues

A few problems come up repeatedly during setup. Knowing the cause saves time.

”claude: command not found” When the Hook Runs

This is the most common issue, especially on macOS and Windows. The hook runs in a different shell context than your interactive terminal, so PATH may not include the directory where claude lives.

The fix is to add the absolute path to the binary at the top of the hook script:

# Mac (Homebrew install)
export PATH="$PATH:/opt/homebrew/bin:/usr/local/bin"

# Windows (Git Bash)
export PATH="$PATH:/c/Users/YourName/AppData/Local/Programs/claude-code"

# Linux (typical install)
export PATH="$PATH:$HOME/.local/bin"

If you’re not sure where claude lives, run which claude in your interactive terminal and copy that path into the hook.

Hook Runs but Produces No Output

If the hook runs silently and exits with status 0, the issue is usually that no staged files matched the extensions in the EXTENSIONS variable. Check what you actually staged with git diff --cached --name-only. If you see .md, .json, or other excluded extensions, that’s expected behavior - the simplifier focuses on code files.

If you genuinely have code files staged and still see no output, add set -x near the top of the hook to enable debug tracing. You’ll see every command the hook runs, which usually pinpoints the failure.

Simplifier Times Out on Large Changesets

For commits with 50+ files or very large file diffs, the simplifier may exceed the default Claude Code timeout. Two ways to handle this:

1. Scope the hook to specific directories you actively iterate on. Edit the script to filter staged files: STAGED_FILES=$(... | grep "^src/").
2. Skip the hook for bulk changes that are mostly mechanical (dependency upgrades, formatter runs, generated code commits) using git commit --no-verify.

Bulk refactors are exactly the kind of work the simplifier was not designed for - it shines on the small, incremental commits where structural noise creeps in.

Hook Conflicts With Other Pre-Commit Tools

Many teams already run pre-commit (the Python framework), Husky, or lint-staged. The Claude Code Simplifier hook coexists fine with all of them - the trick is ordering.

If you use the pre-commit framework, add the simplifier as a local hook in .pre-commit-config.yaml:

- repo: local
  hooks:
    - id: claude-simplifier
      name: Claude Code Simplifier
      entry: claude simplify --staged
      language: system
      types: [text]
      stages: [commit]

Run formatting and linting first (Prettier, ESLint, Black, Ruff), then the simplifier. Structural cleanup after formatting catches issues formatters can’t see.

Diff Suggestions Look Wrong

Occasionally the simplifier suggests a change that breaks behavior. This is rare but treat it as a hard signal: do not apply the change. Document the case (file, suggestion, why it’s wrong) and either:

1. Update your CLAUDE.md to document the convention the simplifier missed, or
2. File a report on the Anthropic Claude Code GitHub issues with a minimal repro.

The simplifier is conservative by design - if it ever crosses from “structural cleanup” into “behavioral change,” that’s a bug worth surfacing.

Skipping the Hook

For emergencies - hotfixes, urgent pushes, or cases where you’ve reviewed and deliberately disagree with the suggestion:

git commit --no-verify

This skips all pre-commit hooks, including the claude code simplifier pre-commit hook. Use it sparingly. The point of the setup is to make the cleanup automatic, so bypassing it regularly defeats the purpose.

Frequently Asked Questions

Will it change my logic?

No. The simplifier targets structural noise - redundancy, naming inconsistency, dead code, misleading comments. It does not touch logic, conditionals, or outputs. Functionality is preserved by design. If you ever see a suggested diff that alters behavior, treat that as a bug and skip the change rather than apply it. The hook is a review checkpoint, not a forced rewrite.

What if it suggests a change I do not want?

Review the diff before the re-stage step. Apply the changes you agree with, skip the ones you do not. The hook does not force you to apply everything - it just blocks the commit so you have to look at it. If a particular suggestion keeps surfacing on code you have deliberately written that way, document the convention in your CLAUDE.md file. The simplifier reads project conventions from there and stops flagging patterns you have explicitly endorsed.

How long does it add to each commit?

Roughly 20-60 seconds for typical file sizes. For larger changesets it can take longer. The hook only runs on staged files, not the entire codebase, so it stays fast in practice. If you frequently stage large refactors and the wait becomes painful, you can scope the hook to specific directories or file extensions in the EXTENSIONS variable. For emergencies, git commit --no-verify skips the hook entirely.

What file types does it scan?

The hook scans .js .ts .tsx .jsx .py .go .rb .rs .java .cs .cpp .c .h .swift .kt .php. Edit the EXTENSIONS variable in the hook script to add or remove types for your stack. Markdown, JSON, YAML, and configuration files are excluded by default because the simplifier focuses on code-structural noise rather than prose or data formatting. Add them only if you have a strong reason - they generate false positives more often than not.

Can I customize what the hook checks for?

The plugin’s behavior is configured by your CLAUDE.md file. If you document your project’s coding standards there, the simplifier uses them as the reference. This means it enforces your conventions, not generic ones. See the Git hooks documentation for additional hook configuration options. Most teams iterate on CLAUDE.md for a few weeks until the hook’s suggestions consistently match what reviewers would have asked for in pull requests.

Does this work with GitHub Actions or CI?

Pre-commit hooks run locally only. They do not execute in CI pipelines. For CI-level enforcement, you would need a separate integration that calls the simplifier on changed files in a workflow step. If your team uses GitHub or GitLab for version control, see our guide to the best version control tools for how these platforms handle automated checks natively. Treat the local hook as the fast feedback loop and CI as the safety net.

Final Thoughts

The claude code simplifier pre-commit hook is most useful in the middle of development - not at the start of a clean codebase, but after a few weeks of active iteration when technical debt starts accumulating faster than you notice. Users on Claude Code feel this faster than most because the assistant generates working code so quickly that structural debt outpaces a reviewer’s bandwidth.

The pattern is consistent across real-world usage: redundant code that crept in during rapid iteration, naming that drifted across sessions, comments that used to be accurate. The hook catches it before it ships. Teams who run Claude Code alongside cloud-hosted IDEs report similar patterns - the simplifier acts as a final cleanup gate regardless of which surface generated the code.

The cleanup is real. The automation is the part that actually makes it stick. If you want to explore other ways to extend Claude Code’s capabilities, our guide to building MCP servers covers how to connect external tools and data sources to your workflow, and our Claude Code hooks deep dive explains the full PreToolUse/PostToolUse/Stop event model the simplifier piggybacks on.

Related Guides

• Claude Code Hooks Deep Dive - Master PreToolUse, PostToolUse, and Stop hooks
• Claude Code Prompt Engineering - The CRISP framework for better coding sessions
• Claude Code Tips and Tricks - Power user workflows that save hours
• Building MCP Servers Guide - Extend Claude Code with custom integrations

External Resources

• Claude Code Plugin Documentation (Anthropic)
• Git Hooks Documentation