Bug: Claude Code Runs Node.js Hooks On Python Projects

by Alex Johnson 55 views

Introduction

In the realm of modern software development, the integration of various tools and technologies is crucial. However, when these integrations lead to unexpected behavior, it can disrupt the development process. This article delves into a specific bug encountered in Claude Code, where Node.js hooks are erroneously executed on Python projects. This issue not only causes unnecessary errors but also highlights the importance of project-specific configurations in integrated development environments (IDEs). Let's explore the intricacies of this bug, its impact, and potential solutions.

Problem Summary: Node.js Hooks on Python Projects

The core issue revolves around Claude Code, a development tool, incorrectly executing npm/biome PostToolUse hooks on Python FastAPI projects. These projects, crucially, do not have a package.json file, which is essential for Node.js projects. This misexecution results in "ENOENT" errors after every use of the Edit tool, disrupting the workflow and causing unnecessary confusion. Understanding the root cause and the steps to reproduce this bug is vital for developers and the Claude Code team to address the problem effectively.

The Specifics of the Error

Every time the Edit tool is utilized within Claude Code, an error message surfaces, indicating the failure of the PostToolUse hook. The error message explicitly states:

⏺ PostToolUse:Edit [cd "$CLAUDE_PROJECT_DIR" && npm run biome:check] failed with non-blocking status 
 code 254: npm error code ENOENT
 npm error syscall open
 npm error path /Users/devhub/WebstormProjects/polirate/political-fraud-detection-ml/package.json
 npm error errno -2
 npm error enoent Could not read package.json: Error: ENOENT: no such file or directory, open 
 '/Users/devhub/WebstormProjects/polirate/political-fraud-detection-ml/package.json'

This error clearly points to an issue with npm (Node Package Manager) attempting to access a package.json file in a Python project where it is not expected to exist. The ENOENT error, which stands for "Error No Entry," signifies that the system cannot find the specified file, in this case, package.json.

Impact of the Issue

While the error is classified as minor and non-blocking, its frequent occurrence makes it a significant annoyance. Every instance of using the Edit tool triggers this error, creating noise and potentially obscuring more critical issues. For developers, this means constantly encountering an irrelevant error message, which can lead to confusion and a sense of unease about the project's setup. The cumulative effect of these minor disruptions can impact productivity and overall user experience.

Environment Details

To fully understand the context of this bug, it's essential to examine the environment in which it occurs. The bug was observed in a specific setup, which includes the operating system, Claude Code version, project type, and working directory. These details provide valuable clues about the potential causes and help in replicating the issue for debugging purposes.

Key Environmental Factors

  • Platform: macOS (Darwin 24.5.0)
  • Claude Code Version: Latest
  • Project Type: Python FastAPI ML service
  • Working Directory: /Users/devhub/WebstormProjects/polirate/political-fraud-detection-ml

The operating system, macOS, is a common development environment, but its specific version (Darwin 24.5.0) might hold relevance. The latest version of Claude Code is crucial as it indicates that the bug is present in the most recent release, thus affecting current users. The project type, a Python FastAPI ML service, is a critical detail because it explicitly states that the project is Python-based and should not be subject to Node.js-specific hooks. The working directory provides the exact location of the project, aiding in reproducing the issue in a similar environment.

Detailed Project Configuration Analysis

To pinpoint the source of the erroneous behavior, a thorough analysis of the project configuration was conducted. This involved examining various hook configuration locations and settings files to identify any potential misconfigurations or unintended settings that might be triggering the Node.js hooks in a Python project. The systematic approach to this analysis helps rule out common configuration errors and narrows down the possible causes of the bug.

Investigating Hook Configuration Locations

The investigation focused on several key locations where hooks might be configured:

  • Project Hook Configuration:
    • File: .claude/config/hooks.json
    • Content: Only contains Python-specific hooks using the code-style-guardian agent. No npm/biome references were found.
  • Settings Files Checked:
    • ~/.claude/settings.json: Does not exist.
    • .claude/settings.json: Does not exist.
    • .claude/settings.local.json: Contains only Python-specific permissions and hook config references.
    • .claude/config/debug.json: Contains only Python debugging settings.

The absence of npm/biome references in the project-specific hook configuration (.claude/config/hooks.json) indicates that the issue is not due to a misconfigured project-level setting. Similarly, the non-existence of global settings files (~/.claude/settings.json and .claude/settings.json) and the presence of only Python-specific settings in .claude/settings.local.json and .claude/config/debug.json further suggest that the problem lies elsewhere.

Comprehensive Search Results

To ensure no hidden configurations were missed, a comprehensive search was conducted within the .claude directory. The search targeted keywords related to the erroneous behavior:

  • Searched the entire .claude directory for "npm", "biome", and "PostToolUse".
  • No matches were found.

This exhaustive search confirms that there are no explicit references to Node.js hooks within the Claude Code configuration files, reinforcing the conclusion that the issue is not due to user-defined settings.

Project Context and Technology Stack

Understanding the project's context and technology stack is crucial for diagnosing the bug. This Python FastAPI ML service has a well-defined set of technologies, none of which involve Node.js. This reinforces the expectation that Node.js hooks should not be executed in this project.

  • Key Project Characteristics:
    • Uses Python 3.11+
    • FastAPI framework
    • SQLAlchemy + PostgreSQL
    • scikit-learn + TensorFlow for ML
    • Poetry/pip for dependency management
    • Has requirements.txt, pyproject.toml, alembic.ini
    • No JavaScript/Node.js components whatsoever

The project's reliance on Python-specific tools and frameworks, such as FastAPI, SQLAlchemy, scikit-learn, and TensorFlow, clearly indicates that it is a Python project. The presence of requirements.txt, pyproject.toml, and alembic.ini further supports this. The explicit absence of JavaScript/Node.js components solidifies the expectation that Node.js hooks should not be triggered.

Root Cause Analysis: Cross-Project Hook Inheritance

The investigation points towards a likely root cause: cross-project hook inheritance. Claude Code appears to be executing a hardcoded or default npm/biome PostToolUse hook, irrespective of the project type, the absence of a package.json file, and the project-specific hook configurations that define only Python tooling. This suggests that hooks from sibling Node.js projects are being inappropriately applied to Python projects.

Implications of Cross-Project Hook Inheritance

This behavior indicates a significant flaw in the hook execution logic within Claude Code. Ideally, hooks should be executed contextually, based on the project type and configuration. The current implementation seems to lack this contextual awareness, leading to the erroneous execution of Node.js hooks in Python projects. This cross-project contamination can lead to unexpected errors and disrupt the development workflow.

Expected vs. Actual Behavior

To better illustrate the issue, it's helpful to contrast the expected behavior with the actual behavior observed in Claude Code. This comparison highlights the discrepancy and underscores the need for a fix.

Expected Behavior

Claude Code should exhibit the following behaviors:

  1. Detect project type correctly: Accurately identify a Python FastAPI project based on the presence of Python-specific files and the absence of Node.js-related files.
  2. Not execute JavaScript/Node.js hooks on Python projects: Avoid triggering Node.js hooks in projects that are clearly Python-based.
  3. Respect project-specific hook configurations: Only execute hooks defined in the project's configuration, such as Python-specific hooks.

Actual Behavior

In contrast, Claude Code is currently exhibiting the following behavior:

  • Executing npm/biome hooks despite the project being a pure Python project with no JavaScript dependencies or configuration.

This discrepancy between the expected and actual behavior highlights the bug's impact. The erroneous execution of Node.js hooks in a Python project is a clear deviation from the intended functionality and can lead to a degraded user experience.

Reproduction Steps

To facilitate the debugging process, clear and concise reproduction steps are essential. These steps allow developers to quickly replicate the issue and verify the fix.

Steps to Reproduce the Bug

  1. Create or work in a Python project that does not have a package.json file.
  2. Set up a .claude/config/hooks.json file with only Python-specific hooks.
  3. Use the Edit tool to modify any file within the project.
  4. Observe the npm/biome error in the output.

By following these steps, developers can consistently reproduce the bug, making it easier to test and validate potential solutions.

Impact Assessment

Understanding the impact of the bug is crucial for prioritizing its fix. The impact assessment considers the severity, frequency, and user experience implications of the issue.

Key Impact Factors

  • Severity: Minor (non-blocking but annoying)
  • Frequency: Every Edit tool usage
  • User Experience: Creates noise and confusion about project setup

While the bug is classified as minor because it doesn't block the development process, its high frequency (every Edit tool usage) makes it a significant annoyance. The constant appearance of the npm/biome error creates noise and can confuse users about the project's setup. This can lead to a negative user experience and potentially impact productivity.

Suggested Fixes

Based on the analysis, several fixes can address the bug. These suggestions focus on improving project type detection, hook execution logic, and configuration handling within Claude Code.

Proposed Solutions

  1. Check for project type before executing language-specific hooks: Implement logic to identify the project type (e.g., Python, JavaScript) and execute only the relevant hooks.
  2. Only run npm/biome hooks when package.json exists or the project is explicitly JavaScript/TypeScript: Ensure that Node.js hooks are only executed in projects where they are applicable.
  3. Respect user-defined hook configurations and not inject default hooks that conflict with the project type: Prioritize user-defined hooks and avoid injecting default hooks that might conflict with the project's configuration.
  4. Add project type detection logic to prevent cross-language hook contamination: Enhance the project type detection mechanism to prevent hooks from being applied across different language contexts.

These fixes aim to ensure that hooks are executed contextually, based on the project type and configuration, thereby resolving the issue of Node.js hooks being erroneously executed in Python projects.

Conclusion

The bug where Claude Code executes Node.js hooks on Python projects highlights the importance of contextual awareness in integrated development environments. The erroneous execution of Node.js hooks in a Python project not only causes unnecessary errors but also underscores the need for robust project type detection and hook execution logic. By implementing the suggested fixes, Claude Code can ensure that hooks are executed appropriately, enhancing the user experience and streamlining the development workflow. Addressing this bug will contribute to a more reliable and efficient development environment for users working with diverse project types.

For more information on best practices in software development and debugging, consider exploring resources from trusted websites such as Stack Overflow. This platform offers a wealth of knowledge and community support for developers encountering similar issues.

This issue replaces #5384 with improved structure while preserving all technical details and investigation findings.