zhongwei/gh-basher83-lunar-claude-plugins-devops-python-tools

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Zhongwei Li 765529cd13 Initial commit

2025-11-29 18:00:18 +08:00

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Slash Commands in the SDK

Learn how to use slash commands to control Claude Code sessions through the SDK

Slash commands provide a way to control Claude Code sessions with special commands that start with /. These commands can be sent through the SDK to perform actions like clearing conversation history, compacting messages, or getting help.

Discovering Available Slash Commands

The Claude Agent SDK provides information about available slash commands in the system initialization message. Access this information when your session starts:

options: { maxTurns: 1 } options: { maxTurns: 1 } })) { if (message.type === "system" && message.subtype === "init") {

console.log("Available slash commands:", message.slash_commands);      console.log("Available slash commands:", message.slash_commands);
      // Example output: ["/compact", "/clear", "/help"]
    }

import asyncio
from claude_agent_sdk import query

async def main():
    async for message in query(

prompt="Hello Claude",          prompt="Hello Claude",
          options={"max_turns": 1}
      ):
          if message.type == "system" and message.subtype == "init":
              print("Available slash commands:", message.slash_commands)

              # Example output: ["/compact", "/clear", "/help"]

  asyncio.run(main())

Sending Slash Commands

Send slash commands by including them in your prompt string, just like regular text:

options: { maxTurns: 1 } options: { maxTurns: 1 } })) { if (message.type === "result") {

console.log("Command executed:", message.result);      console.log("Command executed:", message.result);
    }

import asyncio
from claude_agent_sdk import query

async def main():

    # Send a slash command

async for message in query(      async for message in query(
          prompt="/compact",
          options={"max_turns": 1}
      ):
          if message.type == "result":
              print("Command executed:", message.result)

  asyncio.run(main())

Common Slash Commands

`/compact` - Compact Conversation History

The /compact command reduces the size of your conversation history by summarizing older messages while preserving important context:

options: { maxTurns: 1 } options: { maxTurns: 1 } })) { if (message.type === "system" && message.subtype === "compact_boundary") {

console.log("Compaction completed");      console.log("Compaction completed");
      console.log("Pre-compaction tokens:", message.compact_metadata.pre_tokens);
      console.log("Trigger:", message.compact_metadata.trigger);
    }

import asyncio
from claude_agent_sdk import query

async def main():
    async for message in query(

prompt="/compact",          prompt="/compact",
          options={"max_turns": 1}
      ):
          if (message.type == "system" and
              message.subtype == "compact_boundary"):
              print("Compaction completed")
              print("Pre-compaction tokens:",
                    message.compact_metadata.pre_tokens)
              print("Trigger:", message.compact_metadata.trigger)

  asyncio.run(main())

`/clear` - Clear Conversation

The /clear command starts a fresh conversation by clearing all previous history:

options: { maxTurns: 1 } options: { maxTurns: 1 } })) { if (message.type === "system" && message.subtype === "init") {

console.log("Conversation cleared, new session started");      console.log("Conversation cleared, new session started");
      console.log("Session ID:", message.session_id);
    }

import asyncio
from claude_agent_sdk import query

async def main():

    # Clear conversation and start fresh
```python
async for message in query(      async for message in query(
        prompt="/clear",
        options={"max_turns": 1}
    ):
        if message.type == "system" and message.subtype == "init":
            print("Conversation cleared, new session started")
            print("Session ID:", message.session_id)

asyncio.run(main())

Creating Custom Slash Commands

In addition to using built-in slash commands, you can create your own custom commands that are available through the SDK. Custom commands are defined as markdown files in specific directories, similar to how subagents are configured.

File Locations

Custom slash commands are stored in designated directories based on their scope:

Project commands: .claude/commands/ - Available only in the current project
Personal commands: ~/.claude/commands/ - Available across all your projects

File Format

Each custom command is a markdown file where:

The filename (without .md extension) becomes the command name
The file content defines what the command does
Optional YAML frontmatter provides configuration

Basic Example

Create .claude/commands/refactor.md:

Refactor the selected code to improve readability and maintainability.
Focus on clean code principles and best practices.

This creates the /refactor command that you can use through the SDK.

With Frontmatter

Create .claude/commands/security-check.md:

---
allowed-tools: Read, Grep, Glob
description: Run security vulnerability scan
model: claude-sonnet-4-5
---

Analyze the codebase for security vulnerabilities including:

- SQL injection risks
- XSS vulnerabilities
- Exposed credentials
- Insecure configurations

Using Custom Commands in the SDK

Once defined in the filesystem, custom commands are automatically available through the SDK:

options: { maxTurns: 3 } options: { maxTurns: 3 } })) { if (message.type === "assistant") {

console.log("Refactoring suggestions:", message.message);      console.log("Refactoring suggestions:", message.message);
    }

  // Custom commands appear in the slash_commands list
  for await (const message of query({
    prompt: "Hello",
```python
options: { maxTurns: 1 }    options: { maxTurns: 1 }
  })) {
    if (message.type === "system" && message.subtype === "init") {

// Will include both built-in and custom commands // Will include both built-in and custom commands console.log("Available commands:", message.slash_commands); // Example: ["/compact", "/clear", "/help", "/refactor", "/security-check"] }


```python Python theme={null}
import asyncio
from claude_agent_sdk import query

async def main():

# Use a custom command
```python
async for message in query(      async for message in query(
        prompt="/refactor src/auth/login.py",
        options={"max_turns": 3}
    ):
        if message.type == "assistant":
            print("Refactoring suggestions:", message.message)

    # Custom commands appear in the slash_commands list
    async for message in query(
        prompt="Hello",
        options={"max_turns": 1}
    ):
        if message.type == "system" and message.subtype == "init":
            # Will include both built-in and custom commands
            print("Available commands:", message.slash_commands)
            # Example: ["/compact", "/clear", "/help", "/refactor", "/security-check"]

asyncio.run(main())

Advanced Features

Arguments and Placeholders

Custom commands support dynamic arguments using placeholders:

Create .claude/commands/fix-issue.md:

---
argument-hint: [issue-number] [priority]
description: Fix a GitHub issue
---

Fix issue #$1 with priority $2.
Check the issue description and implement the necessary changes.

Use in SDK:

options: { maxTurns: 5 } options: { maxTurns: 5 } })) { // Command will process with $1="123" and $2="high"

if (message.type === "result") {    if (message.type === "result") {
      console.log("Issue fixed:", message.result);
    }

import asyncio
from claude_agent_sdk import query

async def main():

    # Pass arguments to custom command
```python
async for message in query(      async for message in query(
        prompt="/fix-issue 123 high",
        options={"max_turns": 5}
    ):

# Command will process with $1="123" and $2="high"

        if message.type == "result":
            print("Issue fixed:", message.result)

asyncio.run(main())

Bash Command Execution

Custom commands can execute bash commands and include their output:

Create .claude/commands/git-commit.md:

---
allowed-tools: Bash(git add:*), Bash(git status:*), Bash(git commit:*)
description: Create a git commit
---

## Context

- Current status: !`git status`
- Current diff: !`git diff HEAD`

## Task

Create a git commit with appropriate message based on the changes.

File References

Include file contents using the @ prefix:

Create .claude/commands/review-config.md:

---
description: Review configuration files
---

Review the following configuration files for issues:

- Package config: @package.json
- TypeScript config: @tsconfig.json
- Environment config: @.env

Check for security issues, outdated dependencies, and misconfigurations.

Organization with Namespacing

Organize commands in subdirectories for better structure:

.claude/commands/
├── frontend/
│   ├── component.md      # Creates /component (project:frontend)
│   └── style-check.md     # Creates /style-check (project:frontend)
├── backend/
│   ├── api-test.md        # Creates /api-test (project:backend)
│   └── db-migrate.md      # Creates /db-migrate (project:backend)
└── review.md              # Creates /review (project)

The subdirectory appears in the command description but doesn't affect the command name itself.

Practical Examples

Code Review Command

Create .claude/commands/code-review.md:

---
allowed-tools: Read, Grep, Glob, Bash(git diff:*)
description: Comprehensive code review
---

## Changed Files

!`git diff --name-only HEAD~1`

## Detailed Changes

!`git diff HEAD~1`

## Review Checklist

Review the above changes for:

1. Code quality and readability
2. Security vulnerabilities
3. Performance implications
4. Test coverage
5. Documentation completeness

Provide specific, actionable feedback organized by priority.

Test Runner Command

Create .claude/commands/test.md:

---
allowed-tools: Bash, Read, Edit
argument-hint: [test-pattern]
description: Run tests with optional pattern
---

Run tests matching pattern: $ARGUMENTS

1. Detect the test framework (Jest, pytest, etc.)
2. Run tests with the provided pattern
3. If tests fail, analyze and fix them
4. Re-run to verify fixes

Use these commands through the SDK:

options: { maxTurns: 3 } options: { maxTurns: 3 } })) { // Process review feedback }

// Run specific tests for await (const message of query({ prompt: "/test auth",

options: { maxTurns: 5 }    options: { maxTurns: 5 }
  })) {
    // Handle test results
  }

import asyncio
from claude_agent_sdk import query

async def main():

# Run code review
```python
async for message in query(      async for message in query(
        prompt="/code-review",
        options={"max_turns": 3}
    ):

        # Process review feedback

        pass

    # Run specific tests
    async for message in query(
        prompt="/test auth",
        options={"max_turns": 5}
    ):
        # Handle test results
        pass

asyncio.run(main())

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