Claude Code: The Autonomous Coding Agent (March 2026)

# Claude calls this internally:
bash(command="pytest tests/ -v --tb=short", timeout=60)
# Returns: stdout, stderr, exit_code

# Read a file
text_editor(command="view", path="/project/src/auth.py")

# Find in file
text_editor(command="view", path="/project/src/auth.py", view_range=[1, 50])

# Edit (surgical replacement)
text_editor(
    command="str_replace",
    path="/project/src/auth.py",
    old_str="def authenticate(user, password):",
    new_str="def authenticate(user: str, password: str) -> AuthResult:"
)

# Create new file
text_editor(command="create", path="/project/tests/test_auth.py", file_text="...")

# Start session (reads CLAUDE.md automatically)
claude

# With specific model
claude --model claude-3-7-sonnet-20250219

# With MCP config
claude --mcp-config .claude/mcp.json

# Single task, JSON output
claude -p "Fix all type errors in src/" \
  --output-format json \
  --max-turns 20

# Pipe from file
echo "Refactor src/utils.py to use async/await" | claude -p -

# Stream output
claude -p "Add logging to all API endpoints" --output-format stream-json

import asyncio
from claude_code_sdk import query, ClaudeCodeOptions

async def run_coding_task(task: str) -> str:
    options = ClaudeCodeOptions(
        max_turns=30,
        allowed_tools=["bash", "str_replace_based_edit_tool"],
        system_prompt_suffix="Always run tests after making changes.",
    )
    
    messages = []
    async for message in query(prompt=task, options=options):
        messages.append(message)
    
    return messages[-1].content[0].text

result = asyncio.run(run_coding_task(
    "Add input validation to all POST endpoints in src/api/"
))

{
  "permissions": {
    "allow": [
      "bash(pytest*)",           // Always allow test runs
      "bash(ruff*)",             // Always allow linting
      "bash(git diff*)",         // Always allow git reads
      "str_replace_based_edit_tool"  // Always allow file edits
    ],
    "deny": [
      "bash(rm -rf*)",           // Block destructive deletions
      "bash(curl https://external*)", // Block external network
      "bash(pip install*)"       // Block package installs without approval
    ]
  }
}

# .github/workflows/ai-fix.yml
name: AI Bug Fix
on:
  issues:
    types: [labeled]

jobs:
  ai-fix:
    if: github.event.label.name == 'ai-fix'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - name: Run Claude Code
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
        run: |
          pip install claude-code
          
          ISSUE_BODY="${{ github.event.issue.body }}"
          
          claude -p "Fix the following bug: $ISSUE_BODY
          
          Rules:
          - Read the relevant files first
          - Make minimal changes
          - Run tests and verify they pass
          - Do not change unrelated code
          " --output-format json --max-turns 15 > result.json
      
      - name: Create Pull Request
        uses: peter-evans/create-pull-request@v5
        with:
          title: "AI Fix: ${{ github.event.issue.title }}"
          body: "Automated fix by Claude Code"
          branch: "ai-fix/${{ github.event.issue.number }}"