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# Troubleshooting & FAQ ​

## Installation ​

Q: `pip install anthropic` fails with SSL error
A: Update pip: `python -m pip install --upgrade pip`. If on Windows behind a corporate proxy, set `set HTTPS_PROXY=http://proxy:port`.

Q: `python` not found on Windows
A: Install from python.org. Check "Add Python to PATH" during installation.

Q: `ModuleNotFoundError: No module named 'yaml'`
A: `pip install pyyaml`

## Labs ​

Q: Lab returns "No input provided"
A: Check you're passing `messages` parameter, not `prompt`. The mock LLM expects: `messages=[{"role": "user", "content": "your prompt"}]`

Q: Agent loops forever
A: `MAX_ITERATIONS` is not set or is too high. Set it to 10-15 for labs.

Q: Tool call returns empty result
A: The mock LLM generates tool calls based on keyword detection. If your prompt doesn't contain trigger words (read, search, write), it won't generate tool calls.

Q: `str_replace_editor` not found
A: That's an Anthropic-specific tool type. The mock LLM only supports basic tool_use blocks. Use the standard tool format shown in the labs.

## Skills ​

Q: Installed skills don't appear in `/skills` menu
A: Restart Claude Code after installation. Skills are loaded at startup.

Q: Skill says "not user-invocable"
A: Check the YAML frontmatter has `user-invocable: true`. Kit master files intentionally omit this (they're documentation, not invocable skills).

Q: `$ARGUMENTS` not being replaced
A: `$ARGUMENTS` is a placeholder. The agent (Claude Code / Pi) replaces it with your input when you invoke the skill via `/command`.

## API Keys ​

Q: "This model is not available" from Anthropic
A: You might need to request access to Claude Sonnet 4 / Opus 4. Check docs.anthropic.com for available models for your tier.

Q: Mock LLM works but real API returns 401
A: Check `ANTHROPIC_API_KEY` is set correctly. Test with: `python -c "import os; print(os.environ.get('ANTHROPIC_API_KEY', 'NOT SET')[:10])"`

Q: OpenRouter returns 402 Payment Required
A: Your free credits may be exhausted. Add payment method or switch to a different provider.

## General ​

Q: The course files use `\u2192` characters that show as garbage
A: The course uses Unicode arrows (→) in diagrams. If your terminal doesn't support UTF-8, set `$env:PYTHONIOENCODING='utf-8'` on Windows or use a UTF-8 capable terminal (Windows Terminal, iTerm2, Ghostty).

Q: How do I cite this course?
A: Reference "Agentic Engineering Course" with the module and lesson number.

Q: Can I teach this course?
A: Course materials are provided for personal study. Contact for teaching license.