# Contributing to Hermes Agent

Thank you for contributing to Hermes Agent! This guide covers everything you need: setting up your dev environment, understanding the architecture, deciding what to build, and getting your PR merged.

---

## Contribution Priorities

We value contributions in this order:

1. **Bug fixes** — crashes, incorrect behavior, data loss. Always top priority.
2. **Cross-platform compatibility** — Windows, macOS, different Linux distros, different terminal emulators. We want Hermes to work everywhere.
3. **Security hardening** — shell injection, prompt injection, path traversal, privilege escalation. See [Security](#security-considerations).
4. **Performance and robustness** — retry logic, error handling, graceful degradation.
5. **New skills** — but only broadly useful ones. See [Should it be a Skill or a Tool?](#should-it-be-a-skill-or-a-tool)
6. **New tools** — rarely needed. Most capabilities should be skills. See below.
7. **Documentation** — fixes, clarifications, new examples.

---

## Should it be a Skill or a Tool?

This is the most common question for new contributors. The answer is almost always **skill**.

### Make it a Skill when:

- The capability can be expressed as instructions + shell commands + existing tools
- It wraps an external CLI or API that the agent can call via `terminal` or `web_extract`
- It doesn't need custom Python integration or API key management baked into the agent
- Examples: arXiv search, git workflows, Docker management, PDF processing, email via CLI tools

### Make it a Tool when:

- It requires end-to-end integration with API keys, auth flows, or multi-component configuration managed by the agent harness
- It needs custom processing logic that must execute precisely every time (not "best effort" from LLM interpretation)
- It handles binary data, streaming, or real-time events that can't go through the terminal
- Examples: browser automation (Browserbase session management), TTS (audio encoding + platform delivery), vision analysis (base64 image handling)

### Should the Skill be bundled?

Bundled skills (in `skills/`) ship with every Hermes install. They should be **broadly useful to most users**:

- Document handling, web research, common dev workflows, system administration
- Used regularly by a wide range of people

If your skill is official and useful but not universally needed (e.g., a paid service integration, a heavyweight dependency), put it in **`optional-skills/`** — it ships with the repo but isn't activated by default. Users can discover it via `hermes skills browse` (labeled "official") and install it with `hermes skills install` (no third-party warning, builtin trust).

If your skill is specialized, community-contributed, or niche, it's better suited for a **Skills Hub** — upload it to a skills registry and share it in the [Nous Research Discord](https://discord.gg/NousResearch). Users can install it with `hermes skills install`.

---

## Development Setup

### Prerequisites

| Requirement | Notes |
|-------------|-------|
| **Git** | With `--recurse-submodules` support |
| **Python 3.11+** | uv will install it if missing |
| **uv** | Fast Python package manager ([install](https://docs.astral.sh/uv/)) |
| **Node.js 18+** | Optional — needed for browser tools and WhatsApp bridge |

### Clone and install

```bash
git clone --recurse-submodules https://github.com/NousResearch/hermes-agent.git
cd hermes-agent

# Create venv with Python 3.11
uv venv venv --python 3.11
export VIRTUAL_ENV="$(pwd)/venv"

# Install with all extras (messaging, cron, CLI menus, dev tools)
uv pip install -e ".[all,dev]"
uv pip install -e "./mini-swe-agent"
uv pip install -e "./tinker-atropos"

# Optional: browser tools
npm install
```

### Configure for development

```bash
mkdir -p ~/.hermes/{cron,sessions,logs,memories,skills}
cp cli-config.yaml.example ~/.hermes/config.yaml
touch ~/.hermes/.env

# Add at minimum an LLM provider key:
echo 'OPENROUTER_API_KEY=sk-or-v1-your-key' >> ~/.hermes/.env
```

### Run

```bash
# Symlink for global access
mkdir -p ~/.local/bin
ln -sf "$(pwd)/venv/bin/hermes" ~/.local/bin/hermes

# Verify
hermes doctor
hermes chat -q "Hello"
```

### Run tests

```bash
pytest tests/ -v
```

---

## Project Structure

```
hermes-agent/
├── run_agent.py              # AIAgent class — core conversation loop, tool dispatch, session persistence
├── cli.py                    # HermesCLI class — interactive TUI, prompt_toolkit integration
├── model_tools.py            # Tool orchestration (thin layer over tools/registry.py)
├── toolsets.py               # Tool groupings and presets (hermes-cli, hermes-telegram, etc.)
├── hermes_state.py           # SQLite session database with FTS5 full-text search, session titles
├── batch_runner.py           # Parallel batch processing for trajectory generation
│
├── agent/                    # Agent internals (extracted modules)
│   ├── prompt_builder.py         # System prompt assembly (identity, skills, context files, memory)
│   ├── context_compressor.py     # Auto-summarization when approaching context limits
│   ├── auxiliary_client.py       # Resolves auxiliary OpenAI clients (summarization, vision)
│   ├── display.py                # KawaiiSpinner, tool progress formatting
│   ├── model_metadata.py         # Model context lengths, token estimation
│   └── trajectory.py             # Trajectory saving helpers
│
├── hermes_cli/               # CLI command implementations
│   ├── main.py                   # Entry point, argument parsing, command dispatch
│   ├── config.py                 # Config management, migration, env var definitions
│   ├── setup.py                  # Interactive setup wizard
│   ├── auth.py                   # Provider resolution, OAuth, Nous Portal
│   ├── models.py                 # OpenRouter model selection lists
│   ├── banner.py                 # Welcome banner, ASCII art
│   ├── commands.py               # Slash command definitions + autocomplete
│   ├── callbacks.py              # Interactive callbacks (clarify, sudo, approval)
│   ├── doctor.py                 # Diagnostics
│   ├── skills_hub.py             # Skills Hub CLI + /skills slash command
│   └── skin_engine.py            # Skin/theme engine — data-driven CLI visual customization
│
├── tools/                    # Tool implementations (self-registering)
│   ├── registry.py               # Central tool registry (schemas, handlers, dispatch)
│   ├── approval.py               # Dangerous command detection + per-session approval
│   ├── terminal_tool.py          # Terminal orchestration (sudo, env lifecycle, backends)
│   ├── file_operations.py        # read_file, write_file, search, patch, etc.
│   ├── web_tools.py              # web_search, web_extract (Firecrawl + Gemini summarization)
│   ├── vision_tools.py           # Image analysis via multimodal models
│   ├── delegate_tool.py          # Subagent spawning and parallel task execution
│   ├── code_execution_tool.py    # Sandboxed Python with RPC tool access
│   ├── session_search_tool.py    # Search past conversations with FTS5 + summarization
│   ├── cronjob_tools.py          # Scheduled task management
│   ├── skill_tools.py            # Skill search, load, manage
│   └── environments/             # Terminal execution backends
│       ├── base.py                   # BaseEnvironment ABC
│       ├── local.py, docker.py, ssh.py, singularity.py, modal.py, daytona.py
│
├── gateway/                  # Messaging gateway
│   ├── run.py                    # GatewayRunner — platform lifecycle, message routing, cron
│   ├── config.py                 # Platform configuration resolution
│   ├── session.py                # Session store, context prompts, reset policies
│   └── platforms/                # Platform adapters
│       ├── telegram.py, discord_adapter.py, slack.py, whatsapp.py
│
├── scripts/                  # Installer and bridge scripts
│   ├── install.sh                # Linux/macOS installer
│   ├── install.ps1               # Windows PowerShell installer
│   └── whatsapp-bridge/          # Node.js WhatsApp bridge (Baileys)
│
├── skills/                   # Bundled skills (copied to ~/.hermes/skills/ on install)
├── optional-skills/          # Official optional skills (discoverable via hub, not activated by default)
├── environments/             # RL training environments (Atropos integration)
├── tests/                    # Test suite
├── website/                  # Documentation site (hermes-agent.nousresearch.com)
│
├── cli-config.yaml.example   # Example configuration (copied to ~/.hermes/config.yaml)
└── AGENTS.md                 # Development guide for AI coding assistants
```

### User configuration (stored in `~/.hermes/`)

| Path | Purpose |
|------|---------|
| `~/.hermes/config.yaml` | Settings (model, terminal, toolsets, compression, etc.) |
| `~/.hermes/.env` | API keys and secrets |
| `~/.hermes/auth.json` | OAuth credentials (Nous Portal) |
| `~/.hermes/skills/` | All active skills (bundled + hub-installed + agent-created) |
| `~/.hermes/memories/` | Persistent memory (MEMORY.md, USER.md) |
| `~/.hermes/state.db` | SQLite session database |
| `~/.hermes/sessions/` | JSON session logs |
| `~/.hermes/cron/` | Scheduled job data |
| `~/.hermes/whatsapp/session/` | WhatsApp bridge credentials |

---

## Architecture Overview

### Core Loop

```
User message → AIAgent._run_agent_loop()
  ├── Build system prompt (prompt_builder.py)
  ├── Build API kwargs (model, messages, tools, reasoning config)
  ├── Call LLM (OpenAI-compatible API)
  ├── If tool_calls in response:
  │     ├── Execute each tool via registry dispatch
  │     ├── Add tool results to conversation
  │     └── Loop back to LLM call
  ├── If text response:
  │     ├── Persist session to DB
  │     └── Return final_response
  └── Context compression if approaching token limit
```

### Key Design Patterns

- **Self-registering tools**: Each tool file calls `registry.register()` at import time. `model_tools.py` triggers discovery by importing all tool modules.
- **Toolset grouping**: Tools are grouped into toolsets (`web`, `terminal`, `file`, `browser`, etc.) that can be enabled/disabled per platform.
- **Session persistence**: All conversations are stored in SQLite (`hermes_state.py`) with full-text search and unique session titles. JSON logs go to `~/.hermes/sessions/`.
- **Ephemeral injection**: System prompts and prefill messages are injected at API call time, never persisted to the database or logs.
- **Provider abstraction**: The agent works with any OpenAI-compatible API. Provider resolution happens at init time (Nous Portal OAuth, OpenRouter API key, or custom endpoint).
- **Provider routing**: When using OpenRouter, `provider_routing` in config.yaml controls provider selection (sort by throughput/latency/price, allow/ignore specific providers, data retention policies). These are injected as `extra_body.provider` in API requests.

---

## Code Style

- **PEP 8** with practical exceptions (we don't enforce strict line length)
- **Comments**: Only when explaining non-obvious intent, trade-offs, or API quirks. Don't narrate what the code does — `# increment counter` adds nothing
- **Error handling**: Catch specific exceptions. Log with `logger.warning()`/`logger.error()` — use `exc_info=True` for unexpected errors so stack traces appear in logs
- **Cross-platform**: Never assume Unix. See [Cross-Platform Compatibility](#cross-platform-compatibility)

---

## Adding a New Tool

Before writing a tool, ask: [should this be a skill instead?](#should-it-be-a-skill-or-a-tool)

Tools self-register with the central registry. Each tool file co-locates its schema, handler, and registration:

```python
"""my_tool — Brief description of what this tool does."""

import json
from tools.registry import registry


def my_tool(param1: str, param2: int = 10, **kwargs) -> str:
    """Handler. Returns a string result (often JSON)."""
    result = do_work(param1, param2)
    return json.dumps(result)


MY_TOOL_SCHEMA = {
    "type": "function",
    "function": {
        "name": "my_tool",
        "description": "What this tool does and when the agent should use it.",
        "parameters": {
            "type": "object",
            "properties": {
                "param1": {"type": "string", "description": "What param1 is"},
                "param2": {"type": "integer", "description": "What param2 is", "default": 10},
            },
            "required": ["param1"],
        },
    },
}


def _check_requirements() -> bool:
    """Return True if this tool's dependencies are available."""
    return True


registry.register(
    name="my_tool",
    toolset="my_toolset",
    schema=MY_TOOL_SCHEMA,
    handler=lambda args, **kw: my_tool(**args, **kw),
    check_fn=_check_requirements,
)
```

Then add the import to `model_tools.py` in the `_modules` list:

```python
_modules = [
    # ... existing modules ...
    "tools.my_tool",
]
```

If it's a new toolset, add it to `toolsets.py` and to the relevant platform presets.

---

## Adding a Skill

Bundled skills live in `skills/` organized by category. Official optional skills use the same structure in `optional-skills/`:

```
skills/
├── research/
│   └── arxiv/
│       ├── SKILL.md              # Required: main instructions
│       └── scripts/              # Optional: helper scripts
│           └── search_arxiv.py
├── productivity/
│   └── ocr-and-documents/
│       ├── SKILL.md
│       ├── scripts/
│       └── references/
└── ...
```

### SKILL.md format

```markdown
---
name: my-skill
description: Brief description (shown in skill search results)
version: 1.0.0
author: Your Name
license: MIT
platforms: [macos, linux]          # Optional — restrict to specific OS platforms
                                   #   Valid: macos, linux, windows
                                   #   Omit to load on all platforms (default)
metadata:
  hermes:
    tags: [Category, Subcategory, Keywords]
    related_skills: [other-skill-name]
---

# Skill Title

Brief intro.

## When to Use
Trigger conditions — when should the agent load this skill?

## Quick Reference
Table of common commands or API calls.

## Procedure
Step-by-step instructions the agent follows.

## Pitfalls
Known failure modes and how to handle them.

## Verification
How the agent confirms it worked.
```

### Platform-specific skills

Skills can declare which OS platforms they support via the `platforms` frontmatter field. Skills with this field are automatically hidden from the system prompt, `skills_list()`, and slash commands on incompatible platforms.

```yaml
platforms: [macos]            # macOS only (e.g., iMessage, Apple Reminders)
platforms: [macos, linux]     # macOS and Linux
platforms: [windows]          # Windows only
```

If the field is omitted or empty, the skill loads on all platforms (backward compatible). See `skills/apple/` for examples of macOS-only skills.

### Skill guidelines

- **No external dependencies unless absolutely necessary.** Prefer stdlib Python, curl, and existing Hermes tools (`web_extract`, `terminal`, `read_file`).
- **Progressive disclosure.** Put the most common workflow first. Edge cases and advanced usage go at the bottom.
- **Include helper scripts** for XML/JSON parsing or complex logic — don't expect the LLM to write parsers inline every time.
- **Test it.** Run `hermes --toolsets skills -q "Use the X skill to do Y"` and verify the agent follows the instructions correctly.

---

## Adding a Skin / Theme

Hermes uses a data-driven skin system — no code changes needed to add a new skin.

**Option A: User skin (YAML file)**

Create `~/.hermes/skins/<name>.yaml`:

```yaml
name: mytheme
description: Short description of the theme

colors:
  banner_border: "#HEX"     # Panel border color
  banner_title: "#HEX"      # Panel title color
  banner_accent: "#HEX"     # Section header color
  banner_dim: "#HEX"        # Muted/dim text color
  banner_text: "#HEX"       # Body text color
  response_border: "#HEX"   # Response box border

spinner:
  waiting_faces: ["(⚔)", "(⛨)"]
  thinking_faces: ["(⚔)", "(⌁)"]
  thinking_verbs: ["forging", "plotting"]
  wings:                     # Optional left/right decorations
    - ["⟪⚔", "⚔⟫"]

branding:
  agent_name: "My Agent"
  welcome: "Welcome message"
  response_label: " ⚔ Agent "
  prompt_symbol: "⚔ ❯ "

tool_prefix: "╎"             # Tool output line prefix
```

All fields are optional — missing values inherit from the default skin.

**Option B: Built-in skin**

Add to `_BUILTIN_SKINS` dict in `hermes_cli/skin_engine.py`. Use the same schema as above but as a Python dict. Built-in skins ship with the package and are always available.

**Activating:**
- CLI: `/skin mytheme` or set `display.skin: mytheme` in config.yaml
- Config: `display: { skin: mytheme }`

See `hermes_cli/skin_engine.py` for the full schema and existing skins as examples.

---

## Cross-Platform Compatibility

Hermes runs on Linux, macOS, and Windows. When writing code that touches the OS:

### Critical rules

1. **`termios` and `fcntl` are Unix-only.** Always catch both `ImportError` and `NotImplementedError`:
   ```python
   try:
       from simple_term_menu import TerminalMenu
       menu = TerminalMenu(options)
       idx = menu.show()
   except (ImportError, NotImplementedError):
       # Fallback: numbered menu for Windows
       for i, opt in enumerate(options):
           print(f"  {i+1}. {opt}")
       idx = int(input("Choice: ")) - 1
   ```

2. **File encoding.** Windows may save `.env` files in `cp1252`. Always handle encoding errors:
   ```python
   try:
       load_dotenv(env_path)
   except UnicodeDecodeError:
       load_dotenv(env_path, encoding="latin-1")
   ```

3. **Process management.** `os.setsid()`, `os.killpg()`, and signal handling differ on Windows. Use platform checks:
   ```python
   import platform
   if platform.system() != "Windows":
       kwargs["preexec_fn"] = os.setsid
   ```

4. **Path separators.** Use `pathlib.Path` instead of string concatenation with `/`.

5. **Shell commands in installers.** If you change `scripts/install.sh`, check if the equivalent change is needed in `scripts/install.ps1`.

---

## Security Considerations

Hermes has terminal access. Security matters.

### Existing protections

| Layer | Implementation |
|-------|---------------|
| **Sudo password piping** | Uses `shlex.quote()` to prevent shell injection |
| **Dangerous command detection** | Regex patterns in `tools/approval.py` with user approval flow |
| **Cron prompt injection** | Scanner in `tools/cronjob_tools.py` blocks instruction-override patterns |
| **Write deny list** | Protected paths (`~/.ssh/authorized_keys`, `/etc/shadow`) resolved via `os.path.realpath()` to prevent symlink bypass |
| **Skills guard** | Security scanner for hub-installed skills (`tools/skills_guard.py`) |
| **Code execution sandbox** | `execute_code` child process runs with API keys stripped from environment |
| **Container hardening** | Docker: all capabilities dropped, no privilege escalation, PID limits, size-limited tmpfs |

### When contributing security-sensitive code

- **Always use `shlex.quote()`** when interpolating user input into shell commands
- **Resolve symlinks** with `os.path.realpath()` before path-based access control checks
- **Don't log secrets.** API keys, tokens, and passwords should never appear in log output
- **Catch broad exceptions** around tool execution so a single failure doesn't crash the agent loop
- **Test on all platforms** if your change touches file paths, process management, or shell commands

If your PR affects security, note it explicitly in the description.

---

## Pull Request Process

### Branch naming

```
fix/description        # Bug fixes
feat/description       # New features
docs/description       # Documentation
test/description       # Tests
refactor/description   # Code restructuring
```

### Before submitting

1. **Run tests**: `pytest tests/ -v`
2. **Test manually**: Run `hermes` and exercise the code path you changed
3. **Check cross-platform impact**: If you touch file I/O, process management, or terminal handling, consider Windows and macOS
4. **Keep PRs focused**: One logical change per PR. Don't mix a bug fix with a refactor with a new feature.

### PR description

Include:
- **What** changed and **why**
- **How to test** it (reproduction steps for bugs, usage examples for features)
- **What platforms** you tested on
- Reference any related issues

### Commit messages

We use [Conventional Commits](https://www.conventionalcommits.org/):

```
<type>(<scope>): <description>
```

| Type | Use for |
|------|---------|
| `fix` | Bug fixes |
| `feat` | New features |
| `docs` | Documentation |
| `test` | Tests |
| `refactor` | Code restructuring (no behavior change) |
| `chore` | Build, CI, dependency updates |

Scopes: `cli`, `gateway`, `tools`, `skills`, `agent`, `install`, `whatsapp`, `security`, etc.

Examples:
```
fix(cli): prevent crash in save_config_value when model is a string
feat(gateway): add WhatsApp multi-user session isolation
fix(security): prevent shell injection in sudo password piping
test(tools): add unit tests for file_operations
```

---

## Reporting Issues

- Use [GitHub Issues](https://github.com/NousResearch/hermes-agent/issues)
- Include: OS, Python version, Hermes version (`hermes version`), full error traceback
- Include steps to reproduce
- Check existing issues before creating duplicates
- For security vulnerabilities, please report privately

---

## Community

- **Discord**: [discord.gg/NousResearch](https://discord.gg/NousResearch) — for questions, showcasing projects, and sharing skills
- **GitHub Discussions**: For design proposals and architecture discussions
- **Skills Hub**: Upload specialized skills to a registry and share them with the community

---

## License

By contributing, you agree that your contributions will be licensed under the [MIT License](LICENSE).