hermes-agent/CONTRIBUTING.md
Teknium 3dfb357001 feat(cross-platform): psutil for PID/process management + Windows footgun checker
## Why

Hermes supports Linux, macOS, and native Windows, but the codebase grew up
POSIX-first and has accumulated patterns that silently break (or worse,
silently kill!) on Windows:

- `os.kill(pid, 0)` as a liveness probe — on Windows this maps to
  CTRL_C_EVENT and broadcasts Ctrl+C to the target's entire console
  process group (bpo-14484, open since 2012).
- `os.killpg` — doesn't exist on Windows at all (AttributeError).
- `os.setsid` / `os.getuid` / `os.geteuid` — same.
- `signal.SIGKILL` / `signal.SIGHUP` / `signal.SIGUSR1` — module-attr
  errors at runtime on Windows.
- `open(path)` / `open(path, "r")` without explicit encoding= — inherits
  the platform default, which is cp1252/mbcs on Windows (UTF-8 on POSIX),
  causing mojibake round-tripping between hosts.
- `wmic` — removed from Windows 10 21H1+.

This commit does three things:

1. Makes `psutil` a core dependency and migrates critical callsites to it.
2. Adds a grep-based CI gate (`scripts/check-windows-footguns.py`) that
   blocks new instances of any of the above patterns.
3. Fixes every existing instance in the codebase so the baseline is clean.

## What changed

### 1. psutil as a core dependency (pyproject.toml)

Added `psutil>=5.9.0,<8` to core deps. psutil is the canonical
cross-platform answer for "is this PID alive" and "kill this process
tree" — its `pid_exists()` uses `OpenProcess + GetExitCodeProcess` on
Windows (NOT a signal call), and its `Process.children(recursive=True)`
+ `.kill()` combo replaces `os.killpg()` portably.

### 2. `gateway/status.py::_pid_exists`

Rewrote to call `psutil.pid_exists()` first, falling back to the
hand-rolled ctypes `OpenProcess + WaitForSingleObject` dance on Windows
(and `os.kill(pid, 0)` on POSIX) only if psutil is somehow missing —
e.g. during the scaffold phase of a fresh install before pip finishes.

### 3. `os.killpg` migration to psutil (7 callsites, 5 files)

- `tools/code_execution_tool.py`
- `tools/process_registry.py`
- `tools/tts_tool.py`
- `tools/environments/local.py` (3 sites kept as-is, suppressed with
  `# windows-footgun: ok` — the pgid semantics psutil can't replicate,
  and the calls are already Windows-guarded at the outer branch)
- `gateway/platforms/whatsapp.py`

### 4. `scripts/check-windows-footguns.py` (NEW, 500 lines)

Grep-based checker with 11 rules covering every Windows cross-platform
footgun we've hit so far:

1. `os.kill(pid, 0)` — the silent killer
2. `os.setsid` without guard
3. `os.killpg` (recommends psutil)
4. `os.getuid` / `os.geteuid` / `os.getgid`
5. `os.fork`
6. `signal.SIGKILL`
7. `signal.SIGHUP/SIGUSR1/SIGUSR2/SIGALRM/SIGCHLD/SIGPIPE/SIGQUIT`
8. `subprocess` shebang script invocation
9. `wmic` without `shutil.which` guard
10. Hardcoded `~/Desktop` (OneDrive trap)
11. `asyncio.add_signal_handler` without try/except
12. `open()` without `encoding=` on text mode

Features:
- Triple-quoted-docstring aware (won't flag prose inside docstrings)
- Trailing-comment aware (won't flag mentions in `# os.kill(pid, 0)` comments)
- Guard-hint aware (skips lines with `hasattr(os, ...)`,
  `shutil.which(...)`, `if platform.system() != 'Windows'`, etc.)
- Inline suppression with `# windows-footgun: ok — <reason>`
- `--list` to print all rules with fixes
- `--all` / `--diff <ref>` / staged-files (default) modes
- Scans 380 files in under 2 seconds

### 5. CI integration

A GitHub Actions workflow that runs the checker on every PR and push is
staged at `/tmp/hermes-stash/windows-footguns.yml` — not included in this
commit because the GH token on the push machine lacks `workflow` scope.
A maintainer with `workflow` permissions should add it as
`.github/workflows/windows-footguns.yml` in a follow-up. Content:

```yaml
name: Windows footgun check
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with: {python-version: "3.11"}
      - run: python scripts/check-windows-footguns.py --all
```

### 6. CONTRIBUTING.md — "Cross-Platform Compatibility" expansion

Expanded from 5 to 16 rules, each with message, example, and fix.
Recommends psutil as the preferred API for PID / process-tree operations.

### 7. Baseline cleanup (91 → 0 findings)

- 14 `open()` sites → added `encoding='utf-8'` (internal logs/caches) or
  `encoding='utf-8-sig'` (user-editable files that Notepad may BOM)
- 23 POSIX-only callsites in systemd helpers, pty_bridge, and plugin
  tool subprocess management → annotated with
  `# windows-footgun: ok — <reason>`
- 7 `os.killpg` sites → migrated to psutil (see §3 above)

## Verification

```
$ python scripts/check-windows-footguns.py --all
✓ No Windows footguns found (380 file(s) scanned).

$ python -c "from gateway.status import _pid_exists; import os
> print('self:', _pid_exists(os.getpid())); print('bogus:', _pid_exists(999999))"
self: True
bogus: False
```

Proof-of-repro that `os.kill(pid, 0)` was actually killing processes
before this fix — see commit `1cbe39914` and bpo-14484. This commit
removes the last hand-rolled ctypes path from the hot liveness-check
path and defers to the best-maintained cross-platform answer.
2026-05-08 12:57:33 -07:00

34 KiB

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 — macOS, different Linux distros, and WSL2 on Windows. We want Hermes to work everywhere.
  3. Security hardening — shell injection, prompt injection, path traversal, privilege escalation. See Security.
  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?
  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. Users can install it with hermes skills install.


Development Setup

Prerequisites

Requirement Notes
Git With --recurse-submodules support, and the git-lfs extension installed
Python 3.11+ uv will install it if missing
uv Fast Python package manager (install)
Node.js 20+ Optional — needed for browser tools and WhatsApp bridge (matches root package.json engines)

Clone and install

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]"

# Optional: RL training submodule
# git submodule update --init tinker-atropos && uv pip install -e "./tinker-atropos"

# Optional: browser tools
npm install

Configure for development

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=***" >> ~/.hermes/.env

Run

# 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

# Preferred — matches CI (hermetic env, 4 xdist workers); see AGENTS.md
scripts/run_tests.sh

# Alternative (activate the venv first). The wrapper is still recommended
# for parity with GitHub Actions before you open a PR:
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               # Central slash command registry (CommandDef), autocomplete, gateway helpers
│   ├── 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 (Parallel/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

Adding a New Tool

Before writing a tool, ask: should this be a skill instead?

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

"""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,
)

Wire into a toolset (required): Built-in tools are auto-discovered: any tools/*.py file that contains a top-level registry.register(...) call is imported by discover_builtin_tools() in tools/registry.py when model_tools loads. There is no manual import list in model_tools.py to maintain.

You must still add the tool name to the appropriate list in toolsets.py (for example _HERMES_CORE_TOOLS or a dedicated toolset); otherwise the tool registers but is never exposed to the agent. If you introduce a new toolset, add it in toolsets.py and wire it into the relevant platform presets.

See AGENTS.md (section Adding New Tools) for profile-aware paths and plugin vs core guidance.


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

---
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)
required_environment_variables:    # Optional — secure setup-on-load metadata
  - name: MY_API_KEY
    prompt: API key
    help: Where to get it
    required_for: full functionality
prerequisites:                     # Optional legacy runtime requirements
  env_vars: [MY_API_KEY]           #   Backward-compatible alias for required env vars
  commands: [curl, jq]             #   Advisory only; does not hide the skill
metadata:
  hermes:
    tags: [Category, Subcategory, Keywords]
    related_skills: [other-skill-name]
    fallback_for_toolsets: [web]       # Optional — show only when toolset is unavailable
    requires_toolsets: [terminal]      # Optional — show only when toolset is available
---

# 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.

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.

Conditional skill activation

Skills can declare conditions that control when they appear in the system prompt, based on which tools and toolsets are available in the current session. This is primarily used for fallback skills — alternatives that should only be shown when a primary tool is unavailable.

Four fields are supported under metadata.hermes:

metadata:
  hermes:
    fallback_for_toolsets: [web]      # Show ONLY when these toolsets are unavailable
    requires_toolsets: [terminal]     # Show ONLY when these toolsets are available
    fallback_for_tools: [web_search]  # Show ONLY when these specific tools are unavailable
    requires_tools: [terminal]        # Show ONLY when these specific tools are available

Semantics:

  • fallback_for_*: The skill is a backup. It is hidden when the listed tools/toolsets are available, and shown when they are unavailable. Use this for free alternatives to premium tools.
  • requires_*: The skill needs certain tools to function. It is hidden when the listed tools/toolsets are unavailable. Use this for skills that depend on specific capabilities (e.g., a skill that only makes sense with terminal access).
  • If both are specified, both conditions must be satisfied for the skill to appear.
  • If neither is specified, the skill is always shown (backward compatible).

Examples:

# DuckDuckGo search — shown when Firecrawl (web toolset) is unavailable
metadata:
  hermes:
    fallback_for_toolsets: [web]

# Smart home skill — only useful when terminal is available
metadata:
  hermes:
    requires_toolsets: [terminal]

# Local browser fallback — shown when Browserbase is unavailable
metadata:
  hermes:
    fallback_for_toolsets: [browser]

The filtering happens at prompt build time in agent/prompt_builder.py. The build_skills_system_prompt() function receives the set of available tools and toolsets from the agent and uses _skill_should_show() to evaluate each skill's conditions.

Skill setup metadata

Skills can declare secure setup-on-load metadata via the required_environment_variables frontmatter field. Missing values do not hide the skill from discovery; they trigger a CLI-only secure prompt when the skill is actually loaded.

required_environment_variables:
  - name: TENOR_API_KEY
    prompt: Tenor API key
    help: Get a key from https://developers.google.com/tenor
    required_for: full functionality

The user may skip setup and keep loading the skill. Hermes only exposes metadata (stored_as, skipped, validated) to the model — never the secret value.

Legacy prerequisites.env_vars remains supported and is normalized into the new representation.

prerequisites:
  env_vars: [TENOR_API_KEY]       # Legacy alias for required_environment_variables
  commands: [curl, jq]            # Advisory CLI checks

Gateway and messaging sessions never collect secrets in-band; they instruct the user to run hermes setup or update ~/.hermes/.env locally.

When to declare required environment variables:

  • The skill uses an API key or token that should be collected securely at load time
  • The skill can still be useful if the user skips setup, but may degrade gracefully

When to declare command prerequisites:

  • The skill relies on a CLI tool that may not be installed (e.g., himalaya, openhue, ddgs)
  • Treat command checks as guidance, not discovery-time hiding

See skills/gifs/gif-search/ and skills/email/himalaya/ for examples.

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:

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 native Windows (plus WSL2). When writing code that touches the OS, assume any platform can hit your code path.

Before you PR: run scripts/check-windows-footguns.py to catch the common Windows-unsafe patterns in your diff. It's grep-based and cheap; CI runs it on every PR too.

Critical rules

  1. Never call os.kill(pid, 0) for liveness checks. os.kill(pid, 0) is a standard POSIX idiom to check "is this PID alive" — the signal 0 is a no-op permission check. On Windows it is NOT a no-op. Python's Windows os.kill maps sig=0 to CTRL_C_EVENT (they collide at the integer value 0) and routes it through GenerateConsoleCtrlEvent(0, pid), which broadcasts Ctrl+C to the entire console process group containing the target PID. "Probe if alive" silently becomes "kill the target and often unrelated processes sharing its console." See bpo-14484 (open since 2012 — will never be fixed for compat reasons).

    Preferred: use psutil (a core dependency — always available):

    import psutil
    if psutil.pid_exists(pid):
        # process is alive — safe on every platform
        ...
    

    If you specifically need the hermes wrapper (it has a stdlib fallback for scaffold-phase imports before pip install finishes), use gateway.status._pid_exists(pid). It calls psutil.pid_exists first and falls back to a hand-rolled OpenProcess + WaitForSingleObject dance on Windows only when psutil is somehow missing.

    Audit grep for new callsites: rg "os\.kill\([^,]+,\s*0\s*\)". Any hit in non-test code is presumptively a Windows silent-kill bug.

  2. Use shutil.which() before shelling out — don't assume Windows has tools Linux has. wmic was removed in Windows 10 21H1 and later. ps, kill, grep, awk, fuser, lsof, pgrep, and most POSIX CLI tools simply don't exist on Windows. Test availability with shutil.which("tool") and fall back to a Windows-native equivalent — usually PowerShell via subprocess.run(["powershell", "-NoProfile", "-Command", ...]).

    For process enumeration: PowerShell's Get-CimInstance Win32_Process is the modern replacement for wmic process. See hermes_cli/gateway.py::_scan_gateway_pids for the pattern.

  3. termios and fcntl are Unix-only. Always catch both ImportError and NotImplementedError:

    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
    
  4. File encoding. Windows may save .env files in cp1252. Always handle encoding errors:

    try:
        load_dotenv(env_path)
    except UnicodeDecodeError:
        load_dotenv(env_path, encoding="latin-1")
    

    Config files (config.yaml) may be saved with a UTF-8 BOM by Notepad and similar editors — use encoding="utf-8-sig" when reading files that could have been touched by a Windows GUI editor.

  5. Process management. os.setsid(), os.killpg(), os.fork(), os.getuid(), and POSIX signal handling differ on Windows. Guard with platform.system(), sys.platform, or hasattr(os, "setsid"):

    if platform.system() != "Windows":
        kwargs["preexec_fn"] = os.setsid
    else:
        kwargs["creationflags"] = subprocess.CREATE_NEW_PROCESS_GROUP
    

    Preferred: for killing a process AND its children (what os.killpg does on POSIX), use psutil — it works on every platform:

    import psutil
    try:
        parent = psutil.Process(pid)
        # Kill children first (leaf-up), then the parent.
        for child in parent.children(recursive=True):
            child.kill()
        parent.kill()
    except psutil.NoSuchProcess:
        pass
    
  6. Signals that don't exist on Windows: SIGALRM, SIGCHLD, SIGHUP, SIGUSR1, SIGUSR2, SIGPIPE, SIGQUIT, SIGKILL. Python's signal module raises AttributeError at import time if you reference them on Windows. Use getattr(signal, "SIGKILL", signal.SIGTERM) or gate the whole block behind a platform check. loop.add_signal_handler raises NotImplementedError on Windows — always catch it.

  7. Path separators. Use pathlib.Path instead of string concatenation with /. Forward slashes work almost everywhere on Windows, but subprocess.run(["cmd.exe", "/c", ...]) and other shell contexts can require backslashes — convert with str(path) at the subprocess boundary, not inside Python logic.

  8. Symlinks need elevated privileges on Windows (unless Developer Mode is on). Tests that create symlinks need @pytest.mark.skipif(sys.platform == "win32", reason="Symlinks require elevated privileges on Windows").

  9. POSIX file modes (0o600, 0o644, etc.) are NOT enforced on NTFS by default. Tests that assert on stat().st_mode & 0o777 must skip on Windows — the concept doesn't translate. Use ACLs (icacls, pywin32) for Windows secret-file protection if needed.

  10. Detached background daemons on Windows need pythonw.exe, NOT python.exe. python.exe always allocates or attaches to a console, which makes it vulnerable to CTRL_C_EVENT broadcasts from any sibling process. pythonw.exe is the no-console variant. Combine with CREATE_NO_WINDOW | DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP | CREATE_BREAKAWAY_FROM_JOB in subprocess.Popen(creationflags=...). See hermes_cli/gateway_windows.py::_spawn_detached for the reference implementation.

  11. subprocess.Popen with .cmd or .bat shims needs shutil.which to resolve. Passing "agent-browser" to Popen on Windows finds the extensionless POSIX shebang shim in node_modules/.bin/, which CreateProcessW can't execute — you'll get WinError 193 "not a valid Win32 application". Use shutil.which("agent-browser", path=local_bin) which honors PATHEXT and picks the .CMD variant on Windows.

  12. Don't use shell shebangs as a way to run Python. #!/usr/bin/env python only works when the file is executed through a Unix shell. subprocess.run(["./myscript.py"]) on Windows fails even if the file has a shebang line. Always invoke Python explicitly: [sys.executable, "myscript.py"].

  13. Shell commands in installers. If you change scripts/install.sh, make the equivalent change in scripts/install.ps1. The two scripts are the canonical example of "works on Linux does not mean works on Windows" and have drifted multiple times — keep them in lockstep.

  14. Known paths that are OneDrive-redirected on Windows: Desktop, Documents, Pictures, Videos. The "real" path when OneDrive Backup is enabled is %USERPROFILE%\OneDrive\Desktop (etc.), NOT %USERPROFILE%\Desktop (which exists as an empty husk). Resolve the real location via ctypes + SHGetKnownFolderPath or by reading the Shell Folders registry key — never assume ~/Desktop.

  15. CRLF vs LF in generated scripts. Windows cmd.exe and schtasks parse line-by-line; mixed or LF-only line endings can break multi-line .cmd / .bat files. Use open(path, "w", encoding="utf-8", newline="\r\n") — or open(path, "wb") + explicit bytes — when generating scripts Windows will execute.

  16. Two different quoting schemes in one command line. subprocess.run (["schtasks", "/TR", some_cmd]) → schtasks itself parses /TR, AND the some_cmd string is re-parsed by cmd.exe when the task fires. Different parsers, different escape rules. Use two separate quoting helpers and never cross them. See hermes_cli/gateway_windows.py:: _quote_cmd_script_arg and _quote_schtasks_arg for the reference pair.

Testing cross-platform

Tests that use POSIX-only syscalls need a skip marker. Common ones:

  • Symlinks → @pytest.mark.skipif(sys.platform == "win32", ...)
  • 0o600 file modes → @pytest.mark.skipif(sys.platform.startswith("win"), ...)
  • signal.SIGALRM → Unix-only (see tests/conftest.py::_enforce_test_timeout)
  • os.setsid / os.fork → Unix-only
  • Live Winsock / Windows-specific regression tests → @pytest.mark.skipif(sys.platform != "win32", reason="Windows-specific regression")

If you monkeypatch sys.platform for cross-platform tests, also patch platform.system() / platform.release() / platform.mac_ver() — each re-reads the real OS independently, so half-patched tests still route through the wrong branch on a Windows runner.


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: scripts/run_tests.sh (recommended; same as CI) or pytest tests/ -v with the project venv activated
  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 macOS, Linux, and WSL2
  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:

<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
  • 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 — 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.