cross-ai 0.2.0

Agent monitoring proxy and session manager — PTY wrapping, network interception, Slack relay, and gating

cross

Configurable Runtime Oversight and Safety Standard

cross makes AI agents more trustworthy and more capable with lightweight gating and monitoring.

Not sure you need this? Ask your agent to explain why you do.

Why cross

Your agents are overeager. They're so locked in on your task that they'll rm -rf an errant directory or push your credentials public without a second thought.

cross is a minimal-friction harness of deterministic and LLM checking layers to guard against errors and misalignment. It pairs agents with spotters which screen actions and monitor sessions with separate context and fresh eyes. It expands the capability-safety frontier and relieves the pit that's been growing in your stomach since you stopped reviewing tool calls 🙂.

New: cross supports gate and sentinel screening via Claude Code, and so adds no cost at the margin for Claude subscribers!

Quick Start

pip install cross-ai               # or: pip install cross-ai[slack] for Slack integration
cross setup                        # interactive setup wizard (starts daemon automatically on macOS)

Or install from source:

git clone https://github.com/rfdearborn/cross && cd cross
pip install -e ".[dev]"

Then point your agent's API traffic through cross. For Claude Code, add a shell wrapper:

# In your .zshrc / .bashrc
claude() { cross wrap -- claude "$@"; }

cross wrap does two things: wraps the agent in a PTY for I/O control, and routes API traffic through the local proxy (ANTHROPIC_BASE_URL=http://localhost:2767) for structured monitoring and gating.

How It Works

cross evaluates every tool call through a 3-layer pipeline:

Tool call arrives
       |
       v
 +-----------+     no match     +----------+
 |  Denylist  | --------------> |  ALLOW   |
 |   Gate     |                 +----------+
 +-----------+
       | match
       v
 +-----------+     false pos    +----------+
 |  LLM Gate  | --------------> |  ALLOW   |
 |  (review)  |                 +----------+
 +-----------+
       | confirmed
       v
  BLOCK / ESCALATE
  (feedback to agent / human review)

       --- meanwhile, in the background ---

 +-----------+
 | Sentinel  |  periodic review of all activity
 +-----------+

Layer 1: Denylist gate -- Fast deterministic pattern matching against YAML rules. Sub-millisecond, zero cost. Catches destructive commands (rm -rf /), credential exfiltration, reverse shells, system path writes, and more. Intentionally broad -- it's a triage filter, not a final judge.

Layer 2: LLM gate -- Only invoked when the denylist flags a call. Reviews the tool call with full context (user intent, recent tool history, why it was flagged) and renders a verdict: ALLOW (false positive), BLOCK (confirmed dangerous), or ESCALATE (needs human review). This is why the denylist can be aggressive without generating noise -- the LLM catches false positives.

Layer 3: Sentinel -- Async periodic reviewer that watches the full event stream over time. Detects patterns that per-call evaluation misses: tool calls that don't match user intent, suspicious sequences (read credentials then network call), escalating privilege patterns, and agents working around restrictions. Reports to the dashboard and Slack.

Blocked tool calls are suppressed from the API response stream. The proxy automatically retries with the block reason injected, so the agent self-corrects without user intervention. For critical threats (credential exfiltration, reverse shells), the session is halted entirely until a human intervenes.

Supported Agents

• Claude Code -- validated, full PTY + proxy + tool-level gating
• OpenClaw -- validated, PTY + tool-level gating via beforeToolCall hook. cross wrap -- openclaw automatically injects a Node.js hook that gates every tool call through the cross daemon
• Any CLI agent -- cross wrap -- <agent-command> provides PTY wrapping and API proxy for any CLI agent
• Any agent using Anthropic APIs -- set ANTHROPIC_BASE_URL=http://localhost:2767

Dashboard

cross ships with a built-in web dashboard at http://localhost:2767. No dependencies, no setup -- it's always active when the daemon is running.

The dashboard shows:

• Pending approvals -- escalated tool calls waiting for human review, with Approve/Deny buttons
• Live event feed -- real-time stream of tool calls, gate decisions, and sentinel reviews

You can also manage pending escalations from the CLI:

cross pending                          # list pending escalations
cross pending approve <tool_use_id>    # approve
cross pending deny <tool_use_id>       # deny

Configuration

LLM Providers

cross uses LLMs for the gate reviewer and sentinel. The default is claude (cli/claude), which uses your existing Claude Code subscription -- no API key needed. You can also use any other supported provider:

Provider	Model format	API key env var	Notes
Claude Code	cli/claude (or just claude)	(none needed)	Default. Uses your Claude subscription via claude -p
Google Gemini	google/gemini-3-flash-preview	GOOGLE_API_KEY	Free tier available
Anthropic	anthropic/claude-haiku-4-5	ANTHROPIC_API_KEY
OpenAI	openai/gpt-4o	OPENAI_API_KEY
Ollama	ollama/llama3	(none needed)	Local models

Configure via environment variables (all prefixed CROSS_):

# LLM gate (default uses Claude Code, no key needed)
CROSS_LLM_GATE_MODEL=cli/claude

# Or use an API provider
CROSS_LLM_GATE_MODEL=google/gemini-3-flash-preview
CROSS_LLM_GATE_API_KEY=...          # or set GOOGLE_API_KEY

# Sentinel
CROSS_LLM_SENTINEL_MODEL=cli/claude
CROSS_LLM_SENTINEL_INTERVAL_SECONDS=60

Or use cross setup for guided interactive configuration.

Denylist Rules

Default rules ship with cross and cover destructive commands, credential exfiltration, reverse shells, and system path writes. Customize with YAML files in ~/.cross/rules.d/:

# ~/.cross/rules.d/my-rules.yaml
rules:
  - name: no-docker-push
    tools: [Bash]
    field: command
    action: block
    description: Prevent pushing Docker images
    patterns:
      - 'docker\s+push\b'

# Disable a default rule by name
disable:
  - destructive-rm

Rules support patterns (regex, case-insensitive) and contains (substring matching), and can target specific tools and input fields.

All Settings

Settings can be set via environment variables (CROSS_ prefix) or .env files. cross loads ~/.cross/local.env (personal overrides, survives cross setup), then ~/.cross/.env (generated by setup), then .env in the working directory:

Setting	Default	Description
listen_port	2767	Proxy listen port
gating_enabled	true	Enable the denylist gate
llm_gate_enabled	true	Enable LLM review of flagged calls
llm_gate_shadow	false	Shadow mode: LLM decides but human makes the final call
llm_gate_threshold	escalate	Min denylist action to trigger LLM review
llm_sentinel_enabled	true	Enable periodic LLM sentinel reviews
llm_sentinel_interval_seconds	60	Seconds between sentinel review cycles
gate_approval_timeout	300	Seconds to wait for human approval on escalation
rules_dir	~/.cross/rules.d	Custom rules directory

Architecture

cross uses two complementary interception layers:

PTY wrapper (cross wrap) -- Wraps any CLI agent in a pseudo-terminal for full I/O control. Enables bidirectional messaging relay (Slack/dashboard to agent), terminal-to-phone handoff, and session management. Agent-agnostic.

Network proxy -- Intercepts API traffic via ANTHROPIC_BASE_URL redirect. Parses streaming SSE responses, buffers tool_use blocks for gate evaluation, and suppresses blocked calls from the response stream. Provides structured monitoring with zero agent modification.

Both layers are coordinated by the daemon (cross daemon), which runs the proxy, gate chain, sentinel, dashboard, and optional Slack plugin as a single process.

Notification Channels

• Web dashboard (default) -- zero dependencies, always active at /cross/dashboard
• Slack (optional) -- gate decisions, sentinel reviews, and interactive approval buttons. Configure with CROSS_SLACK_BOT_TOKEN and CROSS_SLACK_APP_TOKEN. Install the slack extra: pip install cross-ai[slack].

Development

git clone https://github.com/rfdearborn/cross
cd cross
pip install -e ".[dev,slack]"
python -m pytest tests/

Ruff for linting (ruff check).

License

MIT