OpenCode Auto-Mode Plugin

Automatic command approval for OpenCode, implementing LLM-based two-stage classification pipeline with configurable block rules, escalation thresholds, and fallback behaviors.

Features

• Two-Stage Classification: Fast pattern-matching filter (Stage 1) + LLM semantic classification (Stage 2)
• 53 Default Block Rules: Covers destructive operations, system configuration, security, credentials, cloud, database, version control, and more
• 10 Allow Exceptions: Safe carve-outs for common developer actions (compound commands require all-segment match)
• Secret Guard: Detects embedded credentials, Bearer tokens, URL credentials, obfuscated paths; always returns ask regardless of fallback settings
• Configurable Fallback: ask-user, allow, or deny on LLM errors/timeouts (with automatic retry on HTTP 408/429/5xx)
• Escalation System: Consecutive and total denial thresholds with user intervention
• Per-Segment Trust Boundary: Protected commands and paths matched per shell segment; compound commands (&&, |, $(, newlines) checked individually
• Config Reload: Content SHA-1 signature-based detection (not mtime); defers on unparseable files
• Deny-and-Continue: Auto-retry, ask-user, or both modes
• Prompt Injection Detection: Zero-width normalization, fenced command wrapping, file content sanitization
• Per-Agent Allow-List: OpenCode permission allow-lists cached per-agent (no cross-agent leakage)
• Telemetry Dataset: Optional JSONL export of classifier decisions + user outcomes (raw LLM verdict + full reason, with shared id across classification/approval) for fine-tuning a small command classifier
• Extensible Rules: Add custom block rules and allow exceptions via config
• Property-Based Testing: Mathematical guarantees on pure function behavior

Installation

Add the plugin to your opencode.jsonc (or ~/.config/opencode/opencode.jsonc):

{
  "$schema": "https://opencode.ai/config.json",
  "plugins": ["@lerg96/opencode-auto-mode"],
}

OpenCode will automatically download and activate the plugin on startup.

Local Development Install

git clone https://github.com/lerg96/opencode-auto-mode.git
cd opencode-auto-mode
npm install
npm run build

See docs/SETUP.md for detailed installation instructions.

Configuration

After installation, create a config file at ~/.config/opencode/auto-mode.jsonc:

{
  "llm": {
    "provider": "anthropic",
    "model": "claude-sonnet-4-20250514",
    "timeout": 5000,
  },
  "denyMode": "auto-retry",
  "escalation": {
    "consecutive": 3,
    "total": 20,
  },
  "fallback": {
    "onTimeout": "ask-user",
    "onError": "ask-user",
  },
}

See docs/CONFIGURATION.md for the complete configuration guide.

Block Rules Overview

The plugin ships with 53 default block rules covering:

| Category | Examples | | ---------------- | -------------------------------------------------------------------------------------------------- | | Destruction | rm -rf, docker rm -f, docker system prune -f, DROP TABLE, dd if=, mkfs, xargs rm | | System Config | sudo, sudo chmod, systemctl restart/stop/disable, /etc/, chmod 777, recursive chmod -R | | Security | ~/.ssh/, ~/.env, cat .*id_rsa, echo $VAR | | Execution (soft) | python -c import os, subprocess(), .system(), .Popen() | | Execution (high) | curl \| sh, wget \| sh, docker run --privileged | | Network | openssl, iptables, ufw, nmap | | Database | DELETE FROM (no WHERE), TRUNCATE, DROP TABLE | | Version Control | git -f push, git push --force, git reset --hard | | Cloud | kubectl delete, iam:..., aws iam | | System Admin | crontab -e, insmod, modprobe, shutdown, reboot |

Plus 10 allow exceptions for safe operations like chmod 644, docker ps, systemctl status, etc.

All rules are matched per shell segment for compound commands. Allow exceptions must match every segment to exempt a compound command.

Adding Custom Rules

Add custom block rules in your auto-mode.jsonc:

{
  "blockRules": [
    {
      "id": "BR-CUSTOM-001",
      "type": "pattern",
      "pattern": "dangerous-command",
      "category": "custom",
      "description": "Block custom dangerous command",
      "severity": "high",
      "enabled": true,
    },
  ],
  "allowExceptions": [
    {
      "id": "AE-CUSTOM-001",
      "type": "pattern",
      "pattern": "safe-operation",
      "description": "Allow safe operation",
      "enabled": true,
    },
  ],
}

Custom rules are merged with the 53 default rules. Allow exceptions take precedence over all block rules.

Architecture

The plugin uses a modular monolith architecture with:

• Secret Guard: Runs before all checks; detects secret paths, credentials, Bearer tokens, obfuscated paths — always returns ask
• ConfigManager: Loads/reloads config via SHA-1 signature; applies defaults via structuredClone
• OpenCode Allow-List: Bypasses the classifier for explicitly allowed actions (opencode.jsonc permissions, cached in-memory per session)
• PatternMatcher: Regex and substring matching with ReDoS protection and ReDoS-safe exception segment checking
• RuleEvaluator: Trust boundary → allow exceptions → block rules evaluation flow
• LlmClient: Ollama-compatible LLM calls with HTTP error retry (408/429/5xx) and structured LlmHttpError/LlmParseError exceptions
• SessionState: In-memory session state management (bounded at 200, LRU)
• DenyAndContinueService: Configurable deny modes
• EscalationService: Denial threshold monitoring
• InjectionProbe/ProtectionService: Prompt injection detection with zero-width normalization and lastIndex reset

License

MIT