Trait-Driven Design Pattern

ZeroClaw’s architecture is built on Rust traits, which define explicit extension points for swappable components. This design provides compile-time guarantees, type safety, and clear boundaries between subsystems.

Why Traits?

From AGENTS.md §2:

Trait + factory architecture is the stability backbone

Extension points are intentionally explicit and swappable

Most features should be added via trait implementation + factory registration, not cross-cutting rewrites

Benefits:

Compile-Time Safety: Invalid implementations won’t compile
Explicit Contracts: Trait signatures document what each component must provide
Zero-Cost Abstraction: Trait dispatch is optimized away in release builds
Testability: Easy to create mock implementations for testing
Parallel Development: Multiple implementations can be developed independently

Core Traits Overview

Trait	Module	Purpose
`Provider`	`src/providers/traits.rs`	Model inference backends
`Channel`	`src/channels/traits.rs`	Messaging platform integrations
`Tool`	`src/tools/traits.rs`	Agent capabilities (shell, files, etc.)
`Memory`	`src/memory/traits.rs`	Persistence backends
`Sandbox`	`src/security/traits.rs`	OS-level isolation
`Peripheral`	`src/peripherals/traits.rs`	Hardware board interfaces
`RuntimeAdapter`	`src/runtime/traits.rs`	Execution environment adapters
`Observer`	`src/observability/traits.rs`	Telemetry and observability

Provider Trait

The Provider trait defines the interface for LLM backends:

#[async_trait]
pub trait Provider: Send + Sync {
    /// Query provider capabilities (native tools, vision, etc.)
    fn capabilities(&self) -> ProviderCapabilities {
        ProviderCapabilities::default()
    }

    /// Convert tool specs to provider-native format
    fn convert_tools(&self, tools: &[ToolSpec]) -> ToolsPayload {
        ToolsPayload::PromptGuided {
            instructions: build_tool_instructions_text(tools),
        }
    }

    /// Simple one-shot chat
    async fn simple_chat(
        &self,
        message: &str,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<String>;

    /// Chat with system prompt
    async fn chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<String>;

    /// Structured chat with tool support
    async fn chat(
        &self,
        request: ChatRequest<'_>,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<ChatResponse>;

    /// Check if native tool calling is supported
    fn supports_native_tools(&self) -> bool {
        self.capabilities().native_tool_calling
    }

    /// Warm up HTTP connection pool
    async fn warmup(&self) -> anyhow::Result<()> {
        Ok(())
    }
}

Provider Capabilities

Providers declare their capabilities to enable intelligent adaptation:

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct ProviderCapabilities {
    /// Native tool calling via API primitives
    pub native_tool_calling: bool,
    /// Vision / image input support
    pub vision: bool,
}

Example - OpenAI Provider:

pub struct OpenAiProvider {
    base_url: String,
    credential: Option<String>,
    max_tokens_override: Option<u32>,
}

#[async_trait]
impl Provider for OpenAiProvider {
    fn capabilities(&self) -> ProviderCapabilities {
        ProviderCapabilities {
            native_tool_calling: true,
            vision: true,
        }
    }

    async fn chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<String> {
        let mut messages = Vec::new();
        if let Some(sys) = system_prompt {
            messages.push(Message {
                role: "system".into(),
                content: sys.into(),
            });
        }
        messages.push(Message {
            role: "user".into(),
            content: message.into(),
        });
        
        // Send to OpenAI API...
    }
}

See Providers for complete details.

Channel Trait

The Channel trait defines the interface for messaging platforms:

#[async_trait]
pub trait Channel: Send + Sync {
    /// Human-readable channel name
    fn name(&self) -> &str;

    /// Send a message through this channel
    async fn send(&self, message: &SendMessage) -> anyhow::Result<()>;

    /// Start listening for incoming messages (long-running)
    async fn listen(&self, tx: tokio::sync::mpsc::Sender<ChannelMessage>) -> anyhow::Result<()>;

    /// Check if channel is healthy
    async fn health_check(&self) -> bool {
        true
    }

    /// Signal typing indicator
    async fn start_typing(&self, _recipient: &str) -> anyhow::Result<()> {
        Ok(())
    }

    /// Stop typing indicator
    async fn stop_typing(&self, _recipient: &str) -> anyhow::Result<()> {
        Ok(())
    }

    /// Whether this channel supports progressive message updates
    fn supports_draft_updates(&self) -> bool {
        false
    }

    /// Send interactive approval prompt (for supervised mode)
    async fn send_approval_prompt(
        &self,
        recipient: &str,
        request_id: &str,
        tool_name: &str,
        arguments: &serde_json::Value,
        thread_ts: Option<String>,
    ) -> anyhow::Result<()>;
}

Example - Telegram Channel:

pub struct TelegramChannel {
    bot_token: String,
    allowed_users: HashSet<String>,
    pairing_guard: Arc<PairingGuard>,
}

#[async_trait]
impl Channel for TelegramChannel {
    fn name(&self) -> &str {
        "telegram"
    }

    async fn send(&self, message: &SendMessage) -> anyhow::Result<()> {
        // Split message if > 4096 chars (Telegram limit)
        let chunks = split_message_for_telegram(&message.content);
        
        for chunk in chunks {
            let payload = serde_json::json!({
                "chat_id": message.recipient,
                "text": chunk,
                "parse_mode": "Markdown",
            });
            
            // Send via Telegram Bot API...
        }
        
        Ok(())
    }

    async fn listen(&self, tx: tokio::sync::mpsc::Sender<ChannelMessage>) -> anyhow::Result<()> {
        // Long-polling loop
        loop {
            let updates = self.get_updates().await?;
            for update in updates {
                // Validate user is paired/allowed
                if !self.pairing_guard.is_paired(&update.user_id) {
                    continue;
                }
                
                let msg = ChannelMessage {
                    id: update.message_id,
                    sender: update.user_id,
                    content: update.text,
                    // ...
                };
                
                tx.send(msg).await?;
            }
        }
    }
}

See Channels for complete details.

Tool Trait

The Tool trait defines agent capabilities:

#[async_trait]
pub trait Tool: Send + Sync {
    /// Tool name (used in LLM function calling)
    fn name(&self) -> &str;

    /// Human-readable description
    fn description(&self) -> &str;

    /// JSON schema for parameters
    fn parameters_schema(&self) -> serde_json::Value;

    /// Execute the tool with given arguments
    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult>;

    /// Get the full spec for LLM registration
    fn spec(&self) -> ToolSpec {
        ToolSpec {
            name: self.name().to_string(),
            description: self.description().to_string(),
            parameters: self.parameters_schema(),
        }
    }
}

Example - Shell Tool:

pub struct ShellTool {
    security: Arc<SecurityPolicy>,
    runtime: Arc<dyn RuntimeAdapter>,
    syscall_detector: Option<Arc<SyscallAnomalyDetector>>,
}

#[async_trait]
impl Tool for ShellTool {
    fn name(&self) -> &str {
        "shell"
    }

    fn description(&self) -> &str {
        "Execute a shell command in the workspace directory"
    }

    fn parameters_schema(&self) -> serde_json::Value {
        json!({
            "type": "object",
            "properties": {
                "command": {
                    "type": "string",
                    "description": "Shell command to execute"
                },
                "approved": {
                    "type": "boolean",
                    "description": "Explicit approval for high-risk commands",
                    "default": false
                }
            },
            "required": ["command"]
        })
    }

    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult> {
        let command = args.get("command")
            .and_then(|v| v.as_str())
            .ok_or_else(|| anyhow::anyhow!("Missing 'command' parameter"))?;
            
        let approved = args.get("approved")
            .and_then(|v| v.as_bool())
            .unwrap_or(false);
        
        // Validate command against security policy
        let risk = self.security.validate_command_execution(command, approved)
            .map_err(|e| anyhow::anyhow!("Security policy violation: {}", e))?;
        
        // Execute via runtime adapter
        let output = self.runtime.execute_shell(command).await?;
        
        Ok(ToolResult {
            success: output.status.success(),
            output: String::from_utf8_lossy(&output.stdout).to_string(),
            error: if output.status.success() {
                None
            } else {
                Some(String::from_utf8_lossy(&output.stderr).to_string())
            },
        })
    }
}

See Tools for complete details.

Memory Trait

The Memory trait defines persistence backends:

#[async_trait]
pub trait Memory: Send + Sync {
    /// Backend name
    fn name(&self) -> &str;

    /// Store a memory entry, optionally scoped to a session
    async fn store(
        &self,
        key: &str,
        content: &str,
        category: MemoryCategory,
        session_id: Option<&str>,
    ) -> anyhow::Result<()>;

    /// Recall memories matching a query (keyword search)
    async fn recall(
        &self,
        query: &str,
        limit: usize,
        session_id: Option<&str>,
    ) -> anyhow::Result<Vec<MemoryEntry>>;

    /// Get a specific memory by key
    async fn get(&self, key: &str) -> anyhow::Result<Option<MemoryEntry>>;

    /// List all memory keys, optionally filtered
    async fn list(
        &self,
        category: Option<&MemoryCategory>,
        session_id: Option<&str>,
    ) -> anyhow::Result<Vec<MemoryEntry>>;

    /// Remove a memory by key
    async fn forget(&self, key: &str) -> anyhow::Result<bool>;

    /// Count total memories
    async fn count(&self) -> anyhow::Result<usize>;

    /// Health check
    async fn health_check(&self) -> bool;
}

Example - Markdown Memory:

pub struct MarkdownMemory {
    workspace_dir: PathBuf,
}

#[async_trait]
impl Memory for MarkdownMemory {
    fn name(&self) -> &str {
        "markdown"
    }

    async fn store(
        &self,
        key: &str,
        content: &str,
        category: MemoryCategory,
        _session_id: Option<&str>,
    ) -> anyhow::Result<()> {
        let entry = format!("- **{key}**: {content}");
        
        let path = match category {
            MemoryCategory::Core => self.core_path(),
            MemoryCategory::Daily => self.daily_path(),
            _ => return Err(anyhow::anyhow!("Unsupported category")),
        };
        
        self.append_to_file(&path, &entry).await
    }

    async fn recall(
        &self,
        query: &str,
        limit: usize,
        _session_id: Option<&str>,
    ) -> anyhow::Result<Vec<MemoryEntry>> {
        let all = self.read_all_entries().await?;
        let query_lower = query.to_lowercase();
        
        let mut matches: Vec<_> = all.into_iter()
            .filter(|entry| entry.content.to_lowercase().contains(&query_lower))
            .collect();
            
        matches.truncate(limit);
        Ok(matches)
    }
}

See Memory for complete details.

Factory Pattern

Traits are instantiated via factory functions that map string keys to implementations:

Provider Factory

// src/providers/mod.rs
pub fn create_provider(name: &str, config: &Config) -> Result<Box<dyn Provider>> {
    match name {
        "openai" => Ok(Box::new(OpenAiProvider::new(config)?)),
        "anthropic" => Ok(Box::new(AnthropicProvider::new(config)?)),
        "ollama" => Ok(Box::new(OllamaProvider::new(config)?)),
        "gemini" => Ok(Box::new(GeminiProvider::new(config)?)),
        _ => Err(anyhow::anyhow!("Unknown provider: {}", name)),
    }
}

Channel Factory

// src/channels/mod.rs
pub fn start_channels(config: &Config) -> Result<Vec<Box<dyn Channel>>> {
    let mut channels = Vec::new();
    
    if let Some(telegram_config) = &config.telegram {
        channels.push(Box::new(TelegramChannel::new(telegram_config)?));
    }
    
    if let Some(discord_config) = &config.discord {
        channels.push(Box::new(DiscordChannel::new(discord_config)?));
    }
    
    // ... other channels
    
    Ok(channels)
}

Tool Factory

// src/tools/mod.rs
pub fn default_tools(
    security: Arc<SecurityPolicy>,
    runtime: Arc<dyn RuntimeAdapter>,
) -> Vec<Box<dyn Tool>> {
    vec![
        Box::new(ShellTool::new(security.clone(), runtime.clone())),
        Box::new(FileReadTool::new(security.clone())),
        Box::new(FileWriteTool::new(security.clone())),
    ]
}

pub fn all_tools(
    security: Arc<SecurityPolicy>,
    runtime: Arc<dyn RuntimeAdapter>,
    memory: Arc<dyn Memory>,
) -> Vec<Box<dyn Tool>> {
    let mut tools = default_tools(security.clone(), runtime.clone());
    
    tools.extend(vec![
        Box::new(MemoryStoreTool::new(memory.clone())),
        Box::new(MemoryRecallTool::new(memory.clone())),
        Box::new(BrowserTool::new(security.clone())),
        Box::new(HttpRequestTool::new(security.clone())),
    ]);
    
    tools
}

Adding New Implementations

To add a new component:

Implement the trait in a new submodule
Register in factory function with a stable key
Add tests for factory wiring and core behavior
Update docs reference (e.g., providers-reference.md)

Example workflow from AGENTS.md §7.1:

# 1. Create new provider file
src/providers/new_provider.rs

# 2. Implement Provider trait
impl Provider for NewProvider { ... }

# 3. Register in factory
// src/providers/mod.rs
"new_provider" => Ok(Box::new(NewProvider::new(config)?)),

# 4. Add tests
#[test]
fn factory_creates_new_provider() { ... }

Best Practices

Trait Implementation

Keep default methods simple: Use conservative defaults
Document behavior: Trait docs should explain contracts
Handle errors explicitly: Return anyhow::Result with context
Avoid blocking: Use async for I/O operations

Factory Registration

Use stable keys: Factory keys are user-facing (“openai”, “telegram”)
Handle aliases internally: Don’t expose implementation details
Validate early: Check config before constructing
Fail fast: Return errors during factory construction

Dependency Injection

Pass Arc<T> for shared state: Arc<SecurityPolicy>, Arc<dyn Memory>
Clone Arc, not data: Arc::clone(&security) is cheap
Use trait objects: Arc<dyn Trait> for polymorphism

Next Steps

Providers - Provider system deep dive
Channels - Channel system architecture
Tools - Tool system and security
Memory - Memory backends and persistence

Getting Started

Core Concepts

Guides

Operations

Trait-Driven Design

Trait-Driven Design Pattern

Why Traits?

Core Traits Overview

Provider Trait

Provider Capabilities

Channel Trait

Tool Trait

Memory Trait

Factory Pattern

Provider Factory

Channel Factory

Tool Factory

Adding New Implementations

Best Practices

Trait Implementation

Factory Registration

Dependency Injection

Next Steps

Build docs developers (and LLMs) love

Getting Started

Core Concepts

Guides

Operations

​Trait-Driven Design Pattern

​Why Traits?

​Core Traits Overview

​Provider Trait

​Provider Capabilities

​Channel Trait

​Tool Trait

​Memory Trait

​Factory Pattern

​Provider Factory

​Channel Factory

​Tool Factory

​Adding New Implementations

​Best Practices

​Trait Implementation

​Factory Registration

​Dependency Injection

​Next Steps

Build docs developers (and LLMs) love

Trait-Driven Design Pattern

Why Traits?

Core Traits Overview

Provider Trait

Provider Capabilities

Channel Trait

Tool Trait

Memory Trait

Factory Pattern

Provider Factory

Channel Factory

Tool Factory

Adding New Implementations

Best Practices

Trait Implementation

Factory Registration

Dependency Injection

Next Steps