add-rpc

name	add-rpc
description	Guide for adding new RPC calls to Pengu. Use when implementing new RPC commands, adding server-client communication methods, or extending the RPC interface with new functionality.

Adding RPC Calls Guide

Overview

Pengu uses a WebSocket-based RPC (Remote Procedure Call) system for communication between different components. The RPC system allows the frontend, backend, electron main process, remote servers, and terminal blocks to communicate with each other through well-defined commands.

This guide covers how to add a new RPC command to the system.

Key Files

• pkg/wshrpc/wshrpctypes.go - RPC interface and type definitions
• pkg/wshrpc/wshserver/wshserver.go - Main server implementation (most common)
• emain/emain-wsh.ts - Electron main process implementation
• frontend/app/store/tabrpcclient.ts - Frontend tab implementation
• pkg/wshrpc/wshremote/wshremote.go - Remote server implementation
• frontend/app/view/term/term-wsh.tsx - Terminal block implementation

RPC Command Structure

RPC commands in Pengu follow these conventions:

• Method names must end with Command
• First parameter must be context.Context
• Remaining parameters are a regular Go parameter list (zero or more typed args)
• Return values can be either just an error, or one return value plus an error
• Streaming commands return a channel instead of a direct value

Adding a New RPC Call

Step 1: Define the Command in the Interface

Add your command to the WshRpcInterface in pkg/wshrpc/wshrpctypes.go:

type WshRpcInterface interface {
    // ... existing commands ...
    
    // Add your new command
    YourNewCommand(ctx context.Context, data CommandYourNewData) (*YourNewResponse, error)
}

Method Signature Rules:

• Method name must end with Command
• First parameter must be ctx context.Context
• Remaining parameters are a regular Go parameter list (zero or more)
• Return either error or (ReturnType, error)
• For streaming, return chan RespOrErrorUnion[T]

Step 2: Define Request and Response Types

If your command needs structured input or output, define types in the same file:

type CommandYourNewData struct {
    FieldOne   string `json:"fieldone"`
    FieldTwo   int    `json:"fieldtwo"`
    SomeId     string `json:"someid"`
}

type YourNewResponse struct {
    ResultField string `json:"resultfield"`
    Success     bool   `json:"success"`
}

Type Naming Conventions:

• Request types: Command[Name]Data (e.g., CommandGetMetaData)
• Response types: [Name]Response or Command[Name]RtnData (e.g., CommandResolveIdsRtnData)
• Use json struct tags with lowercase field names
• Follow existing patterns in the file for consistency

Step 3: Generate Bindings

After modifying pkg/wshrpc/wshrpctypes.go, run code generation to create TypeScript bindings and Go helper code:

task generate

This command will:

• Generate TypeScript type definitions in frontend/types/gotypes.d.ts
• Create RPC client bindings
• Update routing code

Note: If generation fails, check that your method signature follows all the rules above.

Step 4: Implement the Command

Choose where to implement your command based on what it needs to do:

A. Main Server Implementation (Most Common)

Implement in pkg/wshrpc/wshserver/wshserver.go:

func (ws *WshServer) YourNewCommand(ctx context.Context, data wshrpc.CommandYourNewData) (*wshrpc.YourNewResponse, error) {
    // Validate input
    if data.SomeId == "" {
        return nil, fmt.Errorf("someid is required")
    }
    
    // Implement your logic
    result := doSomething(data)
    
    // Return response
    return &wshrpc.YourNewResponse{
        ResultField: result,
        Success:     true,
    }, nil
}

Use main server when:

• Accessing the database
• Managing blocks, tabs, or workspaces
• Coordinating between components
• Handling file operations on the main filesystem

B. Electron Implementation

Implement in emain/emain-wsh.ts:

async handle_yournew(rh: RpcResponseHelper, data: CommandYourNewData): Promise<YourNewResponse> {
    // Electron-specific logic
    const result = await electronAPI.doSomething(data);
    
    return {
        resultfield: result,
        success: true,
    };
}

Use Electron when:

• Accessing native OS features
• Managing application windows
• Using Electron APIs (notifications, system tray, etc.)
• Handling encryption/decryption with safeStorage

C. Frontend Tab Implementation

Implement in frontend/app/store/tabrpcclient.ts:

async handle_yournew(rh: RpcResponseHelper, data: CommandYourNewData): Promise<YourNewResponse> {
    // Access frontend state/models
    const layoutModel = getLayoutModelForStaticTab();
    
    // Implement tab-specific logic
    const result = layoutModel.doSomething(data);
    
    return {
        resultfield: result,
        success: true,
    };
}

Use tab client when:

• Accessing React state or Jotai atoms
• Manipulating UI layout
• Capturing screenshots
• Reading frontend-only data

D. Remote Server Implementation

Implement in pkg/wshrpc/wshremote/wshremote.go:

func (impl *ServerImpl) RemoteYourNewCommand(ctx context.Context, data wshrpc.CommandRemoteYourNewData) (*wshrpc.YourNewResponse, error) {
    // Remote filesystem or process operations
    result, err := performRemoteOperation(data)
    if err != nil {
        return nil, fmt.Errorf("remote operation failed: %w", err)
    }
    
    return &wshrpc.YourNewResponse{
        ResultField: result,
        Success:     true,
    }, nil
}

Use remote server when:

• Operating on remote filesystems
• Executing commands on remote hosts
• Managing remote processes
• Convention: prefix command name with Remote (e.g., RemoteGetInfoCommand)

E. Terminal Block Implementation

Implement in frontend/app/view/term/term-wsh.tsx:

async handle_yournew(rh: RpcResponseHelper, data: CommandYourNewData): Promise<YourNewResponse> {
    // Access terminal-specific data
    const termWrap = this.model.termRef.current;
    
    // Implement terminal logic
    const result = termWrap.doSomething(data);
    
    return {
        resultfield: result,
        success: true,
    };
}

Use terminal client when:

• Accessing terminal buffer/scrollback
• Managing VDOM contexts
• Reading terminal-specific state
• Interacting with xterm.js

Complete Example: Adding GetPenguInfo Command

1. Define Interface

In pkg/wshrpc/wshrpctypes.go:

type WshRpcInterface interface {
    // ... other commands ...
    PenguInfoCommand(ctx context.Context) (*PenguInfoData, error)
}

type PenguInfoData struct {
    Version      string            `json:"version"`
    BuildTime    string            `json:"buildtime"`
    ConfigPath   string            `json:"configpath"`
    DataPath     string            `json:"datapath"`
}

2. Generate Bindings

task generate

3. Implement in Main Server

In pkg/wshrpc/wshserver/wshserver.go:

func (ws *WshServer) PenguInfoCommand(ctx context.Context) (*wshrpc.PenguInfoData, error) {
    return &wshrpc.PenguInfoData{
        Version:    wavebase.PenguVersion,
        BuildTime:  wavebase.BuildTime,
        ConfigPath: wavebase.GetConfigDir(),
        DataPath:   wavebase.GetPenguDataDir(),
    }, nil
}

4. Call from Frontend

import { RpcApi } from "@/app/store/wshclientapi";

// Call the RPC
const info = await RpcApi.PenguInfoCommand(TabRpcClient);
console.log("Pengu Version:", info.version);

Streaming Commands

For commands that return data progressively, use channels:

Define Streaming Interface

type WshRpcInterface interface {
    StreamYourDataCommand(ctx context.Context, request YourDataRequest) chan RespOrErrorUnion[YourDataType]
}

Implement Streaming Command

func (ws *WshServer) StreamYourDataCommand(ctx context.Context, request wshrpc.YourDataRequest) chan wshrpc.RespOrErrorUnion[wshrpc.YourDataType] {
    rtn := make(chan wshrpc.RespOrErrorUnion[wshrpc.YourDataType])
    
    go func() {
        defer close(rtn)
        defer func() {
            panichandler.PanicHandler("StreamYourDataCommand", recover())
        }()
        
        // Stream data
        for i := 0; i < 10; i++ {
            select {
            case <-ctx.Done():
                return
            default:
                rtn <- wshrpc.RespOrErrorUnion[wshrpc.YourDataType]{
                    Response: wshrpc.YourDataType{
                        Value: i,
                    },
                }
                time.Sleep(100 * time.Millisecond)
            }
        }
    }()
    
    return rtn
}

Best Practices

1. Validation First: Always validate input parameters at the start of your implementation

2. Descriptive Names: Use clear, action-oriented command names (e.g., GetFullConfigCommand, not ConfigCommand)

3. Error Handling: Return descriptive errors with context:

   return nil, fmt.Errorf("error creating block: %w", err)
   

4. Context Awareness: Respect context cancellation for long-running operations:

   select {
   case <-ctx.Done():
       return ctx.Err()
   default:
       // continue
   }
   

5. Consistent Types: Follow existing naming patterns for request/response types

6. JSON Tags: Always use lowercase JSON tags matching frontend conventions

7. Documentation: Add comments explaining complex commands or special behaviors

8. Type Safety: Leverage TypeScript generation - your types will be checked on both ends

9. Panic Recovery: Use panichandler.PanicHandler in goroutines to prevent crashes

10. Route Awareness: For multi-route scenarios, use wshutil.GetRpcSourceFromContext(ctx) to identify callers

Common Command Patterns

Simple Query

func (ws *WshServer) GetSomethingCommand(ctx context.Context, id string) (*Something, error) {
    obj, err := wstore.DBGet[*Something](ctx, id)
    if err != nil {
        return nil, fmt.Errorf("error getting something: %w", err)
    }
    return obj, nil
}

Mutation with Updates

func (ws *WshServer) UpdateSomethingCommand(ctx context.Context, data wshrpc.CommandUpdateData) error {
    ctx = waveobj.ContextWithUpdates(ctx)
    
    // Make changes
    err := wstore.UpdateObject(ctx, data.ORef, data.Updates)
    if err != nil {
        return fmt.Errorf("error updating: %w", err)
    }
    
    // Broadcast updates
    updates := waveobj.ContextGetUpdatesRtn(ctx)
    wps.Broker.SendUpdateEvents(updates)
    
    return nil
}

Command with Side Effects

func (ws *WshServer) DoActionCommand(ctx context.Context, data wshrpc.CommandActionData) error {
    // Perform action
    result, err := performAction(data)
    if err != nil {
        return err
    }
    
    // Publish event about the action
    go func() {
        wps.Broker.Publish(wps.PenguEvent{
            Event: wps.Event_ActionComplete,
            Data:  result,
        })
    }()
    
    return nil
}

Troubleshooting

Command Not Found

• Ensure method name ends with Command
• Verify you ran task generate
• Check that the interface is in WshRpcInterface

Type Mismatch Errors

• Run task generate after changing types
• Ensure JSON tags are lowercase
• Verify TypeScript code is using generated types

Command Times Out

• Check for blocking operations
• Ensure context is passed through
• Consider using a streaming command for long operations

Routing Issues

• For remote commands, ensure they're implemented in correct location
• Check route configuration in RpcContext
• Verify authentication for secured routes

Quick Reference

When adding a new RPC command:

• Add method to WshRpcInterface in pkg/wshrpc/wshrpctypes.go (must end with Command)
• Define request/response types with JSON tags (if needed)
• Run task generate to create bindings
• Implement in appropriate location:
  • wshserver.go for main server (most common)
  • emain-wsh.ts for Electron
  • tabrpcclient.ts for frontend
  • wshremote.go for remote (prefix with Remote)
  • term-wsh.tsx for terminal
• Add input validation
• Handle errors with context
• Test the command end-to-end

Related Documentation

• WPS Events: See the wps-events skill - Publishing events from RPC commands