Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/code-yeongyu/oh-my-opencode/llms.txt

Use this file to discover all available pages before exploring further.

Oh My OpenCode is an OpenCode plugin that extends the base editor with agents, hooks, tools, and orchestration capabilities. This guide covers the plugin interface and extension points.

​
Plugin Architecture

The plugin follows a four-phase initialization: 
// src/index.ts
const OhMyOpenCodePlugin: Plugin = async (ctx) => {
  // Phase 1: Load configuration
  const pluginConfig = loadPluginConfig(ctx.directory, ctx)

  // Phase 2: Create managers
  const managers = createManagers({
    ctx,
    pluginConfig,
    tmuxConfig,
    modelCacheState
  })

  // Phase 3: Create tools
  const toolsResult = await createTools({
    ctx,
    pluginConfig,
    managers
  })

  // Phase 4: Create hooks
  const hooks = createHooks({
    ctx,
    pluginConfig,
    modelCacheState,
    backgroundManager: managers.backgroundManager,
    isHookEnabled,
    safeHookEnabled,
    mergedSkills: toolsResult.mergedSkills,
    availableSkills: toolsResult.availableSkills
  })

  // Phase 5: Assemble plugin interface
  return createPluginInterface({
    ctx,
    pluginConfig,
    managers,
    hooks,
    tools: toolsResult.filteredTools
  })
}

export default OhMyOpenCodePlugin
Source: src/index.ts:16

​
PluginContext

The OpenCode plugin context provides core APIs: 
interface PluginContext {
  directory: string                    // Working directory
  client: PluginClient                 // API client
  logger: Logger                       // Plugin logger
}

interface PluginClient {
  session: SessionAPI                  // Session management
  tui: TuiAPI                          // UI notifications/toasts
  provider: ProviderAPI                // Model provider access
}
Source: src/plugin/types.ts

​
Plugin Interface

The plugin interface defines 8 OpenCode hook handlers: 
interface PluginInterface {
  config: ConfigHandler                                    // 6-phase config pipeline
  tool: ToolsRecord                                        // 26 tools
  "chat.message": ChatMessageHandler                      // First-message variant, setup
  "chat.params": ChatParamsHandler                        // Model params adjustment
  event: EventHandler                                      // Session lifecycle
  "tool.execute.before": ToolExecuteBeforeHandler         // Pre-tool guards
  "tool.execute.after": ToolExecuteAfterHandler           // Post-tool modifications
  "experimental.chat.messages.transform": TransformHandler // Message transformation
  "experimental.session.compacting"?: CompactionHandler    // Context compaction
}
Source: src/plugin/types.ts

​
Creating Custom Tools

Tools follow the factory pattern createXXXTool() → ToolDefinition.
1
Define Tool Types
2
Create src/tools/my-tool/types.ts:
3
import { z } from "zod"

export const MyToolArgsSchema = z.object({
  input: z.string().describe("Input to process"),
  options: z.object({
    verbose: z.boolean().optional().describe("Verbose output")
  }).optional()
})

export type MyToolArgs = z.infer<typeof MyToolArgsSchema>
4
Implement Tool Logic
5
Create src/tools/my-tool/tools.ts:
6
import type { ToolDefinition } from "@opencode-ai/plugin"
import type { PluginContext } from "../../plugin/types"
import { MyToolArgsSchema, type MyToolArgs } from "./types"
import { log } from "../../shared"

export function createMyTool(ctx: PluginContext): ToolDefinition {
  return {
    name: "my_tool",
    description: "Process input and return result",
    input_schema: MyToolArgsSchema,
    execute: async (args: MyToolArgs) => {
      log("my_tool: executing", { input: args.input })

      try {
        const result = await processInput(args.input, args.options)
        return {
          content: result,
          metadata: {
            timestamp: new Date().toISOString(),
            verbose: args.options?.verbose ?? false
          }
        }
      } catch (error) {
        return {
          error: `Tool execution failed: ${error.message}`,
          isError: true
        }
      }
    }
  }
}

async function processInput(
  input: string,
  options?: { verbose?: boolean }
): Promise<string> {
  // Implementation
  return `Processed: ${input}`
}
7
Export Tool
8
Create src/tools/my-tool/index.ts:
9
export { createMyTool } from "./tools"
export type * from "./types"
10
Register in Tool Registry
11
Add to src/plugin/tool-registry.ts:
12
import { createMyTool } from "../tools/my-tool"

export function createToolRegistry(args: {
  ctx: PluginContext
  pluginConfig: OhMyOpenCodeConfig
  managers: Managers
  skillContext: SkillContext
  availableCategories: AvailableCategory[]
}): ToolRegistryResult {
  const { ctx, pluginConfig } = args

  const allTools: Record<string, ToolDefinition> = {
    // ... existing tools
    my_tool: createMyTool(ctx)
  }

  const filteredTools = filterDisabledTools(allTools, pluginConfig.disabled_tools)

  return { filteredTools, taskSystemEnabled }
}
Source: src/plugin/tool-registry.ts:41

​
Tool Registry Structure

The tool registry assembles tools from factories: 
const allTools: Record<string, ToolDefinition> = {
  // File operations (built-in from @opencode-ai/plugin)
  ...builtinTools,

  // Search tools
  ...createGrepTools(ctx),
  ...createGlobTools(ctx),
  ...createAstGrepTools(ctx),

  // Session management
  ...createSessionManagerTools(ctx),

  // Background tasks
  ...createBackgroundTools(managers.backgroundManager, ctx.client),

  // Delegation
  call_omo_agent: createCallOmoAgent(ctx, managers.backgroundManager, pluginConfig.disabled_agents),
  task: createDelegateTask({ manager: managers.backgroundManager, /* ... */ }),

  // Skills
  skill_mcp: createSkillMcpTool({ manager: managers.skillMcpManager, /* ... */ }),
  skill: createSkillTool({ commands, skills: mergedSkills, /* ... */ }),

  // System
  interactive_bash,
  look_at: createLookAt(ctx),

  // Task system (conditional)
  ...taskToolsRecord,

  // Editing (conditional)
  ...hashlineToolsRecord
}
Source: src/plugin/tool-registry.ts:121

​
Manager System

Managers handle stateful subsystems: 
export interface Managers {
  backgroundManager: BackgroundManager        // Background task orchestration
  tmuxSessionManager: TmuxSessionManager      // Terminal multiplexing
  skillMcpManager: SkillMcpManager            // Skill MCP lifecycle
  configHandler: ConfigHandler                // Dynamic config loading
}

export function createManagers(args: {
  ctx: PluginContext
  pluginConfig: OhMyOpenCodeConfig
  tmuxConfig: TmuxConfig
  modelCacheState: ModelCacheState
  backgroundNotificationHookEnabled: boolean
}): Managers {
  const backgroundManager = createBackgroundManager({
    client: args.ctx.client,
    directory: args.ctx.directory,
    maxConcurrentPerModel: args.pluginConfig.background?.max_concurrent_per_model ?? 5,
    notificationEnabled: args.backgroundNotificationHookEnabled
  })

  const tmuxSessionManager = createTmuxSessionManager({
    ctx: args.ctx,
    config: args.tmuxConfig,
    backgroundManager
  })

  const skillMcpManager = createSkillMcpManager({
    ctx: args.ctx
  })

  const configHandler = createConfigHandler({
    ctx: args.ctx,
    pluginConfig: args.pluginConfig,
    modelCacheState: args.modelCacheState
  })

  return {
    backgroundManager,
    tmuxSessionManager,
    skillMcpManager,
    configHandler
  }
}
Source: src/create-managers.ts

​
Config Handler

The config handler implements a 6-phase config pipeline: 
interface ConfigHandler {
  (phase: ConfigPhase): Promise<ConfigResult>
}

type ConfigPhase =
  | "provider"           // Model provider configuration
  | "plugin-components"  // Plugin metadata
  | "agents"             // Agent registry
  | "tools"              // Tool availability
  | "mcps"               // MCP server list
  | "commands"           // Slash command discovery
Implementation: 
export function createConfigHandler(args: {
  ctx: PluginContext
  pluginConfig: OhMyOpenCodeConfig
  modelCacheState: ModelCacheState
}): ConfigHandler {
  return async (phase: ConfigPhase) => {
    switch (phase) {
      case "provider":
        return handleProviderPhase(args)
      case "plugin-components":
        return handlePluginComponentsPhase(args)
      case "agents":
        return handleAgentsPhase(args)
      case "tools":
        return handleToolsPhase(args)
      case "mcps":
        return handleMcpsPhase(args)
      case "commands":
        return handleCommandsPhase(args)
      default:
        return { success: false, error: "Unknown phase" }
    }
  }
}
Source: Referenced in src/plugin-interface.ts

​
Hook System Integration

Hooks are composed and wired to the plugin interface: 
function createPluginInterface(args: {
  ctx: PluginContext
  pluginConfig: OhMyOpenCodeConfig
  managers: Managers
  hooks: CreatedHooks
  tools: ToolsRecord
}): PluginInterface {
  return {
    config: managers.configHandler,
    tool: args.tools,

    "chat.message": createChatMessageHandler(args),
    "chat.params": createChatParamsHandler(args),
    event: createEventHandler(args),
    "tool.execute.before": createToolExecuteBeforeHandler(args),
    "tool.execute.after": createToolExecuteAfterHandler(args),
    "experimental.chat.messages.transform": createTransformHandler(args),

    "experimental.session.compacting": async (input, output) => {
      await args.hooks.compactionTodoPreserver?.capture(input.sessionID)
      await args.hooks.claudeCodeHooks?.["experimental.session.compacting"]?.(input, output)
      if (args.hooks.compactionContextInjector) {
        output.context.push(args.hooks.compactionContextInjector(input.sessionID))
      }
    }
  }
}
Source: src/plugin-interface.ts and src/index.ts:76

​
Tool Execution Lifecycle

Tool execution flows through hooks: 
1. Agent requests tool
2. tool.execute.before hooks (guards, validation, injection)
3. Tool execution (createXXXTool().execute())
4. tool.execute.after hooks (truncation, validation, metadata)
5. Result returned to agent

​
Before Hook Pattern

"tool.execute.before": async (
  input: {
    toolName: string
    arguments: Record<string, unknown>
    sessionID: string
  },
  output: {
    proceed: boolean        // Set to false to block execution
    error?: string          // Error message if blocked
    modifiedArgs?: unknown  // Replace arguments
  }
) => {
  // Validation logic
  if (shouldBlock(input)) {
    output.proceed = false
    output.error = "Blocked due to validation failure"
  }
}

​
After Hook Pattern

"tool.execute.after": async (
  input: {
    toolName: string
    arguments: Record<string, unknown>
    result: unknown
    sessionID: string
  },
  output: {
    modifiedResult?: unknown  // Replace tool result
  }
) => {
  // Result transformation
  if (needsModification(input.result)) {
    output.modifiedResult = transform(input.result)
  }
}

​
Disabling Tools

Tools can be disabled via configuration: 
{
  "disabled_tools": ["my_tool", "another_tool"]
}
The filterDisabledTools() function removes disabled tools: 
import { filterDisabledTools } from "../shared/disabled-tools"

const filteredTools = filterDisabledTools(allTools, pluginConfig.disabled_tools)

​
Testing Tools

Test tool factories and execution: 
import { describe, test, expect } from "bun:test"
import { createMyTool } from "./tools"

describe("createMyTool", () => {
  const mockCtx: PluginContext = {
    directory: "/test",
    client: {} as PluginClient,
    logger: console
  }

  describe("#given valid input", () => {
    describe("#when execute is called", () => {
      test("#then returns processed result", async () => {
        const tool = createMyTool(mockCtx)
        const result = await tool.execute({ input: "test" })

        expect(result.content).toBe("Processed: test")
        expect(result.metadata.timestamp).toBeDefined()
      })
    })
  })

  describe("#given execution error", () => {
    test("#then returns error result", async () => {
      const tool = createMyTool(mockCtx)
      const result = await tool.execute({ input: "" })

      expect(result.isError).toBe(true)
      expect(result.error).toContain("failed")
    })
  })
})

​
Plugin State

Manage plugin-wide state: 
import { createModelCacheState } from "./plugin-state"

const modelCacheState = createModelCacheState()

// Store session model
modelCacheState.set(sessionID, {
  providerID: "anthropic",
  modelID: "claude-opus-4-6",
  variant: "extended"
})

// Retrieve session model
const cached = modelCacheState.get(sessionID)
Source: src/plugin-state.ts

​
Logging

Use the shared logger: 
import { log } from "./shared"

log("my-tool: processing input", {
  input: args.input,
  sessionID: ctx.sessionID
})
Output: Logs to /tmp/oh-my-opencode.log

​
Error Handling

Follow error handling conventions: 
try {
  const result = await riskyOperation()
  return { content: result }
} catch (error) {
  log("my-tool: operation failed", { error: error.message })
  return {
    error: `Operation failed: ${error.message}`,
    isError: true
  }
}
Anti-pattern: Never use empty catch blocks: 
// WRONG
try {
  await operation()
} catch (e) {}

// CORRECT
try {
  await operation()
} catch (error) {
  log("operation failed", { error })
  // Handle or rethrow
}

​
Plugin Build Pipeline

Build the plugin: 
bun run build
Output:
  • dist/index.js — ESM bundle
  • dist/index.d.ts — TypeScript declarations
  • dist/schema.json — Configuration schema
Build Configuration: tsconfig.json, bun.build.ts
  • Plugin Entry: src/index.ts
  • Plugin Interface: src/plugin-interface.ts
  • Tool Registry: src/plugin/tool-registry.ts
  • Manager Creation: src/create-managers.ts
  • Hook Composition: src/create-hooks.ts
  • Plugin Types: src/plugin/types.ts
  • Config Handler: src/plugin-handlers/

Build docs developers (and LLMs) love

Get started for freeTalk to us