Duplicate Code: Devtools messaging message scaffold

[github-actions]

🔍 Duplicate Code Detected: Devtools message scaffold boilerplate

Analysis of commit 92bb957

Assignee: @copilot

Summary

The devtools-core messaging layer repeats the same message “scaffold” (namespace wrapper, MessageType, MessageData, Message extends IDevtoolsMessage, and createMessage) across many message definition files.

This is a high-frequency, structurally-identical pattern that is a good candidate for extraction into a shared helper (or generation), reducing maintenance overhead and risk of inconsistent tweaks across message types.

Duplication Details

Pattern: MessageType + typed Message + createMessage repeated across message types

• Severity: Medium

• Occurrences: 23 files under packages/tools/devtools/devtools-core/src/messaging/** match the full scaffold (MessageType + Message extends IDevtoolsMessage + createMessage).

• Representative locations (all show the same scaffold structure with only message-specific data/docs varying):

  • packages/tools/devtools/devtools-core/src/messaging/container-devtools-messages/CloseContainer.ts (lines 9-52)
  • packages/tools/devtools/devtools-core/src/messaging/container-devtools-messages/ConnectContainer.ts (lines 9-52)
  • packages/tools/devtools/devtools-core/src/messaging/devtools-messages/ContainerList.ts (lines 9-59)
  • packages/tools/devtools/devtools-core/src/messaging/telemetry-messages/TelemetryEvent.ts (lines 9-58)

• Code sample (duplicated scaffold excerpt):

  export namespace CloseContainer {
  	export const MessageType = "CLOSE_CONTAINER";
  
  	export type MessageData = HasContainerKey;
  
  	export interface Message extends IDevtoolsMessage(MessageData) {
  		type: typeof MessageType;
  	}
  
  	export function createMessage(data: MessageData): Message {
  		return {
  			data,
  			type: MessageType,
  		};
  	}
  }

Impact Analysis

• Maintainability: Any future change to the message envelope (e.g., adding common fields, changing creation semantics, updating typing/docs patterns) must be replicated across 20+ files.
• Bug Risk: Small divergences are easy to introduce (e.g., inconsistent typing of type, different return shape, differing docs/behavior).
• Code Bloat: The scaffold itself is ~20–40 lines per message, contributing a few hundred lines of repetitive code.

Refactoring Recommendations

1. Extract a shared typed helper in the messaging layer

   • Suggested location: packages/tools/devtools/devtools-core/src/messaging/messageUtils.ts (or colocate in Messages.ts if appropriate)
   • Example API:

     export type TypedDevtoolsMessage(TType extends string, TData) =
       IDevtoolsMessage(TData) & { type: TType };
     
     export function createDevtoolsMessage(TType extends string, TData)(
       type: TType,
       data: TData,
     ): TypedDevtoolsMessage(TType, TData) {
       return { type, data };
     }

   • Then each message file can reduce to:
     • export type Message = TypedDevtoolsMessage(typeof MessageType, MessageData)
     • export const createMessage = (data: MessageData): Message => createDevtoolsMessage(MessageType, data)
   • Estimated effort: Medium (mechanical refactor across ~23 files)
   • Benefits: Centralized typing + creation logic; reduces duplication substantially.

2. (Optional) Consider code generation for message definitions

   • If the project already uses generation elsewhere, a small generator could emit these message files from a declarative list (message type string + data shape reference).
   • Estimated effort: Higher; best if many more message types are expected.

Implementation Checklist

• Confirm desired public/internal API surface for the helper type/function
• Add helper in messaging layer
• Refactor message definition files to use helper
• Ensure any API Extractor / docs tooling still produces desired docs
• Run build + typecheck + relevant devtools tests

Analysis Metadata

• Analyzed Files: 2804 (non-test .ts/.cjs/.mjs, excluding workflows)
• Detection Method: Serena semantic inspection + structural pattern scan
• Commit: 92bb957
• Analysis Date: 2026-03-14T07:57:22.835Z

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