var awslambda declaration conflicts with @types/aws-lambda namespace declaration (TS2300)

[rubenfonseca]

Description

When using @aws/lambda-invoke-store alongside @types/aws-lambda, TypeScript compilation fails with:

error TS2300: Duplicate identifier 'awslambda'.

Root Cause

@aws/lambda-invoke-store declares awslambda as a variable:

declare global {
    var awslambda: {
        InvokeStore?: InvokeStoreBase;
        [key: string]: unknown;
    };
}

@types/aws-lambda declares awslambda as a namespace:

declare global {
    namespace awslambda {
        class HttpResponseStream extends Writable { ... }
    }
}

TypeScript does not allow both a var and namespace with the same identifier.

Reproduction

1. Create a project with both dependencies:

   {
     "dependencies": {
       "@aws-lambda-powertools/batch": "^2.29.0",
       "@types/aws-lambda": "8.10.159"
     }
   }

2. Run tsc - you will see the duplicate identifier error.

Proposed Solution

Change the global declaration from var to namespace to allow TypeScript declaration merging (as proposed in PR #18).

Current Workaround

Set skipLibCheck: true in tsconfig.json.

Environment

• @aws/lambda-invoke-store: 0.2.1
• @types/aws-lambda: 8.10.159
• TypeScript: 5.9.3

[dil-atelegdi]

I've experienced the very same issue.