Upgrade TypeScript from 5.1.3 to 5.9.2

[Copilot]

This PR upgrades the project's TypeScript version from 5.1.3 to 5.9.2, bringing performance improvements and modern language features to the codebase.

Changes Made

Core Upgrade

• TypeScript: Updated from ^5.1.3 to ^5.9.2 in package.json
• Microsoft ESLint Config: Updated from 0.2.1 to 0.2.4 for better compatibility

TypeScript Configuration Updates

• Compilation Target: Updated from "es6" to "es2018" to support modern JavaScript features including regex flags used in gulpfile
• Library Checking: Enabled "skipLibCheck": true to handle type definition incompatibilities in external libraries that haven't been updated for TypeScript 5.9 yet

Code Compatibility Fixes

Fixed Buffer/Uint8Array type compatibility issues in src/commands/tags/TagFileSystem.ts that arose due to stricter type checking in TypeScript 5.9:

Before:

public async readFileImpl(_context: IActionContext, node: ITagsModel): Promise<Uint8Array> {
    const fileContent: string = this.getFileContentFromTags(await this.getTagsFromNode(node));
    return Buffer.from(fileContent); // TypeScript 5.9 error: Buffer not assignable to Uint8Array
}

const buf = Buffer.from(content, 0) // TypeScript 5.9 error: invalid overload

After:

public async readFileImpl(_context: IActionContext, node: ITagsModel): Promise<Uint8Array> {
    const fileContent: string = this.getFileContentFromTags(await this.getTagsFromNode(node));
    return new Uint8Array(Buffer.from(fileContent)); // Explicit conversion
}

const buf = Buffer.from(content.buffer, content.byteOffset, content.byteLength); // Proper buffer creation

Verification

All builds and workflows continue to function correctly:

• ✅ TypeScript compilation (npm run build)
• ✅ Webpack development build (npm run webpack)
• ✅ Webpack production build (npm run webpack-prod)
• ✅ ESLint linting (shows version support warnings but functions correctly)

Notes

ESLint displays warnings about TypeScript 5.9 not being officially supported by the current @typescript-eslint version, but linting continues to work correctly. The Microsoft ESLint configuration currently constrains the TypeScript ESLint plugin to v5.x, which is sufficient for this upgrade.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• update.code.visualstudio.com
  • Triggering command: node ./out/test/runTest.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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