Disallow unsafe type assertions

[gundermanc]

Summary

Disallow unsafe type assertions (casting one type to another). This is a practice that is widespread throughout the codebase. It is one of one of the contributing factors behind #18621, which caused a significant disruption to users of Gemini CLI that log in with a Google account.

This change just enables the rule and blanket-suppresses the existing errors to avoid introducing any new ones.

I will follow up with the actual bug fix.

Changes that run into this error should replace their unsafe type assertion (use of 'as') with safer type assertions, either through the use of 'instanceof', 'typeof', 'Zod', or via user-defined type guards

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

Summary of Changes

Hello @gundermanc, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the codebase's type safety by enabling a new ESLint rule that prohibits unsafe type assertions. This strategic move aims to prevent a category of runtime errors that have historically caused user-facing issues. While the rule is now active, existing violations are temporarily suppressed, setting the stage for a systematic refactoring effort to adopt more robust type-checking mechanisms in subsequent development cycles.

Highlights

• Enabled new ESLint rule: The @typescript-eslint/no-unsafe-type-assertion rule has been enabled across the codebase to disallow unsafe type casting using the as keyword. This rule is applied to all product code files (packages/*/src/**/*.{ts,tsx}), excluding test files.
• Blanket suppression of existing errors: To facilitate a phased migration and avoid immediate build failures, all existing instances of unsafe type assertions have been suppressed with // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion comments. This allows the rule to be active without requiring immediate refactoring of all existing code.
• Improved code robustness and safety: This change is a proactive step to enhance code quality and prevent potential runtime errors that can arise from unchecked type assertions, addressing a class of issues that previously led to disruptions for users.
• Future refactoring required: The current suppressions are temporary. Future work will involve replacing these unsafe type assertions with safer alternatives such as instanceof, typeof, or user-defined type guards, as outlined in the PR description.

Changelog

• eslint.config.js
  • Added a new configuration block to enable the @typescript-eslint/no-unsafe-type-assertion rule as an error for all TypeScript and TSX files within packages/*/src/ directories, excluding test files.
• packages/a2a-server//*.ts**
  • Added // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion comments to numerous existing type assertions to suppress the newly enabled ESLint rule.
• packages/cli//*.ts**
  • Added // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion comments to numerous existing type assertions to suppress the newly enabled ESLint rule.
• packages/core//*.ts**
  • Added // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion comments to numerous existing type assertions to suppress the newly enabled ESLint rule. In some cases, existing eslint-disable-next-line comments were updated to include the new rule.
• packages/vscode-ide-companion//*.ts**
  • Added // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion comments to numerous existing type assertions to suppress the newly enabled ESLint rule.

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[gemini-code-assist]

Code Review

This pull request is a great step towards improving type safety by enabling the no-unsafe-type-assertion ESLint rule. While the primary goal is to suppress existing violations to unblock further work, I've identified a few instances where a direct fix is not only possible but also addresses potential bugs. My review focuses on these critical areas to enhance the immediate impact of this change.

[gemini-code-assist]

This type assertion is critically unsafe. Casting an empty object {} to AgentSettings creates an object that does not conform to the interface, as it will be missing required properties like kind and workspacePath. While the current implementation might handle this gracefully due to checks in setTargetDir, it creates a fragile contract and can lead to runtime errors if getConfig or its dependencies ever rely on other properties of AgentSettings.

Instead of suppressing this error, it's better to refactor getConfig to accept a Partial<AgentSettings> and handle the optional properties safely. This would make the contract explicit and prevent future bugs.

[gemini-code-assist]

This type assertion is incorrect and will cause a runtime error. The on event emitter in Node.js yields an array of arguments, not a single argument. Therefore, msg is an array (e.g., [ToolConfirmationResponse]), and you should be accessing the first element msg[0].

Suggested change

	const response = msg as ToolConfirmationResponse;
	const response = msg[0] as ToolConfirmationResponse;

[gemini-code-assist]

This function uses two unsafe type assertions. It can be refactored to be fully type-safe by correctly typing the return object from the start.

  >(from: T, ...fields: K[]): Partial<T> {
    const ret: Partial<T> = {};
    for (const field of fields) {
      if (field in from) {
        ret[field] = from[field];
      }
    }
    return ret;
  }

[github-actions]

Size Change: +15.9 kB (+0.07%)

Total Size: 23.9 MB

Filename	Size	Change
./bundle/gemini.js	23.9 MB	+15.9 kB (+0.07%)

ℹ️ View Unchanged

Filename	Size
./bundle/sandbox-macos-permissive-closed.sb	1.03 kB
./bundle/sandbox-macos-permissive-open.sb	890 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB
./bundle/sandbox-macos-restrictive-closed.sb	3.29 kB
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB

_{compressed-size-action}