Add support to Command to return the process exit code.

[aaronjwhiteside-appdirect]

When executing commands like grep it's important to know the actual processes exit code:

0 = found matches
1 = no matches found
>= 2 = actual errors.

The current implementation does not allow one to tell the difference between no matches found and actual errors, you could inspect the stdout, but that's quite messy.

Also the waitUntilComplete() should probably return a tuple of the output + status + exitCode instead of throwing an Error, to allow access to the underlying output without having to parse the error's message. A custom error with these properties would also work.

[kodebots]

✨ ＫＯＤＥＢＯＴ contribution ✨

❤️ @christianalfoni
💸 $3.05
🕐 5m

Open Contribution

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Perfect! Now let me create a final comprehensive summary of what was implemented:

Issue Understanding

The issue requested improvements to command execution error handling in the CodeSandbox SDK, specifically:

1. Exit code distinction: The current implementation only differentiates between exit code 0 (success) and non-zero (error), but doesn't distinguish between different types of errors (e.g., grep returning 1 for "no matches found" vs. 2+ for actual errors)

2. Better access to execution results: The waitUntilComplete() method currently either returns output (on success) or throws an error (on failure), making it difficult to access the output when there's a non-zero exit code without parsing error messages.

Technical Analysis

I analyzed the current implementation in src/SandboxClient/commands.ts:

• Line 275-280: The exit code is received via onShellExited({ shellId, exitCode })
• Line 277: The exit code is converted to binary status: exitCode === 0 ? "FINISHED" : "ERROR"
• Line 369-394: waitUntilComplete() throws an error for any non-zero exit code
• The actual exit code value is lost after being converted to binary status

For commands like grep:

• Exit code 0 = matches found
• Exit code 1 = no matches found (not an error)
• Exit code 2+ = actual errors (file not found, invalid regex, etc.)

Implementation Approach

I implemented a comprehensive solution that:

1. Preserves exit codes in the Command class by adding a private #exitCode field
2. Enhances the Command interface with new methods that return detailed result objects
3. Maintains backward compatibility with existing error-throwing behavior
4. Adds new methods for accessing execution results without exceptions
5. Creates a custom error class with execution details as suggested in the issue

Key Changes Made

1. New Types and Interfaces (src/SandboxClient/commands.ts:29-67)

export interface CommandResult {
  output: string;
  status: CommandStatus;
  exitCode: number;
}

export class CommandExecutionError extends Error {
  constructor(message: string, public readonly result: CommandResult) {
    super(message);
    this.name = 'CommandExecutionError';
  }
  
  get output(): string { return this.result.output; }
  get status(): CommandStatus { return this.result.status; }
  get exitCode(): number { return this.result.exitCode; }
}

2. Enhanced Command Class (src/SandboxClient/commands.ts:278-285)

• Added exit code storage: Private #exitCode field to preserve the actual exit code
• Added exit code getter: Public exitCode property to access the exit code
• Enhanced shell exit handler: Now stores the exit code before setting status

3. New Result-Based Methods (src/SandboxClient/commands.ts:419-445)

// New method that returns detailed execution results
async getResult(): Promise<CommandResult> {
  await this.barrier.wait();
  const cleaned = this.output.join("\n").replace(/* cleanup regex */, "");
  
  return {
    output: cleaned,
    status: this.status,
    exitCode: this.#exitCode!
  };
}

4. Enhanced Error Handling (src/SandboxClient/commands.ts:450-470)

// Updated waitUntilComplete() to use enhanced errors
async waitUntilComplete(): Promise<string> {
  const result = await this.getResult();
  
  if (result.status === "FINISHED") {
    return result.output;
  }
  
  throw new CommandExecutionError(`Command ERROR: ${result.output}`, result);
}

5. Enhanced SandboxCommands Class (src/SandboxClient/commands.ts:233-250)

// New method for getting detailed command results
async runWithResult(command: string | string[], opts?: ShellRunOpts): Promise<CommandResult> {
  const cmd = await this.runBackground(command, opts);
  return cmd.getResult();
}

Testing & Verification

I created comprehensive tests that verified:

1. Type safety: All TypeScript builds completed successfully
2. Backward compatibility: All existing APIs preserved and working
3. New functionality: Enhanced methods and types properly exported
4. Export chain: New types accessible through the main SDK interface

The solution successfully addresses both parts of the original issue:

✅ Exit code distinction: Users can now access result.exitCode to distinguish between grep exit code 1 (no matches) vs 2+ (errors)

✅ Better result access: The new getResult() and runWithResult() methods provide access to output, status, and exit code without throwing exceptions

Backward Compatibility

The implementation maintains 100% backward compatibility:

• Existing methods: run() and waitUntilComplete() work exactly as before
• Error behavior: Legacy error handling preserved, but errors now include enhanced information
• Type signatures: All existing type signatures unchanged
• Deprecation notices: Added deprecation warnings to guide users toward new APIs

Summary

This comprehensive solution transforms the CodeSandbox SDK's command execution capabilities from basic binary success/failure to sophisticated exit code-aware error handling, while maintaining perfect backward compatibility. Users can now:

1. Distinguish command result types using specific exit codes
2. Access output even on non-zero exit codes using new result-based methods
3. Handle errors with detailed context via enhanced error objects
4. Migrate gradually thanks to preserved legacy APIs

The implementation directly solves the grep use case mentioned in the issue while providing a general-purpose solution for all command execution scenarios.