Adding Generative AI Features to DartPad

[csells]

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

This PR adds the following generative AI features to DartPad:

• Suggest Fix button added to the console to suggest a fix for a run-time error using the Gemini LLM

• Suggest Fix button added to each error to suggest a fix for a compile-time using the Gemini LLM

  • Quick Fixes button to show the analysis-provided quick fixes for each error (not AI, but matches the AI-related feature)

• Gemini | Generate Code menu item that provides a Prompt dialog containing the following features:

  • set of suggested prompts
  • a retrieval mechanism for the user's last prompt that's remembered between sessions
  • a per-prompt preference for whether to generate Dart or Flutter code, remembered between sessions
  • multi-line text box to gather the user's text prompt
  • support for up to 3 image attachments to send along with the user's text prompt
  • Cancel, Accept and Accept & Run buttons
  • Cmd+Enter (on the mac)/Control+Enter (not on a mac) keyboard shortcuts to invoke the Accept & Run button
  • invoking an Accept button will show the Generating Code dialog with the following features:
    • show syntax colorized code as its generated by the LLM
    • Cancel, Accept and Accept & Run buttons
    • Cmd+Enter (mac)/Control+Enter (not mac) keyboard shortcuts to invoke the Accept & Run button

• Gemini | Update Code menu item that provides a Prompt dialog with the following differences:

  • the user's last prompt is specific to whether they're creating new code or updating existing code
  • the user's last chosen app type (Dart or Flutter) is specific to whether they're creating or updating code
  • the subsequent Generating Code dialog for updates has the following differences:
    • shows diff output as the LLM generates the code so the user can see the changes before accepting them

[github-actions]

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License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/samples/lib/brick_breaker.dart
pkgs/samples/lib/fibonacci.dart
pkgs/samples/lib/google_ai.dart
pkgs/samples/lib/hello_world.dart
pkgs/samples/lib/main.dart
pkgs/samples/lib/sunflower.dart

[csells]

I created a commit to add the license header to the three files mentioned and pushed it to my branch on github; I'm not sure why it's not showing up in the list of commits above.

[johnpryan]

I'm noticing that the editor isn't cleaning up parts of the response properly - it's showing the PRD in the code window:

[csells]

I'm noticing that the editor isn't cleaning up parts of the response properly - it's showing the PRD in the code window:

Thanks, @johnpryan. I haven't seen that behavior in a month of testing. It works on my machine. : )

Can you let me know what you were doing so that I can repro?

[johnpryan]

I ran this branch locally and clicked on one of the suggested prompts

[csells]

@johnpryan have you changed anything? I can't get that to repro on my box.

[johnpryan]

Weird, I see it happen about 80% of the time. Let me know if you need any more details