chore: form extension rework

[tomkis]

fixes #1472

[tomkis]

@dosu what are the affected docs in docs folder?

[dosubot]

Hi @tomkis! I'm Dosu and I’m helping the agentstack team.

The affected docs in the docs folder are:

• docs/build-agents/forms.mdx (new, comprehensive guide to the form extension: quickstart, usage, field types, layout)
• docs/build-agents/hello-world.mdx (modified, now references the new forms doc)
• docs/docs.json (modified, likely to register the new forms doc)

All these changes were made in PR #1137. No other docs in the folder were changed by the form extension rework.

To reply, just mention @dosu.

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[tomkis]

@jenna-winkler this is a breaking change for the 0.4.X users, we'll bump up the version to 0.5.0.

We should provide migration guide that can be prepared from the diff in documentation in this PR.

[tomkis]

We should probably refactor this and use the extension client and parse as service extension cc @jezekra1

[tomkis]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant and well-executed rework of the form extension, splitting it into a service extension for initial forms and a UI extension for dynamic form requests. This refactoring improves modularity and clarifies the distinction between different form use cases. The changes are consistently applied across the Python SDK, TypeScript SDK, CLI, and UI applications, and the documentation has been updated accordingly. I've identified a couple of issues: a potential KeyError and a typo in the Python SDK, and a state mutation bug in the React UI. Once these are addressed, this will be a solid improvement to the codebase.

[tomkis]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant and well-executed refactoring of the form extensions. The original FormExtension is split into FormServiceExtension for initial, agent-demanded forms, and RequestFormExtension for dynamic, UI-requested forms. This separation greatly improves clarity and the developer experience. The changes are consistently applied across the Python SDK, TypeScript SDK, CLI, UI components, and documentation. The new APIs are more intuitive, especially with the improved model-based form parsing. Overall, this is an excellent improvement. I have a couple of minor suggestions to clean up a small piece of potentially confusing code in the UI context providers.

[tomkis]

/gemini review

[gemini-code-assist]

Code Review

This pull request is a significant and well-executed refactoring of the form extensions, separating initial form services from dynamic UI form requests. The changes are consistent across the Python SDK, TypeScript SDK, CLI, and documentation, leading to a much clearer and more robust API. I've found one high-severity issue in the UI implementation where incorrect metadata could be sent for initial form submissions, and I've provided a fix. Once that's addressed, this will be an excellent improvement.