feat(tools): support middlware in dotprompt export

[MichaelDoyle]

Added support for middleware in the createPrompt endpoint for dev-ui (i.e. prompt export).

Made some clean-up/improvements to YAML rendering.

• Filtering empty objects/arrays
• Fixed various formatting and encoding issues
• Better UX around unsupported message/part types

I think this strikes the right balance. Nota bene, Dev UI can always choose to omit these types (and does in some scenarios).

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[gemini-code-assist]

Code Review

This pull request introduces support for a use field in prompt frontmatter and API requests to handle middleware references. It also includes a new cleanupFrontmatter utility to remove empty or null values from the generated YAML and refactors message part stringification for better maintainability. Feedback was provided to correct the schema type for the use field in CreatePromptRequestSchema, suggesting the use of MiddlewareRefSchema instead of ModelReferenceSchema to maintain consistency across the API.

[MichaelDoyle]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces support for middleware in prompt frontmatter and enhances the rendering of messages in Dotprompt templates. Key changes include adding a "use" field to the prompt schemas and refactoring the "fromMessages" utility to gracefully handle unsupported message parts, such as tool requests and responses, by omitting them with descriptive comments. Additionally, a new "cleanupFrontmatter" function ensures cleaner YAML output by removing empty or null values. I have no feedback to provide.

[MichaelDoyle]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces middleware support to prompt frontmatter and refactors the prompt rendering logic to handle unsupported message parts and clean up frontmatter metadata. The reviewer suggested improving the consistency of the anyOmitted flag to account for partially omitted messages and recommended using more idiomatic TypeScript patterns, such as the in operator for property checks and Object.keys() for object iteration.

[ssbushi]

LGTM. +1 to gemini-code-review comments.