improvement(subblock-defaults): custom defaults for subblocks if needed

[icecrasher321]

Summary

Right now, we always set subblock values to null which isn't always appropriate. We need to be able to custom defaults for subblocks. Added this as a field into subblock configs.

Type of Change

• Bug fix

Testing

Manually. Used for temperature and tools in the Agent block right now.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
sim	Ready	Preview	Comment	Sep 10, 2025 0:10am

1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
docs	Skipped			Sep 10, 2025 0:10am

[greptile-apps]

Greptile Summary

This PR introduces support for custom default values in sub-blocks instead of always initializing them to null. The change adds a defaultValue field to the SubBlockConfig interface in the type definitions, allowing block configurations to specify appropriate initial values for their sub-blocks.

The implementation modifies the collaborative workflow hook to use these custom defaults via the nullish coalescing operator (subBlock.defaultValue ?? null), maintaining backward compatibility while enabling blocks to define sensible starting values. The Agent block configuration has been updated to demonstrate this functionality with temperature sliders defaulting to 0.5 and 1.0 respectively, and the tools array defaulting to an empty array.

This change addresses a user experience issue where certain field types like sliders and arrays were poorly served by null defaults. Temperature sliders need numeric values for proper rendering, and tool arrays function better with empty arrays than null values. The enhancement fits well within the existing block-driven architecture, allowing configurations to be more self-contained and user-friendly by reducing manual setup requirements.

Confidence score: 4/5

• This PR is generally safe to merge with only minor considerations needed around comprehensive testing
• Score reflects solid implementation with good backward compatibility, but lacks automated tests for the new functionality
• Pay close attention to the collaborative workflow hook to ensure the defaultValue logic works correctly across all block types

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[greptile-apps]

logic: Missing implementation: This field is defined but not used during block initialization. In addBlock() method of WorkflowStore, subblocks are still initialized with value: null regardless of defaultValue